University of South FloridaScholar Commons
Reports Tampa Bay Area Study Group Project
1-1-2002
Historical and current observations on macroalgaein the Hillsborough Bay EstuaryJ.O.R. JohanssonBay Study Group, City of Tampa
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Scholar Commons CitationJohansson, J.O.R., "Historical and current observations on macroalgae in the Hillsborough Bay Estuary" (2002). Reports. Paper 38.http://scholarcommons.usf.edu/basgp_report/38
HISTORICAL AND CURRENT OBSERVATIONS ON MACROALGAE IN THE HILLSBOROUGH BAY ESTUARY (TAMPA BAY), FLORIDA. Johansson, J.O.R., Bay Study Group, City of Tampa, Tampa FL. Complaints from citizens of Tampa in the early 1960's about obnoxious odors emanating from decaying macroalgae (Gracilaria) along the western shore of Hillsborough Bay resulted in one of the earliest studies undertaken to control eutrophication of an estuary. Results from the study, which were published in 1969, linked the build-up of macroalgae along the shore, and poor bay water quality, to wastewater discharges to the bay with high nutrient and organic content. The study identified the City of Tampa’s wastewater plant and the Central Florida fertilizer industry as the two major sources of nutrient pollution to the bay. The study concluded that large reductions of nutrient discharges were needed from these sources, specifically of nitrogen, to improve water quality and to restore a diverse ecosystem to the bay. From the mid 1970's to the early 1980's, local and state regulations, primarily aimed at reducing point-source nutrient pollution, resulted in large phosphate reductions and a near 65% reduction in dissolved inorganic nitrogen discharges to the bay. By the mid 1980's, Hillsborough Bay showed signs of lessened eutrophication. These signs included a near 50 percent decrease in phytoplankton biomass and new growth of submerged seagrass. Despite the nutrient reductions, macroalgae biomass appeared to remain high and odor complaints were still being received by the City of Tampa from citizens on the western side if Hillsborough Bay. In 1983, the city contracted for a year-long study of macroalgae biomass and distribution in the bay. Surprisingly, this study found areas with much higher biomass than that reported in the 1969 study. Attempts to link macroalgae biomass to bay water quality and other potentially important variables were inconclusive in this study. To improve the understanding of macroalgae dynamics it was recommended that long-term monitoring of the macroalgae in the bay be initiated. Subsequently, the City of Tampa initiated a Hillsborough Bay macroalgae monitoring program that since 1986 has been providing consistent monthly biomass and species composition information from five fixed transects. In addition to the transect monitoring, low level aerial observations are conducted on a near monthly schedule for estimations of bay-wide macroalgae and seagrass coverage. Results indicate that the annual bay-wide macroalgae coverage has decreased near steadily from about 300ha in the late 1980's to less than 30ha since 1997. Estimated average monthly bay biomass has decreased from a peak of near 150tons wet weight in 1988 to less than 1ton wet weight since 1997. Macroalgae species composition during the 15 year monitoring period has often been dominated both in terms of biomass and frequency of occurrence by Gracilaria spp. Other major species include: Spyridia filamentosa, Ulva lactuca, Agaridhiella tenera, and the attached alga Caulerpa prolifera
HISTORICAL AND CURRENT HISTORICAL AND CURRENT OBSERVATIONS OF MACROALGAE IN OBSERVATIONS OF MACROALGAE IN HILLSBOROUGH BAY (TAMPA BAY), HILLSBOROUGH BAY (TAMPA BAY),
FLORIDAFLORIDA
CITY OF TAMPACITY OF TAMPABAY STUDY GROUPBAY STUDY GROUP
J.O.R. JOHANSSONJ.O.R. JOHANSSONW. M. AVERYW. M. AVERYG.V. PINSONG.V. PINSON
K.B. HENNENFENTK.B. HENNENFENTJ.J. PACOWTAJ.J. PACOWTA
TAMPA BAY AND WATERSHEDTAMPA BAY AND WATERSHED
HILLSBOROUGH BAYHILLSBOROUGH BAY
HISTORICALHISTORICAL BACKGROUNDBACKGROUND
BAYSHORE BLVD.BAYSHORE BLVD.
2635
91
1029 FERTILIZERIND+ALAFIA RCITY OF TAMPA
OTHERS
8670
130
450
DINDIN TPTP
DIN AND TP LOADING TO HILLSBOROUGH BAY IN 1967DIN AND TP LOADING TO HILLSBOROUGH BAY IN 1967--6868
mtonsmtons/yr/yr
TAMPA TRIBUNE NOVEMBER 16, 1969TAMPA TRIBUNE NOVEMBER 16, 1969
0
5
10
15
20
25
30
35
40
45
50
1956 1961 1966 1971 1976 1981 1986 1991 1996 2001
YEAR
PO4,
ppm
ALAFIA RIVER PO4 CONCENTRATIONSALAFIA RIVER PO4 CONCENTRATIONS
DIN LOAD FROM COT WWTP AND NITRAM INC.
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1952 1955 1958 1961 1964 1967 1970 1973 1976 1979 1982 1985 1988 1991 1994 1997 2000
YEAR
DIN
LO
AD
, mto
ns/y
r
COT WWTP NITRAM INC.
DIN LOAD AND CHLOROPHYLLHILLSBOROUGH BAY
0
500
1000
1500
2000
2500
3000
3500
4000
4500
1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998
YEAR
DIN
LO
AD, m
tons
/yr
0
10
20
30
40
50
60
CH
LOR
OP
HY
LL-a
, ug/
l
DINLOAD CHLOROPHYLL
AUGUST 1991AUGUST 1991
OCTOBER 2001OCTOBER 2001
JANUARY 1984JANUARY 1984
CITY OF TAMPA MACROALGAE CITY OF TAMPA MACROALGAE MONITORINGMONITORING
TRANSECT SAMPLINGTRANSECT SAMPLING
MONITORING TRANSECTSMONITORING TRANSECTS
CITY OF TAMPA MACROALGAE CITY OF TAMPA MACROALGAE MONITORINGMONITORING
AREALAREAL COVERAGECOVERAGE
FLIGHT PATHS AND MACROALGAE AERIAL OBSERVATIONSFLIGHT PATHS AND MACROALGAE AERIAL OBSERVATIONS
MONTHLY AREAL COVERAGE AND TRAWL ESTIMATED BIOMASS OF MACROALGAE IN HILLSBOROUGH BAY
0
100
200
300
400
500
600
700
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
YEAR
CO
VER
AG
E, h
a
0
50
100
150
200
250
300
350
TRA
NSEC
T BI
OM
ASS
, gw
w/m
2
COVERAGE
TRANSECTBIOMASS
MACROALGAE AREAL COVERAGE AND BIOMASS IN HILLSBOROUGH BAY
0
50
100
150
200
250
300
350
400
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
YEAR
ANN
UAL
AV
ERA
GE
CO
VER
AG
E, h
a
0
50
100
150
200
ANN
UALA
VER
AG
E BI
OM
ASS
, mto
nsw
w
COVERAGE
BIOMASS
MACROALGAE MACROALGAE COMPOSITIONCOMPOSITION
GRACILARIA VERRUCOSAGRACILARIA VERRUCOSA
GRACILARIA SP. 2GRACILARIA SP. 2
SPYRIDIA FILAMENTOSASPYRIDIA FILAMENTOSA
ULVA LACTUCAULVA LACTUCA
AGARDHIELLA TENERAAGARDHIELLA TENERA
CAULERPA PROLIFERACAULERPA PROLIFERA
MACROALGAE SPECIES OCCURRENCE AND BIOMASS (TRAWL COLLECTIONS)
0
1000
2000
3000
4000
5000
6000
7000
Grac. ve
rr.Spy
r. fil.
Ulva la
tac.
Agar. t
enera
Grac. S
p.2
Chaeto
m. grac
.
Chaeto
m. cras
saCau
l. prol
if. 18 14 11 27 6 23 12 15 8 22 24 26 25 16
SPECIES
TOTA
L B
IOM
ASS,
gw
w/m
2
0
100
200
300
400
500
600
700
CO
UN
T O
F O
CC
UR
REN
CE
BIOMASS
OCCURRENCE
ANNUAL MACROALGAE SPECIES COMPOSITION (TRAWL COLLECTIONS)
0
10
20
30
40
50
60
70
80
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
YEAR
BIO
MAS
S, g
ww
/m2
Grac. verGrac. sp. 2Agar. teneraUlva lact.Spyr. fil.
MACROALGAE COMPOSITION BY MONTH (TRAWL COLLECTIONS)
0
5
10
15
20
25
30
1 2 3 4 5 6 7 8 9 10 11 12
MONTH
BIO
MAS
S, g
ww
/m2
Grac. verrGrac. sp. 2Agar. teneraUlva lact.Spyr. fil.
CONCLUSIONCONCLUSION
MACROALGAE AND SEAGRASS COVERAGE, AND CHLOROPHYLL-a CONCENTRATIONS IN HILLSBOROUGH BAY
0
50
100
150
200
250
300
350
40019
50
1952
1954
1956
1958
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
YEAR
MAC
ROA
LGAE
AND
SEA
GRA
SS C
OVE
RAG
E,
ha
0
10
20
30
40
50
60
70
80
CHL
OR
OPH
YLL-
a CO
NCE
NTR
ATI
ON
, ug/
l
MACROALGAE COVERAGE
SEAGRASS COVERAGE
CHLOROPHYLL-a CONC
Valiela, et al. 1997
THE ENDTHE END