Measure of stress response induced by temperature and salinity changes on hatched larvae of three marine gastropod species

To better understand the cascade of molecular reactions leading to delayed development and mortality of early life stages of marine intertidal gastropods, in response to temperature and salinity changes associated with climate change, three biomarkers: total antioxidant capacity, lipid peroxidation and lysosomal stability were investigated on hatched larvae. Encapsulated embryos of three marine gastropod species (Bembicium nanum, Siphonaria denticulata and Dolabrifera brazieri), which have already proven responsive to thermal and osmotic variations, were exposed to six combinations of temperature (22 °C and 30 °C) and salinity (25‰, 35‰ and 45‰) until the larvae hatched. Time to hatching was affected by salinity and temperature in all three species. High salinity (45‰) generally retarded the hatching process although the response was species-specific for temperature. Total antioxidant capacity and lipid peroxidation were also highly species-specific with the general trend showing that these biomarkers were adversely affected by high temperature (30 °C) at salinities of 25‰ and 45‰. Bembicium nanum lysosomal destabilisation increased significantly with an increase in temperature and salinity (30 °C and 45‰) and this was associated with delayed development and increased mortality. Investigations on the additional biomarker, lysosomal stability, gave a clearer picture of the numerous and complex molecular and cellular mechanisms leading to mortality and underdevelopment in response to environmental stress for this species. As few differences were observed in the enzymatic biomarkers total antioxidant capacity and lipid peroxidation between hatched larvae and the previously investigated encapsulated embryo response to thermal and osmotic stress, it is suggested that further studies could be undertaken using embryos encapsulated in egg masses, as it is less time consuming than working on hatched larvae.

Research Highlights
► The hatching process of gastropods larvae is temperature and salinity dependant.
► The TAOC and LP of gastropod larvae were affected by thermal and osmotic stress.
► No direct link was found between lysosomal destabilisation and oxidative stress.
► Gastropods' lysosomal stability could only be measured on hatched larvae.
► Working on hatched larvae was less efficient and more time consuming.