1. longitudinal patterns in ecological organization of rivers patterns in species richness patterns...
TRANSCRIPT
1. Longitudinal Patterns in ecological organization of Rivers
•Patterns in species richness•Patterns in species composition •Patterns in functional organization•Patterns in habitats and environmental template
2. Processes and Mechanisms…
ln N
o. o
f Sp
ecie
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Catchment Area (ln km2)
ln Fish = 1.42 + .23 * ln Area; R2 = .31
Species area curves for Stream Fish in356 Catchments: Lower Peninsula, Michigan
3
3.25
3.5
3.75
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4.25
4.5
4.75
5.5 6 6.5 7 7.5 8 8.5 9 9.5
Basin Area (ln km2)
ln Fish = 1.25 + .36 * lnArea; R 2 = .83
Species Diversity of Stream Fish Assemblages
in 18 Major River Basins: Lower Peninsula, Michigan
ln N
o. o
f Sp
ecie
sln
No.
of
Spec
ies
(Sepkowski and Rex 1974) Bivalve [Unionidae] spp in Atlantic coastal rivers
Longitudinal Zonation in species composition
Observations•Carpenter (1928)•Huet (1949-1962)•Illies et al. (1955,1963)•Statzner (1986)
Theories
Huet’s fish-zones of Western Europe (1949-1962)
Huet’s “slope rule” for western European streams
Source areas: glacial meltwaters, springs, wetlands, lakes.small very cold, low to moderate slopes, fauna variable
Mean monthly temp rises to 20 C; high oxygen concentrationsflow is turbulent; erosional, gravel-cobble substrate predominateFauna is cold stenothermal. No true plankton.
Mean monthly temp above 20 C; oxygen deficits may occur.Flow is slower, tends towards laminar. Sand and finer substrates are dominant.Fauna is eurythermal and most species well-adapted to lentic settings.Plankton develops.
Crenon
Rhithron
Potamon
Illies (1955) Major River Zones
Latitude: high middle lowIllies and Botosaneanu (1963)
Illies (1955)
Variables associated with longitudinal patterning•changes in biological community•temperature•substrate•hydraulics (slopes, velocities, power dissipation)
Processes associated with longitudinal structure•changing landscape controls on carbon production [light, nutrs, alloch source]
•demographic equilibria•changing temperatures•patterns in hydraulic stress and disturbance•increasing habitat diversity with hydrologic scale•population interactions (predation, competition, and disease)
•{changes in water quality}
What causes Longitudinal variation in biological communities?
The River Continuum Concept[RCC]
Vanote et al 1980
Key ideas in the RCC
Hydraulic gradients organize carbon sources for the food webHydraluic gradients organize temperature variability
Community composition equilibrates to carbon sourcesSpecies diversity reflects temperature variability
emphasis on continua [gradients] rather than zones
Sources and fate of organic carbon
two general categories for sources
allochthonous from “outside”soil water, leaves, woody debris, blown in insects,etc.
autochthonous from “self”aquatic primary producers:vascular plants, algae, autotrophic bacteria
•terrestrial versus aquatic origin•here versus there
background concepts
decomposers
allocthonous
autochthonous
DETRITALPOOL
[algae+ macrophytes]
invertivorous fish /birds
grazersshredderscollector-gathersfilter-feeders
invertpredators
[terrestrial
leaves, wood, DOC]
piscivorous fish
piscivorous birds /mammals
Bacteria & fungi
Veloc
Light
Nutrients
Veg
Edge/area
RCC background concepts
NR411 trophic role: decomposer producer consumerRiver Food Web food web position: primary primary secondary tertiaryBASICS trophic category: herbivore invertivore piscivore
functional feeding designation: grazer shredder filter-feeder collector predator predatorCommon Name Principal Taxa?? bacteria x?? fungi xmacro Algae Chlorophyceae and others xdiatoms Bacillariophyceae xmosses Bryophytes xaquatic plants Macrophytes xsow Bugs Isopoda xscuds Amphipoda x xsnails Gastropoda x x xclams Bivalvia xmayflies Ephmeroptera x xstoneflies Plecoptera x x xdragonflies Odonata xdamselflies Odonata xbugs Hemiptera x xalder and dobson fliesMegaloptera xcaddisflies Trichoptera x x x2-winged flies [e.g. midges, blackflies]Diptera x x x x xbutterflies Lepidoptera xcrayfish Decapoda x xboney fishes teleost fishes x x x xbirds x xmammals otter, mink, beaver, people x x
detritivore/omnivore
various spp [kingfishers, mergansers, herons]
Relative importance of autochthonous and allochthonous inputs often a matter of physical opportunitye.g. lakes versus small woodland stream
allo>autoCPOM
auto>allo
allo?autoDOC
sometimes a matter of human intervention-e.g.: organic pollution
Death, Detritus and Decomposition
allochthonous inputs are already usually dead or soon dead -> detrital carbonautochthonous carbon eventually dies -> detrital carbonbecause HOH is a solvent, the chemical nature of detritus rapidly diverges from that of living carbon
role of the biota
bacteria & fungi colonize detrital surface and enzymatically extract labile compounds
larger macro-invertebrate shredders (caddisflies, craneflies, some stoneflies, amphipods etc.) mechanically breakup larger pieces (CPOM) while feeding on attached decomposers and in some cases on the CPOM itself…
really feeding on the microbial community on the CPOM; like peanut butter on a cracker
Carbon form Lipids Carbohydrates Cellulose/structural polysaccharides
Protein
Deciduous leaf 8 22 29 9Deciduous wood 2-6 1-2 36-50 insigbacteria 10-35 5-30 4-32 50-60fungi 1-42 8-60 2-15 14-52Aq. macrophytes 4-5 20-70 14-61 8-35
Decomposition in an aquatic environment
DecompositionAutolysis + leaching + mechanical breakdown + biochemical mineralization by respiration
generally involves a serial reduction in both size and quality
CPOM->FPOM->VFPOM<->DOM -> INORG Cmediated by biology
bacteria,fungi,shredders, fp detritivore
Example plant K (days -1) T50 T90
White oak (Quercus alba) .005 or less 4.6 months >15 monthsDogwood (Cornus amomum) .010-.015 1.5-2.5 months 8 months
Cattail (Typha latifolia) .01 2.5 months 8 monthsNajas (N.flexilis) .022 1+ month < 4 monthsPondweed (Potomogeton spp.) ~.1 1 week < 1 month
masst = massinit * e -Kt
Decomposition rates
time% r
emai
ning
•differential decomposition rates•Allochthonous: willow>alder>dogwood>maple>aspen>oak>pine&spruce•Autochthonous: algae> submersed aquatic macrophytes> emergent/terrestrial macrophytes
• life cycle timing of shredders often cued to cued to leaf fall in temperate NA
2 sources: allochthonous and authochthonous2 pathways: detrital and herbivorous
decomposers
allocthonous
autochthonous
DETRITALPOOL
[algae+ macrophytes]
invertivorous fish /birds
grazersshredderscollector-gathersfilter-feeders
invertpredators
[terrestrial
leaves, wood, DOC]
piscivorous fish
piscivorous birds /mammals
Bacteria & fungi
P/R = Ecosystem Photosynthesis /Respiration
P/R ~ autoch /(autoch + alloch)
P/R ~ total carbon produced/ total carbon respired
Photosynthesis Respiration
OrgCarbon
Photosynthesis Respiration
OrgCarbon
P/R>1
P/R<1
Allocthonousinputs
Respiration
OrgCarbon
P/R<1Photosynthesis
autotrophic
heterotrophic
Heterotrophic(dystrophic)
Advective transport
“downstream”
The River Continuum Concept[RCC]
Vanote et al 1980
Caveats…
Species- Area Relationships
Darlington 1952Preston 1962MacArthur and Wilson 1967
Number of individuals
Num
ber
of ta
xa
Observed: log-normal distribution
Log S = .263 J/m + 3.17S …# of sppJ …# of individuals in samplem …# of individuals in rarest spp
if randomly dispersedJ~ area sampled
S = c AREA Z
Z =theoretical = .26insular fauna= .23-.35non-insular = .12-20
Sample size
Imm
igra
tion
rat
e
Number of species
Ext
irpa
tion
rat
eIm
mig
rati
on r
ate
Number of speciesE
xtir
pati
on r
ate
smaller
larger
MacArthur and Wilson’s
Equilibrium Theory
[Island Biogeography 1967]harsher
milder
Imm
igra
tion
rat
e
Number of species
Ext
irpa
tion
rat
eIm
mig
rati
on r
ate
Number of species
Ext
irpa
tion
rat
e
upstream
Downstream-larger upstream species pool Demographic equilibrium
applied to river networks
Harsher-less storage
Milder-more storage-
Dowbstream equilib.
Upstream equilib.
Temperature
its’ effect on biologyis profound
Zonation and temperature
Some thermal changes are more important than other
SHORTWAVE RAD.
LONGWAVE RAD.
CONDUCTION
CONVECTION
EVAPORATION
BLACKBODY
Ground water
ADVECTION
Tributaries
ADVECTION
dheat/dt = Radiation (short-wave) f(SA,sunlight)Radiation (long-wave) f(SA,air temp)Back Radiation f(SA, water temp)Convection f(SA,temp diff,wind)Conduction f(Perim,soil temp)Evaporation f(SA,humidity,wind)Advection f(source temps)
Heat Balance Equation:
Water temp = heat units/volume * 1/specific heat
Proximate mechanism:heat Budget
dheat = Radiation (short-wave) f(SA,sunlight)Radiation (long-wave) f(SA,air temp)Back Radiation f(SA, water temp)Convection f(SA,air-water temp diff, wind)Conduction f(Perim,soil-water temp diff)Evaporation f(SA,water temp, humidity,wind)Advection f( confluing source temps)
when dheat = 0, temperature equilibrium (constant)
Temp equil = T0 e-kt
Proximate mechanism:heat Budget
Longitudinal effects:
Te
Velocity?
Volume (Q) ?
Proximate mechanism:heat Budget
Runoff routing
GW routing
Ultimate mechanism:landscape
dheat/dt =
Radiation (short-wave) f(SA,sunlight)Radiation (long-wave) f(SA,air temp,riparian structure)Back Radiation f(SA, water temp)Convection f(SA,air-water temp diff, wind)Conduction f(Perim,soil-water temp diff)Evaporation f(SA, temp, humidity diff,wind)Advection f( confluing source temps &vol)
Stratification effects f(lentic volume,SA,strat)
riparian shade,climateriparian shade,climatewater temperaturechannel shape,climate
channel shape,climatewind, riparian conditions
hydro-geology,landuse
lakes,wetlands,reservoirs
Key modifying factors
heat content proportional to volumeheat flux proportional to surface area
0
5
10
15
20
25
30
0 2000 4000 6000 8000 10000 12000 14000 16000
July
mea
n C
o
Watershed Area km2
Diel effects:
Te_day
Te_night
Velocity?
Volume (Q) ?
Proximate mechanism:heat Budget
0
2
4
6
8
10
12
14
16
1
162
323
484
645
806
967
1128
1289
1450
1611
1772
1933
2094
2255
2416
2577
2738
2899
-2
0
2
4
6
8
10
12
14
16
18
1
163
325
487
649
811
973
1135
1297
1459
1621
1783
1945
2107
2269
2431
2593
2755
2917
Upper CedarApril, 2003
Lower CedarApril, 2003
0
2
4
6
8
10
12
14
16
18
20
0 2000 4000 6000 8000 10000 12000 14000 16000
Dai
ly f
lux
Co
0
5
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25
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0 2000 4000 6000 8000 10000 12000 14000 16000
July
mea
n C
o
Watershed Area km2
0
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0 2000 4000 6000 8000 10000 12000 14000 16000
Dai
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lux
Co
Longitudinal Gradients in depth, velocity, substrate, shear stress,
Velocity
Diffusion,Reaeration
&metabolism
Position and
movement
shear
substrate
Habitat utilization
Catastrophicdisturbance
703.136
1.38952e-008
xt
yt
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axx
axy
axz
ayx
ayy
ayz
azx
azy
azz
.5
.3
.1
.75
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.1
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.7
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xr .01yr .007zr .05
A Lotka-Volterra 3 species simulation
kx 600ky 1000kz 500
dx/dt = rX - (kxX - yxY - zxZ) 1/kx
dy/dt = rY - (kyY - xyX - zyZ) 1/ky
dz/dt = rZ - (kzZ - yzY - xzX) 1/kz
redbluegreen
703.136
9.98855e-009
xt
yt
zt
endt1 timet
Disturbance frequency = 0
xt
yt
zt
timet
rate of increase carrying capacities
Disturbance frequency = 2
578.394
1.43438
xt
yt
zt
endt1 timet
Disturbance frequency = 4
703.136
9.98855e-009
xt
yt
zt
endt1 timet
Disturbance frequency = 0
455.165
10
xt
yt
zt
endt1 timet
Disturbance frequency = 7
466.805
1.99872
xt
yt
zt
endt1 timet
Disturbance frequency = 13
xt
yt
zt
timet
703.136
9.98855e-009
xt
yt
zt
endt1 timet
Disturbance frequency = 0
Disturbance frequency = 20
26.2597
1.17644e-044
xt
yt
zt
endt1 timet
Disturbance frequency = 100
Log Frequency of Disturbance
Num
ber
of s
peci
esT
otal
pop
ulat
ion
size
Intermediate Disturbance Hypothesis
0.0 0.1 1.02 3 4 5 6 7 8 2 3 4 5 6 7 8 2 3
(Critical SS for d84 / RS) bankfull
1.0
10.0
100.0
1000.0
10000.0
2.03.04.06.0
20.030.040.060.0
200.0300.0400.0600.0
2,000.03,000.04,000.06,000.0
20,000.030,000.040,000.060,000.080,000.0
Be
nth
ic B
iom
ass
(m
g m
-2)
Nutrient gradients and the regional structure of stream communities
C.H.Riseng, M.J Wiley and R.J. Stevenson2
Geomorphic effects on Biology
What kinds of Disturbances might potentially shape stream insect communities?
High Flow events (Floods)
Low flow events (Droughts)
Pathogen outbreaks (Disease)
Velocity
Diffusion,Reaeration
&metabolism
Position and
movement
shear
substrate
Habitat utilization
Catastrophicdisturbance
Fick’s Law
again provides a basic description of this diffusive process
diff rate = K (saturation - concentration) diff rate = kA/L (pO2 inside - pO2 outside)
k=rate constant characteristic of the type of tissue oxygen must diffuse across (gill, cell wall. etc.)A= exchange surface area where diffusion can occurL= diffusion distance (how far molecules must travel)(pO2 inside - pO2 outside)= gradient in partial pressure of oxygen
Because the rate of molecular diffusion is faster in air than in water all organismsthat take dissolved oxygen from the water to support their metabolism face a fundamental physical constraint related to diffusion rate:
(pO2 inside - pO2 outside) gradient in oxygen concentration
effectively depends on the external oxygen concentration since internal oxygen levels almost always low
for a simple imaginary organism
time
resprate
begins with resp rate set by kA/L and the external O2 concentrationbut rate of resp decreases with timeoccurs because of O2 depletion immediately around exchange surface
average diffusiondistance
average diffusiondistance
average diffusiondistance
time 1
time 2
time 3
time
resprate
Intrinsic problem with diffusion in water
due to relatively low diffusion coeff in water
solution: ventilate replace water at exchange surface
Stenacron
As the environmental O2 concentration declines, the concentration gradient in Fick’s eq, also declines... regulators must compensate by ventilating more rapidly in order to decrease the diffusion distance and offset the gradient decline.
Many aquatic animals actively ventilate exchange surfaces
ventilation periodically replaces spent water controlling deterioration of diffusion distance
animals which manipulate diffusion distance or other parameters of Fick’s law are called respiratory regulators
animals ventilate by different methodse.g. mayflies, fish, dragonflies
regulators
conformers
oxygen concentration
respirationrate
Not all aquatic animals invest energy and tissue in diffusion regulation
organisms which let their respiration rate vary with ambient O2 levels are calledrespiratory [ metabolic] conformers
For conformerscurrent velocity can act as asubstitute for O2 concentration in terms of regulatingrespiration rates.
For regulators reduced velocityrequires more work and therefore energy
Concentration-velocity tradeoffs
Heterotroph oxygen requirements
Even regulators have a concentration below which they can not further compensate by ventilation, below that critical concentration metabolic rate declines with declining oxygen. For regulators, this critical concentration represents a concentration threshold below which an organisms energy supply rapidly declines.
When respiration rates are only sufficient meet current maintenance costs, there is no excess eenergy to invest in foraging, growth or reproduction. The concentration of oxygen which provides only this level of respiration is known as the incipient lethal level, since an organism/population (although it may live for some time) cannot achieve reproductive below this level.
At some low concentration (the acute lethal level) respiration rate is so far below immediate maintenance needs that rapid death follows.
}scope foractivity
critical concentration
incipient lethal levelacute lethal level
maintenance rateRespiration
rate
Oxygen concentration ---->
Sublethal affects of low oxygen
When [O2] lies between the critical concentration and the incipient lethal level, an organisms ability to do physiological work is diminished.
reduced oxygen can have important sublethal affects on feeding, growth, locomotion and even survival
•Concentrations below 1-2 ppm are lethal to a wide array of aquatic organisms. •Concentrations below 4 ppm are lethal to many, a common regulatory water quality standard.•Some organisms can survive <1 ppm (are especially tolerant) and dominate low oxygen environments.
•Velocity - [O2] tradeoffs can be important here too, especially for conformers.
Lethal Limits
Acute lethal levels of oxygen vary considerably between organisms
Acu
te le
thal
[O
2] p
pm
1 2 3 4 5 6 current velocity cm sec-1
ATMOSPHEREHenry's law
for gases dissolved in water
[c]=solubility * partial pressure
[c] is the equilibrium saturation conc
= the concentration the system reaches if left alone
note it is independent of starting concentration
What determines Oxygen concentrations?
ATMOSPHEREHenry's law
[c]=solubility * partial pressure
[c] is an important benchmark if water conc > henry's saturation value then atm is a sink if O2 is less than saturation concentration: atmosphere is a source
Henry's law applies to all gases in the atmosphere
Different partial pressures and different solubility lead to different
concentrations in aqueous solution.
CO2 02 N2
Partial pressure% 0.03 20.99 78.0 ppm
solubility at 0 C 3350 ppm 69.5 ppm 28.8 ppmsolubility at 10 C 2320 ppm 53.7 ppm 22.6 ppmsolubility at 20 C 1690 ppm 43.3 ppm 18.6 ppmsolubility at 30 C 1260 ppm 35.9 ppm 15.9 ppm
saturation at 0C 1.005 ppm 14.5 ppm 22.4 ppmsaturation at 10C 0.70 ppm 11.1 ppm 17.5 ppmsaturation at 20C 0.51 ppm 8.9 ppm 14.2 ppmsaturation at 30C 0.38 ppm 7.2 ppm 11.9 ppm
Fick’s Law provides a basic description of the rate at which diffusive processes occur.
diffusion rate = K ([Saturation] - [O2 ] )
k = rate constant, sometimes called the diffusivityBulk reaeration rate
k = f[molecular diffusivity and eddy diffusion (turbulence)]
How long does it takeOxygen to reach saturation?
ATMOSPHERE
ATMOSPHERE
time
diffusionrate
Saturation0
Fick’s Law implies that Oxygen concentration approach equilibrium asymptotically When [saturation-DO] is large, rates of exchange with the atm are highWhen [saturation-DO] is small, rates of exchange are small
The direction of oxygen exchange depends on Henry’s law•if over-saturated (supersaturated) water will lose oxygen to atmosphere•if under-saturated, water will gain oxygen from the atmosphere
diffusion rate = K ([Saturation] - [O2 ] )
MassInput 1
Input 2
Output 1
Output 2
Boxes = mass storagearrows = rates of flux
then
mass in storage per unit time = inputs - outputs
For the example diagram above
d/dt Mass=[ (Input 1 + Input 2) - (Output 1 + Output 2)]
Using a Mass Balance Approach
photosynthesis respiration
diffusive aeration
O2
ATM
O2 = Photosynthesis - Respiration diffusion
d/dt O2=[ P - R k([saturation]-[O2])]
Mass balance for O2
Respiration due organic pollutionCarbon and nitrogen
(ss +diss)
diffusive aeration
O2
ATM
O2 = Respiration diffusion
d/dt O2=[R k([saturation]-[O2])]
predicts an temporary oxygen sag downstream form sewage plant effluents
Streeter-Phelps Model
DAY DAYNIGHT
diffusion
P - R
supersaturated
+++++++++++++++++++++----------------------------------++
++++++++++------------------------------------++++++++
100% Saturation 100% Saturation
DAY DAYNIGHT
diffusion
P - R
supersaturated
---++++++++++++++++++--------------------------------------
+++++++++-------------------------------++++++++
100% Saturation 100% Saturation
DAY DAYNIGHT
diffusion
P - R
supersaturated
-+++++++++++++++++-------------------------------+++++++++++------------------------------------++++++++++
100% Saturation 100% Saturation
When biological rates are high (e.g., nutrient-rich systems like agricultural streams) or diffusion rates are relatively slow (e.g. stagnant ponds), biological processes can swamp diffusion rates and lead to widely fluctuating diel curves
The shape of this diel oxygen curve is determined by the relative magnitude of the component rates [diffusion, photosynthesis and respiration]. When diffusion rates are high due a high reaeration coefficient (k) and biological rates are relatively low, almost no diel sag is detectable-- diffusion swamps the P-R term in the mass balance.
Diffusion is a constant process, but biological activity is not. Photosynthesis varies in a regular diel fashion following the availability of light. The O2 mass balance equation can be thought of as having two distinct forms:
during the day DO=P-R± k[saturation-DO] but
during the night DO=R± k[saturation-DO] since P=0
Velocity
Diffusion,Reaeration
&metabolism
Position and
movement
shear
substrate
Habitat utilization
Catastrophicdisturbance
WhereHomogeneous longitudinal units[ geomorphic/ecologic]
dataLandscape (GIS) dataRegistered field dataModel projections
Mapping approaches to Longitudinal Structure
Current examples: MRI-VSEC (IL,WI verions); TNC Macrohabitat ClassificationsUSGS Aquatic GAP programGeomorphic Valley Segment Classifications [Hupp]Geomorphic Reach Classifications [Rosgen]
ScaleValley segments
ReachesBasins
What is Ecological Unit Mapping?
Hydrologiccharacter
Biologicalcharacter
Chemicalcharacter
IntegratedEcologicalCharacter
of a River Segment
“Identifying the basic [structural] units of nature” (Rowe 1991)
Geomorphiccharacter
Raisin Rivermainstem units Central role of GIS
Michigan Rivers Inventory
VSEC units MAP10 km
270 main river segments and
400 tributary units[mri-vsec v1.1]
filamentousoverstory
stalkedoverstory
adnateunderstory
filamentousoverstory
stalkedoverstory
adnateunderstory
filamentousoverstory
stalkedoverstory
adnateunderstory
Navicula
Gomphonema
Stigeoclonium
Grazers:
Animals that feed on living algae or macrophyte tissue. Some are free roaming, others are central-lace foragers making short excursions out from some central tube or burrow.Specialization by growth form common but not by plant species.
Food types: algae, vascular plant tissue (rare)
examples: many mayflies, many midges, many cased caddisflies, some stoneflies
Shredders:
Animals that feed on large allochthonous organic carbon fragments (e.g.leaves) which have been colonized by bacterial and fungal communities. Some shedders have commensal gut flora to assist in the digestion of cellulose. A few have specialized enzymes to assist in the same task..
Food types: coarse particulate carbon (CPOM), and associated microflora
examples: Cranefly larvae (Tipula), Giant stoneflies (Pteronarcys), many cased caddisflies, scuds
Filter Feeders:
Animals that feed by filtering suspendedOrganic material from the water column. Filtering mechanisms can be anatomical [e.g. blackflies]or more elaborate constructions involving silk capture nets[e.g. some Caddisflies and midges]
Food types: animal, algae, detritus
examples: blackflies, net-spinning caddisflies, burrowing mayflies
Collector-gatherers:
Omnivorous animals that feed by moving around the substrate in search of fine particulate organic matter (FPOM) which is either ingested on the spot, or retrieved and accumulated at some central tube or burrow. Often includes embedded algae and even small animals.
Food types: algae, detritus
examples: some mayflies, many midges and worms (tubificids), scuds
Predators:
Animals that feed on other animals. An invertivore feeds principally on invertebrates.
Food types: animal tissue
examples: dragonflies, many stoneflies, water scorpions and other bugs, most smaller fishes