Sound vary from polyhaline to euhaline (> 

 10 ppt) conditions. Gorsline (1'363) 

 alluded to the vertical isohaline 

 conditions of the estuary except for areas 

 that are deep or near the inlets. 

 Livinqston (1*^78, 1984a), however, has 

 documented seasonal vertical salinity 

 stratification in various parts of the 

 estuary, especially in areas affected most 

 directly by the river. Differences of 

 surface and bottom salinities of as much 

 as 5-10 ppt during periods of 

 stratification further complicate the 

 exact dimensions of the salinity regime in 

 a given area of the bay system through 

 time. However, by most statistical 

 measures, river flow is the chief 

 determinant of the salinity structure of 

 the estuary (Meeter and Livingston 1P78). 



periods of high local precipitation 

 (Figure 14). Salinitv qenerally peaks 

 during the fall drought 

 (October-November), Long-term salinity 

 trends follow river flow fluctuations; low 

 salinity was noted for a prolonged period 

 throughout the estuary during the heavy 

 river flow conditions of the winter of 

 1972-73, although various factors combine 

 to shape the long-term (multiyear) 

 salinity trends in the estuary. Various 

 statistical analyses (Meeter and 

 Livingston 1978; Meeter et al . 1°79) have 

 made a strong association of Apalachicola 

 River flow with the spatial/temporal 

 distribution of salinitv throughout the 

 bay system. 



There are persistent seasonal 

 patterns of salinity in the Apalachicola 

 estuary, although such patterns are 

 modified by annual variation of river flow 

 and fluctuations of local rainfall. Low 

 bay salinities coincide with high river 

 flows during winter and spring periods; 

 secondary salinity reductions occur in the 

 bay system during late summer-early fall 



Table 2. Bottom salinities in parts per 

 thousand at stations in the Apalachicola 

 estuary. All data represent 5-year means 

 (1972-77) with maxima and minima for this 

 period. A cluster analysis was made to 

 group the stations according to salinity 

 type. 



Apalachicola 

 estuary areas 



Bottom salinities (ppt) 



Sta- Mini- Maxi- 5-yr 

 tion mum mum mean 



Outer Bay- 



River dominated- 



-1 



-lA 



-IE 



-IC 



-IX 



[—2 

 -3 



0.0 

 3.0 

 6.9 

 1.4 

 0.0 



33.7 

 35.6 

 31.6 

 33.7 

 32.0 



I — 4 



0.0 28.1 

 0.0 22.0 

 0.0 31.8 



Upper (East) bay — 



Sike's Cut- 



4A 

 5 

 h— 5A 

 5B 

 5C 

 6 



0.0 

 0.0 

 0.0 

 0.0 

 0.0 

 0.0 



26.2 

 28.0 

 27.3 

 25.7 

 27.8 

 23.0 



15.7 

 22.1 

 15.7 

 20.4 

 17.8 



10.4 

 4.8 

 9.6 



3.6 

 7.4 

 5.1 

 3.8 

 4.3 

 3.6 



Stotion 1 



Q. 



a. 



< 

 (A 



i "r iiiii' " iii "" i| I ' "" I " I ' I "" I |i " iii 'M ii| 



1972 1973 1974 1975 1976 1977 I97e 1979 1980 1981 1982 



Station 2 



a. 

 a. 



< 

 CO 



IB 10.6 35.5 28.6 



" I "" I I """ I' "" I I I I 'I I I 



1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 



YEAR and MONTH 



Figure 14. Surface salinity (5-month 

 moving averages) at stations 1 and 5 

 (Apalachicola Bay, East Bay) taken monthly 

 from 1972 through 1982. 



17 



