Reproduction Under Stress: Acute Effect of Low Salinities and Heat Waves on Reproductive Cycle of Four Ecologically and Commercially Important Bivalves

The impacts of climate change on the structure and functioning estuaries is a major focus concern, even more when affected species support important fisheries as bivalves Ruditapes decussatus , philippinarum Venerupis corrugata Cerastoderma edule in Europe. Their reproductive performance, context stressors, had not been investigated so far. Our objective was to experimentally evaluate acute stress effects over gonad development after 6 days low salinity autumn, winter spring well 4 heatwave during emersion summer. These are most probable extreme events that should face our latitudes. Four different ramps (5–20, 10–25, 15–30, 30–30) were created simulated tidal cycles mesocosms for experiments. Also four sediment heatwaves at (20–20, 20–27, 20–32, 20–37°C) done cycle. Both stresses such short periods compromised reproduction; response species-specific varied with time year, therefore, stage gametogenic In December, sexual resting beginning gametogenesis, delay gametogenesis lower salinities recorded species. However, peak period (March May), responses observed: abnormal oocytes R. resorption gametes haemocytic infiltration V. . Likewise temperatures higher than 32°C provoked gonadal severe invasion corrugata, C. but no effect both environmental stressors might be related allocation energy from reproduction toward defense repair mechanisms ensure survival. Contrastingly, triggered massive spawning could lead mismatch between presence larvae phytoplankton, causing potentially starvation thus reducing recruitment success. Reproduction theses would if episodes spring, those these experiments, followed by Furthermore impact magnified this situation happens consecutive years preventing replenishment shellfish beds.