Temperature and pressure tolerance of larvae of Crepidula fornicata suggest thermal limitation of bathymetric range

The extant deep-sea fauna is thought to result from recolonisation of this environment by shallow-water organisms following climate-driven mass extinctions. Planktonic larval tolerance to high pressure is considered an important preadaptation for successful deep-sea invasion. In this study, the pressure and temperature tolerance of a species without any known confamilial deep-sea relative were assessed for the first time. Early- and late-veliger larvae of the shallow-water species Crepidula fornicata were subjected to a temperature/hydrostatic pressure regime from 5 to 25 A degrees C and from 0.1 to 40 MPa. Although early and late veliger survived pressures equivalent to 2,000 m water depth or greater at all temperatures, decreased larval activity indicated significant sublethal temperature and pressure effects. Reduced larval activity of early veliger at low temperatures suggests that the bathymetric range of this species may be thermally constrained. A mechanistic model is proposed to explain the emerging pattern of ontogenetic shifts in pressure tolerance of shallow-water benthic invertebrates.