IV. DISCUSSION 



1. Study Design Restrictions . 



The accuracy of the data collected and the validity of its interpre- 

 tation are dependent upon the adequacy of the study design. In order to 

 properly assess the environmental impact of the beach nourishment program 

 three components are necessary: (a) quantitative prenourishment base-line 

 information; (b) immediate and short-term impact determinations; and (c) a 

 long-term effects study. Components (a) and (b) have been addressed by other 

 investigators (Saloman, 1976; Saloman, Naughton and Taylor, in preparation, 

 1982) and component (c) has been addressed by this report. The adequacy of 

 the sampling design used for this study is discussed in Appendix D. 



2. General Characterization of Abiotic Parameters . 



Values for temperature, salinity, and dissolved oxygen observed in 

 this study can be considered typical for nonestuarine northern Gulf of 

 Mexico waters . The seasonal variations recorded for this study correspond 

 well with those observed by Saloman (1976) . Salinity and temperature vvere 

 essentially uniform throughout the sampling area, and dissolved oxygen varied 

 only slightly. Several rainstorms occurred during sampling, and small changes 

 of salinity and water temperatures were detected at the nearshore stations 

 and surface offshore waters. These variations were generally small and 

 short lived due to the active mixing of waters in the surf and nearshore 

 zones. Saloman, Naughton, and Taylor (in preparation, 1982) noted seasonal 

 fluctuations in salinities that indicated an estuarine influence of St. 

 Andrew Bay on some stations, possibly affecting recruitment in an unpredict- 

 able manner. Temperature extremes from winter to summer probably influence 

 community structure by dictating reproductive seasons, but the relatively 

 deep nearshore waters act to dampen rapid changes of water temperature. 

 None of the physical parameters observed in this study could be considered 

 stressful or limiting factors for faunal diversity or abundance within 

 their observed ranges. 



The sediments within the study area are very similar alongshore and 

 at comparable distances from shore. Gorsline (1966) comments on the 

 strikingly uniform textures of Florida's west coast, but also notes that 

 there are specific subtle variations in specific parts of the beach. More- 

 over,, these beach zones are periodically altered in response to surf 

 conditions. In view of Gorsline 's observations, the differences of grain - 

 size parameters from 1974-75 to 1979-80 (Tables 9 and 10) could be attri- 

 buted to small changes of exact sample location. The most notable differ- 

 ences in sediment composition were among the percentages of silt-clay, 

 organic carbon, and carbonate. However, due to the extremely low levels 

 of these three components, the differences cannot be considered biologically 

 important and could be attributed to sampling and processing variations. 

 The moderate wave energy of the area, together with the relatively steep- 

 sloping nearshore zone, has resulted in a surface substrata that is almost 

 entirely free of silt-clay sized particles and organic detritus. 



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