Science Portrait: Felix Mark

Felix Mark is a marine ecophysiologist at Alfred Wegener Institute. He investigates the effects of climate change on two closely-related fish species in the Arctic. Due to rising water temperatures, the Atlantic cod is moving northwards and might take over the habitat of the native polar cod.


Three perspectives on ocean acidification

Learn from Hans-Otto Pörtner, coordinating lead author of the fifth IPCC report, how the ocean really fares. Follow Felix Mark to the Arctic, as he sets out to investigate how fish react to their changing environment. And join Jelle Bijma on a journey into the past, as he tries to unveil the archive of the history of Earth.

    •    The ocean - A changing ecosystem
    •    Atlantic and Polar Cod under stress
    •    Traces of the past


A dive into the reef

Few sea inhabitants are affected so strongly by the rising temperatures and the drop in the pH value of the oceans than the stony coral. Ocean acidification means that the corals run out of energy to form their lime skeleton. In addition, the rise in water temperature prevents the symbiosis between the corals and unicellular algae, the so-called zooxanthellae. These zooxanthellae live in the coral, supply it with energy and nutrients and also give it its colour. Temperature stress leads corals to reject their zooxanthellae. This causes the corals to pale and frequently to die due to the lack of energy supply. Scientists from the Alfred Wegener Institute currently wish to find out how quickly the coral reefs are changing and whether the animals are able to adapt to the environmental changes. 




A strong case for limiting climate change

Ocean Acidification

A strong case for limiting climate change

In November 2017, the German research network on ocean acidification BIOACID (Biological Impacts of Ocean Acidification) reaches its conclusion after eight years of extensive interdisciplinary scientific activity.

Tropical coral reefs lose two thirds of their zooplankton through ocean acidification

Climate change

Tropical coral reefs lose two thirds of their zooplankton through ocean acidification

Tropical coral reefs lose up to two thirds of their zooplankton through ocean acidification. This is the conclusion reached by a German-Australian research team that examined two reefs with so-called carbon dioxide seeps off the coast of Papua New Guinea. At these locations volcanic carbon dioxide escapes from the seabed, lowering the water's acidity to a level, which scientists predict for the future of the oceans. The researchers believe that the decline in zooplankton is due to the loss of suitable hiding places. It results from the changes in the coral reef community due to increasing acidification. Instead of densely branched

Press release

A question of light: Ocean acidification slows algae growth in the Southern Ocean

In a recent study, scientists at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), demonstrate for the first time that ocean acidification could have negative impacts on diatoms in the Southern Ocean. In laboratory tests they were able to observe that under changing light conditions, diatoms grow more slowly in acidic water. In so doing, Dr Clara Hoppe and her team have overturned the widely held assumption that sinking pH values would stimulate the growth of these unicellular algae.