Declines in diversity were evident at control stations 1 and 2 

 during the winter, when values dropped to less than half their values 

 at all other sampling dates. This, again, resulted in part from large 

 concentrations of E, nitens at these stations, as well as from seasonal 

 fluctuations in the abundance of other species. 



V. DISCUSSION 



Studies of benthic communities have contributed much to our under- 

 standing of the role of stress and disturbance in the marine environment 

 (Boesch and Rosenberg, in preparation, 1982) . Because most benthic 

 organisms are sedentary and relatively long-lived, their response to 

 man-induced stresses, such as offshore dredging, can readily be analyzed 

 statistically, yielding much information for use in coastal resource 

 management . 



Our analysis of benthic fauna within the borrow areas showed no 

 lasting detrimental effects on numbers of species, faunal densities, or 

 species diveristy from dredging that occurred 5 years previously. 

 In fact, data combined from borrow stations showed significantly 

 greater numbers of species and individuals than that from control 

 stations. Species diversity values were also unusually higher at the 

 borrow stations. 



Our findings are generally in accord with those of two other recent 

 studies of offshore dredging in Florida, both designed to assess short- 

 term ecological effects. Saloman, Naughton, and Taylor (in preparation, 

 1982) found that the fauna within a borrow pit off Panama City (Bay 

 County) showed rapid postnourishment recovery that was nearly complete 

 after 1 year. Similarly, in an unpublished study of a borrow area 

 located 11.1 kilometers off Duval County in northeastern Florida, no 

 significant differences were found 1 year after dredging between bor- 

 row and control stations in numbers of taxa, faunal densities, or 

 species diversities (Applied Biology, Inc., 1979). 



These observations are different from those reported by Saloman 

 (1974) in his study of a borrow area created 3 years previously off 

 Treasure Island (Pinellas County) on the west coast of Florida. He 

 found low densities and diversities of benthic fauna within the borrow 

 area compared to surrounding, relatively undisturbed bottom. He 

 attributed these differences to thick deposits (> 3 meters) of 

 gelatinous, organic-rich sediments that had accumulated in the borrow 

 area, resulting in low dissolved oxygen concentrations. These 

 conditions did not develop off Hillsboro Beach, probably because of the 

 low concentration of suspended particulates and the relatively strong 

 longshore currents and eddies (Marsh, et al . , 1978). 



Reasons for the quantitative and qualitative differences between 

 borrow and control stations are difficult to ascertain. Sediment 

 composition, including grain size, is an important determinant of 



