Abstract
- A variety of theories, especially functional-group theories, have proposed that adult infauna may regulate community by affecting the survival or behavior of settling larvae and juveniles. The influence of adult suspention- and deposit-feeding bivalves (Macoma balthica and Mya arenaria) on infaunal recruitment was studied to observe the potential importance of such interactions. The two clams were transplanted at various densities into buckets of defaunated sediment during the spring of two years. Both species had generally similar effects on the densities of other fauna. Total macrofaunal abundance was reduced by both Mya arenaria and Macoma balthica, with the greatest decline occurring at highest clam densities. The densities of individual species were also affected, but the influence of the two clams varied among taxa and between years. The results suggest that Macoma balthica and Mya arenaria may alter community composition through a variety of direct and indirect effects upon recruitment. However, the pattern of effects is not consistent with the predicted by functional-group theories of faunal interactions in soft substrates. Indirect effects of the clams, resulting from their influence on one or two dominant taxa, may be more important on short time scales in determining the abundances of certain fauna.