The Effects of Temperature and Salinity Stressors on the Survival, Condition and Valve Closure of the Manila Clam, <i>Venerupis philippinarum</i> in a Holding Facility

Abstract

We investigated the response of the Manila clam Venerupis philippinarum to possible temperature and salinity changes in a holding facility. First, clams were exposed to four temperatures for 15 days. Valve closure and survival of clams exposed to seawater at 18 °C were higher than that of those exposed to seawater at 24 °C. Second, clams were exposed to six salinities for 15 days. Survival of clams exposed to two salinity fluctuation conditions (24–30 and 27–24 psu) was lower than that of clams exposed to constant 30 psu conditions. Valve closures of clams exposed to constant low salinity conditions (24 psu) and two salinity fluctuation conditions (24–30 and 27–24 psu) were higher than those exposed to constant 30 psu conditions. Lastly, clams were exposed to two different temperatures and three different salinity conditions for 8 days. Valve closure and survival decreased significantly under the combination of 24 °C and 18 psu. These results suggest that an increase in temperature or a wider range of salinity fluctuations are detrimental to the survival of the Manila clam. The synergistic effect of temperature and salinity stressors may decrease the survival period of clams compared to the effect of a single stressor.

Keywords

• warming
• freshening
• salinity fluctuation
• multiple stressors
• stock holding