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

Abstract

Abstract 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.

Keywords

• Pen shell
• Atrina pectinata Lineage 2
• Survival analysis
• Low salinity
• Gradual and rapid decreases
• Temperature