The abilities of estuarine species to respond to salinity fluctuations by behavioural and physiological responses can determine the maintenance of populations, particularly in the context of climate change. The native clams Ruditapes decussatus and Venerupis corrugata, the native cockle Cerastoderma edule and the introduced clam Ruditapes philippinarum are important resources in Galician (NW Spain) coast. As inhabitants of estuaries, these species are exposed to frequent salinity fluctuations as a result of heavy rains. This study investigated the short-term sublethal effects of salinity drops on their physiological (scope for growth, SFG) and behavioural (valve closure and burrowing activity) responses. Bivalves were exposed to simulated tidal cycles and similar salinities to the field conditions, i.e., four salinity ramps (5–20, 10–25, 15–30 and 30–30) during six days over three different periods of the year (autumn, winter and spring). The overall response was the same for all species under the lower salinities (5, 10 and 15), with a dramatic reduction of pumping activity, SFG and burrowing. Results differed among species under the higher salinities (20, 25 and 30). While C. edule was the most affected species in autumn showing no recovery despite having higher SFG compared to the venerids, R. decussatus was more resistant in all seasons despite having the lowest SFG compared to the rest of species. In winter, V. corrugata was the most vulnerable due to lower SFG at the lowest salinities. All species showed a compensation pattern in spring that led to non-recovery of individuals. Burrowing ability had similar patterns to SFG in autumn and winter but differed in spring, when recovery was the general pattern. The decrease of burrowing ability at lower salinities during stress seen to some degree in all species can increase vulnerability to predation. Results suggest that differential responses of lower activity over time could be related to the physiological condition and habitat preferences of each species and should be taken in consideration for management plans in the context of climate change. The results drive a discussion of the usefulness of SFG as the metric with which to assess salinity stress in adult bivalves and the need in future research to increase frequency and duration of stresses in concert with variables such as food availability.

河口物种通过行为和生理响应对盐分波动的响应能力可以决定种群的维持，特别是在气候变化的情况下。蛤c Ruditapes decussatus和Venerupis corrugata，蛤cock Cerastoderma edule和引进的蛤Ru Ruditapes philippinarum是加利西亚（西班牙西北部）海岸的重要资源。作为河口居民，这些物种由于暴雨而经常遭受盐度波动的影响。这项研究调查了盐度下降对其生理（生长范围，SFG）和行为（阀门关闭和穴居活动）响应的短期亚致死作用。双壳类动物在一年中的三个不同时期（秋季，秋季，春季，春季，春季，春季，春季，秋季，春季，秋季，春季，秋季，冬季和春季）。在较低盐度（5、10和15）下，所有物种的总体反应都相同，抽水活度，SFG和穴位显着降低。在较高盐度（20、25和30）下，物种间的结果有所不同。而秋茄是秋季受影响最严重的物种，尽管其SFG高于维纳德族，但仍未恢复，尽管所有物种中的SFG最低，但其R. decussatus在所有季节都更具抵抗力。冬季，V。corrugata由于最低的SFG和最低的盐度，它是最脆弱的。所有物种在春季均表现出补偿模式，导致个体无法恢复。秋季和冬季，穴居能力与SFG有相似的模式，而春季则有所不同，春季是恢复的一般模式。在所有物种中，在一定压力下盐度较低时穴居能力的降低都可能增加其对捕食的脆弱性。结果表明，随着时间的推移，较低活动的不同响应可能与每种物种的生理状况和栖息地偏好有关，在气候变化的背景下，应将其纳入管理计划中。