The Effects of Temperature and Salinity Stressors on the Survival, Condition, and Valve Closure of the Manila Clam, Venerupis philippinarum 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℃ were higher than that of those exposed to seawater at 24℃. 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 of those exposed to constant 30 psu conditions. Lastly, clams were exposed to two different temperatures and three different salinities conditions for 8 days. Valve closure and survival decreased significantly under the combination of 24℃ 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.

Assessing the risks to clam farming in Northern Vietnam within a climate change context

“…High temperature at noon in summer, in conjunction with low water levels on the grow‐out ground (during low tide, or in puddles on the grow‐out ground), has an extreme effect on cultured clams, seeming to ‘boil’ them (Figure 6a). These findings align with previous studies in which temperatures outside the bivalve's optimal range can affect their respiration, metabolic activity, feeding, ingestion rates, growth and survival (Bae et al, 2021; Han et al, 2008; Hornstein et al, 2018; Xiao et al, 2014). Research also demonstrated that temperatures beyond the species' optimal range influence the bivalve's immune system, leading to a less effective response to infectious disease agents (Matozzo et al, 2012; Nardi et al, 2021; Rahman et al, 2018).…”