Spatial variation in abundance of prey and diet of trumpeter (Pelates sexlineatus: Teraponidae) associated with Zostera capricorni seagrass meadows

Abstract

Abstract The diet of juveniles of Pelates sexlineatus was examined at six estuaries, separated by tens to hundreds of kilometres, and two sites within each estuary, separated by hundreds of metres to kilometres. Fish were collected in Zostera capricorni seagrass meadows along the coast of New South Wales (Australia). Spatial variability in diet was compared with the abundance of prey. Pelates sexlineatus had a broad diet (27 different prey) but generally preferred crustaceans (harpacticoid copepods, gammarid amphipods, ostracods and tanaids), although at some sites other prey items were important (e.g. polychaetes, nematodes and foraminiferans). Composition of the diet varied among estuaries and between sites. Proportional representation of the different size of prey eaten by the three sizes of juveniles (40-54, 55–74 and 75–94 mm standard length) was similar. Fish generally preferred prey smaller than 1 mm. Abundance of prey also varied at both spatial scales. At five of the 12 sites, there was a significant correlation between abundance of prey in the seagrass meadows and abundance of prey in the diet. Variation in the composition of the diet was partly explained by spatial variation in abundance of prey. When crustaceans were not abundant in the seagrass, P. sexlineatus had a broad diet, taking both benthic and planktonic prey items. It is concluded therefore that trophic linkages between P. sexlineatus and benthic invertebrates may vary greatly with spatial scales from hundreds of metres to hundreds of kilometres, and are strongly related to availability of prey in seagrass habitats.