Environmental drivers of fine-scale predator and prey spatial dynamics in Sydney harbour, Australia, and adjacent coastal waters

Yuri Niella*, Amy F. Smoothey, Matthew D. Taylor, Victor M. Peddemors, Robert Harcourt

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Greater Sydney is the largest coastal city in Australia and is where bull sharks (Carcharhinus leucas) are present every summer and autumn. A decade of acoustic telemetry data was used to identify drivers of space use for bull sharks and their potential prey, according to standardised 6-h intervals using dynamic Brownian bridge movement models. Influences of environmental, physical, and biological variables on the areas of space use, location, and predator–prey co-occurrence were investigated with generalised additive mixed models. Rainfall in the catchment affected space use for all animals (i.e. teleost species and both sexes of sharks), with varying temporal responses. Male sharks responded most promptly to high rainfall moving upstream in < 1 day, followed by teleosts (2 to 7 days), and female bull sharks after 4 days. Environmental luminosity affected male shark dispersal and space use, possibly indicating use of visual cues for foraging. Physical characteristics of habitat were important factors driving spatial overlaps between predator and prey in estuarine areas. In sandy embayments < 10-m deep, males and female bull sharks overlapped with different species, whereas males and silver trevally (Pseudocaranx georgianus) co-occurred in deep holes (> 30 m). Shark size influenced overlap between sexes, with smaller females less likely to co-occur with larger males (~ 50 cm). Variability in space use suggests spatial segregation by sex and size in bull sharks, with individuals targeting similar prey, yet either in different areas or at different times, ultimately enabling them to exploit different resources when in the same habitats.

    Original languageEnglish
    Number of pages15
    JournalEstuaries and Coasts
    Early online date16 Nov 2021
    DOIs
    Publication statusE-pub ahead of print - 16 Nov 2021

    Bibliographical note

    Copyright the Author(s) 2021. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

    Keywords

    • Acoustic telemetry
    • Bull sharks
    • Climate change
    • Intra-specific interactions
    • Movement patterns
    • Predator–prey interactions
    • Refined shortest paths (RSP)
    • Urbanisation

    Fingerprint

    Dive into the research topics of 'Environmental drivers of fine-scale predator and prey spatial dynamics in Sydney harbour, Australia, and adjacent coastal waters'. Together they form a unique fingerprint.

    Cite this