- Title
- Lethal and sub-lethal effects of catchment-derived stressors on fisheries productivity
- Creator
- McLuckie, Catherine M.
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2021
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Runoff following rainfall events can cause negative impacts on estuarine water quality, impairing ecological functions and disrupting the physiology of the organisms that live there. Additional stressors result from catchment land practices and climate change, causing impacts on estuarine species recruitment, abundance, distribution, growth, and condition. In New South Wales, Australia, Eastern School Prawn (Metapenaeus macleayi) fisheries have experienced declining productivity over the last ten years and increasing occurrence of catchment-derived stressors in estuaries contribute to this problem. The aim of this research was to quantify the lethal and sub-lethal effects of modified catchment runoff to determine which stressors cause the most harm to juvenile School Prawn, and therefore, which remediation measures will result in the greatest increase in productivity. The effect of pH (4–7.5) on survival, predation escape response (PER), and respiration rates at two salinities (27 and 14.5) was evaluated. While mortality appeared to be greater in the high salinity treatment, there was no significant relationship between proportional survival and pH for either salinity treatment. Respiration was significantly slower under acidic conditions and the average PER was almost twice as fast at pH 7.5 compared to pH 5 (which is within the range encountered in estuaries following rain events), indicating prawns may fall prey to predation more easily in acidic conditions. The effect of salinity on the mortality, growth, and metabolite profiles was evaluated across a salinity gradient ranging from 0.2–36 over 60 days. No prawns survived in the lowest salinity treatment, but survival was >70% for all other salinities. Relative somatic condition was negatively correlated with salinity, indicating lower salinities promote enhanced condition. Total fatty acid and total amino acid concentrations were positively correlated. Alpha-aminoadipic acid showed a significant positive relationship with salinity. Individual fatty acids and amino acid profiles showed some changes in response to salinity, suggesting several shifts in cellular chemistry with potential metabolic consequences. The effect of aluminium was evaluated as high concentrations can be found in estuaries adjacent to acid sulfate soils. The effect of hypoxia (dissolved oxygen < 2 mg L-1) was evaluated both with (0.5 mg L-1) and without aluminium. The key result was that there was a significant increase in survival with increasing dissolved oxygen (DO). LC50 (expected 50% survival) was ~0.9 mg L-1 DO regardless of aluminium exposure, although survival decreased at higher DO concentrations in the presence of aluminium. Total fatty acid and total amino acid concentrations were significantly greater in the muscle tissues from prawns subjected to hypoxia, regardless of aluminium. Docosahexaenoic acid, stearic acid, palmitic acid, and behenic acid contributed to dissimilarity in fatty acid profiles among treatments. Leucine, isoleucine, phenylalanine, and asparagine contributed to dissimilarity in amino acid profiles among treatments. The effect of the pesticide imidacloprid (0–4 µg L-1) was evaluated over 8 days. A non-linear relationship between exposure concentration and tissue concentration was found, with tissue concentrations peaking at exposures of 1.4 µg L-1. Exposure influenced the organism metabolome likely reflecting alterations in metabolic homeostasis, such as fatty acid composition changes indicating shifting lipid homeostasis. The positive correlation between exposure concentration and moulting frequency may represent a mechanism through which prawns expel the contaminant from their bodies. These results indicate that School Prawn experience several sub-lethal effects when exposed to these stressors, with implications for their health, and for other crustacean species in estuaries that drain coastal floodplains, as well as for the fisheries that rely on them.
- Subject
- fisheries productivity; salinity; penaeid prawns; estuary; pH; pesticide; dissolved oxygen; aluminium; metabolomics; thesis by publication
- Identifier
- http://hdl.handle.net/1959.13/1507368
- Identifier
- uon:56014
- Rights
- Copyright 2021 Catherine M. McLuckie
- Language
- eng
- Full Text
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