4 2 



concentrated plantings of small clams, but protected clams show very low 

 death rates from disease and other causes. Meroenaria grows very slowly 

 after the first 2 or 3 years. Old clams are common in commercial catches. 

 Tray-held hard clams had very low mortalities when protected from pre- 

 dation for 10 years. Clams in natural populations are scattered, in 

 contrast to oysters on planted grounds, and disease-caused mortalities have 

 not been evident. Diseases of hard clam have not been studied in Chesapeake 

 Bay. - J.L.M. 



Andrews, Jean. 1971. 



Sea Shells of the Texas coast. Univ. Texas Press, Austin, 285 p. 



Southern quahog, Meroenaria oampechiensis (Gmelin, 1790) . Length 3 to 6 in. 

 Dirty gray to whitish; interior white, rarely with purple blotches; 

 porcellaneous. Valves equal; ovate trigonal; inequilateral; inflated. 

 Sculpture of numerous concentric growth lines; near the beaks they are 

 farther apart; shell very heavy. Lunule as wide as long; 3 cardinals in 

 each valve; left middle cardinal split. Two muscle scars are connected 

 by a pallial line with small, angular sinus. No periostracum visible. 

 M. oampechiensis has not been used commercially as has M. meroenaria. 

 Habitat: offshore; common. Chesapeake Bay to Florida, Texas, and Cuba; 

 Miocene to Recent. Mevoenaria oampechiensis texana (Dall, 1902) . Length 

 3 to 5 in. Dirty white, often with brown zigzag marks; interior white, 

 occasionally marked with purple. Surface sculpture with irregular large 

 concentric growth lines; central area of each valve glossy and smooth in 

 older clams; very heavy and porcellaneous. Lunule 3/4 as wide as long; 

 3 cardinal teeth in each valve; left middle cardinal split. Two muscle 

 scars are connected by a pallial line with small angular sinus; margin 

 faintly crenulate. Lives in bays, in open bays and inlet-influenced areas. 

 Fairly common. Range: northern Gulf of Mexico to Tampico, Mexico. 

 Pleistocene to Recent. Meroenaria mercenavia is not listed as present. 

 - J.L.M. 



43 



Andrews, Wallace H. , Cecile D. Diggs , and Clyde R. Wilson. 1975. 



Evaluation of a medium for the rapid recovery of Escherichia coli from 

 shellfish. Appl. Microbiol. 29(1): 130-131. 



A medium which shortens the time necessary to identify and enumerate E. coli in 

 estuarine waters was evaluated for use in recovery of E. coli from Meroenaria 

 meroenaria and Crassostrea virginiaa. Productivity of E. coli by this medium 

 was comparable to that of the lengthier Am. Pub. Health Assn. method and false 

 positives were reduced substantially. - modified author's abstract. - J.L.M. 



44 



Andrews, W. H. , C. D. Diggs, J. J. Miescier, C. R. Wilson, W. N. Adams, 

 S. A. Furfari, and J. F. Musselman. 1976. 



Validity of members of the total coliform and fecal coliform groups for 

 indicating the presence of Salmonella in the quahaug, Meroenaria meroenaria. 

 J. Milk Food Technol. 39(5): 322-324. 



No samples of Meroenaria meroenaria taken from waters classified as safe for 

 shellfish harvesting, over a period of 24 months, contained Salmonella. 

 Criteria for safe waters were: 1) no more than 70 MPN total coliforms/100 ml 

 water; or 2) no more than 14 MPN fecal coliforms/100 ml water. Salmonella 

 also was not detected in quahog samples meeting the wholesale market quality 

 standard of 230 fecal coliforms/100 g shellfish, as specified by the National 

 Shellfish Sanitation Program. Fecal coliform MPN of quahog meats increased 

 more closely with increase in total and fecal coliform MPN of the waters 

 than did total coliform MPN of meats. Five Salmonella serotypes, including 

 S. paratyphi B., were found singly and in combination in a small number of 

 quahog samples from waters in which total coliform MPN/100 ml was over 200, 

 and in which fecal coliform MPN/100 ml was over 14. - J.L.M. 



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