Drivers of abundance and spatial distribution of reef-associated sharks in an isolated atoll reef system.

摘要: We investigated drivers of reef shark demography across a large and isolated marine protected area, the British Indian Ocean Territory Marine Reserve, using stereo baited remote underwater video systems. modelled abundance against biotic abiotic variables at 35 sites reserve found that biomass low trophic order fish (specifically planktivores) had greatest effect on abundance, although models also included habitat (depth, coral cover site type). There was significant variation in composition assemblage different atolls within reserve. In particular, deepest sampled (a seamount 70-80m visited for first time this study) recorded numbers scalloped hammerhead sharks (Sphyrna lewini) not observed elsewhere. Size structure most abundant common species, grey (Carcharhinus amblyrhynchos), varied with location. Individuals an bank were 30% smaller than those main atolls, size significantly biased towards range young year (YOY). The 18 individuals judged to be YOY represented offspring between four six females, so, whilst inconclusive, these data suggest possible use pupping by sharks. importance (i.e. potential prey) predicting spatial is consistent other studies both terrestrial systems which prey availability may more important predictor predator distribution suitability. This result supports need ecosystem level rather species-specific conservation measures support recovery. partitioning amongst species life-stages implies include diversity habitats types area adequate protection reef-associated assemblages.