Embryonic and larval biology of Liocarcinus holsatus and Necora puber (Crustacea: brachyura: portunidae)

Abstract

The effects of temperature and salinity on embryonic development, and including diet on larval development of the swimming crabs Liocarcinus holsatus and Necora puber were investigated in the laboratory. The temperature-development rate relationships were then used to construct graphical models to try and explain the temporal and spatial variations in larval distribution and abundance which occur in the sea. Hatching of L. holsatus and N. puber occurred at temperatures and salinities between 8–20°C and 20–40% o, respectively. Larvae of L. holsatus could tolerate relatively lower salinities and temperatures than those of N. puber. Furthermore, L. holsatus developed more successfully in a greater salinity range at low temperatures than N. puber. Conversely, N. puber did so in a greater salinity range at higher temperatures. These attributes seem to be a reflection of adaptation in the sea where the eggs and larvae of L. holsatus are produced earlier in the year and at lower temperatures than those of N. puber. For both species, hatching and larval development were more successful at combinations of low temperature-low salinity and high temperature-high salinity. A mixture of algae and formulated diet was best for larval development and survival. The appearance of L. holsatus larvae in the plankton a month earlier than those of N. puber is considered to be a result of faster embryonic development in the former species.