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Quantification of the impacts of urbanization and land use on fish
communities in Valley Creek Watershed, Chester County, PA
A Thesis
Submitted to the Faculty
of
Drexel University
by
Luanne Yvonne Steffy
in partial fulfillment of the
requirements for the degree
of
Master of Science in Environmental Science
April 2003
DEDICATIONS
This thesis is dedicated to my parents, Herbert and Beverly Steffy, for their
encouragement and patience as I worked to complete my degree and this research. Thanks
to my dad, for first introducing me to science and getting me interested in enjoying the
beauty of nature. Thanks to my mom for always being my biggest fan in whatever I was
doing. I am blessed to have you both as parents and am so thankful for your love, prayers
and support in everything.
ACKNOWLEDGMENTS
This project could not have been completed without the combined efforts of many
dedicated and willing people to whom I owe a great deal of thanks.
First, I would like to thank Dr. Sue Kilham for not only providing me with the
opportunity to do this research but for guiding and encouraging me along the way. Thanks
for taking a chance on me with this project and for your patience as I learned about the
process of doing scientific research. I admire your dedication and your professionalism.
Thanks for all your help and effort in editing this manuscript.
I would also like to thank the other members of my committee, Dr. Claire Welty and
Dr. Bob Brulle for giving of their time and expertise to read and comment on this research.
Your insight has been invaluable in understanding the multi-disciplinary issues involved in
this type of research. Additionally, thanks to Dr. Aaron Packman, the fourth P.I. on this
project for his contributions to this work. I also need to say thank you to Dr. Jim Spotila for
showing me the ropes of electro-fishing, allowing me to use his field equipment and for his
help in learning to identify the Valley Creek fish species. Thanks to Jennifer Elwood, for
working with me and helping me obtain the various permits and licenses needed for this
kind of field research.
The extensive amount of field work required for this research was a sometimes
overwhelming endeavor and it absolutely could not have been done without the help of the
other graduate students on this project or the many other students who volunteered their
time. Thanks to Rob Ryan for his dedication and willingness to help collect samples with me
even in the dead of winter. Your scientific advice and answers to countless questions have
been very much appreciated. Thanks to Angela McGinty for her willingness to help in the
field and for being someone I could come to for whatever. Your constant encouragement
and moral support have kept me going and mean more to me than you know. Thanks to
Clay Emerson for his help with fish collection and more importantly with ArcView,
Photoshop and every other computer question I ever had. I also need to mention and thank a
lot of other people that helped with fieldwork, lab work and data collection along the way:
Christy Wojculewski, Jason Kopanic, Anika McKessey, Meshagae Hunte, Jaclyn Dispensa,
Jorge Matos, Eric Snee, Andrea Gingrich, Seth Sickle, John Hopkins, Martin Sotola, Lance
Kellam and Sebastian Interlandi.
I would clearly be remiss if I did not include a word of thanks to some other people
who had a great impact on getting me to this point. Thanks to Dr. John Cruzan of Geneva
College for opening my eyes to the beauty and possibility of ecological field research.
Taking your ecology class the first time I really knew what I wanted to do with the rest of
my life. Also, thanks to all the professors and staff at AuSable Institute of Environmental
Science-Great Lakes. The experiences and opportunities I was given there have proven to
be invaluable many times over.
Additional thanks, to Bryan Lambert of Valley Forge National Historic Park for
allowing us to work in the park and for his willingness to share previous data with me.
Thanks to the many people at the PA DEP, PA Fish and Boat Commission,Chester County
Health Department, and Cahill & Associates that were willing to provide me with past data
as well. Thanks again to Drs. Welty, Kilham, Brulle and Packman for having the vision of
this multi-disciplinary research. Last, but certainly not least, a big thank you to the National
Science Foundation for funding this entire project.
TABLE OF CONTENTS
LIST OF TABLES...................................................................................................... vii LIST OF FIGURES ................................................................................................... viii ABSTRACT ..................................................................................................................x 1. INTRODUCTION .....................................................................................................1 2. PREVIOUS RESEARCH..........................................................................................8 3. MATERIALS AND METHODS ............................................................................10 3.1 Fish community parameters.............................................................................11 3.2 Physical parameters .........................................................................................14 4. RESULTS................................................................................................................17 4.1 Species composition .......................................................................................17 4.2 Temperature effects ........................................................................................18 4.3 Brown trout distribution .................................................................................19 4.4 Percent impervious surface cover and fish diversity ......................................20 4.5 Jaccard similarity index ..................................................................................21 4.6 Adjacent station similarity..............................................................................23 4.7 Local vs. regional diversity.............................................................................24 4.8 Land use comparisons.....................................................................................25 4.9 Specific anthropogenic changes .....................................................................26 4.10 Stream flow and drought ................................................................................27 4.11 Influence of sedimentation .............................................................................29 4.12 Length and mass trends ..................................................................................31
4.13 Impact of stream order....................................................................................33 4.14 Physical factors...............................................................................................34 5. DISCUSSION..........................................................................................................35 6. CONCLUSIONS .....................................................................................................50 LIST OF REFERENCES.............................................................................................53 APPENDIX A: TABLES ............................................................................................58 APPENDIX B: FIGURES ..........................................................................................73
LIST OF TABLES 1. Locations and summary of sampling stations in Valley Creek watershed.......................................................................................58
2. Summary of water quality data by station in Valley Creek watershed.......................................................................................59
3. Species list of fish collected in Valley Creek watershed.........................60 4. Fish communities by station ....................................................................61 5. Fish communities by section of creek .....................................................62 6A. Summary of significant linear regression relationships between fish community parameters and physical watershed parameters for the entire Valley Creek watershed.................................................................63 6B. Summary of the significant linear relationships between fish community parameters and physical watershed parameters for Valley Creek branch...........................................................................................64 6C. Summary of the significant linear relationships between fish community parameters and physical watershed parameters for Little Valley Creek branch ...............................................................................65
7. Salmo trutta distributions in Valley Creek watershed............................66 8. Jaccard’s similarity index – year to year comparisons ...........................67
9. Jaccard’s similarity index – upstream adjacent station comparisons .....68
10. Stream flow summary for Valley Creek watershed, Summer 2001
and Summer 2002 ....................................................................................69
11A. Sediment grain size analysis for 5 stations in Valley Creek watershed ................................................................................................70
11B. Fine sediment composition for 5 stations in Valley Creek watershed ................................................................................................70
12. Comparison of water quality data for station 4 (LeBoutiller Rd),
Valley Creek watershed...........................................................................71
13. Summary of length and mass data for fish species, 2001 and 2002 ........72
LIST OF FIGURES
1. Location of Valley Creek watershed ........................................................73
2. Sampling stations, Valley Creek watershed .............................................74
3. Percent impervious area vs. species diversity, 2001 and 2002.................75
4A. Valley Creek fish distribution by station, summer 2001 .........................76
4B. Valley Creek fish distribution by station, summer 2002 .........................77 5A. Fish species composition for station 1.....................................................78
5B. Fish species composition for station 2 .....................................................79
5C. Fish species composition for station 3 .....................................................80 5D. Fish species composition for station 4.....................................................81
5E. Fish species composition for station 5 ....................................................82 5F. Fish species composition for station 6.....................................................83
5G. Fish species composition for station 7.....................................................84
5H. Fish species composition for station 8.....................................................85
5I. Fish species composition for station 9 .....................................................86 5J. Fish species composition for station 10 ...................................................87
5K. Fish species composition for station 11...................................................88
5L. Fish species composition for station 12 ...................................................89 5M. Fish species composition for station 15 ...................................................90
6A. Schematic of fish species diversity values for Valley Creek watershed, 2001 ........................................................................................91
6B. Schematic of fish species diversity values for Valley Creek watershed, 2002 ........................................................................................91 7A. Land use in entire Valley Creek watershed ..............................................92
7B. Land use in Valley Creek branch............................................................93
7C. Land use in entire Little Valley Creek branch ........................................94 8. Industrial sites in Valley Creek Watershed ............................................95 9A. Fish mass distribution, Valley Creek 2001.............................................96 9B. Fish mass distribution, Valley Creek 2002 .............................................96 9C. Fish length distribution, Valley Creek 2001 ...........................................97 9D. Fish length distribution, Valley Creek 2001...........................................97 10A. Fish mass distribution, Little Valley Creek 2001 ...................................98 10B. Fish mass distribution, Little Valley Creek 2002 ...................................98
10C. Fish length distribution, Little Valley Creek 2001 .................................99
10D. Fish length distribution, Little Valley Creek 2002 .................................99
11. Scatterplot of fish length vs. mass ........................................................100
ABSTRACT
Quantification of the impacts of urbanization and land use on fish communities in Valley Creek Watershed,
Chester County, PA
Luanne Y. Steffy Susan S. Kilham, PhD
Valley Creek watershed, located in southeastern Pennsylvania, is a small fourth order
stream that empties into the Schuylkill River at Valley Forge National Historic Park, thirty-
five kilometers northwest of metropolitan Philadelphia. Valley Creek has supported a
naturally reproducing population of brown trout (Salmo trutta) since 1985. Because of the
uniqueness of this coldwater species in the area, the Commonwealth of Pennsylvania has
named Valley Creek an Exceptional Value Stream. There are two main branches comprising
the watershed, Valley Creek and Little Valley Creek. The geologic framework of Valley
Creek is distinctive because the majority of the basin lies in a carbonate formation while the
tributaries from the north and south originate in crystalline and siliciclastic formations. The
64 km2 watershed has been under extreme urbanization pressure in the past 25 years. Open
space is being turned into residential developments, commercial office parks and roads to
connect them. As a result the watershed is rapidly increasing in impervious surface cover.
As of early 2002, Valley Creek watershed as a whole was nearly 18% impervious by area.
Urbanization has been shown to have negative effects on aquatic systems through a variety
of mechanisms. The purpose of this study was to quantify some of the effects that land use
changes from urbanization have on urban streams, specifically fish communities, at a
watershed scale. The long-term effects of continued urbanization were identified, as data
from the present study were compared to similar work completed nearly 10 years ago.
Fifteen sampling stations were chosen throughout the watershed. Sampling and water quality
measurements were done seasonally from Fall 2000 – Summer 2002. Regressions of fish
community data versus physical watershed data indicated significant relationships. However,
these relationships were different for both branches of the stream, which indicated that the
branches were functionally independent. Increased stream temperatures from urban run-off
are cause for concern for brown trout in Valley Creek. All but one station’s summer mean
temperatures were above the preferred range for brown trout. Fish communities responded
locally to land use parameters, especially percent impervious area. Three stations located in
areas of highest impervious surface cover were able to overcome a detrimental effect on the
fish community due to a large influx of groundwater. The geology and the groundwater
inputs through springs into Valley Creek were essential in interpreting the ecological data.
Short-term effects of drought occurred as the fish communities changed dramatically in 2002
during a severe regional drought. Flow decreased an average of 25% from the summer of
2001 to the summer of 2002. Traditionally, the western upstream end of the watershed was
under the most intense urbanization pressures but more recently urbanization spread
eastward and the resulting effects on the fish communities were obvious. Species
composition was quite unique at each of the 15 stations owing to the effect of local land use
in each station’s drainage area as quantified by the Jaccard similarity index. Patterns of
increasing fish diversity, abundance, and species richness with increasing stream order were
not observed. Valley Creek system, being an urban stream, does not follow the River
Continuum Concept and acts more as a series of separate sections rather than a contiguous
unit.
CHAPTER 1: INTRODUCTION
Urbanization is characterized as an increase in human habitation, coupled with
increased per capita energy consumption and extensive modification of the landscape,
creating a system that does not depend principally on local natural resources to exist. The
word urbanization is an all-inclusive term for all the activities that are involved with growth
of cities and increases in human activities (McDonnell and Pickett 1990). Even though
urbanization brings drastic modification of landscape, it is generally thought to have limited
negative effects on stream fish communities when its components are considered as single
events. However, long-term cumulative effects of urbanization could be comparable to
those resulting from high intensity disturbance of streams (Weaver and Garman 1994).
The extent of urban influence within a given watershed is a function not only of the
position of that watershed in relation to population centers, but also of the size of the
watershed in relation to the population centers (Limburg and Schmidt 1990). Large urban
areas like Philadelphia and its sprawling suburbs most easily and readily affect small
watersheds like Valley Creek, a small urban stream in Chester County, Pennsylvania. Paul
and Meyer (2001), in their review of streams in the urban landscape, state that the ecological
implications of urbanization are far less studied than the chemical effects. They go on to say
that although urban effects on invertebrates have been studied the most, far less is known
about the responses of fish assemblages to an urban environment. There is no published
information on behavioral ecology, community interactions or biomass and production of
non-salmonid fishes in urban streams. The present study seeks to investigate some of these
relationships and community interactions in an urban stream, particularly involving fish
assemblages and how they respond to land use changes associated with on-going
urbanization.
Streams are naturally physically harsh environments, where organisms are never
without the risk of floods, drought, temperature and oxygen stress and a constantly evolving
channel. As a result it has often been suggested that abiotic factors might have a greater
influence in running waters compared with other environments. In reality, some
combination of biotic and abiotic interactions determine the structure of aquatic
communities. It can also be argued that because stream biota are generally adapted to the
conditions they normally experience, small deviations might be devastating to species
adapted to very predictable conditions. But, large fluctuations might be the norm for species
adapted to variable conditions (Allen 1995).
Urban streams differ greatly from natural systems. Urbanization profoundly changes
the hydrology, morphology, water quality and ecology of streams and the severity of these
changes is directly linked to the degree of watershed imperviousness (Schueler and Galli
1992). In Maryland, fish diversity decreased dramatically in watersheds having 12-15%
impervious surface cover (ISC), with fish being absent above 30-50% impervious area
(Klein 1979). Also in Maryland, fish diversity decreased above 10-12% impervious area
(Schueler and Galli 1992). Increases in impervious surface cover also affect species
richness. Schueler and Galli (1992) report a significant reduction in species richness above
12% ISC. In Wisconsin, fish index of biotic integrity (IBI) decreased rapidly at 10% ISC
(Wang, et al. 1997). In Canada, fish IBI decreased sharply above 10% ISC but streams with
high riparian cover were less affected (Steedman 1988). Because the flow in urban streams
is often dependent upon surface and stormwater runoff, the temperatures in urban streams
are generally higher than in undisturbed watersheds. The change in urban summer stream
temperatures from an undeveloped reference stream baseline can be a direct function of
watershed imperviousness (Schueler and Galli 1992).
Urbanization has been targeted as the driving force behind much of the ecological
degradation of the Valley Creek Watershed. Despite the dramatic threat urbanization poses
to ecosystems, there has not been a thorough synthesis of the ecological effects of
urbanization on streams. There are reviews discussing the impacts of urbanization, physical
factors associated with drainage, urban stream management, and some general reviews
aimed at engineers and invertebrate biologists, but the ecological effects of urban growth on
stream ecosystems have received less attention (Paul and Meyer 2001).
Valley Creek is a 64 km2 urbanized watershed in southeastern Pennsylvania about 35
km (20 mi) northwest of Philadelphia (Figure 1). The two main branches, Valley Creek and
Little Valley Creek, converge and empty into the Schuylkill River at Valley Forge National
Historic Park (VFNHP). Both branches of the stream have tributaries entering the main
channel from both the north and the south. The biggest tributary, Crabby Creek, is in the
southeastern corner of the watershed, coming into Little Valley Creek from the south hills.
The main channels of Valley Creek and Little Valley Creek lie in a carbonate
geologic formation, however the tributaries that flow into each arm originate in non-
carbonate regions. Sixty-eight percent of the watershed is over a limestone/dolomite
substratum (Sloto 1990). The diverse geology of this basin is reflected in the water
chemistry and water quality of Valley Creek and as a result it is difficult to compare Valley
Creek with any other streams in the region.
Valley Creek is unusual for small headwater streams in this region in a number of
ways: 1) the pattern of urbanization is the opposite of what is usually expected; the majority
of the urbanization and resulting environmental concerns are upstream and the last 4 km of
the creek are relatively unaffected in VFNHP; 2) Valley Creek is considered a cool water
fishery due to the large proportion of groundwater in the base flow; 3) the cool water
conditions allow for a naturally reproducing population of brown trout, Salmo trutta; and as
a result Valley Creek has been designated an Exceptional Value stream by the
Commonwealth of Pennsylvania; 4) there are numerous Superfund and other contaminated
sites within the watershed. The most notable include Paoli Rail Yard, Foote Mineral
Company, Knickerbocker Landfill and Bishop Tube Company. In addition, there is
continual commercial and residential development throughout the watershed.
Valley Creek watershed along with a majority of Chester County was settled in the
mid-1700’s with a majority of the land being used for agricultural purposes. Clear-cut
farming was common and as the land was stripped for development the creek was subjected
to heavy sediment loading (Chester County Planning Commission 1998). Dams were
created along Valley Creek during this time to accompany the numerous mills and as a result
the natural dynamics of sediment transport were altered (Kemp 1994). In addition to the
accumulating sedimentation problem, the dams impeded natural movements of fish along
stream lengths. Dams like these were very prominent characteristics of the watershed in the
19th century (Owens 1993). A shift from agricultural practices to unregulated municipal and
industrial waste discharge was a major problem and as recently as 25 years ago the stream
was said to have resembled an open sewer line (Heister 1979). In more recent years, the
amount of sewage inputs into the stream appears to have declined, based on decreased
coliform counts (Moore 1989). Sloto (1987) stated that the change in the eutrophic
condition of Valley Creek watershed was based on the switch by a majority of the domestic
wastewater producers from leaky septic systems to public sewer lines. As of 2001, 25% of
the watershed was utilizing private septic systems with the major land use in these areas
being residential. Kemp (1994) reported that the urbanization rate was at its peak in Valley
Creek watershed from 1968-1980 based on data from the Delaware Valley Planning
Commission. Over this period, agricultural and open space land usage decreased more than
20% in the Valley Creek branch and 15% in the Little Valley Creek basin.
Industrial operations have introduced contaminants into the watershed, such as poly-
chlorinated biphenyls (PCBs), trichloro ethylene (TCE), polyaromatic hydrocarbons
(PAHs), and bromide. The PCBs in sediments and in fish tissue are over the legal limit for
human consumption (Dolinger 1997) and there are current efforts to remove some of this
contaminated sediment (EPA 2002). As a result of the PCB problem, in 1985, the
Pennsylvania Fish and Boat Commission stopped stocking trout in to the stream and
designated Valley Creek, once a highly regarded trout fishery, as a catch-and-release only
stream (Owens 1993). Most recently, the increase in development has been linked with
increased-volume peak flows, greatly increased sediment loading and sinkholes (Kochanov
1993, Pizzuto et al. 2000, Paul and Meyer 2001)
Because the Schuylkill River is a warm-water system, the assemblage of cool water
fish in Valley Creek are somewhat isolated and have no real epicenter for recolonization
(Kemp 1994). Therefore any comparisons in fish community parameters, such as diversity,
with other similar sized watersheds in the region are difficult. Brown trout require high-
quality habitat, suitable spawning habitat and especially a restricted temperature range. This
habitat must include high water flow, gravel and areas of low siltation. All three of these
variables are decreasing in Valley Creek as a direct result of urbanization.
This research is part of National Science Foundation funded grant #EAR-0001884
under the Water and Watersheds Competition to evaluate the effects of urbanization on
Valley Creek watershed. The research idea was inspired by a series of articles in the
Philadelphia Inquirer (Mastrull et al. 1999) entitled “An Acre an Hour” which stated that in
the Philadelphia metropolitan region open space was disappearing at the rate of one acre
every hour. Valley Creek watershed was chosen because of the baseline data that was
available from other research done at Drexel University in the past 10 years (Kemp 1994,
Dolinger 1997, Knouft 1997).
The other aspects of this project include groundwater, surface water, surface/sub-
surface interactions, stormwater modeling, and social science components. The ecological
aspects of this research as explained in this manuscript were examined in light of these other
components of the overall project. Few other studies offer such explanations or stress the
importance of looking at streams at a watershed scale. Without the knowledge of other
research going on simultaneously, much of the collected data would be unexplainable at
best. Other studies in the literature concerning small headwater streams are based on one or
two stations, compared to a host of other streams of similar size (Leonard and Orth 1986,
Steedman 1988, Wang et al. 1997). This research is best understood when considered in its
proper context, as an integral part in understanding the complexity of an urban watershed as
opposed to many other studies which focus on one species or one point source problem.
CHAPTER 2: PREVIOUS RESEARCH
Previous research on Valley Creek was done by Drexel University on the effects of
urbanization and PCB contamination on the brown trout in 1994, 1996, and 1997 (Kemp
and Spotila 1997, Knouft and Spotila 2002, Dolinger 1997). This research showed the range
of S. trutta becoming increasingly restricted because of degradation within the watershed
(Knouft 1996, Kemp and Spotila 1997). There was lower growth and survival of S. trutta in
the worst PCB contaminated sites along the stream (Knouft 1996). Brown trout are top
predators in the aquatic food chain and are affected by impacts on all of the trophic levels
below them; but they are also the most sensitive species as well. Brown trout act as an
indicator species in the Valley Creek system and help gauge the amount of degradation that
has taken place locally.
As mentioned, Valley Creek is different from many urban watersheds in that it has
extensive growth and development at its headwater tributaries and relatively less
downstream. Upstream areas have biota characterized by pollution-tolerant species of
invertebrates and loss of fish spawning habitat due to high sedimentation loads (Kemp and
Spotila 1997). Dramatic changes in the fish community and the benthic invertebrate
community demonstrate the deleterious effects associated with watershed alterations (Kemp
and Spotila 1997). Dolinger (1997) also found that biota in Little Valley Creek had much
higher levels of PCBs than the Valley Creek section did. The data showed a clear food web
biomagnification of PCBs in the organisms of Valley Creek and Little Valley Creek.
The present study is an extension and expansion of some aspects of the other three
studies but at the same time is very different. This research is most similar to Kemp’s work
from 1993. In the Valley Creek system, much has changed in the way of land use in the last
ten years. Additionally, in September of 1999, Hurricane Floyd hit southeastern
Pennsylvania and many morphological changes occurred in small streams like Valley Creek.
During this storm, Valley Creek reached a maximum peak flow of 178 m3s-1 (6,280 cfs) on
September 16, 1999 with a mean for same day being 57 m3s-1 (2,020 cfs) (USGS 2000).
Local observers stated that this flood washed out all the sediment in the stream channel
down to the bare bedrock. No studies have been done since the hurricane went through and
as a result nothing is known about how Valley Creek was affected ecologically or what
happened to the fish assemblages it supported prior to this event.
The primary previous source of groundwater and geologic information for Valley
Creek watershed was Sloto (1990). His report stated that the watershed contains a
productive assemblage of fractured rock aquifers within its basin. Groundwater flow travels
generally in a northeasterly direction. The western groundwater divide occurs one-half mile
west of the surface water divide. Groundwater flows beneath the surface water divide on its
eastern edge toward the Schuylkill River (Sloto, 1990). A variety of other studies are
relating to the quarries, sinkholes, and Superfund and NPL sites have been completed by
federal and local groups in the Valley Creek watershed (Sloto 1987,1988, 1990; Moore
1989, Kochanov 1993, PA DEP 1998, EPA 1999, 2000; Cahill 1999).
CHAPTER 3: METHODS AND MATERIALS
I sampled 15 stations seasonally from Fall 2000 through Summer 2002 (Figure 2).
These stations were spread throughout the watershed and were intentionally chosen to be
upstream and downstream of known contaminant sites. Stations were also in headwater
reaches of both branches, at downstream sites on each branch, at the mouth of the creek and
on the major tributary, Crabby Creek. This allowed me to sample the entire watershed and
was vital to understanding the stream system. There were seven sites on Valley Creek, five
on Little Valley Creek and three downstream of the confluence of the two branches.
Sampling took place in January, April, July and October throughout the study.
Electroshock fishing occurred once a year, in the summer, in response to concern from
citizens groups in the watershed about the possible detrimental effects of repeated electro-
shocking on fish. All other fish collection was carried out with dip nets. Fish data from the
two summers were used to describe the fish diversity and year-to-year changes in fish
community structure. Fish collected at other times of the year provided anecdotal
information about each community and were used in other aspects of the overall project.
Using a Smith-Root 110 v. AC backpack electroshocker (70 Hz per 2ms (J3) or 4ms
( J4)) I electro-fished each site along the entire length of the station and made three passes
through each reach to keep a consistent sampling effort throughout (Kemp 1994). The mean
station length was 35 m with a range of 25 m – 50 m. Sampling length was consistent at
each station for both years of this study. Variability in length of sampling reach was due to
the varying locations of natural and man-made endpoints such as large meanders, culverts,
bridges, shallow riffle areas or debris dams. However, each reach included at least one,
usually two, examples of pool, riffle and run. I collected fish stunned with the electroshocker
in dip nets and placed them in buckets full of stream water. On rare occasions, I used
MS222 to sedate large fish to reduce thrashing and decrease the chance of injury to the fish.
I identified, weighed and measured on site and returned most immediately to the stream.
Some fish were taken back to Drexel University for other analyses. I weighed fish (± 7g)
with the smallest fish all being grouped into a < 7g class. I measured fish (± 0.5 cm) using a
standard fish board containing a meter stick to the nearest centimeter. All fish handling and
transporting procedures were approved by the Institutional Animal Care and Use Committee
of Drexel University. In addition, all samples were collected under a Pennsylvania
scientific collecting permit, state fishing licenses and a permit from the National Park
Service for work in VFNHP.
I measured water quality seasonally at each station with a Quanta HydroLab. This
instrument recorded temperature, pH, conductivity, dissolved oxygen, depth and salinity. I
recorded the physical characteristics of each site seasonally and any differences in land use,
stream structure, dominant sediment type, channel morphology, and water level.
3.1 Fish community parameters
Locations of each site sampled throughout the two years of this project are summarized
in Table 1 along with physical information about each station. This includes stream order,
distance from mouth (km), area in sub-basin (km2) and percent impervious surface cover
(ISC) in each sub-basin. The following parameters were calculated from the fish
community data: species richness, abundance, diversity, community similarity, evenness,
length and mass. Because the Valley Creek watershed consists of two main branches which
converge about 5 km from the mouth, fish community parameters were derived for each
station, the north branch (Valley Creek) which includes the three downstream stations
(unless otherwise noted), the southern branch (Little Valley Creek) and for the entire
watershed. Fish community parameters were compared versus watershed physical
characteristics (i.e. temperature, stream order and impervious surface cover (ISC)). The
parameters used were calculated in the following manner:
• species richness – Species richness at each site was the total number of fish species
obtained through electrofishing at each site. There was no minimum number of
individuals needed to be counted in this category.
• abundance – Abundance was the total number of each fish species caught through
electrofishing at a particular site.
• diversity - Species diversity is a measure of the number of species in relation to the
number of individuals. Species diversity was calculated using Simpson’s index of
diversity (Simpson 1949) which is defined as:
D = 1 / Σ pi2
where D = Simpson’s index of diversity and
pi = relative proportion of ith species as a fraction of the whole
Simpson’s diversity index was chosen for comparison to previous work done in Valley
Creek.
similarity index - Jaccard’s similarity index is a measure of how similar two
communities are in terms of species present. This measure is used in conjunction
with species diversity to describe a given community and is defined as:
R = (C/[N1 + N2 – C ]) x 100
where R = Jaccard’s index of similarity
C = the number of taxa in common for the same station at two different points in
time (or at different locations at the same point in time)
N1 = number of taxa at time point number one (or location number one)
N2 = number of taxa at time point number two (or location number two)
• evenness – Evenness is a measure of how a population is distributed among the
species present, and is a value between 0 and 1 (i.e. if one species dominates a
population, the evenness value will be low). Species evenness was calculated using
the following formula:
E = D/e-Σpi(ln(pi))
where E= species evenness at site
D= Simpson’s diversity index and
pi = relative proportion of ith species as a fraction of the whole
• length and mass – Length and mass of individual fish were taken in the field and fish
were grouped into size classes.
• condition factor- Condition factor is a measure of the physical health of a fish based
on it length and mass. Condition factor was calculated for brown trout, white sucker
and creek chub using the following formula:
CF = mass (g) x 105 / length (mm)
3.2 Physical parameters
• Water temperature, pH, conductivity, dissolved oxygen – I collected these readings
seasonally with the Quanta HydroLab (Table 2)
• Distance from mouth – I calculated distance of each site from the mouth using a
Global Positioning System (GPS) unit and the mapping capabilities of ArcView
Geographic Information System (GIS).
• Stream order – Stream order is a measure of the relative size of streams. Stream
order for the various sections of Valley Creek watershed was delineated by Kemp in
1994 and those reported values were used for analysis in this study.
• Riparian buffer – Riparian buffer zones are the areas along streams and rivers that
include the natural vegetation that helps to buffer the stream from a variety of
disturbances. The width of the riparian buffer at each station was measured with a
tape measure on the left and right banks. The values used in analyses were the sum
of the length of the riparian corridor at each station.
• Stream flow – Stream flow was provided by a USGS gauge (# 01473169) located
downstream of the confluence, about 4 km upstream of the mouth. These data were
acquired from the USGS website [www.usgs.gov] showing real-time data for Valley
Creek. The discharge, in cubic feet per second (cfs), is recorded continuously every
fifteen minutes and the mean daily flow is archived. (1 cfs = 0.0283 cubic meter per
second (m3s-1)). The 15 minute data were used to calculate monthly means and
summer means for the two years. This gauging station accounts for runoff from
over 90% of the watershed and there are no significant tributaries coming in below
this point. Little Valley Creek accounts for 29% of the stream flow at the gauge on
average and this value was used to calculate mean flows for each branch separately
(R. Ryan, pers. comm.).
• Impervious surface cover (ISC) – Impervious cover was calculated using a GIS layer
from Cahill and Associates from 1995 that was updated using the March 2000 aerial
photographs. This was done using ArcMap 8.1. The sub-basins for each sampling
station were derived using the HEC-GeoHMS 1.1 model running in conjunction with
ArcMap 3.2. The input data were from the USGS Digital Elevation Model at a 30m
resolution (C. Emerson, pers. comm.).
• Sediment grain size - Sediment was dry sieved in the grain size increments of
1cm, 2mm, 75 µm and 50 µm. Percent fine sediments, those in the 75 and 50 µm
fractions, were compared to the fish parameters of a particular station. Sediment
grain size analysis was done at five stations (3, 4, 5, 11 and 12) as part of another
project.
• Land use data – Land use characteristics were derived using ArcView GIS for each
sub-basin. The parcel-level land use data were obtained from Chester County and
the October 2001 version was used for this analysis.
• Geology – geologic information was obtained from GIS layers from Cahill and
Associates. This included the specific geologic type as well as general information
about regions of carbonate or noncarbonate substrate.
CHAPTER 4: RESULTS
4.1 Species Composition
Electrofishing in the summer of 2001 and 2002 at 15 stations in Valley Creek
watershed revealed the presence of 17 species of fish. (Table 3, Figures 4A-4B, Figures 5A-
5M) This was four fewer species than reported by Kemp and Spotila (1997) from
comparable stream sampling completed in 1993. Species collected only once in 2001-2002
included rainbow trout (Oncorhynchus mykiss), brook trout (Salvelinus fontinalis), rock bass
(Ambloplites rupestris) and small-mouth bass (Micropterus dolmeuii). The most abundant
species in the Valley Creek system in the present study was the white sucker (Catostomus
commersoni) followed by blacknose dace (Rhinicthys atratulus) and creek chub (Semotilus
atromaculatus). Brown trout, Salmo trutta, traditionally the most important and highest
quality fish in the system, were fourth in order of abundance. In Little Valley Creek, eleven
species of fish were collected. The most abundant was blacknose dace, followed by white
sucker. In Valley Creek branch, ten fish species were collected. The most abundant was
white sucker, followed by creek chub. Brown trout were primarily located in the middle
reaches of the stream, in the second and third order sections. Species found only
downstream of the confluence of the two branches were rainbow trout, rock bass, and
smallmouth bass. Fish species data from Summer 2001 and Summer 2002 were used to
calculate fish community parameters. A summary of these fish community parameters is
shown by station in Table 4 and by section of stream in Table 5.
4.2 Temperature Effects
Kemp and Spotila (1997) stated that due to the extensive component of groundwater
in the base flow in Valley Creek, the stream was buffered from hot and cold extremes and
large seasonal variations in stream flow. This statement was primarily based on previous
work done by Sloto (1990) in Valley Creek. However, measurements taken for this project
showed that this is not entirely true. A less than 10˚C annual temperature differential is
expected for spring fed streams, while surface water streams can have a 16˚C or higher
differential (Kemp 1994). Of the 13 stations that were flowing year-round in the present
study (Table 2), only one station had less than a 10˚C differential between highest and
lowest temperatures recorded over the two years of sampling. This station (#10) was in the
upper reaches of Valley Creek and there were numerous springs that double the stream flow
over about a 100 m reach (A. McGinty, pers. comm.). The lower dissolved oxygen at this
station also was consistent with high groundwater input. Each of the other watershed
stations had a mean dissolved oxygen value between 8.5 and 10.4 mg/L. This station (#10)
had a mean dissolved oxygen value of 5.8 mg/L (Table 2).
This same station (#10), at Valley Creek Park on the Valley Creek branch, was the
only station that had a mean summer temperature in the preferred range for brown trout.
Every other station on both branches of the creek had summer temperatures well above the
preferred temperature range. The proportion of trout in the Valley Creek fish community is
steadily declining, at least partially owing to this trend of warming and fluctuating
temperatures. The relationship between total number of brown trout and summer water
temperature was significantly negatively correlated with an r2= 0.627 (p= 0.0013).
Proportion of brown trout was also inversely related to mean summer water temperature
(r2= 0.577; p= 0.0026; Table 6A).
Correspondingly, there was also a significant negative correlation between annual
temperature fluctuation and total number of brown trout caught (r2= 0.507; p= 0.0063;
Table 6A). This correlation was stronger when looking only at Valley Creek (r2= 0.783;
p=0.0035; Table 6B). There was also a negative correlation between proportion of brown
trout and the annual temperature differential in the stream (r2= 0.459; p= 0.0110).
Similarly, this relationship was clearer when looking only at Valley Creek, with an r2= 0.741
and p= 0.0060 (Table 6B). Little Valley Creek by itself did not show a significant trend in
the relationship between proportion of brown trout and annual temperature change (Table
6C). This was very likely due to high groundwater impacts (see below). There was as much
as a 20˚C fluctuation from winter to summer at some of the locations downstream of the
confluence with the mean being 16.7˚C (Table 2). Only one station (#10) had an annual
temperature fluctuation that could be considered constant at 5.7˚C
4.3 Brown trout distribution
The highest quality fish, brown trout, decreased 50% proportionately from 1993–
2001, while during the same time period, the proportion of creek chub increased from 4% in
1993 to 22% in 2001 and suckers (white sucker and northern hognose) increased from 19%
in 1993 to nearly 30% in 2001 and 2002.
Kemp (1994) showed that brown trout accounted for 25% of the total number of fish
caught in Valley Creek watershed. In the first year of this study, brown trout made up 13%
of all the fish caught and in the second year that number was down to 10%. Of the 15 sites
sampled during this project, 13 were also sampled by Kemp in 1992-1993. The same
methods of electrofishing and fish collecting were done in both studies so the data would be
comparable. Out of the 13 common sites, brown trout were present at 9 of the sites in 1993,
and by 2001, the number of brown trout caught had decreased at 8 of these sites (Table 7).
In addition, at 5 of these sites, the number of brown trout caught in 2002 had declined even
further. Out of the 13 common sites, 10 sites had a decline in abundance of total fish caught
from 1993 to 2002 (Table 7). There are two other species of salmonids in the Valley Creek
system besides brown trout, Salmo trutta. Historically there have been reproducing
populations of rainbow trout, Oncorhynchus mykiss, and brook trout, Salvelinus fontinalis,
in small populations in the watershed (Kemp 1994). In the present study, only one
individual of each species was collected throughout the two years.
4.4 Percent impervious surface cover and fish diversity
There were no stations that had a catchment less than 13% impervious area, 5
stations were between 13-15%, 6 were between 16-18%, 1 was between 19-24% and 3 were
above 25% impervious area (Table 1). Evaluating diversity as a function of impervious
cover, the fish diversity generally declined with increasing impervious surface somewhere
between 15-17% ISC. The exceptions to this were three stations (5,7,and 15) with high ISC
on Little Valley Creek (Table 6C). The diversity at these three stations was much higher
than would be predicted from the impervious cover model (Figure 3A and 3B). Upon
further investigation, I found that these three stations were located in areas of high
groundwater input, which seemed to have compensated for the higher impervious cover
resulting in relatively high fish species diversity even at levels as high as 32% impervious
cover. In a 1300-m area upstream of these stations, cumulative groundwater inputs
contribute up to 0.004 cubic meter per second (m3s-1) (20-60 gpm) for each station. This
pattern was evident in both 2001 and 2002. Without these three Little Valley Creek stations,
there was a clear pattern of decreasing fish diversity with increasing impervious surface.
Simpson’s diversity index was negatively correlated with increasing impervious surface in
2001 (r2=0.503; p = 0.0217) and 2002 (r2= 0.531; p = 0.0169) when those three stations
were excluded. It should also be noted that the station with the highest percent impervious
cover did not include any brown trout. This suggests that even the incoming groundwater
was not enough to make this habitat suitable for the most sensitive species. The other two
stations at which groundwater was especially important did contain brown trout populations.
No other fish community parameter, (abundance, evenness, or species richness) was
significantly correlation with ISC, with the exception of abundance in Little Valley Creek
branch in 2001 (Table 6C)
4.5 Jaccard similarity index
In order to better characterize changes in fish communities it is beneficial to use
some measure of community resemblance in conjunction with the species diversity index.
Jaccard’s similarity index was used for this purpose. A Jaccard index (R) score of 100
indicates that two communities are identical with respect to types of species present. The
closer the number is to 100, the more similar two communities are for a given sampling time
period. Three types of comparison calculations were done using the Jaccard’s similarity
index. First, a comparison of the fish assemblages from 1993 to 2001 and 1993 to 2002 for
the 12 common stations from Kemp’s (1994) data was completed. These results showed
some major long-term changes in fish species assemblages in the watershed over the 9-year
period. A comparison between the 1993 and 2001/2002 fish community data showed a
range of mean similarity R-values of 23-100 with a mean of 52 (Table 8). Stations 6,11,
and 15 had the least similarity over the 9 years, all with mean R-values of less than 30.
These stations were each in distinct areas of the watershed, but all were impacted greatly by
urbanization, specifically sedimentation, increased surface run-off and decreased riparian
buffer zones. The most similar stations were 2, 9, and 12. These stations were in areas that
were relatively undisturbed and the surrounding riparian land use remained constant over the
9 years. It should be noted that station 12 had a R-value of 100 in 2001 but was dry in 2002
so no fish data were obtained.
Secondly, a similarity comparison of fish species data from 2001 and 2002 at each
station was done. This helped to quantify local dissimilarities that occurred over the course
of the present study and may be linked to observed changes in land use. As expected, the
similarity between the fish communities from 2001 to 2002 was generally greater than the
similarity with the 1993 data. However, there was some variation, with R-values ranging
from 22-100 with a mean of 59. It was surprising that there was so much dissimilarity in
some of the stations fish assemblages just over the one year. These changes may be at least
partially due to the severe decrease in streamflow due to the drought. Station 15 had a score
of 29 for 1993 compared to 2001 and 2002 but a score of 100 for 2001 compared to 2002.
This suggested that some major change in water quality or habitat condition occurred
between 1993 and 2001. Stations with the highest similarity scores between 2001 and 2002
were stations that were located in areas of large groundwater influx, including stations 10
and 15. The influence of groundwater may have lessened the effects of the drought and
enabled the creek to better sustain its fish community.
Third, pooled samples for each branch of the creek and the entire watershed were
compared. This was done to quantify larger-scale changes and test the hypothesis that the
two arms of the creek were quite distinct and responded uniquely to land use changes.
Pooled R-values for the two branches of the creek for 2001 and 2002 showed a lower
similarity in Valley Creek branch (R=66) and a higher similarity score in Little Valley Creek
(R=73), while the entire watershed had an R-value of 79. Some of these differences were
due to the inherent difficulties in capturing and re-capturing all fish species in any given
location. However, the higher Little Valley Creek R-value suggested that this branch had
either been under less intense urbanization pressure or else was better buffered from the
effects of the urbanization. Repeated field visits and observations of the entire watershed
have provided confirmation of this.
4.6 Adjacent station similarity
Jaccard’s similarity index was used to compare each station to the next upstream
station to quantify to what degree the fish assemblages in Valley Creek watershed were
continuous. A more patchy distribution of fish communities was expected based on
repeated visits and fish sampling throughout the project. The Jaccard results confirmed the
distinctness of each station in the watershed, even those near each other. There was very
low similarity between most of the stations, with scores ranging from 22 – 71 in 2001 and
from 29-75 in 2002 (Table 9). The most similar stations in both years were stations 9 and 10
and stations 7 and 15. These were the only stations that were more than 60% similar over
both years of the study. These four stations were also located in high groundwater-fed areas,
which helped keep the habitat and water quality constant despite local land use changes.
These groundwater additions were among the highest inputs in the watershed and although it
is likely not the only influencing factor, it certainly cannot be discounted. The similarity
index also clearly showed the high dissimilarity between station 1 and station 2, owing to
the influence of the warm-water Schuylkill River at station 1.
4.7 Local vs. regional diversity
The spatial pattern of species composition and diversity is very important in
understanding the nature of an urban stream. The number of species that occur within a
region is obviously the upper limit on the number of species that make up any particular
aquatic community. Local environmental conditions largely determine what subset of the
species is represented in any given stream (Allen 1995). This was shown on an even smaller
scale by the two years of fish community data from Valley Creek. Within this one small
stream, the fish assemblages of each of the stations responded to local conditions.
Each station was affected by local land use and the degree of local urbanization in
addition to any cumulative effects. The species diversity at each station was lower than the
total diversity for the watershed. Each station had a unique assemblage of fish and in many
cases the stations upstream and downstream had a quite different group of fish (Figures 4A
and 4B). Species diversity in each branch when calculated as a whole was lower in the
Valley Creek branch, Little Valley Creek branch as well as the entire watershed for 2002
compared to 2001. Only the section of the creek downstream of the confluence had a higher
total diversity in 2002 than in 2001 (Figures 6A and 6B).
4.8 Land use comparisons
Land use in Valley Creek watershed in 2001 was composed of 41% residential
development, 22% commercial properties, 13% open space/public lands, 13% roads, 6%
industrial, 3% utilities, and 2% farms. In the Little Valley Creek and Valley Creek branch
sub-basins, the land use breakdowns were similar to the overall watershed (Figure 7A-7C).
Generally, there was more open space and less residential land use in the Little Valley Creek
branch. The residential development in Little Valley Creek basin consisted of great high
density housing than the Valley Creek branch, which had the majority of the large lot
residential parcels.
Valley Creek sub-basin also contains a majority of the industrial sites in the
watershed (Figure 8). Some of the various land use classifications correlated to fish
community data and showed very interesting trends. As the amount of commercial land
increased in a sub-basin catchment, species diversity decreased (r2= 0.798; p= 0.0164).
Proportion of brown trout at a given station was higher with greater residential land use and
open space/public lands (r2= 0.843; p=0.0278) but decreased with more commercial area.
Based on these few data points, it seems that streams and their fish assemblages are less
affected by residential development than by commercial development.
4.9 Specific anthropogenic changes
The changes in fish abundance from July 2001 to July 2002 were obvious. Some of
these declines were no doubt a result of the drought in the summer of 2002. However, other
more severe declines could be linked to specific land use changes and/or anthropogenic
activities in the area. For example, at station 4, the number of fish caught in 2001 was 33
and in 2002 it was down to 8 fish. In the fall of 2001, there was some bridge construction at
this site and the deep holes in the creek that were habitat for fish were filled in with concrete
and excess construction supplies. The result of this, coupled with the drought, was drastic
for this station.
This example emphasized the importance of not only water quality but also habitat
quality to fish communities. By water quality standards, this station (#4) had suitable
conditions for a diverse assemblage of fish including brown trout. There was a spring inflow
immediately upstream of the station to bring in colder water, the dissolved oxygen content is
relatively high, and the conductivity was normal. However, the habitat that was suitable at
the beginning of the study turned marginal by the last year. For brown trout and other
pollution-intolerant species, habitat must include plenty of cover from overhanging trees or
other debris and deep shaded pools (Boussu 1954, DeVore and White 1978). Without these
habitat requirements, the fish community at this station decreased to almost nothing
regardless of the favorable water quality parameters.
Another example of specific events that had an impact on local ecosystems involved
a quarry in the upper reaches of the Valley Creek branch. The Warner Quarry (see Figure 8
for location) was an active quarry, mining limestone and dolomite until 2000 and, as a
dewatering process, pumped groundwater out of the quarry and into Valley Creek on a
cyclical basis until September 2001. This inflow of clean groundwater entered the stream
above station 8 and made up about a half of the total stream flow. In the summer of 2001,
station 8 had the highest fish species diversity and the largest trout population of any station
throughout the watershed. Additionally, this same station also had high fish species
diversity in 1993 and had the most total fish of any station in the watershed (Kemp 1994).
In September 2001, developers changed the operation of the pump and began building an
office park and allowing the quarry to fill as a decorative lake. This involved clearing of
riparian forest that buffered the tributary exiting the quarry and running the pump at a
constant rate instead of a cyclical one to maintain some flow to the stream while allowing
the quarry to gradually fill. This construction continued throughout the year and was not yet
completed as of December 2002. In the summer of 2002, the fish species diversity and the
trout population of station 8 had declined noticeably. From 1993 to 2002 the total fish
abundance at this sampling location went from 143 to 30 individual fish.
4.10 Stream flow and drought
Stream flow is an important factor when looking at fish community structure and
relationships. The entire northeastern United States including Valley Creek watershed was
very affected in the summer of 2002 by a severe drought, which decreased stream flow by
almost 25% from the previous summer (Table 10). Of the 15 stations sampled in this study,
2 stations were dry both summers and an additional station was dry the second summer.
Two of these stations were located in the headwaters on their respective creeks, and would
therefore be most expected to go dry in times of drought. When the stream flow data for the
summer months was broken down by month, July was the most severely affected month.
Fish sampling was completed during July of both summers. The mean stream flow for July
2001 was 0.433 (m3s-1) (15.3 cfs), which was down almost 30% in 2002 to 0.306 m3s-1 (10.8
cfs).
Additionally, the maximum flow value for any one 15 minute period in 2001 was
10.7 m3s-1 (378 cfs) but in 2002 the max was only 2.7 m3s-1 (94 cfs). Although the decrease
in flow was greatest in July, each month in 2002 had at least a 20% decrease compared to
2001. In June 2002, the mean flow, taken from 15 minute interval data, was deceptive due
to one large storm (16.3 m3s-1 (576 cfs) maximum flow), which raised the mean for the
month. Each month’s mean flow was statistically different from every other month except
for July 2002 and August 2002, which were not significantly different. A significant
difference was also evident between the two summers as a whole (p < 0.0001).
Another interesting observation related to stream flow in Valley Creek was the
intermittent nature of the flow in middle sections of the stream. In small headwater
streams, it is not uncommon for upstream reaches to be seasonally intermittent, but it is
unusual to have a dry section in between two flowing reaches of stream. Station 14, which
was located in the closed Knickbocker landfill, (see Figure 8 for location) was dry in the
spring and summer of 2001 and the summer of 2002 but was flowing during the other 5
sampling periods. It is interesting that even in a non-drought year (summer 2001) this reach
was dry. This unusual pattern of losing reaches can be attributed primarily to the karst
geology of the basin (C. Welty, pers. comm.).
4.11 Influence of Sedimentation
Sediment grain size analysis at five of the sampling stations was performed as part of
another aspect of the larger project on the effects of urbanization on Valley Creek
watershed. These data along with observations of sediment composition and depth at each
station were compared to the species of fish collected at that station as well as the fish
community data. Trends in sediment type were examined and changes in sediment loading
were compared to changes in fish species and/or fish abundance. The data were used to
compare types of fish with kinds of sediment found at a particular location. Stations #3, #4,
#5, #11 and #12 (see Figure 2 for locations) were the stations where sediment grain size
analysis was done multiple times in both 2001 and 2002. These stations were chosen based
on their locations, 11 and 12 being in the headwaters of Valley Creek and Little Valley
Creek, 4 and 5 being just upstream of the confluence and 3 being below the confluence.
The stations showed a very interesting comparison between sediment grain size shifts and
changes in fish abundance and fish species observed.
Station 4 showed the most direct linkage between increasing amounts of fine
sediment and decreasing fish communities (Table 11A). In January of 2001, fine sediments
(< 75 µm) made up 24% of the sediments collected, in April 2001 this had increased to 42%,
and by October 2001 the fine sediments accounted for 48% of the total sample. Thirty-
three fish were collected in July 2001 at this station including seven different species. In
April 2002, the fine sediments at this same station comprised 72% of the total sediment.
Correspondingly, only eight fish were caught at station 4 in July 2002 with no more than
two individuals of any of the five species captured.
Another interesting component of the grain size analysis at this station was the shift
in the size of the fine sediment particles. Grains that are less than 75 µm were considered
fine sediments and in the present study, this fraction was sieved down to 50 µm and < 50
µm. These results showed a clear increase in the finest sediment grain size (< 50µm) from
2% of the total fine sediments in 2001 to over 10% in 2002 (Table 11B). All other observed
variables; temperature, dissolved oxygen, specific conductivity, and pH were similar (Table
12). The long drought throughout the watershed, which greatly decreased the flow, was the
only other factor besides the sediment that changed between the two years. This station was
the most extreme example in this watershed of how increased fine sediment and sediment
loading in general can be detrimental to fish communities. As mentioned earlier in section
4.9 on specific anthropogenic changes, construction in the area was largely responsible for
the increase in fine sediment deposition.
Stations 3 and 5 showed less of an increase in fine sediments and less of a
connection between sediment and fish. Station 3 increased in fine sediments from 15% in
April 2001 to 32% in April 2002. No significant decrease in fish abundance or species
richness was seen. However, the fish community shifted from primarily large white suckers
to a variety of minnow species and smaller suckers. There was no observed shift in the
grain size of the fine sediments at this station.
The fine sediments at station 5 increased from 14% in April 2001 to 18% in October
2002. The fish community at this station decreased slightly in species diversity, abundance,
and species richness along with a decrease in number of brown trout. There were no
significant changes in the particle size of the fine sediments. Station 11, in the upstream
reaches of Valley Creek, had a consistently high percentage of fine sediments over the two
years. In April 2001 and October 2001 the grain size analysis revealed 45% and 41% fine
sediments respectively. In October 2002, station 11 had 24% fines, which is a decrease
from the previous year. These data from 2002 were probably skewed because of the high
variability of flow in the headwaters of Valley Creek. This station had consistently low fish
diversity with pollution- and siltation- tolerant species. Compounding factors here included
low flow, warm temperatures and elevated nutrient levels from an upstream golf course.
Station 12 was dry for the last year of the project due to the severe drought so there were no
fish community data for 2002. The sediment there was composed of 55% fines but this was
less of a factor than the intermittent nature of the stream at this location.
4.12 Length and mass trends
Length and mass measurements taken in the field were categorized and plotted for
each station (Table 13). The general trends were consistent over both years and both
branches of the creek. Stations in the headwaters were composed of primarily small fish and
the length and mass distributions increased downstream. Two characteristics stood out as
being unusual for not following the expected pattern of distribution (Figures 9A-D and
10A-D). First, at the most downstream station on each branch above the confluence (# 4
and # 5) there were very few large fish. Second, downstream of the confluence where
Valley Creek is a fourth order stream, there were generally very few large fish. No
significant changes occurred between the two years in any of the species in mean mass or
length. In both the Little Valley Creek and Valley Creek branches, the major difference
between 2001 and 2002 in fish size distribution was the increased number of smaller fish
and the decreased number of larger fish. While in 2001 there were generally fish in each of
the size categories, in 2002 many of these same size fish were not found and each station
only had a few of the size classes represented (Figures 9A-D and 10A-D). Scatterplots of all
the fish captured over the two years also revealed the fewer number of larger individual fish
in 2002 which may be attributed to the drought (Figure 11).
The condition factors of the salmonids (primarily brown trout) were lower than the
reported values from Kemp and Spotila (1997). This measure of fish condition based on
physical dimensions is widely used by fisheries biologists. Theoretically, the higher the
condition factor, the healthier the fish, with a condition factor of 3.0 or higher being
considered an extremely healthy fish (Carlander 1969). Based on condition factor alone, the
trout in Valley Creek are less healthy than they were in 1993 and may be declining further.
The 1993 data taken by Kemp resulted in a mean condition factor of about 1.6 for the whole
watershed. In the present study, the watershed as a whole had mean condition factors of 1.3
in 2001 and 1.2 in 2002. The mean condition factors of brown trout, Salmo trutta, in the
Valley Creek branch were 1.3 in 2001 and 1.1 in 2002. In Little Valley Creek the brown
trout appeared to be somewhat healthier based on a mean condition factor of 1.3 in both
years. These data showed a significant decline in brown trout health, primarily in the
Valley Creek branch of the watershed. For comparison, condition factor calculations were
done for creek chub and suckers. Creek chub had a mean condition factor of 2.4 in both
2001 and 2002. Suckers, white and hognose combined, had a mean condition factor of 1.6
in 2001 and 2.1 in 2002. Kemp (1994) did not report condition factors of any species other
than brown trout so no other long-term comparisons can be made.
4.13 Impact of stream order
Fishes typically show an increase in number of species and often diversity as well
with increasing stream size (Allen 1995). Stream order at each of the sampling stations is
included in Table 1. The data for Valley Creek showed some variation from this standard.
In 2001, there was a significant difference (p=0.0046) in species richness in stream reaches
of varying orders. However the pattern was unexpected. Species richness increased from
first to second to third order stream sections as expected, but decreased in the fourth order
reaches. The same trend was evident for species diversity in 2001, when fourth order stream
reaches had a decrease in diversity. Additionally, in 2002 there was a more normal pattern
of species diversity increasing with increasing stream order but species richness was not
significantly different between the varying stream orders. The reasons for these unexpected
and unpredictable patterns are unclear but may be linked to the drought in 2002.
As with other parameters discussed previously, the relationship between diversity
and distance from the mouth was quite different when each branch of the creek is considered
separately. On a watershed scale in 2002, species diversity was positively significantly
correlated (r2= 0.403; p=0.0490) to distance from the mouth, but the Valley Creek branch
had a much stronger correlation (r2= 0.743; p = 0.0273) between these two parameters, but
Little Valley Creek showed none (Tables 6A-6C).
4.14 Physical factors
The proportion of brown trout and total number of brown trout were both positively
correlated with the specific conductivity (p= 0.0009; r2 = 0.741 and p= 0.0014; r2 = 0.862)
in Valley Creek. Specific conductivity is naturally linked to geology and is not detrimental
to fish populations at levels seen in the Valley Creek system. The higher specific
conductivity in Valley Creek compared to Little Valley Creek, even though they are
primarily in the same geologic formations, can be explained by the two quarries and the
closed Knickerbocker landfill on the Valley Creek branch. These sources release ions that
raise the conductivity and are directly upstream of the stations that had high diversities and
the largest brown trout populations. No trend correlating brown trout to specific
conductance was evident in Little Valley Creek because there were no major anthropogenic
point sources of higher conductivity. There was a negative relationship in Valley Creek but
not Little Valley Creek was between total number of brown trout and mean dissolved
oxygen values. However, this relationship, which showed that as dissolved oxygen
increases the total number of brown trout decrease, was actually more complex.
This trend was skewed due to the low dissolved oxygen levels and high numbers of
brown trout at station #10 where the temperature was also relatively constant year round
owing to a large groundwater inflow. Other data points, excluding this station, showed no
significant relationship between dissolved oxygen and brown trout.
CHAPTER 5: DISCUSSION
In Valley Creek, temperature is an important limiting factor for the survival and
health of many of the fish it sustains. The impact of stream warming owing to urbanization
can be especially significant for streams that fall in the cool-water or cold-water category
such as Valley Creek. As urbanization continues to occur, it is possible that Valley Creek
could become more of a warm-water system like many of the other similar-sized streams in
the region.
Stream temperature is one of the central organizing features of aquatic communities
in lotic systems. Temperature is important to consider when studying aquatic communities
because it affects the growth and respiration of individual organisms and the productivity of
ecosystems through its many influences upon metabolic processes (Allen 1995). Stream
warming can be lethal to salmonids, such as brown trout, and can also fundamentally alter
invertebrate species composition as well as diatom, periphyton and fungal associations of
streams (Scheuler and Galli 1992). With increasing urbanization comes increased
stormwater run-off from impervious surfaces like parking lots and rooftops. Much of this
warm run-off goes directly into small streams such as Valley Creek. Very little published
data exist on temperature responses of streams to urbanization. Seasonal diurnal
fluctuations were also greater in urban streams and summertime storms resulted in increased
temperature pulses 10-15˚C warmer than in forested streams due to increased run-off from
heated surfaces in Long Island, New York (Pluhowski 1970). This same study showed that
urban streams had mean temperatures 5-8˚C warmer in summer and 1-3˚C colder in the
winter than non-urban reference streams.
Streams are typically classified based on the kind of fish assemblages they support.
The categorization of fish into thermal guilds is based on preferred and upper lethal
temperatures to a particular class of fish. Coldwater fish include trout and salmon, which
generally prefer temperatures around 15˚ C and cannot survive above 24˚ C. Coolwater fish
include suckers and perch, which prefer water temperatures between 18-23˚ C and
temperatures above 32˚ C are lethal. Warmwater fish prefer temperatures above 25˚ C and
have upper lethal limits exceeding 33˚ C; these include bass and sunfish (Horne and
Goldman 1994). Carlander (1969) reported the minimum dissolved oxygen level for brown
trout to be 4.5 mg/L in winter and 3.0 mg/L in the summer.
Temperature is known to be an important limiting factor in brown trout, Salmo
trutta, growth and survival. The optimal growth temperature of brown trout depends on the
acclimation temperature of particular populations and there have been reported values
anywhere between 11.7˚ – 23.9˚C, but the accepted preferred range for the species is 12.4˚–
17.6˚C. (Carlander 1969, Spotila et al. 1979, Kemp and Spotila 1997) The death point was
determined to be anywhere from 22.5 – 26˚C depending on the age of the fish and the
acclimation temperature (Spotila et al. 1979).
Effects of temperature increases can influence an individual organism in a variety of
ways. Spotila et al. (1979) categorized these into five major categories: 1) the organism
may die as a result of the immediate effect of heat, 2) internal alterations in the organism, 3)
death through synergistic effects of heat and other factors such as decreased dissolved
oxygen, 4) an interference with spawning or other life cycle based activities or 5)
competitive displacement by more tolerant species. Brown trout cannot survive higher
temperatures primarily because of respiratory distress. At these higher temperatures, the
metabolic demand for oxygen is higher while the physical property of oxygen solubility is
lower. Temperature and dissolved oxygen are inversely proportional to each other and thus
linked in terms of an organism’s function. Brown trout seem to be able to tolerate lower than
normal dissolved oxygen levels provided that the temperature remains cold. The brown
trout populations in Valley Creek are limited more by temperature and habitat condition than
dissolved oxygen levels.
The thermal problem in Valley Creek is not one of heated effluents flowing into the
creek but is more of a non-point source issue. As a result, it is unlikely that either one of the
first 3 scenarios occur in the Valley Creek system. Interference with spawning, the fourth
effect listed, was not tested in the present study, but seems probable based on what is known
about the spawning temperature requirements of brown trout. Out of the five effects of
thermal increases on fish, the one that is most apparent in Valley Creek is the displacement
of intolerant species like brown trout with more tolerant species like suckers and creek chub.
A decrease in the proportion and total number of brown trout paired with an increased
distribution and population of creek chub and suckers support this idea.
Kemp (1994) stated that the groundwater going into Valley Creek was basically
constant, between 12-15˚C at all times and that because groundwater constitutes a major
proportion of the flow to Valley Creek, the thermal regime of the creek falls somewhere in
the upper range of optimal temperature for brown trout. Seasonal temperature data for the
entire watershed over two years of the present study contradicted this statement.
Groundwater entering Valley Creek through springs was consistently between 10-14˚ C (A.
McGinty, pers. comm.) however the temperature of the stream is not constant even with the
additions of the groundwater. Therefore, the thermal regime of the creek in our study is out
of the preferred range for brown trout throughout a majority of the watershed. Our results
clearly show a large annual fluctuation in temperature at nearly all of the stations throughout
Valley Creek watershed, with some stations having a more than 20˚ C temperature change
from January to July (Table 2).
Perhaps in the past the influx of thermally constant groundwater could counteract the
amount of warm run-off input and keep the creek temperatures at fairly constant levels,
which could support cool water fish assemblages. As the amount of impervious surfaces
increased to nearly 18% in the Valley Creek watershed, the warm water coming in off these
surfaces became greater than the groundwater input, resulting in slowly rising temperatures.
Working synergistically with the increased run off, especially during the summer months, is
an increased use of the aquifer water, low water table, and drought. As a result of this
gradual warming of Valley Creek, summer temperatures are at or very close to the lower end
of the mortality range for brown trout in a majority of the stream. These data suggest that the
amount of disturbance and pollution in Valley Creek watershed is causing a change from
higher quality, more sensitive fish species to more tolerant and opportunistic fish species.
Temperature may be only one of the many compacting factors, but these data show the
decline of brown trout in the Valley Creek system. Additionally, even if the adult brown
trout can survive at slightly higher temperatures, the spawning practices of the species are
also temperature dependent. Brown trout eggs can only hatch in the limited temperature
range of 1.9 – 11.2˚C and time until hatching is also influenced by water temperature
(Carlander 1969). Interrupted or less than ideal spawning conditions could severely threaten
the existing brown trout populations. Therefore, if the warming trend in Valley Creek
continues, the naturally reproducing brown trout population is likely to decline rapidly.
Creek chub may act as a displacement species as the temperature becomes too warm
for the brown trout populations to reproduce and grow. Creek chub have a very similar
niche to brown trout except that they are much more pollution tolerant, meaning they can
survive warmer temperatures, siltation and more shallow water (Leonard and Orth 1986).
White suckers also have wider environmental tolerances, so they often are quite abundant in
more polluted aquatic systems (Pennsylvania Department of Environmental Protection
2002). Kemp and Spotila (1997) noted that creek chub were absent from the Valley Creek
system outside of the upper reaches. In 2001 and 2002, creek chub were found at nearly
every station throughout the watershed. The data from our study clearly show that brown
trout populations in Valley Creek watershed have shifted and that the remaining individuals
have decreased in number.
The two other species of salmonids in the Valley Creek system, rainbow trout and
brook trout are already on the decline. Brook trout are the only native salmonid to Valley
Creek watershed; rainbow trout and brown trout were both introduced species (Kemp 1994).
Salmonids in general are sensitive to rising temperatures. If urbanization were in fact
causing a significant increase in stream temperature in the Valley Creek system, it would be
lethal for these other two species, especially brook trout, which are even more temperature
restricted than brown trout (Spotila et al. 1979).
Kemp (1994) noted the presence of both rainbow trout and brook trout but collected
only three or four individuals. Only one individual of each of these species was collected
during the present study. This could be due to a decline in these populations or a result of
their patchy distribution throughout the watershed. It should also be noted that a remnant
population of brook trout has been historically reported (Kemp 1994 and M. Boyer, pers.
comm.) in the upper reaches of Crabby Creek, but the present study did not sample at this
location. So it is unclear if this population is still intact and reproducing.
How do we know that it was not just random chance that those fish happened to be
there during these sampling periods and that the two years are comparable to each other or
to the fish assemblages reported by Kemp and Spotila (1997)? Many studies have shown
that most species of fish do not travel very far. However, if the water quality becomes too
degraded, the fish would likely move to a more livable section of the stream to avoid death.
Rodriguez (2002) supports this restricted movement paradigm for fish, which states that
adult fish in streams are sedentary and spend most of their lives in short (20-50m) reaches of
a stream. Rodriguez measured the decline of recaptures with distance from home section to
test this hypothesis. The median displacement for 27 salmonid populations was 27.7 m.
For 5 of 6 species looked at in his study, the median displacement was < 51 m. Most
populations appeared to be composed of a majority of stationary individuals with the mobile
proportion exceeding 50% in only 5 of 27 populations. This supports the thinking that local
land use is indeed continuously affecting the same populations of fish.
Knouft and Spotila’s (2002) study of movements of brown trout in Valley Creek
also showed restricted movement patterns. The telemetered brown trout were shown to
spend extended periods of time within a six-meter area interspersed with longer range
movements that ranged from 20 m to 1000 m. Additionally, the trout that moved 1000 m
apparently did so to avoid an iced-over portion of the stream. All long-range movements of
fish in this study were made from a site with a deep pool and or heavy cover to the next
adjacent pool or area of heavy cover.
There has been some debate over the importance of buffer or riparian zones versus
whole catchment approaches to quantifying the impact of land use on water quality in
streams and rivers. Studies have shown conflicting results, some show that buffer
characteristics are more highly correlated with aquatic integrity (Lambert and Allan 1999),
others point to catchment land use as the determining factor (Roth et al. 1996, Allan et al.
1997 and Silva and Williams 2001) and still others say there is a correlation to both buffer
and catchment ( Pan et al. 1999, Richards et al. 1996). Silva and Williams (2001) addressed
this issue looking at a number of streams and rivers using similar GIS tools as were used in
the present study. Their conclusion stated that water quality was better correlated with
catchment-scale landscape than with buffer zones. They also added that the best correlation
was in areas that had both a low ISC and a functioning riparian corridor. Riparian
deforestation associated with urbanization reduces food availability, change stream
temperature, and disrupt sediment, nutrient and toxin uptake from surface runoff (Paul and
Meyer 2001). However, the value of riparian habitat is reduced if the stormwater system is
not functioning as designed or was designed to bypass riparian areas and discharge directly
into the stream.
Wang et al. (1997) suggested that although total urban land use occupies a smaller
area globally than agriculture, it has a disproportionally large effect on biota. It is important
to remember that all urban growth does not have the same effects on biota. This may be a
function of riparian buffer that is more naturally present, to some extent, in residential areas
as opposed to commercial parking lots. Extensive fish surveys in Ohio suggested that
residential development, especially large-lot residential development, had less of an effect
on stream fishes than high density residential or commercial/industrial development (Yoder
1999). Riparian protection and less channel habitat degradation were responsible for
protecting the fauna in these streams, even up to 15% urban land use.
The amount of change in species composition and species diversity among 15
stations in one watershed was quite remarkable. The fish were very sensitive to watershed
characteristics related to water quality and quantity. In urbanized stream catchments, fish
abundances and diversity decline with increasing urbanization. In general, impervious cover
over 15% causes severe degradation of fish fauna (Paul and Meyer 2001).
In Valley Creek, total impervious surface cover in each sub-basin was more strongly
correlated with water quality parameters and fish community parameters than was riparian
corridor size. There may be a number of explanations for these results. The riparian buffer
zones along the creek are very patchy. For example, in Little Valley Creek there is a
kilometer stretch of stream that has excellent riparian habitat upstream and downstream of a
totally impervious steel manufacturing plant.
Furthermore, in the large lot residential developments one owner may have kept the
trees and natural growth along the creek, while the next lot down could have the lawn
mowed all the way down to the edge of the stream. These patterns of urbanization are not
uncommon throughout the watershed and more than likely are quite common in most
urbanized watersheds. An incomplete or choppy riparian corridor is not as effective in
protecting the stream and thus imperviousness of the entire sub-basin becomes the more
important factor. In the present study, no water quality or fish community parameter was
correlated to riparian corridor size. However, impervious surface cover was negatively
correlated (p< 0.10) with species diversity, abundance, evenness and number of brown trout.
Species diversity has been used as one of the major measures of the quality of fish
assemblages in this and other studies. Why is diversity important? Facilitation between
species is a key mechanism by which biodiversity affects the rates of resource use that
govern efficiency and productivity of ecosystems. Cardinale et al. (2002) stated that species
diversity reduces “current shading” and allows diverse assemblages of fish to capture a
greater fraction of suspended resources than is caught by any species monoculture. Changes
in species diversity may alter the probability of positive species interactions resulting in
disproportionately large changes in functioning of ecosystems.
Current ecological theory predicts that species diversity can influence the
consumption of resources that govern ecosystem processes through two types of effects,
complimentary and selection. A complementary effect occurs through either resource
partitioning or facilitative interactions between species and a selection effect occurs
whenever species diversity is correlated with the chance of resource use being dominated by
a single productive taxon. In streams with a mixed assemblage of species, the total
consumption of suspended particulate matter was 66% greater on average than in single
species streams (Cardinale et. al. 2002).
The addition or deletion of fish species from an aquatic community not only affects
the biodiversity but also the structure and functioning of that community. If diversity is
increased by the addition of a high trophic level species, the lower trophic levels will be
affected and the whole feeding regime will be altered (Gerkins 1994). In contrast, if the
“new” species is from a lower trophic level, such an addition may eliminate a prey or alter
the size distribution of the community. Then fish species that had fed on the prey species are
now without a sustainable food supply. If one or more members of the food web are injured,
declining or destroyed, a part of the biodiversity disappears and that deleted part will
influence the entire aquatic community.
One drawback of using a species diversity index to describe a fish community is its
insensitivity to qualitative changes in species composition (Richards 1976). A species
diversity index does not take into account the differences in taxa found at any given
location. Richards (1976) listed three distinct possibilities for having the same diversity at a
location for two separate sampling periods; 1) the species involved and their distributions
remained the same, 2) the species were the same but their relative abundances shifted or 3)
there was an entirely different group of species that had the same numerical qualities as the
original and thus the same species diversity. Jaccard’s similarity index can further be used
to make some useful quantitative comparisons of fish communities occupying adjacent
stations. While the information given in Figures 4A and 4B is useful in visualizing the
differences in the fish assemblages throughout the watershed, a numerical representation of
how similar any given station is to its nearest upstream neighbor is also important. Jaccard’s
similarity index is also important because it shows the stability in the fish assemblages over
time. If the fish communities are relatively consistent, it follows that water quality, habitat
availability and stream chemistry have remained consistent as well. The results from the
Jaccard index scores showed a great dissimilarity between adjacent stations. This supports
the idea that urban watersheds like Valley Creek are not acting as a contiguous unit and that
each section of stream is affected by local land use. Stream sections that are of the same
order, have similar flow regimes, are in the same geologic formation and are only about a
kilometer apart can have very distinct fish assemblages.
Fine sediment as a non-point source pollutant of streams is a major concern in many
urban catchments and Valley Creek is no exception. In this system there was a trend of
increasing fine sediment deposition in periods of lower flow associated with urbanization.
Storms washed out the larger sediment, leaving scour holes that were then filled in with fine
sediment from the exposed soil of various construction sites that washed into the stream as
run-off. It is also important to note that presumably all of the sediment in the stream
channel measured during the course of this study was deposited since the flooding from the
hurricane in the fall of 1999.
Although sediment transport and sedimentation are naturally occurring processes,
they are greatly enhanced by anthropogenic land use practices (Murphy et al. 1981).
Species of fish tend to occur on or near particular substrates, although they are not as closely
connected to the substrate as macroinvertebrates (Allen 1995). However, when it comes to
spawning, the type of substrate becomes vitally important for a majority of fish species.
Many species of fish, including brown trout need clean rocky substrates on which to lay
their eggs and when these natural surfaces get covered with fine sediment spawning is
interrupted. Throughout a majority of the stream system, fine sediment is covering the
natural gravel stream bottom. Heavy silt deposition is detrimental to most aquatic
organisms. It causes scour during high flows, reduces habitat and the exchange of gases and
water by filling in interstices, reduces algal and microbial food supply, changes the
macroinvertebrate community and suffocates many species of fish eggs (Allen 1995, Kemp
and Spotila 1997).
For example, it has been demonstrated that excessive silt and/or fine sediment
particles can retard or prevent development and hatching in brown trout eggs (Cooper 1965,
Shirvell and Dungey 1983, Chapman 1988). Hachmöller et al. (1991) showed that stream
reaches with varying degrees of fine sediment also had different compositions of
macroinvertebrates. As urbanization continues to increase the sediment loading, there will
be less of these rocky bottom areas available, thus theoretically affecting the trout
population. The severe drought that took place throughout the summer of 2002 in the entire
southeastern Pennsylvania region had dramatic effects on the Valley Creek watershed. Not
only was the drought the likely cause of their being fewer total fish along with lower species
diversity, but also the drought was also harmful in terms of increased sediment deposition.
Brown trout are under the most immediate and severe threat of all the species in Valley
Creek due to their high intolerance for warmer temperatures and increased siltation.
Creek chub and white sucker are two species that can tolerate more degraded stream
conditions including increased sediment loading and warmer temperatures. The decrease in
brown trout populations, coupled with an increase in creek chub and white sucker
populations and distributions reflected not only the warming temperatures but also the
increase in fine sediment to the stream. The significant decrease in condition factor of the
brown trout from Kemp’s (1994) study to the present study also supported the declining
health of the brown trout in this system. Condition factor quantifies the physical health of
the fish and an overall decline in condition factor was seen especially in the Valley Creek
branch of the watershed.
Seasonal changes in condition factor have been previously reported with the highest
values coming in the summer months (Carlander 1969). Therefore, condition factors
calculated for Valley Creek were likely at their highest point of the year when sampled and
are comparable to Kemp’s (1994) data. Condition factors for creek chub remained
constant over the two years of our study while sucker species increased in condition factor
from 2001 to 2002. The sustained physical health of creek chub, as shown by condition
factor, suggests a greater ability to withstand the effects of the drought. The increased
condition factor of sucker species reflected an ability to not only sustain their health under
drought conditions, but to use the conditions to their benefit.
Does Valley Creek watershed adhere to the general principles put forth in the River
Continuum Concept? The River Continuum Concept (RCC) (Vannote et al. 1980) has been
the main conceptual framework for examining lotic systems (Allen 1995). It is a theory that
suggests that rivers and streams, from headwaters to mouth, present a continuous gradient of
physical conditions. This gradient should elicit a series of responses within the constituent
populations resulting in a continuum of biotic adjustments and consistent patterns of
loading, transport, utilization and storage of organic matter (Vannote et al. 1980). For
example, in streams, species diversity, richness and abundance is expected to increase as
you move downstream and increase stream order. These increases are the result of
increasing channel width, increasing flow, and greater habitat complexity. Although the
present study did not specifically set out to test the RCC in urban streams and not all aspects
of the RCC were analyzed, there were some obvious trends apparent in the data that
contradicted what is generally accepted for stream systems.
In general, the fish assemblages in Valley Creek do not follow what is expected from
the RCC theory. In the model RCC theoretical stream, fish assemblages would be rather
constant with one or two additions or deletions moving from upstream to downstream. This
was not observed in any systematic fashion throughout the Valley Creek watershed, as fish
assemblages were patchy and non-uniform. According to the RCC, the largest fish would be
in the downstream reaches of the creek where there are wider channels, increased flow and
greater habitat complexity. Again, in the Valley Creek system this was not observed. The
largest fish were found in the middle sections of both branches of the stream, in the second
and third order reaches. In both branches the trend was similar. Smaller, more pollution
tolerant fish were found in the upper most reaches of the stream, the middle sections had the
largest fish and the most brown trout, then from the stations just upstream of the confluence
on each branch to the mouth the fish assemblages started to decline. In the only fourth order
reach in the system, the fish communities were less diverse and the fish were smaller. This
may be a result of the cumulative effect of all the urbanization upstream impacting the
downstream reaches despite the relative undeveloped land use of VFNHP. Allen (1995)
states that despite being a useful way to think about the changes that occur along the length
of a river, there is great uncertainty as to how well the RCC is a reflection of reality. Most,
if not all, of the studies supporting the RCC have been done in relatively undisturbed
watersheds (Allen 1995). Many non-urban streams and rivers do follow the predicted
model of the RCC to some extent (Minshall et al. 1983). It is difficult to expect an urban
stream system to follow the same predicted patterns. So many anthropogenic manipulations
have occurred in stream morphology, water quality and local land use in urban watersheds
that sections of streams can be isolated from each other and often the stream does not act as
a continuous ecosystem. In Valley Creek, this is very evident and should be taken into
consideration during future watersheds studies in urban areas.
The urbanized stream acts more as a series of distinct sections that are connected
physically but do not function as one contiguous unit. Non-urbanized or less degraded
stream systems function as a unit, with consistent diversity patterns, increasing richness and
abundance further downstream. However, this urbanized watershed showed that local land
use characteristics at a particular station affected water quality, temperature, habitat and fish
assemblages in a non-continuous, patchy fashion. Our results show the obvious importance
of a watershed-scale approach. Each of the 15 stations used in the study were distinctive,
emphasizing the complex nature of urbanized stream ecosystems.
CHAPTER 6: CONCLUSIONS
Fish community data from fifteen sampling stations in Valley Creek watershed were
used to establish and document the impacts of urbanization on the fish assemblages this
creek supports. Clear and striking changes were evident in comparing the fish assemblages
from the present study with those collected in the same locations in 1993. Affects of the
drought during the summer of 2002 contributed to changes in fish abundance and size
distribution between 2001 and 2002. Warming stream temperatures throughout the Valley
Creek watershed are impacting the decline of brown trout, Salmo trutta, populations and
distributions. There is a much greater than expected annual fluctuation in stream
temperature, with differences as great as 20°C at some locations. Only one station had a
stable annual stream temperature.
As a result of the warmer temperatures and decreasing water quality, pollution
tolerant species such as creek chub, Semotilus atramaculatus and white sucker, Catostomus
commersoni, have increased in distribution and abundance while brown trout, Salmo trutta,
have declined because they can survive in these degraded conditions. Impervious surface in
the catchment for each station was more highly correlated with all fish community
parameters than size of the riparian corridor. Knowledge of groundwater inputs into Valley
Creek watershed through springs was crucial to understanding the patterns of fish species
diversity. High inputs of groundwater upstream of three Little Valley Creek stations
allowed these locations to support diverse fish assemblages despite up to 30% impervious
surface cover in its sub-basin. Additionally, two of these three stations even maintained
enough water quality to support brown trout populations, which likely would not have been
possible without the influx of clean, cold groundwater.
Jaccard’s similarity index showed a low degree of similarity between corresponding
stations from 1993 to 2001/2002. Some stations also showed a relatively low similarity at
the same stations between 2001 and 2002. There was also a low similarity between some
adjacent stations along the stream in the present study. This shows the long-term effects of
urbanization and the changes it causes in fish assemblages and also supports the idea of an
urban stream being discontinuous due to the localized and short-term presence of
urbanization.
Fine sediment is a significant contributor to the decline of fish communities because
of its detrimental impacts on spawning and suitable habitat. Resulting, at least in part, from
this increased sedimentation load is and will continue to be a shift from pollution intolerant
species to more tolerant ones. In general, the Valley Creek system does not follow the
expected patterns of fish community assemblages as predicted by the River Continuum
Concept (Vannote et al. 1980).
Much has changed in the Valley Creek watershed, from it’s historical land uses of
agriculture with large amounts of open space to the large push of urban growth in the 1980s
and 1990s to the condition it is in today with over 17% impervious surfaces with no end in
sight. This research has documented the vast array of insults and perturbations that have
been and are currently affecting the fish assemblages in Valley Creek watershed.
Kemp (1994) concluded from his work on Valley Creek that:
“The great majority of the Valley Creek system supports a productive,
naturally reproducing population of brown trout…” “Currently the brown
trout population in Valley Creek is in an excellent state of health, judging
from the widespread distribution of adult and juvenile members of this
species, total numbers, and high growth rates observed”…”however dramatic
changes in the fish community and benthic community in the most urbanized
sections of Valley Creek demonstrate the deleterious effects of impacts
associated with the accumulating alteration of the watersheds. … should
impacts due to urbanization continue to accumulate in the central and eastern
portions of the watershed, or intensify in the western end, it is possible that
these areas could experience alterations in the fish and benthic community
similar to those seen in the west end of the watershed now.”
Less than 10 years later, that prediction of the threat that continued urbanization
would have on the Valley Creek system has been realized. Based on size distribution, the
brown trout, Salmo trutta, population is still naturally reproducing but increasing water
temperatures are rapidly limiting habitat availability. The individuals that are left are
declining in numbers as well as physical condition. It is more difficult to distinguish
between the fish communities of the western end of the watershed where there has been
traditionally more urbanization and the rest of the watershed, which is under more current
development. Valley Creek watershed is no longer in “an excellent state of health” and the
conditions will likely worsen as urbanization continues and the basin becomes more
impervious unless changes are made in the planning of urban development and growth.
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APPENDIX A: TABLES Table 1: Locations and summary of sampling stations in Valley Creek watershed
Station
Location
Distance from mouth (km)
% ISC
Area of sub-basin (km2)
1 Valley Creek in VFNHP, mouth of Valley Creek (s.o. = 4)
0.2 16.8 60.7
2* Valley Creek in VFNHP, 300 m downstream of the covered bridge on Rt. 252 (s.o. = 4)
1.6 17.1 58.9
3*# Valley Creek in VFNHP, at Wilson Road and Wilson’s Run tributary (s.o. = 4)
3.1 17.5 57.3
4*# Valley Creek at LeBoutiller Rd., 400 m upstream of confluence with LVC (s.o. = 3)
6.2 13.6 29.6
5*# Little Valley Creek at Mill Road Park, 500 m upstream of confluence with VC (s.o. = 3)
5.5 24.4 16.6
6* Crabby Creek, major tributary to LVC at Westlakes Dr. (s.o. = 2)
6.9@ 16.4 2.3
7* Little Valley Creek at Vanguard Blvd. (s.o. = 2)
9.0 32 7.1
8* Valley Creek at North Valley Rd. (s.o. = 3)
6.9 13.8 29.2
9* Valley Creek at Church Rd. (s.o. = 2)
9.9 14.8 16.9
10 * Valley Creek at Valley Creek Park, Rt. 29 (s.o. = 2)
11.2 14.5 16.0
11*# Valley Creek at Ecology Park, along Conestoga Rd. (s.o. = 2)
14.2 15.2 5.5
12*# Little Valley Creek headwaters along Conestoga Rd. (s.o. = 1)
11.7 25.3 1.8
13* Valley Creek headwaters at Planebrook Rd. (s.o. = 1)
16.0 18.1 2.6
14 Valley Creek at Knickerbocker Landfill (s.o. = 2)
11.7 13.7 15.3
15* Little Valley Creek at North Valley Road (s.o. = 3)
7.2 28.9 10.5
* denotes stations also sampled by Kemp in 1993; # denotes sediment sampling stations; s.o. = stream order; VC= Valley Creek branch; LVC = Little Valley Creek branch; @ Crabby Creek, tributary of LVC
Table 2: Summary of water quality data by station in Valley Creek watershed
diff. = maximum temperature – minimum temperature
Temperature (˚C) Conductivity µS/cm pH Dissolved oxygen
(mg/L)
station range mean diff. range mean mean d.o. range mean
1 1.69 - 22.5 13.7 20.8 378 - 814 610 7.45 8.24 – 11.0 8.99
2 2.65 - 22.9 13.5 20.3 532 - 801 630 7.63 7.96 - 11.9 9.88
3 3.08 - 21.5 13.2 18.4 583 - 792 650 7.63 7.45 - 11.7 9.82
4 5.40 - 21.8 14.3 16.4 510 - 676 610 7.61 7.22 – 10.4 9.36
5 5.23 - 20.2 13.9 15.0 542 - 865 660 7.50 7.13 - 11.1 8.99
6 2.56 - 19.3 13.0 16.8 319 - 488 450 7.35 6.52 - 10.6 8.54
7 3.47 - 20.2 13 16.7 484 - 854 660 7.43 6.54 - 11.5 8.65
8 5.50 - 21.5 13.8 16.0 587 - 808 650 7.60 7.19 - 10.6 9.26
9 6.62 - 19.6 13.3 13.0 726 - 903 830 7.61 6.63 - 10.9 8.89
10 8.06 - 13.8 11.7 5.73 726 - 934 850 7.46 3.84 - 8.40 5.84
11 3.99 - 23.0 14.1 19.0 440 - 733 610 7.67 5.92 - 10.9 8.88
12 2.44 - 22.2 11.8 19.7 359 - 463 390 7.74 4.47 - 10.3 7.63
13 * * * 546 - 753 630 8.15 9.58 - 10.1 9.78
14 * * * 616 - 781 690 7.60 9.33 - 12.8 10.4
15 2.76 - 21.8 13.5 19.1 438- 1378 790 7.61 7.20 - 11.6 9.50
* full stream ranges were not available due to seasonal dryness
Table 3: Species list of fish collected in Valley Creek watershed
In order of abundance for 2001-2002 Catostomus commersoni white sucker Rhinicthys atratulus blacknose dace Semotilus atromaculatus creek chub Salmo trutta brown trout Exoglossum maxillingua cutlips minnow Hypentelium nigricans northern hognose Lepomis macrochirus bluegill Etheostoma olmstedi tessellated darter Lepomis gibbosus pumpkinseed Rhinicthys cataractae longnose dace Notropis spp. shiner spp. Lepomis cyanellus green sunfish Margariscus margarita pearl dace Micropterus dolmeuii smallmouth bass Ambloplites rupestris rock bass Salvelinus fontinalis brook trout Oncorhynchus mykiss rainbow trout Species caught in Valley Creek previously but not in 2001-02 Pimephales promelas fathead minnow 1,4
Cyprinus carpio common carp 1,4
Percina peltata shield darter 1,4
Ameiurus nebulosus brown bullhead 1,2
Lepomis auritus redbreast sunfish 1,4 Pimephales notatus bluntnose minnow 3
Cottus bairdi mottled sculpin 3
Anguilla rostrata american eel 1,2,4 Fundulus diaphanous banded killifish 1,2
Micropterus salmoides largemouth bass 1,4
Etheostoma nigrum johnny darter 1 Esox americanus redfin pickerel 1
Notropis amoenus comely shiner 1 Cyprinella analostana satinfin shiner 1 Notropis hudsonius spottail shiner 1
Notropis procne swallowtail shiner 1
Cyprinella spiloptera spotfin shiner 1
Ameiurus natalis yellow bullhead 1
Semotilus corporalis fallfish 1
Pomoxis nigromaculatus black crappie 1
Erimyzon oblongus creek chubsucker1
Luxilus chrysocephalus striped shiner 1
1 PA DEP for VFNHP 1987 3 Chester County Health Dept. 1976 2 PA Fish and Boat Commission 1983, 1996 4 Kemp 1992-1993
Table 4: Fish community data by station
* sample size too small in 2002 to make any reliable comparisons
- stations were dry summer sampling period
Station Simpson’s Diversity
Evenness Abundance Species Richness
2001 2002 2001 2002 2001 2002 2001 2002 1
2.5 * 0.77 * 21 4 5 3
2
1.8 3.9 0.70 0.84 18 30 5 6
3
2.6 3.7 0.83 0.85 37 68 5 7
4
2.9 * 0.68 * 33 8 7 5
5
3.9 2.3 0.86 0.73 24 16 6 5
6
3.6 2.9 0.96 0.80 18 27 4 6
7
3.2 3.0 0.85 0.94 39 19 6 4
8
5.4 2.9 0.88 0.78 55 30 8 5
9
4.0 2.5 0.81 0.93 36 17 7 3
10
4.0 3.3 0.93 0.90 42 29 5 4
11
2.5 2.0 0.93 0.99 42 17 3 3
12
1.2 - 0.87 - 28 - 2 -
13
- - - - - - - -
14
- - - - - - - -
15
4.4 3.0 0.88 0.78 33 38 6 6
Table 5: Fish community data by section of creek
Location
Simpson’s Diversity
Evenness
Abundance
Species Richness
2001
2002
2001
2002
2001
2002
2001
2002
Valley Creek
branch
5.6
3.7
0.83
0.80
207
101
11
7
Little Valley Creek branch
5.0
3.7
0.84
0.73
142
100
7
10
Downstream of
confluence
4.7
4.5
0.79
0.80
62
102
10
9
Whole
watershed
6.7
5.6
0.81
0.79
426
303
16
11
Table 6A : P values, r2, and n for linear relationships derived from fish community data in Valley Creek watershed, Chester County, PA (N.S. indicates a non-significant relationship if p> 0.05)
% ISC km from mouth stream order summer temp temp. diff. D.O. S.C.species diversity
2001 N.S. N.S. N.S. N.S. N.S. N.S. 0.0423, 0.324, 132002 N.S. 0.049, 0.403, 12 0.0128, 0.560, 12 N.S. N.S. N.S. N.S.
species richness2001 N.S. N.S. N.S. N.S. N.S. N.S. 0.0352, 0.344, 132002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
evenness2001* N.S. 0.0392, 0.360, 13 0.0297, 0.362, 13 N.S. N.S. N.S. N.S.2002* N.S. 0.0317, 0.458, 12 N.S. N.S. N.S. N.S. N.S.
abundance2001 N.S. 0.0498, 0.332, 13 N.S. N.S. N.S. N.S. N.S.2002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
total # brown trout2001+2002 N.S. N.S. N.S. 0.0013, 0.627, 13 0.0063, 0.507, 13 N.S. N.S.
prop. of brown trout2001+2002 N.S. N.S. N.S. 0.0026, 0.577, 13 0.0110, 0.459, 13 N.S. N.S.
* denoted inverse relationship
Table 6B: P values, r2 and n for linear relationships derived from fish community data in Valley Creek branch of Valley Creek watershed, Chester County, PA (N.S. indicates non-significant relationship if p>0.05)
% ISC km from mouth stream order summer temp temp. diff. D.O. S.C.species diversity
2001 0.0217, 0.503, 8 N.S. N.S. N.S. N.S. N.S. N.S.2002 0.0169, 0.531, 6 0.0270, 0.743, 6 0.0184, 0.787, 6 N.S. N.S. N.S. N.S.
species richness2001 N.S. N.S. N.S. N.S. N.S. N.S. N.S.2002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
evenness2001 N.S. N.S. N.S. N.S. N.S. N.S. N.S.2002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
abundance2001 N.S. N.S. N.S. N.S. N.S. N.S. N.S.2002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
total # brown trout2001+2002 N.S. N.S. N.S. 0.0066, 0.733, 8 0.0035, 0.783, 8 0.0245, 0.489, 8 0.0014, 0.741, 8
prop. of brown trout2001+2002 N.S. N.S. N.S. 0.0049, 0.758, 8 0.0060, 0.741, 8 N.S. 0.0009, 0.862, 8
Table 6C : P values, r2, and n for linear relationships derived from fish community data
in Little Valley Creek branch of Valley Creek watershed, Chester County, PA (N.S. indicates non-significant relationship if p>0.05)
% ISC km from mouth stream order temp temp. diff. D.O. S.C.
species diversity2001 N.S. N.S. 0.0214, 0.867, 5 N.S. N.S. 0.0097, 0.920, 5 N.S.2002 N.S. N.S. N.S. N.S. N.S. 0.0437, 0.790, 5 0.0306, 0.833, 5
species richness2001 N.S. N.S. N.S. N.S. N.S. N.S. N.S.2002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
evenness2001 N.S. N.S. N.S. N.S. N.S. N.S. N.S.2002* N.S. 0.0054, 0.989, 5 N.S. N.S. N.S. N.S. N.S.
abundance2001 0.0061, 0.941, 5 N.S. N.S. N.S. N.S. N.S. N.S.2002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
total # brown trout2001+2002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
prop. of brown trout2001+2002 N.S. N.S. N.S. N.S. N.S. N.S. N.S.
* denotes inverse relationship
Table 7: Brown trout distributions in Valley Creek Watershed
Common sites
Had brown trout in 1993
# of brown trout decreased in 2001
# of brown trout decreased more in 2002
total abundance of all fish decreased from 1993-2002
2
3
4
5
6
7
8
9
10
11
12
13
-
-
-
-
15
Table 8: Jaccard similarity index of stations in Valley Creek watershed - year to year
Section 1 - by station Station # 1993 v. 2001 1993 v. 2002 mean score 2001 vs. 2002 1 33 2 30 40 35 22 3 57 86 72 71 4 56 50 53 38 5 50 60 55 57 6 17 29 23 43 7 43 60 52 67 8 70 56 63 63 9 57 100 79 43 10 57 67 62 80 11 33 17 25 67 12 100 - 100 - 15 29 29 29 100 mean 50 54 59
Section 2 - by branch
1993 v. 2001/2002 2001 v. 2002
watershed 68 79
VC 70 66
LVC 50 73
Table 9: Jaccard similarity index of upstream adjacent stations in Valley Creek watershed
Station # 2001 2002
1 and 2 25 29
2 and 3 43 44
3 and 4 50 50
3 and 5 22 50
4 and 8 67 43
8 and 9 50 50
9 and 10 71 75
5 and 15 50 57
7 and 15 71 67
15 and 12 33 -
Table 10: Stream flow summary for Valley Creek watershed Summer 2001 and 2002 cfs cfs Summer 2001 Summer 2002 mean 18.3 mean 13.8med 15 med 10mode 14 mode 10stdev 14.0 stdev 22.8max 378 max 576min 5 min 6.6 24.8% decrease in mean streamflow from 2001 to 2002 June 2001 June 2002 mean 26.3 mean 20.1med 23 med 14mode 24 mode 14stdev 16.1 stdev 36.9max 155 max 576min 14 min 6.6 23.7% decrease in mean streamflow from 2001 to 2002 July 2001 July 2002 mean 15.3 mean 10.8med 14 med 10mode 14 mode 10stdev 12.9 stdev 4.5max 378 max 94min 8.8 min 8.4 29.7% decrease in mean streamflow from 2001 to 2002 August 2001 August 2002 mean 13.6 mean 10.6med 13 med 8.4mode 14 mode 8stdev 8.5 stdev 12.00max 129 max 145min 5 min 6.6 21.9% decrease in mean streamflow from 2001 to 2002
Table 11A: Sediment grain size analysis results for 5 stations in Valley Creek watershed
% fines Station # Jan-01 Apr-01 Oct-01 Apr-02 Oct-02 3 39 15 32 4 24 42 48 72 5 14 18 11 45 41 24 12 55
Table 11B: Fine sediment composition (µm) for 5 stations in Valley Creek watershed
Station 3 75 50 < 50 Station 4 75 50 < 50 Jan. 01 96.5 1.7 1.8 Jan. 01 96.5 1.5 2 Apr. 01 92 0.5 7.5 Apr. 01 95.2 0.1 4.7 Oct. 01 Oct. 01 97 0.8 2.2 Apr. 02 92.7 2.3 5 Apr. 02 88.5 1 10.5 Station 5 75 50 < 50 Station 11 75 50 < 50 Jan. 01 Jan. 01 Apr. 01 87.3 4.3 8.4 Apr. 01 33 0.3 66.7 Oct. 01 Oct. 01 89.7 2.7 7.6 Apr. 02 Apr. 02 Oct. 02 92.7 3 4.3 Oct. 02 82.9 8.8 8.3 Station 12 75 50 < 50 Jan. 01 Apr. 01 21.8 7 71.2 Oct. 01 Apr. 02
Table 12: Comparison of water quality data for station 4 (LeBoutiller Rd), Valley Creek
Temperature ( ˚C)
pH
Conductivity
(mS/cm)
Dissolved
Oxygen (mg/L)
July 2001
20.1
7.1
607
8.22
July 2002
21.8
7.3
586
9.25
Table 13: Summary of length and mass for all fish; 2001/2002
common name # of individuals mean mass (g) mean length (cm)
2001/2002 2001/2002 2001/2002
blacknose dace 59 / 88 <14 / <14 6 / 6
bluegill 24 / 8 36 / 53 9 / 11
brook trout 1 / 0 98/- 26/-
brown trout 55 / 30 124 / 126 19 / 17
common shiner 3 / 5 <14 / <14 6 / 6
creek chub 94 / 26 27 / 32 8 / 9
cutlips minnow 27 / 38 33 / 28 9 / 9
green sunfish 1 / 0 28/- 13/-
longnose dace 5 / 4 <14 / <14 6 / 6
northern hognose 20 / 19 87 / 48 18 / 11
pumpkinseed 12 / 3 36 / - 10 / -
rainbow trout 1 / 0 <14/- 6.5/-
rock bass 2 / 0 56/- 16/-
smallmouth bass 12 / 0 70 / - 10 / -
tessellated darter 5 / 14 <14/ < 14 7/7
white sucker 106 / 68 105 / 75 15 / 14
total abundance 426 / 303
species richness 16 / 11
Figure 1: Location of Valley Creek Watershed
1
2
3
4
6
58
15
7
121311
14
109
Figure 2: Sampling Stations, Valley Creek Watershed
0 1 20.5 Kilometers
Figure 3: Species Diversity vs. Impervious Area 2001 and 2002
0
1
2
3
4
5
6
0 5 10 15 20 25 30 35% Impervious area
Sim
pson
's D
iver
sity
Inde
x
below confluenceValley Little Valley Creek2001 2002 2001 2002 2001 2002
Figure 5A: Station 1
2001
n=1
n=1n=2
n=12
n=5
Brown troutBluegillSmallmouth bassWhite suckerCommon shiner
2002
n=2
n=1
n=1
common shinertessellated darterwhite sucker
Figure 5B: Station 2
2001
n=1
n=1
n=2
n=1
n=13
cutlips minnowbluegillrainbow troutrock basswhite sucker
2002
n=2
n=6 n=6
n=1
n=3
n=12
blacknose dacebluegillcommon shinercutlips minnowlongnose dacetessellated darter
Figure 5C: Station 3
2001
n=12n=20
n=2
n=2
n=1 Blacknose dacewhite suckerhognose suckertesselated dartercutlips minnow
2002
n=2 n=3
n=20
n=1
n=16 n=24
n=2
blacknose dacebrown troutcutlips minnowlongnose dacenorthern hognosetessellated darterwhite sucker
Figure 5D: Station 4
2001
n=2
n=18
n=2
n=1n=5n=5
blacknose dacebluegillbrown troutcreek chubtesselated darterhognose sucker
2002
n=2
n=1
n=2
n=1
n=2
brown troutcreek chubcutlips minnownorthern hognosetessellated darter
Figure 5E: Station 5
2001
n=2
n=1
n=5n=6
n=9n=1
blacknose dacebrown troutcreek chublongnose dace green sunfishwhite sucker
2002
n=2
n=1
n=1
n=2 n=10
blacknose dacebrown troutcreek chubcutlips minnowwhite sucker
Figure 5F: Station 6
2001
n=5
n=5
n=6
n=2
bluegillbrown troutpumpkinseedwhite sucker
2002
n=1n=1n=1
n=12
n=2
n=10
blacknose dacebluegillbrown troutlongnose dacenorthern hognosetessellated darter
Figure 5G: Station 7
2001
n=11
n=9n=17
n=1n=1
blacknose dacebluegillbrown troutcreek chubwhite sucker
2002
n=3
n=7
n=3
n=6
blacknose dacebluegillcreek chubwhite sucker
Figure 5H: Station 8
2001
n=6
n=5
n=14n=14
n=1n=3
n=1
n=9
n=6
blacknose dacebrown troutcreek chubcutlips minnowhognose suckerwhite suckerlongnose dace common shiner tesselated darter
2002
n=16
n=5
n=4
n=2
n=3
blacknose dacebrown troutcutlips minnowtessellated darterwhite sucker
Figure 5I: Station 9
2001
n=3
n=6n=9
n=2
n=15
n=1
blacknose dacebluegillbrown troutcreek chubhognose suckerwhite sucker
2002
n=7n=8
n=2
blacknose dacebrown troutwhite sucker
Figure 5J: Station 10
2001
n=2
n=12
n=12
n=5
n=11
blacknose dacebluegillbrown troutcreek chubwhite sucker
2002
n=13
n=4
n=5
n=7
blacknose dacebrown troutcreek chubwhite sucker
Figure 5K: Station 11
2002
n=8n=9
creek chubwhite sucker
2001
n=17
n=5
n=20
creek chubpumpkinseedwhite sucker
2002 - DRY
Figure 5L: Station 12
2001
n=25n=
3
blacknose dacecreek chub
Figure 5M: Station 15
2001
n=2
n=8
n=2
n=4
n=6
n=11
blacknose dacebluegillbrown troutcreek chubpumpkinseedwhite sucker
2002
n=18
n=12
n=2
n=2n=2
n=2
blacknose dacebluegillbrown troutcreek chubpumpkinseedwhite sucker
2.5 4.0 4.0
13 11 14 10 9 8
1.2
3.2
4.4
3.9
5.4 2.9 2.6 1.8 2.5
12
7
15
5
3.6 6
4 3 2 1
Totals ((taken each section as a whole)) Watershed: 6.3 Main branch: 3.7 Valley Creek: 5.6 Little Valley Creek: 5.0
Figure 6A: Fish Species Diversity Index, 2001
2.0
3.3
Totals (each section taken as a whole) Watershed: 5.6 Main branch: 4.5 Valley Creek: 3.7 Little Valley Creek: 3.7
4 8
9 10 14 11
13
Figure 6B: Fish Sp ** denotes too few fis
2.5
2.9** 3.7 3.9 **
5
15
2.3
3.0
3.5 2.9
2
6
3 2 1
1
ecies D
h for acc
7
iversity Index, 2002
urate and comparable index
Figure 7A: Valley Creek Watershed Land Use in 2001
farms2%
utilities3% roads
13%
public lands13%
commercial22%
residential41%
industrial6%
2%3%
8%
7%
7%
7%
22%
44%
public services
motels
auto shops & gasstationswarehouse
recreation/entertainmentrestaurants and retail
office buildings
vacant land zoned C
20%15%
30%
9%11%
15%
schools federal park landstate & local government local parksnon-profit orgs open space
1%
1%
1%
77%
20%
single family
multi-family
apartments
condos
vacant zoned R
Figure 7B: Valley Creek Land Use in 2001
farms2%
commercial24%
industrial11%
public lands6%
utilities2%
transportation11%
residential44%
1%
3%
23%
11%5%
36%11%
10%
servicesrestaurants & retailoffice buildingsmotelsauto repair/gas stationsrecreation/entertainmentwarehousevacant zoned C
31%
11%17%
29%
12%
schoolsstate and local gov'tlocal parksnon-profit orgsopen space
0.75%
27.60%
0.02%
1.48% 70.16%
apartmentssingle familymulti-familycondosvacant zoned R
Figure 7C: Little Valley Creek Land Use in 2001
farms1%
industrial4%
transportation13%
utilities6%
public lands12%
residential39%
commercial25%
2%
1%
47%
27%
5%4%
11%
3%
restaurants & retailservicesmotelsoffice buildingsauto repair/gas stationswarehouserecreation/entertainmentvacant land zoned C
19%
21%
20%
11%
29%
schoolsnon-profit orgslocal parksstate & local gov'topen space1%
3%4%10%
82%
apartmentsingle familymulti-familycondosvacant land zoned R
Figure 8: Industrial sites in Valley Creek Watershed
0 1 20.5 Kilometers
Paoli Rail Yard
Steel Mill
Bishop Tube CompanyFoote Mineral Site
Malvern TCE
Catanach Quarry
Cedar Hollow Quarry
Knickerbocker Landfill
Figure 9A: Fish Mass Distribution Valley Creek, 2001
0
10
20
30
40
50
60
70
13 11 14 10 9 8 4 3 2 1stations
upstream - dowstream
300 + g
150 - 300 g
30-150 g
< 30 g
Figure 9B: Fish Mass Distribution Valley Creek, 2002
0
10
20
30
40
50
60
70
80
13 11 14 10 9 8 4 3 2 1stations
upstream - downstream
300 + g
150 - 300 g
30-150 g
< 30 g
Figure 9C: Fish Length Distribution Valley Creek, 2001
0
10
20
30
40
50
60
70
13 11 14 10 9 8 4 3 2 1stations
upstream - downstream
31-40 cm26-30 cm21-25 cm16-20 cm11-15 cm8-10 cm< 7.5 cm
Figure 9D: Fish Length Distribution Valley Creek, 2002
0
10
20
30
40
50
60
70
80
13 11 14 10 9 8 4 3 2 1
stationsupstream - downstream
31-40 cm26-30 cm21-25 cm16-20 cm11-15 cm8-10 cm< 7.5 cm
Figure 10A: Fish Mass Distribution Little Valley Creek 2001
0
5
10
15
20
25
30
35
40
45
12 7 15 6 5stations
upstream - downstream
300 + g
150 - 300 g
30-150 g
< 30 g
Figure 10B: Fish Mass Distribution Little Valley Creek, 2002
0
5
10
15
20
25
30
35
40
12 7 15 6 5stationsupstream - downstream
300 + g150 - 300 g30-150 g< 30 g
Figure 10D: Fish Length Distribution Little Valley Creek, 2002
0
5
10
15
20
25
30
35
40
12 7 15 6 5stations upstream - downstream
31-40 cm
26-30 cm
21-25 cm
16-20 cm
11-15 cm
8-10 cm
< 7.5 cm
Figure 10C: Fish Length Distribution Little Valley Creek, 2001
0
5
10
15
20
25
30
35
40
45
12 7 15 6 5stations
upstream - downstream
31-40 cm26-30 cm21-25 cm16-20 cm11-15 cm8-10 cm< 7.5 cm
Figure 11: Scatterplot of Fish Length and Mass, 2001 and 2002
04080
120160200240280320360400440480520560600640
0 5 10 15 20 25 30 35 40 45length (cm)
mas
s (g
)
2001
2002