ChoMohoochee River 

 COAST 



Figure 1. Location of the tri-river 

 drainage system in the southeastern United 

 States showing the relative positions of 

 upland features and the Apalachicola 

 estuary. 



A detailed review of the dimensions 

 of the Apalachicola Bay system (^QOis'n to 

 ?9055'N; 84O20'W to 85O?0'W) (Figure ?) is 

 given by Livingston (1980a). This system 

 is composed of six major subdivisions: 



3,Q81 ha (9,837 acres) 

 ?0,959 ha 



East Bay 

 Apalachicola Bay 



('51,792 acres) 

 St. Vincent Sound 5, "^40 ha 



(13,689 acres) 

 West St. George Sound (to Dog Island) 



14,747 ha (36,440 acres) 

 East St. George Sound 



16,016 ha (39,576 acres) 

 Alligator Harbor 1,637 ha 



(4,045 acres) 



The entire area totals 6?, 879 ha (155,374 

 acres). A natural shoal forms a submerged 

 boundary between Apalachicola Bay and 

 St. George Sound. The bay is bounded on 

 its extreme southern end by three barrier 

 islands: St. Vincent, St. George, and Dog 

 Island. There are four natural openings 

 to the gulf: Indian Pass, West Pass, East 

 Pass, and a pass between Dog Island and 

 Alligator Harbor. A man-made opening 

 (Sike's Cut) was established in the 

 western portion of St. George Island. The 



3.6-m- (12-ft-) deep Intracoastal Waterway 

 extends northwestward from St. George 

 Sound through Apalachicola Bay, up the 

 Apalachicola River to Lake Wimico and then 

 along an artificial channel to St. Andrews 

 Bay to the west. 



The Apalachicola estuary is a lagoon 

 and barrier island complex. It has been 

 classified as a shallow coastal plain 

 estuary oriented in an east-west direction 

 (Dawson 1^55). Because of the placement 

 of the barrier island complex, it coul'^ be 

 called a coastal lagoon. The average 

 depth is between 7 and 3 m at mean low 

 tide (Gorsline 1^163). 



In terms of Pritchard's (1^67) 

 estuarine classification scheme, the 

 Apalachicola Bay system is a width- 

 dominated estuary controlled by lunar 

 tides and wind currents. As such, it is a 

 type D estuary (Conner et al. 1981) in 

 that it is dominated by physical forces 

 (i.e., tidal currents, wind) as a function 

 of its shallow depths. As a result, the 

 bay system is relatively well mixed, 

 although various portions of the estuary 

 are periodically (seasonally) stratified 

 (Livingston 1984a). 



1.^. DRIVING FORCES AND HUMAN INFLUENCE 



The principal driving forces that 

 determine the habitat structure and 

 biological processes of the estuary are 

 river flow, physiography of the basin, 

 seasonal changes of nutrients, and 

 salinity as modified by wind, tidal 

 influences, and freshwater inflows. Tidal 

 influence extends approximately 40 km (?5 

 miles) up the river. As a biological 

 entity (Odum et al. 1'374), 

 (which includes East Bay, 

 Bay, St. Vincent Sound, 

 portions of St. George 

 characterized by upland marshes that grade 

 into soft-sediment areas, vegetated 

 shallow bottoms, and oyster reefs. The 

 oligohaline East Bay merges with 

 mesohaline and oolyhaline portions of 

 Apalachicola Bay, St. Vincent Sound, and 

 St. George Sound. 



The Apalachicola River, the largest 

 in Florida in terms of flow, is the 

 principal source of fresh water to the 

 estuary. The average flow rate is about 



the estuary 

 Apalachicola 

 and western 



Sound), is 



