Molecular level effects of low seawater pH on the marine polychaete Platynereis dumerilii

Wäge, Janine

Biological sciences
August 2015

Thesis or dissertation

© 2015 Janine Wäge. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

Global changes lead to a measurable reduction of ocean pH. These rapid water chemistry changes are expected to have negative effects on ecosystems and keystone sensitive species. It is predicted that many different physiological processes will be altered under low pH conditions. To date, most studies focus on calcifying organisms however there is a need for further investigations into the precise molecular level changes that occur in other marine organisms.

This work investigates the molecular level changes taking place in a non-calcifying, polychaete species P. dumerilii after exposure to acidified seawater, induced by HCl and CO₂. Using laboratory-cultured worms, a targeted approach was employed to examine key genes involved in acid-base regulation and metabolism, as well as a global approach to find other potential mechanisms involved in low pH response. Genes involved in general metabolism and defence processes were down-regulated after exposure with HCl, indicating impacts following exposure. However, the up-regulation of the acid-base transporter NHE and an additional expression of NHE in the anus area of P. dumerilii larvae, may suggest possible compensation mechanisms.

Gene expression profiles were also obtained from P. dumerilii, collected from inside and outside natural CO₂ vents (Ischia, Italy), as well as following a pH translocation experiment. Expression analysis of target genes showed significant differences between the worms from vent sites in comparison to non-vent sites, suggesting that worms in the natural low pH areas are adapted to the different seawater conditions. Collectively this work shows that low seawater pH, induced by both HCl and CO₂, alters the gene expression in P. dumerilii. This provides new knowledge regarding the acid-base regulation mechanisms in a marine polychaete and will help to predict how P. dumerilii may respond to ocean acidification.

School of Biological, Biomedical and Environmental Sciences, The University of Hull
Hardege, Jörg D.; Rotchell, Jeanette M.
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