Assessing the sub-lethal effects of copper, cadmium, pentachlorophenol and 3,4-dichloroaniline on Freshwater rotifers Brachionus calyciflorus using the energy budget biomarkers

Alzahrani, Hamdan (2022) Assessing the sub-lethal effects of copper, cadmium, pentachlorophenol and 3,4-dichloroaniline on Freshwater rotifers Brachionus calyciflorus using the energy budget biomarkers. Doctoral thesis, University of East Anglia.

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Abstract

Chemical pollutants can impact aquatic organisms at different levels of biological organisation, so an understanding of effects at these different levels is important in the assessment of impacts. At the cellular level, the Cellular Energy Allocation (CEA) approach is well established to evaluate energy budget in response to chemical stress. The hypothesis is that toxicants elicit metabolic changes in stressed organisms, depleting their energy reserves and, subsequently, causing adverse impacts on reproduction and growth. However, the CEA is currently limited to very few model aquatic species. Rotifers are potentially suitable models. Having one of the fastest reproductive rates within the metazoans, they are crucial components of aquatic food webs, connecting lower with higher trophic levels. This thesis applied the CEA approach to assess the toxicity of Cu, Cd, PCP, and 3,4-DCA to the freshwater rotifer Brachionus calyciflorus. Firstly, acute and chronic (population density/growth) toxicity tests were conducted to determine LC50, LOEC, and NOEC
and define concentration ranges for CEA assessment. Cu and 3,4-DCA (LC50 0.012 and 123.8; NOEC 0.0024 and 6.5 mg/L), respectively, showed the highest and lowest toxicity. Analytical methods were then developed to measure cellular energy reserve components (Ea: carbohydrate, protein, and lipid) in B. calyciflorus. For the gradient of sub-lethal concentrations assessed relative to the control, Cu and Cd had no effect, but PCP and 3,4-DCA significantly reduced Ea, especially under the highest exposure concentrations. Given time and logistical constraints, consumed energy (Ec) was interpolated from regression models of Ec against Ea (both as % of control) based on published values across different marine taxa (daphnids, enchytraeids, and microalgae). The relevant CEA was then calculated for each toxicant, decreasing under both heavy metal and organic exposures relative to concentrations. Overall, this thesis validates the suitability and sensitivity of CEA for the assessment of chemical stress in rotifers.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Nicola Veasy
Date Deposited: 24 Jan 2024 14:41
Last Modified: 24 Jan 2024 14:41
URI: https://ueaeprints.uea.ac.uk/id/eprint/94242
DOI:

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