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Basic oases in an acidified ocean

A new research project with the Arctic Research Centre investigates whether arctic seaweed forests may act as oases for animals with calcareous shells, animals that are challenged by the climate change induced acidification of the world’s seas.

Photo: Peter Bondo Christensen

Researchers from Aarhus University, IMEDEA in Spain and the Greenland Climate Research Centre[sigh1]  have just received a two-year project aimed at scrutinizing ocean pH, seaweed forests and animal life on the sea bottom. Seaweed forests act as habitats for important commercial species such as scallops, shrimps and common mussels, which all depend on the formation of a calcareous shell around their soft bodies. The climate changes have rendered this formation more difficult. The increased amount of CO2 in the atmosphere increases the CO2 in the ocean, leading to acidification. This disturbs the chemical balances of the oceans and results in a lower content of carbonate minerals that are important construction materials in the growth and shell formation of the animals. However, a dense seaweed forest may come to the aid of bottom animals during ocean acidification.

Expansion of seaweed forests

The results of the project will demonstrate whether the larger seaweed forests may act as ‘basic oases’ in an acidified ocean in the future, oases where small organisms may form shells. In summer the seaweed forests along the coast of Greenland perform photosynthesis 24 hours a day and the dense submerged forests may, via this photosynthesis, increase the pH of the bottom water to levels so high that they locally may counteract the acidification of the ocean. The summer period is exactly the period of the year with strongest significance for the development of small shell-covered animals, and the seaweed induced increase in water pH may render life easier for the animals during the critical growth season. Together with her colleagues senior scientist Dorte Krause-Jensen, manager of the project, has recently shown that the seaweed forests along the west coast of Greenland have the potential to spread in the warmer Arctic of the future. Thus, it is likely that the impact of seaweed forests on the ocean’s pH will be an important phenomenon along large parts of the Greenland coast in the future.

Common mussel as model organism

The investigation into the impact of pH on the shell formation of mussel larvae will be focused on common mussel, a dominant species in the Greenland coastal zone, and knowledge about how climate changes impact its survival capacity is important in order to foresee the future ecosystem along the Greenland coast.

Apart from providing knowledge of the impact of seaweed forests on water pH and their refuge effect for calcareous species, the project will also produce new basic knowledge of pH and the content of calcium carbonates in the oceans around Greenland. Moreover, during the project period the necessary knowhow will be created to allow researchers to evaluate the possibility of including pH measurements in marine monitoring programmes in Greenland.


The research project is financed by DANCEA (Danish Cooperation for Environment in the Arctic) which is administered by the Danish Environmental Protection Agency in close collaboration with the Greenland Self-Government. The project period is two years with two field campaigns – one in 2013 and one in 2014.

If you want to know more about the project ‘pH and the role of the expanding marine vegetation as a buffer against acidification in near-shore areas of Greenland’, please contact project manager and senior scientist Dorte Krause-Jensen, e-mail: dkj@dmu.dk, tel: +45 8715 8799.