Year

2019

Degree Name

Doctor of Philosophy

Department

School of Chemistry

Abstract

Southeast Asia and Melanesia contain the world’s largest deposits of nickel lateritic ores and if the mining of these ores are not adequately managed, adverse environmental impacts will occur. Currently, risk assessment tools and water quality guidelines for the tropics are limited due to the sparse research on how contaminants impact tropical biota. Biological effects data for tropical ecosystems were required to assess the risks of contaminant exposure and to derive appropriate water quality guidelines to protect our aquatic ecosystems and to ensure responsible nickel production in Southeast Asia and Melanesia. The aim of this research was to critically review and develop new data on the biological effects of nickel on tropical marine, estuarine, pelagic and benthic species, with a particular focus on corals and their microbiomes. The toxicity of copper, a common contaminant in tropical marine environments, was also investigated to permit comparisons with previous studies.

Prior to this research, only six reliable chronic toxicity data (toxicity estimates ranged from 24 – 3700 μg Ni/L) had been reported for nickel to tropical marine species and this was insufficient to derive a water quality guideline. To address this data gap, biological effects data for key tropical marine species including two species of microalgae, a coral algal endosymbiont (Symbiodinium), a gastropod, two crustaceans and four species of corals were derived. Toxicity tests utilised chronic endpoints including 72-h growth inhibition for microalgae, 80-96h growth or development for juvenile stages of the gastropod and crustaceans, and 5-h fertilisation success for corals. Toxicity tests with adult corals assessed acute survival over 96 h. For nickel, the 10% effect concentration (EC10) values ranged from 5.5 – 2870 μg Ni/L and the diatom, Ceratoneis closterium was the least sensitive species tested. The most sensitive test was the larval development of the copepod Acartia sinjiensis and this is the most sensitive tropical marine species to nickel reported so far. Overall, the species tested in this study were more sensitive to copper than nickel, EC10 values ranging from 0.97 – 13 μg Cu/L. The most sensitive species and endpoint was growth of C. closterium and the least sensitive was fertilisation in the coral Platygyra daedalea...

This thesis is unavailable until Friday, July 03, 2020

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.