Lockyer, Antony;
(2019)
Marine Invertebrate Sperm as an Indicator of Metal Toxicity.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Elevated concentrations of metals have been reported in the marine environment globally where they have the capacity to be toxic to marine organisms. Of concern are the fertilisation and early development of marine invertebrates which are vulnerable to metal toxicity. Scientific and technological advances have enabled the development of numerous rapid, accurate, and semi-autonomous methods for the assessment of sperm. Consequently, sperm parameters are being recommended as rapid alternative endpoints to fertilisation success. For these parameters to be used as endpoints in water quality guideline derivation, ecological relevance needs to be demonstrated via a proven adverse outcome pathway (AOP). This research assessed the effects of metals (Cu, Zn, Cd and Pb) to fertilisation success in the marine invertebrate Galeolaria caepitosa and found that the primary cause of toxicity was through effects on sperm. When the impact of a toxicant is to sperm, current protocols for fertilisation assays could underestimate toxicity. This study found up to three-fold differences in toxicity estimates at sperm densities that all yield >80% fertilisation in controls. More appropriate toxicity estimates would be achieved by assessing toxicity using low sperm densities, for example, those which achieve only 50% fertilisation success. Alternatively, sperm endpoints could be used to provide sensitive (and conservative) toxicity estimates, provided an AOP has been established. For Cu, effects on sperm motility (%) could account for the effects of metals on fertilisation success, and thus can be used as an indicator of Cu toxicity. For Zn, effects on the ability for sperm to undergo the acrosome reaction can be used as a rapid indicator of effects to fertilisation success. However, For Cd and Pb, effects on fertilisation could not be appropriately represented by any of the sperm endpoints tested here. This research highlights the importance of understanding the mechanism of toxicity to fertilisation success and provides recommendations for future ecotoxicological assessments.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Marine Invertebrate Sperm as an Indicator of Metal Toxicity |
| Event: | UCL |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2019. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10080318 |
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