5. 
The majority of the bloom species are resident in the bay but 
significant blooms occasionally occur due to species which invade 
from the Gulf of Mexico. Blooms of the toxic species Ptvchodiscus 
brevis originate 16-60 km offshore, for reasons as yet unclear, 
and are carried into the bay. Between 1946 and 1982, such 
invasions occurred at least 12 times. 
6. Many of the previous studies utilized analytical procedures which 
limit the quantitative comparison of all data; some uniform 
sampling strategy and analytical procedures are needed to make 
future data more usable. Quarterly sampling and ignoring the 
nanoplankton in taxonomic and production studies are two of the 
problem areas.Primary production studies of phytoplankton in Tampa 
Bay have been summarized by Johansson, Steidinger and Carpenter 
(1985). Table 1 lists the annual rates reported in several 
studies using three different methods. Whether the different 
values over time reflect a real increase in primary production by 
phytoplankton or simply the results of different methods cannot be 
determined at present. 
Table 1. Estimated annual Dhytoplankton production rates in the Tampa 
Bay system (g C/m 2 /yr). From Johannson et al. 1985. 
Dates 
Old 
Hillsborough 
Middle 
Lower 
and Methods 
Tampa Bay 
Bay 
Tampa Bay 
Tampa 1 
1968 
170 
270 
170 
120 
Chlorophyll + 
1 ight 
1965-67 
430 
610 
440 
220 
Oxygen 
1969-72 
290 
580 
490 
180 
Chlorophyll + 
light 
1973-83 
620 
620 
Carbon isotope 
Earlier data may be of limited value due to the methods used (lack 
of grinding), which probably produce an underestimate of chlorophyll ’a’ 
in eutrophic waters; however, it is reasonable to assume a real increase 
in phytoplankton production due to eutrophication. Annual production of 
340 g C/m 2 is suggested as a reasonable estimate for phytoplankton 
primary production in the deeper portions of Tampa Bay, and 509 g C/m 2 
for shallower portions, based on the available data (Johansson et al. 
1985). 
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