Warming of the Mediterranean Sea hampers the resistance of corals and mollusks to ocean acidification

Some calcifiers (mussels, gastropods and corals) protect their shell or skeleton from the corrosive effects of increasing ocean acidification. They can therefore resist some of the damaging effects of increasing ocean acidity generated by the release of carbon dioxide (CO2) in the atmosphere through human activities. This resistance is diminished when organisms are exposed to extended period of elevated temperature (28.5°C). This is a result of an international study (1), co-led by Jean-Pierre Gattuso, research scientist at Laboratoire d’océanographie de Villefranche (CNRS/UPMC), published in the journal Nature Climate Change. These results suggest that the ongoing and future warming of the Mediterranean combined with the rise of its acidity will increase the frequency of mass-mortality events.

The oceans absorb about one fourth of the carbon dioxide (CO2) released by the use of fossil fuel and changes in land use. This amounts to 1 million tons CO2 every hour and leads to large changes in the chemistry of seawater, including an increase in its acidity. This acidification threatens calcifying organisms, those that build shells and skeletons, such as mollusks and corals.

PhD positions in interdisciplinary marine research, Germany 2011

PhD Research Positions in Interdisciplinary Marine Research at University of Kiel, Germany 2011

Study Subject(s):Marine Research (ocean acidification,ecosystem change,marine resources,ocean warming ,sea level rise , ocean hazards, marine life science , ocean governance)

Associate research fellow in ecophysiology of ocean acidification

Ref. P42385
Salary: £24,370 per annum

Fixed Term contract for 13 months

The College of Life and Environmental Sciences wishes to appoint a Postdoctoral Researcher to work in the laboratories of Drs Rod Wilson and Ceri Lewis on a NERC funded grant, to start as soon as possible. This is part of the UKOARP (Ocean Acidification Research Programme) and the project is a collaboration with Swansea University, Plymouth Marine Laboratory, and Strathclyde University. The project will investigate the effects of temperature and CO₂ on the early life stages of marine invertebrates and fish of commercial importance. The PDRA will be based at Exeter, using our new state-of-the-art £6M aquarium facility, and will regularly visit the Centre for Sustainable Aquaculture Research (http://www.aquaculturewales.com/) in Swansea to work on animals undergoing longer term exposures. Data on growth, performance, fitness etc. will feed into population modelling studies and ultimately allow us to address the socio-economic impacts of future ocean conditions on these species.

Threshold of carbonate saturation state determined by a CO2 control experiment

Acidification of the oceans by increasing anthropogenic CO₂ emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies suggest that carbonate dissolution will occur in polar regions and in the deep-sea oceans where saturation state with respect to carbonate minerals (Ω) will be <1 by 2100. However, carbonate in coral reefs distributed in tropical zones will not dissolve because the major carbonate in such reefs is aragonite, and the saturation state with respect to aragonite (Ω_a) is >1. Recent reports demonstrated nocturnal carbonate dissolution reefs, despite Ω_a > 1, probably relate to the dissolution of the minor reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined, and it is unknown whether these dissolution processes actually occur under natural conditions. This work describes the measurement of the dissolution rates of coral aragonite and Mg calcite excreted by marine organisms under conditions of Ω_a > 1 with controlled seawater pCO₂. Laboratory experimental data of the present study show that bulk carbonate sediments sampled from a coral reef start to dissolve when Ω_a = 3.7, and dissolution rates increase with falling Ω_a. Mg-calcite derived from foraminifera and coralline algae dissolved when Ω_a reached 3.4, whereas coralline aragonite started to dissolve when Ω_a was almost 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminifera and coralline algae in reef sediment.

Postdoctoral fellowship in coral biogeochemistry at Rutgers University

Postdoctoral Fellowship available at the Institute of Marine and Coastal Sciences at Rutgers, the State University of New Jersey. We are seeking a highly motivated researcher to conduct independent and collaborative research into the mechanisms of biomineralization in corals, its potential response to ocean acidification and implications for the application of geochemical proxies in corals, with an emphasis on boron isotopes. Preferred fields of experience include:
1) Interactions between biomolecules (“organic matrix”) and the formation of inorganic crystals in biogenic minerals.
2) Biomineraliztion controls on boron isotopes and other proxies of the seawater carbonate system in tropical corals, with an emphasis on controlled laboratory experiments.