ever support a rich or diverse infauna. The exist- 

 ence of soft sediments does not necessarily prechide 

 the presence of a divei-se and abundant bottom 

 fauna (Barnard and Hartman, 1959; Sanders, 

 1960), but where sediments are higlily organic, 

 deposition rapid, and dissolved oxygen low, the 

 benthos is likely to be impoverished (Pratt, 1953: 

 Bader, 1954; Eeisli, 1959; McNulty. AVork, and 

 Moore, 1962; McNulty, 1966). 



Forty-nine species of fishes were cauglit at sta- 

 tions in dredged canals. None were demersal, and 

 the absence of this type of fish in the catch may lie 

 due to lack of food organisms on and in bottom 

 deposits. In conti-ast, SO species of fish were col- 

 lected at stations outside bayfill canals. Even 

 though waters in the open liay accounted for a 

 greater niunher of fish species, oO percent more fish 

 were netted witliin dredged canals. One species, the 

 hay ancliovy. Anrhoa mlfehilli (Valenciennes), 

 was most conunon in tlie canal catch hut the Cuban 

 anchovy, AnrJwa riihaiia (Poey), and the scaled 

 sardine, Htirt'iigiihi pcntnieolac (Goode & Bean), 

 were also abundant. 



BIOMASS AND PRODUCTION 



The major benthie halutats in Boca Ciega Bay 

 are turtle grass l>eds, unvegetated bottom, and 

 oyster reefs. All contain large numbers of species, 

 l>ut the grass bed comnumity is outstanding Ix"- 

 cause it is widespread and highly productive. 



Extensive beds of turtle grass now exist only 

 south and east of the Pinellas Covmty Bayway 

 (fig. 1). Poorer stands are located in central and 

 northern parts of the bay, Imt only in very shallow 

 water. Rein-esentative beds were sampled to com- 

 l)are standing crop in the relatively undisturbed 

 soutliern section of the bay (area A) with that 

 in extensively dredged central (area B) and 

 iiortliern (area (') sections (fig. 10). Dry whole 

 weight of turtle grass in areas A, B, and C av- 

 eraged 1,19s. 1,008, and ;^'20 g./m.-, respectively. 

 The figure for area (' agrees with other biomass 

 estimates of turtle grass in the Gulf of Mexico, but 

 values from areas A and B are two to three times 

 greater (Phillips, 1960a; Odum, 1963). Maximum 

 development of turtle grass probably occurs in the 

 Caribbean wliere Burkholder, Burkholder, and 

 Kivero ( 1959) have oliserved stands having a bio- 

 mass of ;2,S00 g./m.- dry weight. 



Pomeroy (1960) reported an average bioma.ss of 

 about 81 g./m.- for turtle grass sampled randomly 

 along a transect across lower Boca Ciega Bay. This 

 ligure seems low, but no doubt includes values from 

 samples in some sparsely vegetated areas. Since 

 l>ayfi]ls cover bare and vegetated bottom, 80 g./ 

 m.- is in-obably a reasonable factor for calculating- 

 total biomass of tui-tle grass that has been covered 

 by bayfills in Boca Ciega Bay. Using 1,400 hec- 

 tares (;>,50() acres) as the filled area of the bay, we 

 compute that standing crop of turtle grass buried 

 l)y filling is at least 1,133 metric tons. If the area 

 of liayfill canals and other borrow areas were in- 

 cbided in this calculation, the figure would be 

 nearly doubled. 



Our estimate of total primary production in 

 Boca Ciega Bay is liased on work by Pomeroy 

 (1960) and studies in vegetated Texas bays by 

 Ilellier (1962) and Odum and Wilson (1962). An 

 average production figure would be about 5 G.O^/ 

 m.-/day (ca. 2.5 G.C/m.Vday) which is roughly 

 equivalent to 1S.206 kg. /ha./yr. ( 16,213 Ibs./acre/ 

 yr.) of dry organic material or an annual loss of 

 about 25,841 metric tons (28,425 tons) for the 

 1,400 hectares (3,500 acres) of the bay now filled. 



No quantitative study has been made of biomass 

 of animals living among blades of turtle grass, 

 although Moore (1963) and Stephens (1966) esti- 

 mated the alnindance of small invertebrates, and 

 drop-net samples in Texas bays gave data on some 

 larger invertebrates and fishes (Hellier, 195S, 

 1962 ; Jones, Ogletree, Tliompson, and Klenniken, 

 1963). The drop-net studies gave a mean annual 

 standing crop of about 15 g./m.^ wet weight (3 g./ 

 m.- dry weight — 20 percent of wet weight) (Vino- 

 gradov, 1953). Annual fish production is also 

 about 3 g./m.- in Texas bays or about 30 kg./ha./yr. 

 (27 Ibs./acre /yr.) (Hellier, 1962). This figure is 

 below an estimate by Sykes ( 1963) for fishery pro- 

 duction in Gulf estuaries (52 kg./ha./yr., or 46 

 Ibs./acre/yr.). Using Sykes' estimate, we calculate 

 that filling of 1,400 hectares (3,500 acres) has re- 

 duced fishei-y production in Boca Ciega Bay by 73 

 metric tons (80 tons) per year. 



Bioma.ss of invertebrate infauna living among 

 roots and rhizomes of turtle grass was calculated 

 from wet whole weight of animals recoxered by 

 sie\iiig (1.25 ni.- plug samples collected in areas 

 .\, B, and ( '. At area I), the infauna biomass was 

 determined in the same manner for imvejretated 



236 



U.S. FISH AXD WILDLIFE SERVICE 



