DIVERSITY, BIOMASS AND PRODUCTION OF DECAPOD CRUSTACEAN LARVAE IN A CHANGING ENVIRONMENT

There is a latitudinal gradient in the species richness of Decapoda wi th pelagic larvae. For example, only two species of Brachyura are foun d around Svalbard, 54 species are known from the English Channel and s imilar to 100 from the Atlantic coast of the Iberian peninsula. The di stributions of many species are limited by effects of temperature. Int ermoult times of larvae are inversely related to temperature. In the f ield the size of larvae is inversely related to temperature, the relat ionship tending to increase in significance in successive larval stage s. The timing of the seasonal occurrence of larvae of decapod species in the plankton is also related to temperature, to a greater extent th an are seasonal cycles of the holoplankton. These effects of temperatu re on larval development influence the biomass and production of the l arvae in the plankton. Some potential effects of climate change on the distributions and dynamics of planktonic larvae of decapods and conse quent changes in their diversity, biomass and production can be predic ted insofar as temperature is a limiting factor.