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Predator and prey interactions of fishes of a tropical Western Australia river revealed by dietary and stable isotope analyses

Thorburn, D.C., Gill, H. and Morgan, D.L. (2014) Predator and prey interactions of fishes of a tropical Western Australia river revealed by dietary and stable isotope analyses. Journal of the Royal Society of Western Australia, 97 . pp. 363-387.

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Stomach content analyses of fishes occurring in the Fitzroy River, Western Australia, were used to investigate seasonal and ontogenetic changes in the diets and feeding relationships of the most abundant teleost and elasmobranch species. Concurrent analysis of δ13C and δ15N isotope ratios was also used to determine which food resources were energetically important to each species (assimilated) and included less common fishes for which few dietary samples were attained. The use of δ13C and δ15N isotope and stomach content analysis indicated that differences often exist between the food types consumed and those that are energetically important to a species. Dietary analysis suggested that aquatic insects, and to a lesser extent filamentous algae, were important food sources for many of the species present. While stable isotope analysis also suggested that insects are important prey, both insects and algae did not appear to be as important as direct energy sources. In contrast, prey types that persist throughout the year (e.g. fish, molluscs and Macrobrachium spinipes) may be more important sources of energy than dietary data revealed. For example, isotope analysis suggested that fish are an important energy source for a large number of species including several which have been considered to be strict algivores/detritivores. Dietary overlap between species was found to be the highest during the wet season, when prey availability was presumably also high, decreased in the early dry season as fishes became more specialised in their feeding and increased again in the late dry when food became very limited.

Item Type: Journal Article
Murdoch Affiliation(s): School of Veterinary and Life Sciences
Centre for Fish and Fisheries Research
Freshwater Fish Group & Fish Health Unit
Publisher: Royal Society of Western Australia
Copyright: © Royal Society of Western Australia 2014
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