The clam Macoma balthica prevents in situ growth of microalgal mats: implications for meiofaunal assemblages

摘要: The tellinid clam Macoma balthica (L.), a key member of numerous marine temperate soft-bottom communities, was used in laboratory experiments designed to evaluate its impact on developing microalgal mats and meiobenthic assemblages. Experimental jars (100 ml, 33 cm 2 ) were filled with azoic sediment, seeded bivalves at various densities, placed large outdoor water tank constant flow brackish left for 65 d. efficiently kept the sedi- ment surface clean mats. At end experiment, without clams aver- age 99% covered by algae, while (300 4800 ind. m -2 had less than 10% cover average. There highly significant positive correlation between algal number individuals belonging major meiofaunal taxa, i.e. Nematoda (r = 0.61, p < 0.001) Copepoda 0.79, 0.001). In containers high densities (4800 ), numbers nematodes significantly lower low 600 but no such difference found copepods. Multidimensional scaling ordination indicated 3 distinct sig- nificantly different assemblages (ANOSIM, 0.01) density 0, 300 , assemblage structure copepods only or clams. separate we tested if size an initial organic enrichment sediment would affect colonizing meiofauna. results that small also effectively prevented formation development communities depended matter sediment. We concluded indirect effects meiobenthos hindering are much larger any direct effects.