MEPS 445:279-291 (2012)  -  doi:10.3354/meps09423

Deep danger: intra-specific predation risk influences habitat use and aggregation formation of juvenile lemon sharks Negaprion brevirostris

Tristan L. Guttridge1,2,5,*, Samuel H. Gruber2,3, Bryan R. Franks2,4, Steven T. Kessel2,5, Katie S. Gledhill2, Jen Uphill6, Jens Krause7,8, David W. Sims9,10

1Institute for Integrative and Comparative Biology, University of Leeds, L.C. Miall Building, Leeds LS2 9JT, UK
2Bimini Biological Field Station, 15 Elizabeth Drive, South Bimini, Bahamas
3Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science,
4600 Rickenbacker Causeway, Miami, Florida 33149, USA
4Department of Biology, Rollins College, Winter Park Florida 32789, USA
5School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3XQ, UK
6Flinders University, Stuart Drive, Bedford Park, South Australia 5042, Australia
7Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310,
12587 Berlin, Germany
8Department of Biology and Ecology of Fishes, Humboldt-University of Berlin, Philippstrasse 13, 10115 Berlin, Germany
9Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
10Marine Biology and Ecology Research Centre, School of Marine Science and Engineering, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK

ABSTRACT: Non-consumptive or risk effects imposed by predators can influence prey behaviour over different spatio-temporal scales. Prey vulnerability to predation can also be dependent on abiotic conditions, such as tidal height. We conducted direct field observations of juvenile lemon sharks Negaprion brevirostris in a tidally influenced mangrove-inlet. We also used acoustic tracking to determine the movement patterns of juvenile lemon sharks and their predators (sub-adult lemon sharks) across the tidal cycle. Results showed that greater numbers of juvenile lemon sharks used the mangrove-inlet for longer time periods at deeper and warmer high tide depths. This coincided with an increased presence of potential predators (sub-adult lemon sharks) in the surrounding areas. Furthermore, in accordance with body-size dependent anti-predatory investment, smaller juvenile lemon sharks visited the mangrove inlet more often, spent longer there and left latest on average. Our acoustic tracking data also revealed a tidally-influenced pattern, with both juvenile and sub-adult lemon sharks detected at locations inshore over the high tide and offshore during the low tide. We concluded that the mangrove lake served as a ‘refuge’ for juvenile lemon sharks over the high tide, providing safe habitat when inshore areas become accessible to large predators, such as sub-adult lemon sharks. We suggest that these decisions are updated through ontogeny and also with daily fluctuations in abiotic factors, such as water depth. This study provides evidence for how intra-specific predator−prey interactions in a top predator species influence juvenile habitat selection, with potential implications for population structure and regulation.

KEY WORDS: Apex predator · Cannibalism · Elasmobranchs · Refuge use · Risk effects

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Cite this article as: Guttridge TL, Gruber SH, Franks BR, Kessel ST and others (2012) Deep danger: intra-specific predation risk influences habitat use and aggregation formation of juvenile lemon sharks Negaprion brevirostris. Mar Ecol Prog Ser 445:279-291

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