Mulinia lateralis is a small opportunistic bivalve in the family Mactridae. The exterior of the shell is cream to yellowish-orange while the interior is bright white.
HABITAT AND DISTRIBUTION
Mulinia lateralis has a broad geographic range that extends from New Brunswick, NJ to the Yucatan in Mexico (Levinton 1971). The dwarf surf clam is normally found in the soft strata in benthic communities.
Mulinia lateralis occurs in the Indian River Lagoon.
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Mulinia lateralis can live up to two years (Lu et al. 1996). Adults are approximately 15 to 20 mm in length while newly metamorphosed juvenile shell lengths range from 200 to 700 µm (Yongping and Guo 2008). The dwarf surf clam has a short generation time reaching sexual maturity in 1-2 months (Guo and Allen 1994).
Mulinia lateralis can reach average densities of up to 21,000
individual per m2 (Santos and Simon 1980). It is an opportunistic species
that grows and reproduces quickly becoming dominant in areas where
conditions are optimal (Chlaermwat et al. 1991).
The dwarf surf clam has separate sexes (Lu et al. 1996). Mature adults
spawn from May to November. A female will usually release between 0.5 to 2
million eggs during a spawning event (Lu et al. 1996). In the laboratory,
individuals produced 3 x 105 eggs or 2.5 x 109 sperm cells (Guo and Allen
Mulinia lateralis has pelagic planktotrophic larval stages that lives in the plankton from 7-22 days (Mann et al. 1991). Settlement occurs after the larvae reach the pediveliger stage, developing a hinged shell and a foot.
The development of fertilized eggs from the dwarf clam is greatly reduced
at temperatures below and above 20-25°C (Calabrese 1969).
Adult Mulinia lateralis occurs in estuaries where the salinity
varies from 18 to 30 ppt (Lippson and Lippson 1984). In laboratory
experiments, embryos exhibited a high tolerance for salinity changes
developing into normal straight-hinge larvae over a wide range of
salinities 15 to 35 ppt (Calabrese 1969).
Mulinia lateralis is a filter feeder, feeding mainly on suspended bacteria (Chalermwat et al. 1991).
Crabs are a major predator of M. lateralis. Predation is probably the major factor controlling adult population size, at least during warmer months (Virnstein 1979).
Mulinia lateralis numbers increase drastically in the absence of predators.
Calabrese A. 1969. Individual and combined effects of salinity and
temperature on embryos and larvae of the coot clam, Mulinia
lateralis (Say). Biological Bulletin 137:417-428.
Chalermwat K, Jacobson TR, and RA Lutz. 1991. Assimilation of bacteria by
the dwarf surf clam Mulinia lateralis (Bivalvia: Mactridae). Marine
Ecology Progress Series 71:27-35.
Guo X and SK Allen, Jr. 1994. Sex determination and polyploidy gigantism
in the dwarf surfclam (Mulinia lateralis Say). Genetics
Levinton JS. 2001. Genetics, Paleontology, and Macroevolution. Cambridge
University Press, pg. 114.
Lippson AJ and RL Lippson. 1984. Life in Chesapeake Bay. John Hopkins
University Press, Baltimore.
Lu JK, Chen TT, Allen SK, Matsubara T, and JC Burns. 1996. Production of
transgenic dwarf surfclams, Mulinia lateralis, with pantropic
retroviral vectors. Proceeding of the National Academy of Sciences
Mann R, Campos BM, and MW Luckenbach. 1991. Swimming rate and responses of
larvae of three mactrid bivalves to salinity discontinuities. Marine
Ecology Progress Series 68:257-269.
Santos SL and JL Simon. 1980. Response of soft-bottom benthos to annual
catastrophic disturbance in a South Florida estuary. Marine Ecology
Progress Series 3:347-355.
Virnstein RW. 1979. Predation on Estuarine Infauna: Response Patterns of
Component Species. Estuaries (2) 2: 69-86.
Yongping W and X Guo. 2008. Chromosomal mapping of the major ribosomal RNA
genes in the dwarf surfclam. Journal of Shellfish Research 27:307-311.
Melany P. Puglisi and Maribel Thiebaud, Smithsonian Marine Station
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Page last updated: October 1, 2008