Evaluating the landscape of fear between apex predatory sharks and mobile sea turtles across a large dynamic seascape
Date
2015-02-23Author
Hammerschlag, N
Broderick, Annette C.
Coker, JW
Coyne, MS
Dodd, M
Frick, MG
Godfrey, MH
Godley, BJ
Griffin, DBB
Hartog, K
Murphy, SR
Murphy, TM
Nelson, ER
Williams, KL
Witt, MJ
Hawkes, LA
Date issued
2015-02-23
Journal
Ecology
Type
Article
Language
en
Publisher
Ecological Society of America
Rights
© 2015 by the Ecological Society of America
Abstract
The ‘‘landscape of fear’’ model has been proposed as a unifying concept in ecology, describing, in part, how animals behave and move about in their environment. The basic model predicts that as an animal’s landscape changes from low to high risk of predation,
prey species will alter their behavior to risk avoidance. However, studies investigating and evaluating the landscape of fear model across large spatial scales (tens to hundreds of thousands of square kilometers) in dynamic, open, aquatic systems involving apex predators and highly mobile prey are lacking. To address this knowledge gap, we investigated predator–prey relationships between tiger sharks (Galeocerdo cuvier) and loggerhead turtles (Caretta caretta) in the North Atlantic Ocean. This included the use of satellite tracking to examine shark and turtle distributions as well as their surfacing behaviors under varying levels of home range overlap. Our findings revealed patterns that deviated from our a priori predictions based on the landscape of fear model. Specifically, turtles did not alter their surfacing behaviors to risk avoidance when overlap in shark–turtle core home range was high. However, in areas of high overlap with turtles, sharks exhibited modified surfacing behaviors that may enhance predation opportunity. We suggest that turtles may be an important factor in determining shark distribution, whereas for turtles, other life history trade-offs may play a larger role in
defining their habitat use. We propose that these findings are a result of both biotic and physically driven factors that independently or synergistically affect predator–prey interactions in this system. These results have implications for evolutionary biology, community ecology, and wildlife conservation. Further, given the difficulty in studying highly migratory marine species, our approach and conclusions may be applied to the study of other predator–prey systems.
Funders/Sponsor
Bald Head Island Conservancy
British Chelonia Group
Natural Environmental Research Council
WAVE Foundation/Newport Aquarium Cincinnati
PADI project AWARE
SEATURTLE.ORG
Whitener Foundation (NC); an Endangered Species Act Section 6 Cooperative Agreement with
NOAA Fisheries and the Grays Reef National Marine Sanctuary (South Carolina and Georgia)
Batchelor Foundation
Dinsey Conservation Fund
Citation
Ecology, 2015, 96 (8), pp. 2117–2126
ISSN
0012-9658