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Parasites as indicators of movement and population connectivity of a non-diadromous, tropical estuarine teleost: king threadfin Polydactylus macrochir

Authors

  • B. R. Moore,

    Corresponding author
    1. Fishing and Fisheries Research Centre, School of Earth and Environmental Sciences, James Cook University, Townsville, Qld 4811, Australia
    2. Marine Parasitology, School of Biological Sciences, The University of Queensland, Brisbane, Qld 4072, Australia
      Tel.: +61 7 3365 9753; email: bradley.moore1@ my.jcu.edu.au
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  • D. J. Welch,

    1. Fishing and Fisheries Research Centre, School of Earth and Environmental Sciences, James Cook University, Townsville, Qld 4811, Australia
    2. Department for Employment, Economic Development and Innovation, PO Box 1085, Oonoonba, Qld 4811, Australia
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  • S. J. Newman,

    1. Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries, Government of Western Australia, PO Box 20, North Beach, WA 6920, Australia
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  • R. J. G. Lester

    1. Marine Parasitology, School of Biological Sciences, The University of Queensland, Brisbane, Qld 4072, Australia
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Tel.: +61 7 3365 9753; email: bradley.moore1@ my.jcu.edu.au

Abstract

Temporal and spatial patterns in parasite assemblages were examined to evaluate the degree of movement and connectivity of post-recruitment life-history stages of a large, non-diadromous tropical estuarine teleost, king threadfin Polydactylus macrochir, collected from 18 locations across northern Australia. Ten parasites types (juvenile stages of two nematodes and seven cestodes, and adults of an acanthocephalan) were deemed to be suitable for use as biological tags, in that they were considered to have a long residence time in the fish, were relatively easy to find and were morphologically very different to each other which aided discrimination. Univariate and discriminant function analysis of these parasites revealed little difference in temporal replicates collected from five locations, suggesting that the parasite communities were stable over the timeframes explored. Univariate, discriminant function, and Bray–Curtis similarity analyses indicated significant spatial heterogeneity, with Bray–Curtis classification accuracies ranging from 55 to 100% for locations in north-western and northern Australia, 24 to 88% in the Gulf of Carpentaria, and 39 to 88% on the east coast of Queensland. Few differences were observed among locations separated by <200 km. The observed patterns of parasite infection are in agreement with concurrent studies of movement and connectivity of P. macrochir in that they indicate a complex population structure across northern Australia. These results should be considered when reviewing the management arrangements for this species.

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