Doctoral Programme on Marine Ecosystem Health and Conservation
 The MARES Researchers and their Research
Assessing the effects of long-term ocean acidification at CO2 vents off Methana Greece.     
PhD Code: MARES_25_2010:
  • Host institute 1: P7 - University of Plymouth
  • Host institute 2: P16 - Hellenic Centre for Marine Research (HCMR)
Research fields:
  • T1 - Future oceans : temperature changes - hypoxia - acidification
  • T2 - Understanding biodiversity effects on the functioning of marine ecosystems
  • T3 - Biological Invasions
  • Jason Hall-Spencer
  • Eva Krasakopoulou
  • Kai Bischof
Contact Person and email: Jason Hall-Spencer -

Subject description
Hypotheses to be tested: 1) near-future levels of ocean acidification (OA, year 2100 scenarios) may enhance the growth and reproduction of sea grasses and certain invasive macroalgae in natural settings, 2) chronic hypercapnia can lead to an overall reduction in benthic biodiversity, including the loss of numerous calcified species, with negative effects on ecosystem function in intertidal and subtidal habitats, 3) transplant experiments, coupled with sampling along pCO2 gradients, confirm that some species can adapt to long-term acidification by altering skeletal mineralogy, 4) active metazoans (e.g. shrimp and fish) can withstand high levels of CO2 as adults but do not complete their life-histories at naturally acidified sites.
The student will carry out two 6 month research visits to HCMR for fieldwork and training purposes, together with two research visits for collaborative research in algal physiology using the OA suite run by Dr Bischof. The student will examine long-term effects of elevated CO2 on the function of adapted benthic communities and the commercial species they support. This is innovative as such effects are difficult to assess using methods adopted by the German BIOACID, the UK OARP and the EU EPOCA programmes, whereby CO2 levels are manipulated in aquaria and mesocosms over timescales of weeks-months1,2 excluding the feedbacks and indirect effects that occur within natural marine systems2-4. To address this, US and Australian researchers are implementing Free Ocean Carbon Experiments but are hindered by the cost and technical difficulty of imitating OA conditions at sufficient scales and exposure periods to encompass the life cycles of interacting macrobenthos5. This studentship adds value to an existing collaboration between HCMR and UoP under the EU MedSeA programme (Mediterranean Sea Acidification under changing climate), starting March 2011. The studentship addresses objectives T1, T2 and T3 of the MARES call and will provide data (to be archived by MedSeA database managers on PANGAEA) to improve our understanding of long-term OA effects. The supervisory team includes PIs within the EPOCA and MedSeA, optimizing integration of the student’s development within the international marine science community. The lead PI co-authored the “Guide to Best Practices in Ocean Acidification Research”5 which provides the methodological template for this studentship. At UoP all postgraduates undergo training in a suite of transferable skills (see The Plymouth Marine Science Partnership is a group of well-equipped institutions with numerous other PhD students participating in world-leading in OA research, offering opportunities for peer-support.
In an initial 8-month training period the student will review the literature and refine the laboratory and field-based methods needed to monitor variations in carbonate chemistry (including DIC and total alkalinity) that occur around CO2 vents. The student will practice and test these techniques in rockpool habitats local to Plymouth. As part of this training (which may produce publishable data), the student will correlate differences in mean and peak pCO2 levels with observed differences in rockpool macrobenthic community structure and function. He/she will receive training from a UoP SEM technician, to examine the mineralogy and strength of calcifying plants and animals along these gradients. The student will examine the effects of chronic hypercapnia on recruitment, growth, survival, reproduction, calcification and photosynthesis using methods that recently resulted in Nature-published flagship science on the ecosystem effects of OA on rocky shore communities1, seagrass communities6 and rocky habitats7-9. To date this approach has only been carried out at one site (Ischia); the German BIOACID program coordinator notes that “This study is a compelling demonstration of the usefulness of natural CO2 venting sites in assessing the long-term effects of ocean acidification on sea-floor ecosystems, an approach that undoubtedly needs to be further explored”2.
At HCMR, the student will monitor spatial and temporal variability in seawater carbonate chemistry and other major environmental parameters off Methana where CO2 vents are shallow (<10 m depth) and coastal, significantly reducing costs as measurements and sampling will be done using a small boat and by diving. The student will examine whether long-term exposure to elevated CO2 has resulted in similar ecosystem changes to those at Ischia and can therefore be used to predict the wider effects of ocean acidification on the functioning of coastal ecosystems of importance to society. Biodiversity and biomass will be assessed in replicate plots from 380 to mean 1000 and 2000 ppm CO2 using hand-held cores in sediments (e.g. for foraminifera) and 0.5 m2 quadrats on rock (for assessments of the abundance of coralline algae (e.g. Lithophyllum), molluscs (e.g. Mytilus) and echinoderms (e.g. Paracentrotus) along CO2 gradients). Recruitment processes will be assessed using settlement plates deployed at different pCO2 levels and M. galloprovincialis transplants from commercial mussel farms will be used to determine the effects of OA, for example on scope for growth following established methodologies9.
Reproduction and growth (using hole-punched thalli) will be measured on seagrass (e.g. Posidonia) and macroalgae (e.g. Sargassum, Asparagopsis) that are growing in situ as well as in transplants moved within and between plots. Organisms precipitate calcium carbonate in three main forms: magnesian calcite, aragonite and calcite, given in order of decreasing solubility. The student will examine whether calcified algae, foraminifera and corals can adapt their mineralogy depending on the amounts of CO2 in the surrounding seawater. The proposed experiments will provide material that will be worked on under supervision in Bischof’s group to study long-term effects of ocean acidification on marine plants and algae. During field excursions in 2012 repeated visual counts will be used to assess the diversity, behaviour and abundance of shrimps and fish recording the distribution of gravid females and fish nests in relation to CO2 monitoring zones, as juvenile stages can be the most vulnerable to OA effects10, 11.

1.Hall-Spencer JM, Rodolfo-Metalpa R, Martin S, et al. (2008) Volcanic carbon dioxide vents show ecosystem effects of ocean acidification. Nature 454, 96–99.
2. Riebesell U (2008) Acid test for marine biodiversity. Nature 454, 46–47.
3. Miles H, Widdicombe S, Spicer J, Hall-Spencer JM (2007) Effects of anthropogenic seawater acidification on acid-base balance in the sea urchin Psammechinus miliaris. Marine Pollution Bulletin 54, 89-96.
4. Ries JB, Cohen AL & McCorkle DC (2009) Marine calcifiers exhibit mixed responses to CO2-induced ocean acidification. Geology 37, 1131-1134.
5. Barry JP, Hall-Spencer JM & Tyrell T (2009) In situ perturbation experiments: natural venting sites, spatial / temporal gradients in ocean pH, manipulative in situ pCO2 perturbations. In: Guide to Best Practices in Ocean Acidification Research and Data Reporting.
6. Martin S, Rodolfo-Metalpa R, Ransome E, Rowley S, Buia M-C, Gattuso J-P, Hall-Spencer JM (2008) Effects of naturally acidified seawater on seagrass calcareous epibionts. Biology Letters 4, 689-692.
7. Rodolfo-Metalpa R, Lombardi C, Cocito S, Hall-Spencer JM & Gambi MC. (2010) Effects of ocean acidification and high temperatures on the bryozoan Myriapora truncata at natural CO2 vents. Marine Ecology 31, 447-456.
8. Hall-Spencer JM & Rodolfo-Metalpa R (2009) Loss of Mediterranean  marine biodiversity in a high-CO2 world. CIESM 2008. Impacts of acidification on biological, chemical and physical systems in the Mediterranean and Black Seas. No. 36 in CIESM Workshop Monographs [F. Briand Ed.], 124 pages, Monaco.
9. Anestis, A., Portner, H.O., Karagiannis, D., Angelidis, P., Staikou, A., Michaelidis, B. 2010. Response of Mytilus galloprovincialis (L.) to increasing seawater temperature and to marteliosis: metabolic and physiological parameters. Comp. Biochem. Physiol., A., 156, pp 57.
10. Cigliano M, Gambi MC, Rodolfo-Metalpa R, Patti FP & Hall-Spencer JM (2010) Effects of ocean acidification on invertebrate settlement. Marine Biology 157, 2489-2502.
11. Dias B, Hart M, Smart C, & Hall-Spencer JM (2010).  Modern seawater acidification: the response of foraminifers to high-CO2 conditions in the Mediterranean Sea.  Journal of the Geological Society, London. 167, 843-846.

Expected outcomes
This studentship has been designed to provide integrated doctoral training across three leading European marine research institutes . The student will be involved in one of the ESF's 'star projects' of exceptional societal importance with a high media profile (e.g. Euronews and National Geographic Documentaries have covered the project this Autumn (2010). It takes advantage of existing research links between HCMR and adds value to funding obtained by this institutions under MedSeA (beginning 2011). The high public and political profile of the research topic will allow the successful candidate to act as an ambassador for European Higher Education. The project will also provide data that will feed into the decisions being made by the UN, FAO, ICES and IPCC as the PI works closely with these organisations. By pooling the educational and research resources of the three institutes the student will be able to produce the first peer-reviewed assessments of long-term acidification using Greek volcanic vent systems, filling a vital policy gap.The project features on the front cover and throughout the Secretariat of the Convention on Biological Diversity (2009). Scientific Synthesis of the Impacts of Ocean Acidification on Marine Biodiversity. Montreal, Technical Series No. 46, 61 pp. It also features on the front cover and throughout the US National Research Council of the National Academies (2010) Ocean acidification, a national strategy to meet the challenges of a changing ocean. 188 pp.

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