Long-term movement patterns and trophic ecology of blacktip reef sharks (Carcharhinus melanopterus) at Palmyra Atoll

In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: a b s t r a c t a r t i c l e i n f o Animal movements, residence times, and subsequently foraging strategies, should vary with habitat quality. We used acoustic and satellite telemetry, as well as stable isotopes, to look at movement patterns, macro-scale habitat use, and trophic ecology of blacktip reef sharks, Carcharhinus melanopterus, between two lagoons (eastern and western) at Palmyra Atoll, a US National Wildlife Refuge in the central Pacific. Sharks in the Palmyra lagoons have relatively small home ranges and appear to obtain most of their energy from the lagoon ecosystem. Sharks showed low levels of migration between lagoons over periods of several years, and individuals in the larger western lagoon tended to have longer residence times than those in the smaller eastern lagoon. Furthermore, for sharks in the western lagoon, there was no relationship between total length (TL) and δ 15 N, 13 C relative isotope concentrations, or a Body Condition index (BC). For sharks in the eastern lagoon, TL was positively related to δ 15 N and negatively related to δ 13 C and BC. These results suggest that there are low levels of mixing of sharks between lagoons, and these are leading to differences in trophic ecology and potentially foraging success. Although the causative factors behind these differences are unknown, shark home range location can potentially lead to variation in trophic ecology, even over small spatial scales. Animal movements and habitat selection are influenced by a wide range of biotic and abiotic factors, and ultimately determine how successful the individual is at acquiring food, potential mates, and obtaining safety from predators (e.g. Stephens and Krebs, 1986; Lin and Batzli, 2001). Therefore, it is expected that animals will regulate home range size, and residence times within habitats; dependent on feeding strategies, habitat quality, and levels of intra and inter specific competition; potentially over small spatial scales (e.g. Gittleman and Harvey, 1981, Lin and Batzli, 2001). Theoretical models predict that animal turnover rates and residence times within habitats are influenced by habitat quality, with lower turnover rates in optimal habitats (e.g. Winker et al., 1995, Griffen and Drake, 2008). Understanding …