Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Atlantic) Hard Clam

• Main Author: Eversole, Arnold G
• Other Authors: CLEMSON UNIV SC
• Format: Text
• Language: English
• Published: 1987
• Subjects: Biological Oceanography; *CLAMS; ADULTS; BEHAVIOR; COASTAL REGIONS; COMMERCIAL FISHING; CRABS; CURRENTS; DISTRIBUTION; EGGS; ENVIRONMENTAL IMPACT; ENVIRONMENTS; ESTUARIES; FEEDING; FISHERIES; FISHES; HABITATS; HABITS; HIGH DENSITY; HISTORY; INVERTEBRATES; LARVAE; LIFE CYCLES; LIFE(BIOLOGY); MUD; OXYGEN; PARASITES; PARTICULATES; PROFILES; SALINITY; SAND; SEDIMENTS; SHELLFISH; SOUTH ATLANTIC OCEAN; SUBSTRATES; SUSPENDED SEDIMENTS; TAXONOMY; WATER; WATER FLOW; WATER QUALITY; Predators; *Hard clams; *Mercenaria mercenaria; Filter feeding; South Atlantic Ocean
• Online Access: http://www.dtic.mil/docs/citations/ADA189696; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA189696

Species profiles are literature summaries of the taxonomy, morphology, range, life history and environmental requirements of coastal species. They are designed to assist in environmental impact assessment. The hard clam, Mercenaria mercenaria, supports an important commercial fishery in the South Atlantic, averaging about 1 million kg of meats annually from 1979 to 1983. It also is an important constituent of estuarine systems throughout the region. Spawning occurs in the spring and the fall at 16 to 30 C. Plank tonic eggs and larvae are carried by water currents, and larvae set sometime after 6 days of age. Mortality is highest in egg and larval stages, the most sensitive part of the life cycle. Spat display gregarious setting behavior and appear to select sand over finer substrates. Highest densities of clams occur in sandy bottoms with shell. Crab predation is an important factor influencing the density and distribution of clams. Blue crabs and mud crabs appear to be the most important predators. Hard clams are infested by few parasites. Adult clams feed by filtering suspended particulates matter from the water. Growth of clams decreases with size and age. Growth occurs year-round with peaks in spring and fall. Growth of adult hard clams occurs at 9-31 C and at 4-35 ppt (optima near 20 C and 24-28 ppt). Hard clams mature in 2 years and reach commercial size in 3 years in the South Atlantic. Tight-fitting shells permit hard clams to survive poor water quality for short periods. Keywords: Shellfish, Growth(Physiology), Salinity, Temperature, Fisheries, Suspended sediments, Sediments, Feeding habits, Life cycles, Oxygen, Contaminants, Habitat, Hard calm.