Larval performance of the exotic Hemigrapsus sanguineus under increased temperature and food limitation

Abstract

For marine species with complex life cycles, a critical question concerns the response of larval stages to warming. In species with feeding larvae, warming and food limitation may result in negative (additive or synergetic) effects on growth and survival. We experimentally evaluated the combined effects of temperature and food limitation on larval performance of the invasive crab Hemigrapsus sanguineus (local population of Helgoland, North Sea, German Bight). We then compared the performance of H. sanguineus with the native competitor (shore crab Carcinus maenas). Within the studied temperature range (15-24 °C) and under the conditions of food limitation (access to food for 6 hours a day), the primary driver of survival was temperature (low temperatures decreased survival especially at the more advanced stages). Food limitation decreased survival and growth at all temperatures but larvae metamorphosed to megalopa at all food limited conditions. The response of H. sanguineus differed from that of C. maenas where effects low temperatures have little impact on performance but high temperatures enhance the negative effects of food limitation. Hence, these two coexisting species appear to have different larval responses to warming and food limitation, with warming leading to a higher performance of the invasive relative to the native species.