CHAPTER 8 

 COMPARISON WITH OTHER ESTUARIES 



The Apalachicola estuary has been 

 included in a comparison of 14 estuaries 

 on the Atlantic, Gulf of Mexico, and 

 Pacific coasts of the United States (Nixon 

 1983). This study indicated that 

 Apalachicola Bay is a relatively small and 

 shallow estuary, rapidly flushed, with a 

 considerable watershed area (Table 21) 

 when compared to other estuaries in the 

 United States. The cross-sectional area 

 of the Apalachicola estuary (18.1 x 10^ 

 m^) is relatively small comoared to most 

 of the other estuaries. Because of the 

 dimensions of the bay and the volume of 

 freshwater input, Nixon (1983) estimates 

 that dissolved and suspended materials are 

 likely to remain in Apalachicola Bay for a 

 shorter time than in many of the other 

 estuaries in the survey. The relatively 

 high level and strong seasonality of the 

 rainfall in the Apalachicola drainage 

 basin would contribute to the high river 

 discharge rates to the estuary. 

 Approximately f^2% of the surface area of 

 the estuary has salinities that average 

 less than 15 ppt. Apalachicola Bay stands 

 out, along with Mobile Bay and Northern 

 San Fransisco Ray, as a system that 

 resDonds to river discharge in "a major 

 way" (Nixon 1983). 



Because of the physical 

 characteristics and the relatively high 

 annual level of solar radiation, 

 Apalachicola Bay and Kancohe Ray (Hawaii) 

 are the only estuaries of those surveyed 

 in which the bay bottoms fall within the 

 euphotic zone (Nixon 1983). This fact, 

 together with the major impact of the 

 river on the estuary, could help to 

 explain the apparently high productivity 

 of the Apalachicola system. The 

 phytoplankton productivity in the 

 Apalachicola estuary is moderately high 

 (Table ?8). Estabrook (1973) found that 

 such production is similar to that found 



in Tampa Bay. The importance of 

 phosphorus as the limiting nutrient for 

 phytoplankton productivity for various 

 estuaries, including the Apalachicola 

 system, is evident (Nixon 1983). 

 Relatively little of the Apalachicola 

 primary productivity is due to cultural 

 eutrophication from input of nutrients 

 from human wastes. The Apalachicola is 

 the least developed of the estuaries 

 surveyed, with an extremely low population 

 density (Table ?9). The contribution of 

 nutrients from point source discharges to 

 the Apalachicola estuary is extremely low 

 (Table 30). These data indicate that the 

 Apalachicola estuary remains in a 

 relatively natural state compared to other 

 such systems around the country. 



A comparison of zooplankton abundance 

 in different estuaries is difficult 

 because distribution and abundance depend 

 to some degree on mesh size of the nets 

 used to take the samples. A wide variety 

 of mesh sizes has been used in such 

 studies. When compared with other 

 estuaries in the gulf, Apalachicola Bay 

 has a similar or larger zooplankton 

 assemblage in terms of numbers and biomass 

 (Edmisten 1^79). Such numbers are 

 comparable to those taken in various 

 estuaries in the United States (Nixon 

 1983). A comparison of ichthyplankton in 

 the other estuaries indicated that the bay 

 anchovy ( Anchoa mitchil 1 i ) as a dominant 

 species is a common characteristic in half 

 the estuaries surveyed (Nixon 1983). The 

 low numbers of fish eggs in the 

 Apalachicola system, relative to other 

 areas such as Tampa Bay, has been 

 attributed to the relatively low 

 salinities in the Apalachicola estuary 

 (Blanchet 1978). Attempts to make 

 comparisons between the level of primary 

 production and abundance of organisms at 

 higher trophic levels indicate no direct 

 or simple correlation (Nixon 1983). 



112 



