Catchment-specific element signatures in estuarine crocodiles (Crocodylus porosus) from the Alligator Rivers Region, northern Australia

Markich, Scott J., Jeffree, Ross A., & Harch, Bronwyn (2002) Catchment-specific element signatures in estuarine crocodiles (Crocodylus porosus) from the Alligator Rivers Region, northern Australia. Science of the Total Environment, 287(1-2), pp. 83-95.

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The concentrations of Na, K, Ca, Mg, Ba, Sr, Fe, Al, Mn, Zn, Pb, Cu, Ni, Cr, Co, Se, U and Ti were determined in the osteoderms and/or flesh of estuarine crocodiles (Crocodylus porosus) captured in three adjacent catchments within the Alligator Rivers Region (ARR) of northern Australia. Results from multivariate analysis of variance showed that when all metals were considered simultaneously, catchment effects were significant (P≤0.05). Despite considerable within-catchment variability, linear discriminant analysis (LDA) showed that differences in elemental signatures in the osteoderms and/or flesh of C. porosus amongst the catchments were sufficient to classify individuals accurately to their catchment of occurrence. Using cross-validation, the accuracy of classifying a crocodile to its catchment of occurrence was 76% for osteoderms and 60% for flesh. These data suggest that osteoderms provide better predictive accuracy than flesh for discriminating crocodiles amongst catchments. There was no advantage in combining the osteoderm and flesh results to increase the accuracy of classification (i.e. 67%). Based on the discriminant function coefficients for the osteoderm data, Ca, Co, Mg and U were the most important elements for discriminating amongst the three catchments. For flesh data, Ca, K, Mg, Na, Ni and Pb were the most important metals for discriminating amongst the catchments. Reasons for differences in the elemental signatures of crocodiles between catchments are generally not interpretable, due to limited data on surface water and sediment chemistry of the catchments or chemical composition of dietary items of C. porosus. From a wildlife management perspective, the provenance or source catchment(s) of 'problem' crocodiles captured at settlements or recreational areas along the ARR coastline may be established using catchment-specific elemental signatures. If the incidence of problem crocodiles can be reduced in settled or recreational areas by effective management at their source, then public safety concerns about these predators may be moderated, as well as the cost of their capture and removal. Copyright © 2002 Elsevier Science B.V.

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7 citations in Web of Science®
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ID Code: 72746
Item Type: Journal Article
Refereed: Yes
Additional Information: Cited By (since 1996):10
Export Date: 26 May 2014
Source: Scopus
PubMed ID: 11883762
Additional URLs:
Keywords: Catchment specificity, Crocodile, Discriminant analysis, Flesh, Metal, Osteoderm, Catchments, Composition, Metals, Sediments, Dietary items, Estuaries, fresh water, lead, surface water, trace element, crocodilian, estuarine environment, provenance, alligator, animal experiment, article, Australia, bioaccumulation, catchment, classification, estuary, nonhuman, pollution, priority journal, river, sampling, sediment, toxicokinetics, Alligators and Crocodiles, Animals, Environment, Environmental Monitoring, Metals, Heavy, Recreation, Tissue Distribution, Water Pollutants, Crocodylidae (all crocodiles), Crocodylus, Crocodylus porosus
DOI: 10.1016/S0048-9697(01)00995-0
ISSN: 0048-9697
Divisions: Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2002 Elsevier Science B.V. All rights reserved.
Deposited On: 11 Jun 2014 22:51
Last Modified: 21 Jun 2017 16:01

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