Impacts of ocean acidification on fitness and chemical communication in a model marine invertebrate, Nereis succinea

Hartley, Cathryn Jane

Biological sciences
March 2013

Thesis or dissertation

© 2013 Cathryn Jane Hartley. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

Oceanic uptake of anthropogenically produced atmospheric carbon dioxide (CO₂) alters carbonate chemistry and increases the acidity of seawater. Current forecasts estimate the pH of our oceans will drop by 0.3-0.4 pH units by the turn of the century. Past research has focused majorly on the impacts of ocean acidification (OA) upon calcifying organisms and few studies have incorporated longJterm exposure to OA conditions. Additionally, the impacts associated with OA are variable between species.

The presented research shows long-term culture (4-6months) in near future OA conditions (CO₂ enriched to pH 7.8) delays metamorphosis in the marine
polychaete, Nereis succinea. Culture in pH 7.8 seawater also caused interference with the reception of chemical cues in this species. Recognition of 3 feeding stimulants (glycine, taurine and fish food extract) was reduced in adult N.succinea cultured in pH 7.8 seawater for 32 days (in comparison with pH 8.2 cultured control worms). The typical behavioural response of males to female sex pheromone, cysteine-glutathione disulfide (CSSG), was also impacted by culture in acidic conditions (pH 7.8, 4-6 months) with fewer males eliciting expected sexual behaviours and males also requiring a higher dose of pheromone to release gametes in comparison to control cultured males (pH 8.2, 4-6 months).

This thesis discusses how disruption to chemical communication may occur via pH driven conformational change in signal molecules and/or protein receptors, reducing receptor-ligand interactions. As the chemical sense is dominant in ocean environments, any reduction in its efficiency will likely have negative implications for the survival of marine organisms. This research highlights how near future OA will impact several important survival processes in N. succinea (metamorphosis, food detection, sexual behaviour) which in combination may potentially reduce species persistence.

Department of Biological Sciences, The University of Hull
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