Competition in deposit- And suspension-feeding bivalves: Experiments in control led outdoor environments

Abstract

Experiments were carried out in an intertidal and a subtidal outdoor flow-through basin. The effect of bivalve density on growth and survival was studied in the facultative deposit feeder Macoma balthica (L.) and the obligate suspension feeder Cerastoderma edule L. Patches of 0.2 m 2 with densities of maximal 2480 bivalves per m 2 were used. In C. edule growth was density independent, whereas in M. balthica growth decreased with density, indicating intraspecicic competition in M. balthica, but not in C. edule. These different feeding in C. edule. In mixed populations, C. edule and M. balthica did nopt clearly influence each other's growth and survival, indicating that interspecific competition did not occur between the two species. Our experiments support the hypothesis of levinton (1972), that, on local scale, competition is expected more readily in deposit-feeding communities than in suspension-feeding communities.