Decapod life histories and reproductive dynamics in relation to oceanography off southern Africa

Abstract

The reproductive dynamics of seven commercially important southern African decapod crustaceans are contrasted in terms of their lifetime egg production per recruit (E/R). Despite having very different larval life histories, both the shallow-water continental shelf spiny lobsters (Panulirus homarus rubellus and Jasus lalandii) and crab (Scylla serrata) have substantially smaller eggs and higher values of egg per recruit than the deep-water spiny lobsters Palinurus delagoae and P. gilchristi or the crab Chaceon maritae. A single shallow-water oceanic island spiny lobster (Jasus tristani) has similar egg characteristics (size and E/R values) to those of the deep-water lobsters. The hypothesis is presented that large E/R values in the shallow-water spiny lobsters and crabs may be an evolutionary response to high rates of mortality of larval and juvenile stages in the nearshore coastal environment. Small size of eggs is considered to be an adaptation to allow for larger brood sizes and greater egg production in the shallow-water species.