Resource partitioning amongst co-occurring decapods on wellheads from Australia's North-West shelf : an analysis of carbon and nitrogen stable isotopes

On the North West shelf of Australia, assemblages of co-occurring decapods formed the dominant taxa that had colonised a series of petroleum wellheads. Stable isotope analysis was utilised to infer how eleven co-occurring decapods species partition trophic resources and to describe their trophic positions. Examination of δ 13C signatures revealed that some species were specialised in their resource use. For example, the shrimp Rhynchocinetes balssi and the crab Petrolisthes militaris consistently specialised in distinctive components of the resource base compared to other co-occurring decapods. Analysis of δ 15N signatures indicated that the species occupied similar trophic levels. However comparison amongst wellheads revealed that animals at deeper locations (136-152m) were more enriched than shallower locations (82-84m), which is likely to arise from the microbial degradation of particulate organic matter descending from the photic zone.