3. General Faunal Characterization . 



The fauna of the nearshore zone is relatively rich and diverse. The 

 dramatic difference observed in species numbers and faunal densities between 

 corresponding samplings of the two studies (see Figs. 9 and 10) is a function 

 of the normal seasonal variation and not a profound alteration of community 

 composition. The fauna of the area is well represented by the major inverte- 

 brate phyla. The following 14 species that were the dominant fauna for 

 1974-75 were also well represented or dominant during the present study: the 

 polychaetes Dispio uncinata, Magelona riojai, Paraonis fulgens , Sf-olelepis 

 squamata, Spio pettiboneae ; the bivalves Donax texasianus , Ervilia concentrica: 

 the cumacean Mancocuma sp.; the amphipods Acanthohauf, tortus n. sp., 

 Haustorius n. sp., Protohaustorius n. sp . , Pseudohaustorius n. sp.; the 

 anomuran Emerita talpoida and the cephalochordate Branchiostoma floridae. 

 Many of the species collected during this and Saloman's (1976) study are new 

 and not yet described in the literature. 



Variations of species numbers and faunal densities at corresponding 

 stations of the nine transects were observed, but there were no discernible 

 patterns of distribution. The abundance of dominant species was nearly always 

 the same at corresponding stations varying only in their relative proportions. 



The fauna of the control stations CA and CB generally were not similar 

 to the borrow sites Bl and B2. The borrow sites exhibited fewer species and 

 lower faunal densities than the control site, with the exception of November- 

 December when CA had a lower faunal density (Figs. 9 and 10). Patterns of 

 species dominance and relative proportions of dominant species were also dif- 

 ferent (Table 14). Borrow sites seem to be most similar to transect stations 

 3 and 5. These differences may be attributed to the long-term effects of 

 dredging (i.e., possible inhibition of recruitment by certain species). It 

 should be noted that stations CA and CB are not totally acceptable controls 

 for comparative purposes due to the large spatial separation and the deeper 

 depths of the control sites (Fig. 1). Also, data from the transect stations 

 have shown that species composition and faunal densities vary with distance 

 from shore. Therefore, dredging effects at the borrow sites are unclear. 



4. Sediment-Fauna Relationships . 



Substratum type is generally considered the most important factor influ- 

 encing the distribution of benthic organisms (Peterson, 1913, 1915, 1918; 

 Jones, 1956; Thorson, 1957; Sanders, 1958; McNulty, Work, and Moore, 1962; 

 Buchanan, 1963; Nichols, 1970; Young and Rhoads, 1971; Johnson, 1971; Bloom, 

 Simon, and Hunter, 1972; Collard and D'Asaro, 1973; Pearson, 1975; Probert, 

 1975; Conner and Simon, 1979). 



As a result of the moderate wave energy in the study area, the near- 

 shore sediments experience an almost constant agitation. This agitation 

 is reflected in the type of fauna inhabiting the substratum, most being 

 active burrowers. or crawlers capable of reentering the sediments quickly 

 if displaced. There were no species present which require a permanent 

 attachment site and there were few permanent tube dwellers. There were 

 no strong statistical corrrelations between the various sediment parameters 

 (mean grain size, percent silt-clay, organic carbon) and faunal parameters 

 (number of species, faunal density). Physical processes such as wave 



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