Meeting Abstract
Sea surface temperatures have been rising and are predicted to continue rising in coming years because of global warming. In addition, salinity has been decreasing in high latitudes and is expected to continue decreasing due to altered precipitation patterns and glacial melting caused by climate change. Early life stages (larvae and juveniles) should be especially susceptible to these environmental changes since they do not yet have fully developed adult defenses. In this study, we investigated the effects of reduced salinity (20 compared to a control of 30) and altered temperature (15, 20, 25, and 29°C) on the growth rates of juveniles and larvae of the gastropod Crepidula fornicata. Both larval and juvenile growth rates were significantly depressed by low salinity and elevated by higher temperatures. Moreover, the salinity that snails were exposed to as larvae significantly impacted their juvenile growth rates in 4 out of 6 experiments, an example of latent effects, but the magnitude and direction of this effect depended on rearing temperature and parentage. Salinity and temperature had little effect on relative rates of shell vs. tissue growth in juveniles, but had a measurable effect on larvae: the shell mass proportion of larvae reared at 20°C was 27% lower at a salinity of 20 than 30. In conclusion, C. fornicata may experience more favorable conditions in a warmer future: both larval and juvenile growth rates should increase, probably making larvae and juveniles more resistant to predation. However, in regions where salinity is decreasing, C. fornicata larvae and juveniles will likely grow more slowly, thereby increasing predation risk by forcing them to spend more time at more vulnerable smaller sizes.
