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Presented at the NABS Annual meeting, Vancouver, British Columbia, 2004
in Food webs 2
Feeding ecology of fish in coastal lagoons of northern New South Wales, Australia, as determined using gut contents and stable isotope analyses.
W.L. Hadwen1,2, G.L. Russell1, and A.H. Arthington1,2. 1Centre for Riverine Landscapes, Faculty of Environmental Sciences, Griffith University, Nathan QLD 4111, Australia, 2Cooperative Research Centre for Sustainable Tourism
Analyses of feeding ecology have historically been based on gut contents analyses, yet stable isotope analyses have been shown to offer a more temporally integrated assessment of feeding relationships. In this study, the feeding ecology of fish was assessed in two coastal lagoons in northern NSW, Australia. These lagoons have temporally variable freshwater inflows and biotic composition, so both methods were employed to determine the relative importance of available prey items to fish diets.
In both lagoons, there was a relationship between benthic algae and mullet (Mugil cephalus) isotope signatures, suggesting that this species routinely feeds on benthic sediments. Analyses of gut contents corroborated these findings, with all individuals containing large amounts of benthic algae and particulate organic matter.
In contrast, whiting (Sillago ciliata) stomachs contained large numbers of polychaete worms and bivalves. Despite literature data suggesting a strong crustacean contribution to whiting diets, none were found in whiting stomachs in the present study. However, on the basis of stable isotope analyses, the abundant greentail prawns (Metapenaeus bennettae) do contribute to whiting diets. These findings highlight the utility of combined gut contents and stable isotope analyses in reconstructing the feeding ecology of fish in these temporally variable coastal lagoons.
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