to the list of algal species by Phillips (19601>) ; 

 Sprino-er and Woodburn (IDIJO) brought the list 

 of tishes from Tampa Bay up to 108; and unpub- 

 lished work by Bullock and Boss ^ increased the 

 recorded number of mollusks in Boca Ciega Bay 

 from 30 to 175. Nearly 700 species of marine plants 

 and animals have l)een identified from our sam- 

 ])ling in l!)(;o-(U and from other work in the area. 

 Among the major taxa are about 180 species of 

 mollusks, 1'20 polychaete worms, (iO decapod crus- 

 taceans, 20 echinoderms, 110 fishes, and 200 plants. 

 Comparative records show that stations inside 

 deeply dredged canals contain less than 20 percent 

 of the species we recorded for the bay. If fishes 



' See footnote 2. 



are excluded from the species total, nearly 100 per- 

 cent of the organisms recorded come from collec- 

 tions made outside di-edged areas. Invertebrates 

 collected in bayfill canals consisted of onlj- a few 

 polychacte worms, mollusks, blue crabs, and pink 

 shrimp. AA'e conclude, therefore, that soft deposits 

 in the canals are in some way unsuitable for most 

 bottom in^ ei"tebrates found in other areas of the 

 bay. Thorson (1957) and others have demonstrated 

 that larvae of many benthic forms are sensitive to 

 sediment composition and will not metamorphose 

 from a planktonic stage until contact is made with 

 suitable bottom. In 10 year.s, recolonization of 

 canal sediments has been negligible and it appears 

 doubtful that soft sediments of bayfill canals will 



Table 7. — Comparison of sediments al undredged and dredged slalions in Boca Ciega Bay, Fla. (1963-64), showing depth, 

 mean grain size, percentage of ihell and sand by weight (particle size <4 0)i percentage of silt and clay by weight 

 (particle size ^4 0), and percentage of total carbon by weight 



Depth 



Mean grain size 



Percentage of 



shell and sand 



by weight 



Percentage of 



silt and clay 



by weight 



Percentage of 



total carbon 



by weight 



Undredged: 



BCA - 



BCH - 



BCC 



BCE.. 



BCG 



BCI... 



BCL 



BCM 



PB-6; BCN 



D-1 



D-2 



D-3 



D-5 _.. 



D-6 



D-9 



D-10 



PB-3; D-n. 



D-17- 



D-18 



PB-1 



PB-5 



Means 



Dredged: 



BCH 



D-4 



D-7 



D-8! 



D-12 2 



D-13! 



D-14 



PB-2; D-15. 



D-16 



PB^ 



Means 



3.9 



' The phi unit is a logarithmic transformation of the Wentworth grade 

 scale of particle size (Krumbein and Pettijohn, 1938) . 



' Berm of canal not included in calculation of mean. 



' Transitional bottom not included in calculation of mean. 



EFFECTS OF HYDRAULIC DREDGIXG AND COASTAL DEVELOPMENT IX BOCA CIEGA BAY. FLA. 



235 



