Diet of western carp gudgeon (Hypseleotris klunzingeri Ogilby) in an Australian floodplain lake: the role of water level stability

To examine temporal variation in diet, two size classes of western carp gudgeon Hypseleotris klunzingeri were collected from macrophyte habitats in Dugays 2 billabong, a floodplain lake on the River Murray, Victoria, Australia, for 1 year. Fish were collected bimonthly during the day and at night between October 1995 and September 1996. Western carp gudgeon consumed a range of prey, including caddisflies, odonates, shrimps and detritus. The bulk of their diet volume, however, consisted of chironomids and zooplankton. The diets of small and large western carp gudgeon were similar and did not change from day to night. There was, however, high variability across sampling trips in fish diets, both at the community level and among selected prey groups, particularly chironomids, zooplankton and detritus. Community analysis revealed that diets of fish collected from the billabong following stable antecedent water levels were similar and showed little variation, while those collected following fluctuating antecedent water levels showed much more variation. These patterns were mirrored in the volumes of individual diet components.