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Feeding ecology and dietary comparisons among three sympatric Neotrygon (Myliobatoidei: Dasyatidae) species

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Tel.: +61 7 3225 1851; email: i.jacobsen@uq.edu.au

Abstract

The diets of Neotrygon picta, Neotrygon kuhlii and Neotrygon annotata are described using trophic level analysis, index of relative importance (IRI) and non-metric multidimensional scaling ordination (nMDS). They were secondary consumers with trophic levels of between 3·55 and 3·58. Carids were the most important prey category in the diets of N. picta (82·0%IRI) and N. annotata (69·4%IRI); Polychaeta (72·3%IRI) was the most important prey category for N. kuhlii. A significant difference was detected between the volumetric dietary data of all three species (ANOSIM, global R-statistic = 0·742, P < 0·01) and between sequential N. picta and N. kuhlii size classes (ANOSIM, global R-statistics = 0·367–0·403, P < 0·01). Changes in polychaete and carid prey proportions were the primary sources of diet variability. Dietary differences may be linked to variations in disc width, mouth morphology and feeding strategies. This study provides insights into the level of variability within and between the diets and feeding behaviours of Neotrygon species, and the potential for resource partitioning to occur when these species coexist.

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