Recolonization of estuarine sediments by macroinvertebrates: Does microcosm size matter?

Microcosms containing defaunated, fine estuarine sediments were field deployed to assess the effects of microcosm size on the rate of benthic macroinvertebrate recolonization and resulting community structure. Four sizes of microcosms (square acrylic plastic boxes: 7 cm side^?1, 12 cm side^?1, 20 cm side^?1, and 32 cm side^?1, all 6-cm deep) were deployed in upper Perdido Bay, Florida, and colonized for 6 wk. Absolute mean total number of organisms (TNO) differed (α=0.05) among all sizes, while normalized mean TNO (adjusted to 12 cm side^?1 area) did not. Mean total number of taxa (TNT) was different among sizes: 7 cm side^?1, 12 cm side^?1, and 20 cm side^?1, but not between sizes 20 cm side^?1 and 32 cm side^?1. Seven dominant taxa occurred in all size microcosms. Scaling of physical design features (size of microcosm) affected numbers of taxa in recolonization of fine-grained sediments in our study area, but effects on abundance and dominance were minimal.