Interspecific interactions, movement patterns and habitat use in a diverse coastal shark assemblage

Heupel, Michelle R., Munroe, Samantha E. M., Ledee, Elodie J. I., Chin, Andrew, and Simpfendorfer, Colin A. (2019) Interspecific interactions, movement patterns and habitat use in a diverse coastal shark assemblage. Marine Biology, 166 (6). 68.

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Abstract

Sharks are a highly diverse predatory taxon and are regularly found in large, potentially competitive, assemblages. However, the mechanisms that enable long-term coexistence and factors that drive complementary movement are poorly understood. As interspecific interactions can have a large influence on survival and trophic linkages, research on shark assemblages could substantially increase our understanding of marine community dynamics. In this study, we used passive acoustic telemetry to compare the activity space size, spatial overlap and habitat use patterns of six co-occurring shark species from the same family in a tropical nearshore embayment. Our results indicated that all sizes of Rhizoprionodon taylori (a small-bodied, highly productive species) used significantly larger amounts of space (e.g., mean 95% KUD = 85.9 km2) than juveniles of large-bodied, less productive species (e.g., Carcharhinus amboinensis; 62.3 km2) that use nearshore areas as nursery areas. Most large, less productive species appeared risk averse by using less space, while the smaller more productive species took greater risk by roaming broadly. These movement strategies are likely a means of avoiding predation or gaining access to new or additional resources. Spatial overlap patterns varied substantially between species with overlap in core use areas ranging from 1.2 to 27.6%, but were consistent over time. Most species exhibited low spatial overlap, suggesting spatial partitioning to reduce interspecific competition. While a few species exhibited a high degree of spatial overlap (up to 60% of activity space extent), dietary diversity may reduce competition to support co-occurrence. These data suggest that complex interactions occur in communal nurseries in nearshore waters where species are in direct competition for resources at vulnerable life stages.

Item ID: 58314
Item Type: Article (Research - C1)
ISSN: 1432-1793
Keywords: shark, behaviour, movement, resource, ecology
Copyright Information: © Springer-Verlag GmbH Germany, part of Springer Nature 2019
Funders: Marine Tropical Sciences Research Facility (MTSRF), Great Barrier Reef Marine Park Authority (GBRMPA), Australian Research Council (ARC)
Date Deposited: 07 Aug 2019 02:36
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 75%
06 BIOLOGICAL SCIENCES > 0608 Zoology > 060801 Animal Behaviour @ 25%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 50%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960802 Coastal and Estuarine Flora, Fauna and Biodiversity @ 50%
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