DIET AND REPRODUCTIVE ACTIVITY OF THE ESTUARINE ROUNDHERRING GILCHRISTELLA AESTUARIA IN CUBHU, A FRESHWATER COASTAL LAKE IN NORTHERN NATAL, SOUTH AFRICA

Abstract

A study of the diet and reproductive activity of Gilchristella aestuaria revealed that active gonads were present throughout the year. The main breeding season appeared to be from spring through to autumn with two distinct peaks occurring from August to October and February to April. The species diet in Lake Cubhu consisted predominantly of the amphipod Corophium triaenonyx which where actively selected by larger specimens while it appeared that juveniles utilised a filter feeding approach taking copepods and other planktonic organisms. The specific prey items taken varied to some degree from those recorded in other studies but this was largely due to the fact that Cubhu is a freshwater system while most other studies were on G. aestuaria from estuarine localities. The morphology of G. aestuaria in Cubhu, larger eyes and more cylindrical body, is typical of the non-filter feeding G. aestuaria described from systems with low plankton densities where selection of individual prey items takes place.