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.