Thesis
Estuarine contaminants and oyster health in the Richmond River, NSW, Australia
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2023
DOI:
https://doi.org/10.25918/thesis.321
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Abstract
The Richmond River estuary in northern New South Wales, Australia, is categorised as having poor water quality due to intensive agriculture, industrial activities, and urban development in surrounding catchments. This thesis assessed metal(oid) and pesticide contamination in the Richmond River estuary and their impact on Sydney rock oyster (SRO) health and its food (phytoplankton). Spatial variations of metal(oid)s in sediments, and SRO significantly differed between dry and wet conditions, and their concentration correlated to oyster health (survival, condition index, density, and total weight). Multivariate modelling revealed that the oyster parameters were best explained by combined metal(oid)s in sediments and oysters. Twenty-one pesticides were detected in the Richmond River, with complex mixtures of up to 11 pesticides at a single site. Herbicides were the primary type of pesticide (12), and atrazine was detected at all sites. Pesticides of a lipophilic nature accumulated more in oysters than in water. The number and concentration of pesticides in water and oysters showed weak relationships with oyster mortality but correlated moderately with the oyster condition index. When exposed to atrazine, the growth and fatty acid profiles of phytoplankton Tisochrysis lutea and Chaetoceros muelleri were affected significantly, but species response was temperature and light dependent. T. lutea was most sensitive to atrazine at a low light intensity (401±25 Lux) and temperature (24 ºC), with the 96h-IC50 for growth of 2 µg/L. C. muelleri was most susceptible to atrazine at a high light intensity (1938±189 Lux) and temperature (30 ºC), with the 96h-IC50 for growth of 10 µg/L. Fatty acid profiles of T. lutea changed inconsistently with increased atrazine (5-127 µg/L) when cultured at 24 °C, but were not affected by atrazine (12-81 µg/L) at 30 °C. C. muelleri’s fatty acid profiles were only affected by atrazine concentrations of >9 µg/L at 24 °C and >7 µg/L at 30 °C. Overall, this study provides baseline data for metal(ioid) and pesticide contamination in the Richmond River estuary and highlights complex mixtures and pose health risks for the SRO. It further highlights those other environmental parameters, including light and temperature, influence toxicity. Further development of methods to assess multiple stressors and the influence of environmental stressors on contaminant toxicity is required to better understand the impacts of contaminants on ecosystems. A strategy for mitigating chemical contamination in the Richmond River is required to improve the health of natural oyster populations and the potential for aquaculture.
Details
- Title
- Estuarine contaminants and oyster health in the Richmond River, NSW, Australia
- Creators
- Endang Jamal
- Contributors
- Amanda Reichelt-Brushett (Supervisor) - Southern Cross UniversityKirsten Benkendorff (Supervisor) - Southern Cross University
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xiv, 211 pages
- Grant note
- Australia Awards
- Identifiers
- 991013152113702368
- Copyright
- © E Jamal 2023
- Academic Unit
- Faculty of Science and Engineering
- Resource Type
- Thesis