Substrate Choices Made by Marine Larvae Settling in Still Water and in a Flume Flow

摘要

Larvae of several species of invertebrates that live just below the surface of the seabed (infaunal species) are known to make active and consistent choices among sedimentary habitats; generally they choose the sediments most similar to those occurring in the habitats where the adult stages live in the field. But, previous experiments designed to investigate habitat selection by such larvae were conducted almost entirely in still water and never under realistic flow conditions. Therefore, although larvae are able to actively select settlement sites, it is not known whether these choices are exercised in natural field flows. We report here that the larvae of the infaunal polychaete, Capitella sp. I and the infaunal bivalve Mercenaria mercenaria, actively choose appropriate substrates in still water, but the species differ in their selection capabilities under controlled, realistic and defined flow conditions in the laboratory. The experiments were designed to determine the relative importance of active habitat selection versus passive deposition in still water and in a relatively slow, turbulent flow for two infaunal species which vary widely in life-history characteristics. Reprints. (aw)