The role of salinity in physiological responses of bivalves

Abstract

In recent years, financial losses due to salinity changes threat bivalve industry. In natural habitat, marine bivalves should be adapted to a series of environmental stressors, including biotic (virus, bacteria and protozoan) and abiotic (salinity, temperature and heavy metal) factors. It is known that salinity fluctuations able to change distribution and vital parameters of bivalves. Suboptimal salinity conditions resulted in changes in defense mechanism, growth, free amino acid, heart rate, oxygen consumption and filtration rate. However, it is necessary to determine the optimal salinity level of cultured bivalves to avoid the risk of mortality and improve growth rate. Therefore, this study aimed to review the findings from various reports in vitro and in vivo conditions which evaluated physiological and immunological responses of different bivalve species submitted to different salinity concentrations. The information of present study is very important in understanding the physiological responses of bivalves, which are living in highly changeable environment such as estuarine.

Time‐course changes in the regulation of ions and amino acids in the hard clam Meretrix lusoria upon lower salinity challenge

“…FAAs play important roles as intracellular osmolytes in osmoconformer bivalves subjected osmotic stress (Pourmozaffar et al, 2019). Among the FAAs identified in different marine bivalve species, alanine, glutamate, glycine, and taurine have been reported to be the most important for maintaining intracellular osmolality (Pourmozaffar et al, 2019; Sokolowski et al, 2003).…”

Impact of Polycyclic Aromatic Hydrocarbon Accumulation on Oyster Health

“…However, such straightforward effects are not always observed, especially if other abiotic factors are involved, as evidenced by the complete lack of correlation between salinity and tissueconcentration of PAHs in oysters collected from different sites (Bebianno et al, 2007). When bivalve mollusks experience osmotic shock, they often close their valves (Kurihara, 2016) to limit water movement, and then attempt to osmoregulate by deamination of free amino acids (reduce internal concentration) or decomposition of proteins (increase internal concentration) (reviewed in Pourmozaffar et al, 2020). Withdrawal and shell closure has also been associated with starvation since the oyster is no longer feeding (Vignier et al, 2018), which may further complicate additional burdens by placing tighter limits on energy reserves for more prolonged exposure times.…”

“…Withdrawal and shell closure has also been associated with starvation since the oyster is no longer feeding (Vignier et al, 2018), which may further complicate additional burdens by placing tighter limits on energy reserves for more prolonged exposure times. Furthermore, lower salinities have been associated with a host of negative effects on bivalves such as lipid peroxidation in the Mediterranean mussel (Mytilus galloprovincialis) and littleneck clam (Ruditapes philippinarum) (Velez et al, 2016;Freitas et al, 2017), reduced shell length and thickness of the blue mussel (Mytilus edulis) (Maar et al, 2015), reduction in the body cavity index (ratio of the flesh mass to the internal cavity volume) of C. virginica (Heilmayer et al, 2008), reduced growth rate and size of both O. edulis and O. lurida larvae (Robert et al, 1988;Lawlor and Arellano, 2020), and decreased phagocytosis activity coupled with increased hemocyte mortality in several bivalves (reviewed by Pourmozaffar et al, 2020). This could mean that hypoosmotically-weakened oysters are highly susceptible to PAH-compounded health consequences resulting from the increased accumulation of more-soluble PAHs.…”

Evidence of multiple genome duplication events inMytilusevolution

“…The stress response genes presenting positive selection are related or are interacting with Hsp proteins (SIL1 and the archease-like protein). Since the marine environment has considerable concentration of bacteria and viruses, molluscs depend on cellular and molecular mediated immune responses that help them to survive under challenging conditions (Pourmozaffar et al, 2020). That is why filter-feeding animals such as bivalves rely on the intervention of shock proteins which synthesis depends on environmental stressful conditions such as temperature, salinity, hypoxia, heavy metal, and infectious pathogens (Wan et al, 2012).…”