samples with a commercial clam rake within an area of 1/4 mile diameter. 

 Numbers of clams per man-hour varied from 1.0 to 276.0, sizes from 22.8 to 

 160.5 mm. Delineation of the extent and boundaries of larger beds was 

 attempted by replicate sampling. One and three-inch-deep core samples were 

 taken from the center of each station and sediments graded into eight 

 standard particle sizes. Temperature, salinity, water depth, tidal condition, 

 and bottom type data are given. Clam populations are located primarily in the 

 lower portions of the Bay. Absence of significant numbers of clams from 

 shallow areas of the upper bay are attributed to industrial pollution. The 

 largest and most productive area appears to be lower Boca Ciega Bay south to 

 Mullet Key, which is an area of good water flow and rich grass beds. Some 

 yearly recruitment takes place in this region, for more than one year class 

 was present in samples. No hard clams were found in Tampa Bay Inlet at 

 Passage Key, but surf clams, Spisula solidissima stmilis , were abundant. 

 Sediment texture varies with depth, but is uniform within a given depth 

 range. Shallow water sediments in Tampa Bay had a dominant particle size 

 of 0.25 to 0.10 mm (fine sand). There was no correlation of substrate 

 particle size with clam population density. Large populations were 

 associated with seagrass or coarse-grained sediment. Lower Boca Ciega Bay 

 has the largest population of brood clams ; and must be preserved in its 

 present state if large clam populations are to be sustained. Tampa Bay also 

 could be an important producer if properly managed. - W.J.B. 



1685 



Sims, L. J., and T. Dirnberger . 1971. 



A quantitative study of heavy metals in clams. Proc . Pa. Acad. Sci. 45: 

 20-23. 



Could not locate. Search terminated. - J.L.M. 



1686 



Sindermann, Carl J. 1964. 



The Bureau of Commercial Fisheries Biological Laboratory at Oxford: Present and 

 future. U.S. Dept. Interior, Fish Wildl. Serv. , Circ. 200: 8-17. In The 

 Bureau of Commercial Fisheries Biological Laboratory-Oxford, Maryland: Programs 

 and Perspectives. 



Molluscan shellfishes of commercial importance in Chesapeake Bay include 

 American oyster, soft clam, and Mevcenaria mevaenavia. Research at Oxford has 

 included oyster, soft clam, and surf clam. No studies of hard clam are 

 mentioned. - J.L.M. 



1687 



Sindermann, Carl J. 1971. 



Predators and diseases of commercial marine mollusca of the United States. 

 In Symposium on Commercial Marine Mollusks of the United States. Am. 

 Malacol. Un., Inc., Ann. Repts. for 1970: 35-36. 



This brief general summary mentions only oysters specifically. Predation 

 and disease are among important impediments to full expression of biotic 

 potential. These factors are partially density-dependent, and at times may 

 be dominant influences on abundance or population size of commercial mollusks. 

 Major predators are sea stars, f latworms , predaceous and parasitic snails, 

 crabs, fishes, and cephalopods . Problems with drills have been intensified by 

 promiscuous transfers and introductions of mollusks. Competitors like mud 

 blister worms, barnacles, tube worms, and corals can affect growth and survival. 

 Diseases have received most attention in oysters. Neoplasms are known in some 

 bivalves, and nematode parasites have been found. Few mollusk diseases are 

 transmissible to humans, but human disease may be caused by passive transfer of 

 pathogens and chemicals from mollusks used as food, especially when eaten raw. 

 Included are hepatitis, typhoid fever, paralytic shellfish poisoning, and 

 insecticide and heavy metal poisoning. Development of cultural practices for 

 certain commercial mollusks will require techniques for control of these and 

 other environmental factors. - J.L.M. 



467 



