OBSERVATIONS ON THE ECOLOGY OF THE SOFT CLAM, MYA AREN ARIA, IN A SALT POND

Abstract

Observations were made on the ecology of the soft clam, Mya arenaria, in a salt water pond on Martha's Vineyard, Mass., during the summer and fall of 1958. Primary consideration was given to the tolerance of this species to low and fluctuating salinities, the effect of salinity upon rate of growth, and possible correlation between growth rate and the nature and abundance of phytoplankton. Field observations supplemented by laboratory experimentation indicated that Mya longer than 2 mm can tolerate salinities less than 1‰ for at least 24 hrs and can withstand sudden salinity fluctuations of an order of 18‰. Tolerance of clams 2–25 mm in length to low salinities was found to be proportional to their size. Growth rate of clams living under different salinity conditions ranging in mean value from 3.5‰ to 14‰ was found to vary directly with salinity. The fact that the pumping rate of clams was observed to vary directly with salinity within the limits 0–31‰ is considered significant in this respect. Comparisons of growth rates with phytoplankton concentrations suggested that flagellates form an important source of nutrition for Mya and that diatoms may be of relatively little importance. © 1960, by the Association for the Sciences of Limnology and Oceanography, Inc.