Salinity tolerance in blood cockles environmental conditions associated with the presence of Tegillarca granosa and its salinity tolerance: field observations and laboratory experiments

Blood cockle, Tegillarca granosa, is an economically important bivalve, yet its production has declined in recent years. Because blood cockle farming relies on open ecosystems, it is vulnerable to changes in water quality. This study assessed water quality parameters in blood cockle habitats in Lekir, Perak, Malaysia, and examined their relationship with cockle presence. Laboratory experiments were conducted to evaluate salinity tolerance by determining the LC₅₀ for spat and adult cockles, and by assessing survival and growth under different acclimated salinity levels. Field observations showed that stations without blood cockles had higher salinity (29 ppt), while stations with spat and adult cockles had lower salinities (7.6–19.0 ppt), suggesting a potential influence of extreme salinity on distribution. However, laboratory results demonstrated that both spat and adult cockles tolerate a wide salinity range, with high survival across salinities from 4 to 45 ppt. These findings indicate that salinity alone does not explain cockle absence at high-salinity sites. Instead, food availability, reflected by higher chlorophyll-a concentrations, along with favourable temperatures (31.4–32.3°C), may play a more important role in supporting cockle populations. Understanding these factors is essential for improving blood cockle aquaculture and management strategies in the region.