Survival time of juvenile pen shell Atrina pectinata (Bivalvia: Pinnidae) in hyposaline water

摘要

Survival time of juvenile pen shell Atrina pectinata (shell length?≈?34?mm) exposed to hyposaline water without sediments was investigated in laboratory experiments. The bivalves were individually maintained in rearing cups in which salinity was decreased either gradually (over 1–11?h to 12 salinities ranging from 0 to ca. 34?ppt) or rapidly (directly to 21 salinities) at 12 and 24?°C. When the environmental salinity was gradually decreased, survival time differed markedly between the bivalves exposed to: salinities ≤?18.6?ppt (survival time? ?83?h) at 24?°C; and between salinities ≤?15.1 ppt ( ?83?h) at 12?°C. When the environmental salinity was rapidly decreased, survival time, again, differed markedly between the bivalves exposed to: salinities ≤?15.9 ppt ( ?140?h) at 24?°C; and salinities ≤ 21.3 ppt ( ?140?h) at 12?°C. Such sharp decreases in survival time due to reduced salinity led to the selected, statistical models that assume either a sharp exponential increase or stepwise hike in hazard (instantaneous mortality rate) according to salinity reduction. These data and models indicate that juvenile A. pectinata should not be kept at salinities? ?1?day in environments without sediments.