Towards Deep-Sea Toxicology: Experimental Approaches With Echinoderms

As anthropogenic activities expand into the deep sea, it is only recently that the importance of<br/>deep-sea ecosystems and processes to global biogeochemical systems has become clear. If the<br/>potential impact of human activity upon deep-sea organisms and ecosystems is to be understood<br/>and predicted, experimental studies are required to improve our knowledge of their sensitivity to<br/>contamination and disturbance. Echinoderms are integral components of deep-sea benthic<br/>communities and, by virtue of their abundance, they contribute significantly to deep-sea<br/>biogeochemical processes. As such, echinoderms can be considered relevant target organisms for<br/>deep-sea experimental studies.<br/>Three approaches to the investigation of deep-sea anthropogenic impact upon echinoderms<br/>were undertaken in this study. The first was based on contaminant exposure experiments with two<br/>species of shallow-water echinoid, the eurytopic Psammechinus miliaris and the stenotopic<br/>Brissopsis lyrifera. A range of biomarkers was used to assess the responses of the echinoids to<br/>contaminant exposure. Compared with the significant cytological and molecular (assess via qPCR)<br/>responses in P. miliaris, a reduced capacity to respond to contaminant exposure was found in B.<br/>lyrifera at these levels of biological organisation. Stenotopic species are hence recommended for<br/>future experimental studies as proxies for deep-sea echinoderms which, due to their adaptation to<br/>the stable environment of the deep sea, are also considered to have a reduced capacity for<br/>homeostasis in the face of environmental perturbation.<br/>The second experimental approach involved sediment burial experiments, simulating<br/>anthropogenic drilling disturbance, with the deep-water echinoderm species Echinus acutus. ROV<br/>technology was used to perform the burial experiments in situ at 114 m depth. The application of<br/>quantitative PCR molecular biomarker methodology revealed a significant increase in the<br/>expression of a stress-70 protein in response to sediment burial. These results demonstrate the<br/>sensitivity of the qPCR technique to assess an organism’s stress-response, and its relevance to<br/>deep-sea experimental studies.<br/>Finally, the development and successful deployment of an in situ respirometer, the benthic<br/>incubation chamber system (BICS) 2, made possible the acquisition of physiological<br/>measurements from deep-sea echinoderms at the abyssal sea floor at 3500 m. The results revealed<br/>similarities between the oxygen consumption rates of shallow-water and deep-sea echinoderms.<br/>The future performance of in situ deep-sea experimentation is dependent on the development of<br/>experimental equipment that confers the ability to perform experiments in situ with ROV<br/>technology and to obtain results without interference from recovery-related side effects.

Name dc:type.qualificationname

Ph.D.

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of Southampton

Year dc:date.issued

2010

Author dc:creator

• Hughes, Sarah Jane Murty