6 PhD openings on ocean acidification

MARES is a three-year world-class Joint Doctoral Programme operated by a consortium of 24 partner institutions (11 full partners and 13 associated members) originating from 14 countries. It is partly funded by the European Commission. This Doctoral Programme on Marine Ecosystem Health and Conservation has 29 openings for Ph.D. fellowships. Five of them are related to ocean acidification (see below).

Deadline for application: 15 January 2011
More information: http://www.mares-eu.org/index.asp

MARES_05_2010: Multi-decadal variation of calcareous zooplankton and its link to global environmental change

The selected candidate will be enrolled in the doctoral schools of both the University Pierre et Marie Curie (Paris, France) and the University of Plymouth (UK). The work will be performed at the Laboratoire d’Océanographie (Villefranche-sur-mer, France) and the Sir Alister Hardy Foundation for Ocean Sciences (Plymouth, UK).

Subject description
The oceans have absorbed about one third of the carbon dioxide (CO2) emitted in the atmosphere by human activities since pre-industrial time (Sabine et al., 2004). They have therefore limited the global warming induced by this greenhouse gas. This uptake causes profound changes in the chemistry of seawater such as a decrease of pH, referred to as “ocean acidification”, which is superimposed on other global environmental changes such as changes in temperature, stratification and circulation.

Several studies indicate that ocean acidification will affect calcifying organisms such as corals (Gattuso et al., 1998), molluscs (Gazeau et al., 2007) and phytoplankton (Riebesell et al., 2000). The pelagic mollusc pteropods are keystone organisms of various ecosystems by playing a role as a prey for many predators. Because of their fragile aragonitic shell, as shown in short-term perturbation experiments, pteropods are sensitive to a decrease in pH (Comeau et al., 2009). Other calcareous zooplanktonic groups are also affected, for example Foraminifera (Lombard et al., 2010).

Historical data on pteropod populations may provide critical information on the life cycle of calcareous zooplankton and its responses to environmental changes, impossible to obtain with short-term experiments. For example, Ohman et al. (2009) found no changes in the abundance of the mega taxa of calcerous holozooplankton in the California current system during the period 1951- 2008. Data collected in two time-series will be used to investigate the long-term changes in the population of pteropods and foraminifera. The student will have access to data collected in the North-East Atlantic (January 1958 to December 2008) using the Continuous Plankton Recorder (CPR) and in the northwest Mediterranean Sea (February 1995 to January 2007) at the point B time-series station in the Bay of Villefranche-sur-mer. Changes in abundance will be analyzed together with environmental data. Correlations between the abundance of calcareous zooplankton, biotic and physical parameters such as the concentration of chlorophyll, seawater temperature and parameters of the carbonate system will be investigated. Data on the physical parameters will be obtained from historical measurements and from models. The seasonal cycles variations and the changes within the composition of the populations during the time will also be studied.

This work will be performed as part of an on-going collaboration between SAHFOS and LOV (e.g., McQuatters-Gollop et al., 2010). The information collected will be of critical importance in several areas as calcareous zooplankton play an important role in the food webs, biogeochemical cycles (export of carbon and carbonate), as well as for paleooceanographic reconstructions.

Laure Mousseau (mousseau@obs-vlfr.fr)
Martin Edwards (maed@sahfos.ac.uk)
Jean-Pierre Gattuso (gattuso@obs-vlfr.fr)

MARES_07_2010: Influences of pCO2 and temperature on nitrogen fixation and extracellular exopolysaccharide production in diazotrophic unicellular cyanobacteria

Host institute 1: P11 – Université Paris Marie Curie (UPMC)
Host institute 2: P7 – University of Plymouth

Subject description

1. Nitrogen budget and role of nitrogen fixation. Views on the functioning of the nitrogen cycle in the global ocean are changing. As recently as c. 10 y ago estimates of the nitrogen budget revealed imbalances that might be accounted for by nitrogen fixation (Karl et al., 1997), a process by which cyanobacteria fix N2, transform it to NH3 and use it as substrate for growth. The genus Trichodesmium, has been considered the most important diazotroph of open oceans (Carpenter et al. 2004), but unicellular forms, such as Crocosphaera watsonii have also been observed to fix N2 (Zehr et al. 2001). Their abundance and activity in oligotrophic oceans suggests they support an important component of new C production without nitrate consumption (Montoya et al., 2004). Yet, both the physiology of these unicellular diazotrophs and estimates of their fixation potential remain to be explored. 2. Carbon budget and role of EPS production. Quantities of DIC withdrawn from the ocean surface by phytoplankton exceeds estimates of primary production based on the Redfield stoichiometry of nitrate removal. This carbon ‘overconsumption’ implies that the composition of organic matter released during photosynthesis, as extracellular exopolysaccharide, does not show Redfield proportions of C and N and that photo-assimilation of C can continue even when biomass production is limited by nitrogen (Toggweiler (1993). The exuded C-rich DOM and transparent exopolymers (TEP), which varies with species and environmental conditions, facilitate aggregation and particle sinking, thereby affecting DOC transport and the ocean carbon cycle (Engel et al., 2004). TEP are thus defined as a key element in the oceanic carbon cycle as their production may thus increase the efficiency of the biological pump.

3. How about EPS production in diazotrophs? Nitrogen fixation allows a production of organic matter without nitrate consumption. But then, are TEP produced, and how much? In non- diazotrophs, different authors observed that in situ nitrate limitation enhances TEP production (Mari et al. 2001) while others showed that TEP can also be released even under N replete conditions (Claquin et al 2008, Pedrotti et al. in press). The release of extracellular polysaccharides by phytoplankton depends on species, and on environmental growth conditions (nutrient state, light, temperature and carbon dioxide concentrations (Myklestad 1995, Engel et al. 2002 and many others). Crocosphaera releases TEP in conditions of obligate diazotrophy (Dron, Rabouille et al., in prep), so an even higher C excretion could be expected when nitrogen depletion is relieved. It is unclear whether TEP-production is a direct consequence of physiological stage, i.e, does N fixation regulate carbon excretion?

4. Bring the pieces together: what may happen in a changing world? As a consequence of rising pCO2 and the associated decrease in pH combined with enhanced stratification linked to global warming that will reduce inorganic nutrient availability for phyroplankton growth, the future ocean environment will favor diazotrophy (Levitan et al., 2007). However, little is known about the capacity of diazotrophs to physiologically adapt to global climate change.

The activity of Crocosphaera watsonii could represent an important component of primary production in tropical oceans. Using this strain as a model, this project proposes to investigate the effects that predicted changes in global climate could have on growth, N2 fixation and TEP production, and to identify the metabolic processes that regulate this process. In addition, the influence of pCO2 on the bio-availability of essential trace metals will be investigated since TEP are thought to ‘trap’ trace nutrients (such as Fe which is an essential component of the nitrogenase enzyme), but whose role as extracellular reserves of these trace elements is unclear.

We propose to monitor growth, TEP production and the activity of nitrogen fixation under different conditions of nitrate supply, temperature and pCO2 levels.

Experimental developments. Experiments carried out in N-deplete and N-replete environments will allow us to link the nitrogen status of cells to their activity of TEP production. Also, complex regulations are expected, in relation to carbon requirements in cells. Nitrogen fixation is essentially restricted to dark periods (night) so TEP production could be tightly connected to, and possibly inversely correlated to, the regulation of nitrogen fixation. Such experiments, performed (either in continuous or batch cultures) both under present and future pCO2 levels and different temperature, will shed light on (i) the ability of Crocosphaera to survive in a high CO2 world and its response in terms of growth, (ii) changes in the efficiency of the nitrogen fixation process and cells stoichiometry (nitrogen metabolism) and (iii) the changes in the carbon metabolism and the production of EPS.The influence of pCO2 on the availability of essential trace metals will also be investigated, as TEP are ought to trap trace nutrients (Pedrotti et al. in prep). In particular, they adsorb several elements, among which Fe, which is an essential component of the nitrogenase enzyme. The role of TEP as extracellular reserve of these trace elements is unclear, and ultra-structural changes in cells may occur under increased pCO2 conditions that affect the availability of trace metals.

Experimental devices and equipments. This project will exploit the existing approaches and methodologies used at LOV, where a unique and original experimental device has been developed, the SEMPO. This simulator of marine environments is monitored by computers. The system can receive up to four continuous cultures connected to computers and allows for high frequency sampling and on line monitoring of several parameters, such as NO2, NO3, NH4, pH, and temperature. A new system is currently developed at LOV to finely control pCO2 in the water. Facilities at LOV also include a total, organic carbon and nitrogen (CHN analyser), spectrophotometers for TEP analyses and cell counters.

The University of Plymouth (UoP) will contribute to this project by supporting the design of the trace metal experiments, as well as the analysis and interpretation of the collected data. UoP will also provide access to state-of-the-art ICP-MS/OES facilities for trace metal analysis and to the electron microscopy suite for investigating any changes in cell ultra-structural resulting from exposure to the different environmental conditions.


MARES_11_2010: The combined effects of rising temperatures, hypoxia and Ocean acidification on Marine Crustaceans

Host institute 1: P2 – Universität Bremen
Host institute 2: P7 – University of Plymouth

Subject description
Temperature is often referred to as the main factor determining the geographical distribution of marine organisms. For aquatic ectotherms the concept of oxygen and capacity dependent thermal tolerance (OCLT) has successfully been applied to explain climate-induced effects of rising temperatures on species abundance in the field (Pörtner & Farrell 2008). The thermal window of performance in water breathers matches their window of aerobic scope. Loss of performance and the resulting shift in aerobic energy budget towards maintenance reflects the earliest level of thermal stress, caused by limitations in tissue functional capacity, hypoxemia and the progressive mismatch of oxygen supply and demand at the borders of the thermal envelope. Thermal acclimatization during changing seasons or adaptation to a climate regime involves adjusting the width and positioning of thermal windows on the temperature scale. Organismal thermal specialization likely results from temperature dependent trade-offs at several hierarchical levels, from molecular structure to whole organism functioning and may also support maximized energy efficiency.

Various environmental factors like hypoxia or CO2 (ocean acidification) interact with these principle relationships. Recent analyses in the spider crab, Hyas araneus, and the edible crab, Cancer pagurus, demonstrated that CO2 narrows the thermal window with an as yet unclear mechanistic background. Ambient hypoxia is also expected to narrow the organismal thermal window, but clear quantitative evidence has not yet been provided (Ekau et al. 2010). In addition, both CO2 and hypoxia may support passive tolerance to thermal extremes but, at the same time, might exacerbate hypoxemia leading the organism earlier to the limits of its thermal acclimation capacity. Further, preliminary evidence indicates a CO2-induced shift between substrate use and the capacities of various pathways of energy metabolism (anabolism and catabolism). A recent conceptual analysis suggests that the relationships between energy turnover, the capacities of activity, the respective allocation of aerobic power, and the width of thermal windows may lead to an integrative understanding of specialization on climate and sensitivity to climate change. The thermal window concept can be used as a matrix which allows to easily integrate other relevant factors involved in climate change.

This project proposes to investigate the effects of increased temperature, hypoxia and CO2 (using realistic scenarios of ocean hyoxia and acidification) on the cold and the warm sides of the thermal window of key crustacean species selected along a latitudinal cline reaching from the British channel to the Arctic (suitable candidate species being e.g. Hyas araneus, Cancer pagurus and Mysidacea). It will be investigated how various oxygen and CO2 levels in the water influence the temperature- dependent development of a mismatch between the oxygen demand of tissues and whole animal, on the one side, and the oxygen supply by circulatory and ventilatory systems, on the other side. In particular, this project aims to characterise the mechanisms underpinning shifts in thermal limits (pejus and critical temperatures) across seasons (thermal acclimatisation) and environmental clines (thermal adaptation), and the effect that hypoxia and environmental hypercapnia will exert on such mechanisms. One central question of this project is ‘Do environmental hypoxia and hypercapnia influence the thermal acclimation capacity of the marine animals?’. Changes in the expression or kinetic characteristics of enzymes (e.g. COX/CS/PEPCK/HOADH), metabolite profiling, tissue biochemistry and tissue substrate stores (glycogen, lipids, protein) will be characterised, together with changes in the temperature-dependent patterns of acid-base, metabolic and cardiocirculatory regulation. Furthermore, the capacity for extra- and intracellular acid-base regulation and the formation of anaerobic end-products will be analysed to address their potential feedback on functional capacities of e.g. the circulatory system and thus temperature dependent performance, and to investigate their suitability as potential proxies for hypoxia resistance under elevated pressures of other stressors like temperature and CO2.

The approaches and methodology used at AWI include non-invasive NMR imaging and spectroscopy combined with respiratory techniques, studies of acid-base regulation and circulatory and ventilatory performances. Such studies have successfully addressed temperature effects and limitations and also CO2 effects on thermal tolerance. These techniques can now be used to address the signalling mechanisms of acute vs. long-term shifts in thermal tolerance and resolve the functional significance of the interaction between hypoxia and CO2. Led by the University of Bremen, the technique of metabolite profiling will be combined with studies of tissue biochemistry and analyses of energy stores (glycogen, lipids, protein) to identify long term shifts in energy metabolism and substrate use induced by temperature combined with hypoxia and CO2. These analyses will be complemented by studies of enzyme capacities (e.g. COX/CS/PEPCK/HOADH) under the combined action of temperature with either one or all of the combined stressors. The University of Plymouth (UoP) will contribute to this project supporting the design of macrophysiological and evolutionary physiological experiments, as well as the analysis and interpretation within an evolutionary context of collected data. UoP will also provide access to the existing state-of-the-art OA-hypoxia culture and experimental suite, where part of the experimental work will be carried out.

Selected references:
Ekau W, Auel H, Pörtner HO, Gilbert D (2010) Impacts of hypoxia on the structure and processes in pelagic communities (zooplankton, macro-invertebrates and fish). Biogeosciences 7: 1669-1699

Pörtner HO, Farrell AP (2008) Physiology and Climate Change. Science 322: 690-692

MARES_13_2010: Biogeography of Rhodopirellula: physiological traits determing the biotope increment

Host institute 1: P2 – Universität Bremen
Host institute 2: P7 – University of Plymouth
Subject description
Biological invasions involve dispersal and sucessful competition with the indigenous species in an environment that changes nowadays more due to human activities. For microbes, a biogeography was for a long time not existent. “Everything is everywhere, but the environment selects” has been considered as guideline. But in recent years, the biogeography of microorganisms was shown to exist in the form of ecotypes and regional strains. For the attached-living Rhodopirellula, a benthic microaerophilic bacterium, we have recently demonstrated that Rhodopirellula is present as three closely-related species in European seas, with one species in the Baltic Sea, one in the North-Atlantic and one in the Mediterranean Sea (1). Culture-independent studies revealed that Rhodopirellula and other Planctomycetes represent up to five percent of the microorganism in the microoxic top sediment layer of the Wadden Sea, a hotspot of carbon turnover in marine systems encountering naturally changing temperature, light and oxygen concentrations during the tidal cycle (2).

The PhD project will gain insight into the biogeography of Rhodopirellula strains by culture- independent studies of marine surface sediments applying novel PCR primer. These will be developed on the basis of eight genomes of closely related Rhodopirellula strains. The molecular ecology study is expected to provide a high resolution biogeographic map of the actual habitats of the three closely related Rhodopirellula species in European coastal sediments. It is required to observe the habitat border changes in the future.

A key question is an understanding of the physiological differences between the European Rhodopirellula species. To study the adaptation to light, temperature, hypoxia and acidification, the cultivation has to shift from batch to chemostat cultivation. This method enables the study of physiological capacities under environmental conditions in the laboratory. Species competition experiments will be performed with changing conditions. The outcome will be screened by molecular methods and reveal important physiological traits of the strains. These studies provide insight into the chance to invade the next geographical habitat upon change in the environment.

The project requires a large sampling effort for the molecular study. This can be performed within MARES. The first sampling for isolation and cultivation within the EU FP6 network MarBEF was very successful (3). The project includes a stay in the School of Marine Science and Engineering in Plymouth. Time will be spend on sampling along the coast of England and preparation of genomic DNA for molecular analyses. The project will use special laboratories in Plymouth that are devoted to study the influence of light on organisms.

MARES_25_2010: Assessing the effects of long-term ocean acidification at CO2 vents off Methana Greece.

Host institute 1: P7 – University of Plymouth
Host institute 2: P16 – Hellenic Centre for Marine Research (HCMR)

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 http://www.plymouth.ac.uk/pages/view.asp?page=23609). 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.

MARES_26_2010: Assessing the impact of acidification on oyster calcification and growth

Host institute 1: P7 – University of Plymouth
Host institute 2: P11 – Université Paris Marie Curie (UPMC)

Subject description
Ocean acidification resulting from anthropogenic CO2 emissions has lowered, and is predicted to further lower ocean pH (e.g. Caldeira and Wicket 2003). The consequent decrease in calcium carbonate saturation potentially threatens calcifying marine organisms. A number of studies have demonstrated that calcification rates of certain calcareous marine organisms (e.g. the oyster Crassostrea gigas) decline with increasing pCO2 (Gazeau et al. 2007), whilst others note that the biological response of oysters to increased acidification is species-specific and much more variable and complex than previously reported (Findlay, et al. 2009; Miller et al. 2009). Oyster species are important in coastal ecosystems and represent a large part of worldwide aquaculture production. Hence any predicted decrease of calcification in response to ocean acidification is likely to have an impact on coastal biodiversity and ecosystem functioning as well as potentially lead to significant economic loss.

Studies focussing on the biological responses of calcifying biota to acidification (e.g. Gazeau et al. 2007; Findlay, et al. 2009; Miller et al. 2009) have typically undertaken short-term laboratory- based studies lasting days or weeks. As a consequence longer term responses under ‘natural’ conditions, and the spatial and temporal heterogeneity of seawater carbonate chemistry, have hitherto not been adequately addressed.

Aims and Objectives
This project proposes to examine calcification rates of oysters through the analysis of oyster growth under a range of ‘natural’ acidified and non-acidified marine conditions . Applying state-of-the-art chemical labelling of living oysters (Lartaud et al. 2010) we propose to examine shell growth rates, thickness and calcification in response to changes in seawater chemistry (pH, salinity) and temperature. The chemical labelling technique permits the recording of precise growth rates during the life of individuals. This study will therefore for the first time record the longer term perspective (years as opposed to days or weeks) of calcification in response to acidification as well as to other changes in seawater chemistry and temperature.

We have identified a number of study sites along the English Channel and the Atlantic coast, each of which we have previously undertaken research (including chemical labelling of oysters by de Rafelis), which are as follows: 1. Restronguet Creek and the Fal Estuary (Cornwall, UK). These locations are populated by the edible oyster Ostrea edulis and are part of the Port of Truro oyster fishery (believed to be the world’s largest oyster fishery still fished by traditional means). As a result of acid mine drainage the Restronguet Creek Site has a pH of ~7 and is monitored by the UK Environment Agency. 2. Baie des Veys (Normandy) and Marennes–Oléron Bay (Charente–Maritime), France. These two sites belong to the Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER) and represent some of the main Crassostrea gigas oyster-farming areas. Temperature, pH and salinity are recorded daily at these sites and together with the Fal Estuary, they show a range of pH from ~8 – 8.8, a total range consistent with projected future scenarios (e.g. Caldeira and Wicket 2003).

Regular (monthly and bi-monthly) Mn2+ markings (for methodology see Lartaud et al. 2010) will be undertaken in the first and second year of the project. 2 batches of oysters will be harvested from each site (typically 10-20 individuals) in year 1 and year 2. Oysters (both C. edulis and C. gigas) will be bred from “birth” to 2 years. Cathodoluminescence microscopy will be used to reveal the natural luminescence of the shells and artificial sharp luminescence growth bands related to the Mn2+ markings. In addition to measuring shell growth rates, thickness and calcification a range of other analyses will be undertaken and include trace elemental geochemistry and stable isotopic analyses of the oysters from each of the sites. The measurements will compliment the growth data by further tracking temperature and salinity variation.

The results of this project will greatly improve our understanding of calcification associated with changes in seawater chemistry (pH, salinity) and temperature and hence test the veracity of shorter term calcification experiments by providing a longer term perspective. Our research will also provide data for those evaluating future acidification scenarios using the character and response of calcareous marine organisms to past acification episodes (e.g. Findlay, et al. 2009).

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