least abundant in the bay; abundance was highest at stations with low to inter- 

 mediate amounts of silt and clay or where vegetative matter was composed mostly 

 of live seagrasses or detritus. Crustaceans were more abundant in the natural 

 marsh than in the other two areas and showed a definite preference for the sandy 

 substrate in marsh areas. Pelecypods were most abundant numerically in the 

 bay but volumetrically the marsh had the highest standing crop. Nemerteans 

 were most abundant in the marsh and least abundant in the bay. 



In general, the seasonal abundance of polychaetes and nemerteans varied 

 little during the study, whereas crustaceans and pelecypods were abundant 

 only during the spring and early summer. 



52. GODCHARLES, M.F., "A Study of the Effects of a Commercial Hydraulic Clam 

 Dredge on Benthic Communities in Estuarine Areas," Technical Series No. 

 64, Florida Department of Natural Resources, Division of Marine Resources, 

 St. Petersburg, Fla., July 1971. 



A Maryland soft-shell escalator clam dredge, the R/Y Venus, was used in a 

 systematic sampling program to study its effect on representative bottom types 

 (habitats) in Tampa Bay and to conduct clam exploration in Tampa and Boca 

 Ciega Bays, the Cedar Keys area, and the Tarpon Springs vicinity. Six experi- 

 mental stations established in Tampa Bay were visually inspected and sampled 

 with a trynet before dredging and at various intervals after dredging. Benthic 

 plug samples were taken at the final sampling. Sediment samples were also 

 taken to assess textural changes by particle-size analysis. The collected 

 fauna were identified, counted, and in most instances, measured. 



After more than a year no recolonization of seagrasses, Thatassia 

 testudinim and Syringodiion fili forme , occurred in any dredged area. Some re- 

 growth of Cauterpa protifera was observed 86 days after dredging. No increase 

 of clam set was detected during the study. Analyses of trynet hauls showed 

 no faunal variations between dredge and control plots at any time after 

 dredging, and benthic plug samples revealed marked faunal differences at only 

 one station. Redredging with the R/V Venus revealed no faunal declines 

 except for a marked decrease in quahogs, Meraenaria oampechlensis , at one 

 station. 



53. GUNTER, G., "Mortality of Oysters and Abundance of Certain Associates as 

 Related to Salinity," Ecology, Vol. 36, No. 4, Oct. 1955, pp. 601-605. 



A field mortality experiment on oysters was carried out from July 1949 to 

 January 1950 in Copano and Aransas Bays on the south Texas coast. Salinities 

 were higher than usual during this period and the water temperatures during 

 the fall and winter were much higher than normal. Mortality of oysters 

 shielded from predators in baskets was low. 



54. GUNTER, G., "Some Relations of Faunal Distribution to Salinity in Estua- 

 rine Water," Ecology, Vol. 37, No. 3, Oct. 1956. 



55. GUNTER, G., "Some Relations of Estuarine Organisms to Salinity," Li-mnol- 

 ogy and Oceanography, Vol. 6, No. 2, Apr. 1961, pp. 182-190. 



Collectors often ignore salinity while carefully gathering other data for 

 locality records of estuarine organisms. There has been a great deal of 

 research indicating that salinity is a limiting factor to the distribution of 

 many marine organisms, especially as it varies downward; these limits are often 

 quite sharp. Some recent evidence is reviewed. 



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