Total net primary production (carbon reduced by photosynthesis) by 
natural plant communities in Tampa Bay (listed by category in Table 3) is 
estimated at 478.2 x 10° kg/yr. These figures indicate that Tampa Bay 
can be characterized as a phytoplankton-based system when compared to 
other sources of net primary production. By virtue of their high annual 
production, mangroves are the second most important primary producer in 
the estuary. 
In addition to primary production, organic material can be 
transported to the bay from outside sources by streamflow, sewage 
discharges, urban runoff from pavement, rainfall, and groundwater 
discharge. These values account for a total input of organic carbon of 
92.7 x 10° kg/yr, or about 25% of the amount produced by photosynthesis 
(or marine plants) in the bay. This figure was probably much higher 
prior to recent improvements in industrial and municipal discharges, and 
substantial deposits of residual organic matter are still present in bay 
sediments (Ross, Ross and Jerkins 1984). The estimate by those authors 
of current allochthonous sources of organic carbon is somewhat less, 66.7 
vs. 92.7 x 10 6 kg/yr. 
Table 3. Estimated annual production of primary producers based on areal 
coverage in the Tampa Bay system (modified from Johansson 
et al. 1985). 
PRIMARY 
PRODUCER 
PRODUCTION 
(g C/m 2 /yr) 
Seagrass and 
epiphytes 
730 
Macroalgae 
70 
Benthic 
microalgae 
150 
Mangrove 
forests 
1,132* 
AREA TOTAL PRODUCTION PERCENT 
(km 2 ) (g C/yr x 10 6 ) OF TOTAL 
57.5 42.0 8.5 
100.0 7.0 1.4 
200.0 30.0 6.0 
64.5** 73.0 14.7 
Tidal marshes 
300 
Phytoplankton 
340 
(areas >2m deep) 
Phytoplankton 
50 
(areas <2m deep) 
10.5** 
3.2 
0.6 
864.0 
293.8 
59.1 
96.0 
48.0 
9.7 
Riverine forests -- no data available. 
*Estevez and Mosura 1985. 
**Assuming 14% of the bay’s emergent wetlands are tidal marsh. 
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