Distribution and reproductive biology Of Corophium insidiosum (Amphipoda) on the north-east coast of England

The distributions of Corophium insidiosum and C. bonnellii on the shores of Northumberland and Tyne and Wear suggest the former species to be common in areas of high turbidity, and the latter species in relatively clean conditions. In C. insidiosum breeding takes place throughout the year except during the months of November and December when mature females enter a ‘resting’ stage and immature females delay the onset of maturity. There are two main generations per year. Egg production is linked to a semi-lunar rhythm with peaks around the times of spring tides. Fecundity, brood mortality and feeding activity each vary seasonally.