Diet and dietary overlap in fishes of temporary waters of southwestern Australia

Abstract

AbstractThe diets of six species of fish occurring in seasonally inundated waters of the southern acid peat flats of southwestern Australia were studied over a 23 month period. Fishes could be allocated to a benthos/lower water column guild or a midwater column/water surface guild. Segregation on the basis of prey size was noted for one species only, and this species had a larger mouth than the remaining species. Seasonal variation in within‐ and between‐guild overlap was observed. Highest overlap occurred in the mid‐wet season when inundation was greatest and all species foraged in extensive areas of very shallow water. Little segregation based on feeding position within the water column was possible, and some prey species (e. g. simuliid larvae) were particularly abundant at this time. Dietary overlap decreased as the dry season progressed and fish became concentrated in smaller areas of habitat. As fish demonstrated lower levels of food acquisition, this change in overlap was suggested to be in response to increased competition for limited food resources.