Published online by Cambridge University Press: 11 May 2009
INTRODUCTION
Members of the leucosiid genus Ebalia are typical oxystomatous crabs which live on subtidal coarse sediments at depths ranging from a few metres to over 2500 m. Although this genus has an almost worldwide distribution, no studies of the population biology of any species has been made.
Five species of Ebalia occur round British coasts (Ingle, 1980), four of which have also been recorded from the Clyde Sea area (Allen, 1967). During dredging surveys in this region, a sizeable population of Ebalia tuberosa (Pennant) was located in the vicinity of the University Marine Biological Station on Great Cumbrae Island, and regular sampling of this population over a period of two years provided the data on which this study is based.
Apart from a few references to the occurrence of female crabs in berry (Lebour, 1928a, b; Marine Biological Association, 1957; Allen, 1967) and to the occurrence of larvae in the plankton (Jorgensen, 1923, 1925; Lebour, 19286; 1947; Rees, 1952; Williamson, 1956; Marine Biological Association, 1957; Bruce, Colman & Jones, 1963; Crothers, 1966), no other information on the population biology of E. tuberosa is available.