Riesenalgen als Klimaschützer? Unterwasserwälder im Ozean

·23 min·2 clips

Meter-long brown algae form underwater forests that store carbon and protect coasts, but many have been destroyed.

The episode begins by describing underwater kelp forests as one of Earth's largest forests, with brown algae growing as high as three-story houses and playing key roles in coastal protection and carbon storage. Host Carolin Weische introduces the topic, noting that rising sea temperatures, overfishing, and deforestation have destroyed many algae forests globally. The narrative shifts to a dive in South Africa's Great African Sea Forest near Cape Town with marine biologist Janis Landschow, who documents species in False Bay. The dive reveals a dense forest of algae up to 15 meters high, inhabited by fish, anemones, a pyjama shark, and an octopus, illustrating the ecosystem's biodiversity. Landschow explains that kelp forests support endemic species and complex interactions, comparable to tropical rainforests. The episode details the global distribution of kelp forests, found in places like California, Chile, Australia, and Helgoland in Germany, where Dr. Angelika Greif researches species like Laminaria digitata and Saccharina latissima. These algae grow rapidly, up to 60 centimeters a day in some cases, absorbing CO2 through photosynthesis. Research indicates kelp forests store about 1,500 grams of carbon per square meter per year, more than coral reefs or tropical rainforests, but the duration of storage is shorter due to faster turnover. A key insight involves fucoidan, a polysaccharide produced by brown algae that resists decomposition and may enhance long-term carbon storage in the ocean. The FUBLUK project, led by Greif, studies fucoidan emissions under controlled conditions. The episode then visits Portugal, where NGO Seaforester, led by Paul Buchan, attempts to reforest kelp by breeding spores in containers and deploying them in the Atlantic. However, reforestation faces hurdles like fish predation, insufficient light, and climate change impacts. Greif expresses skepticism about artificial relocation, noting that breeding heat-tolerant lines may not withstand multiple stressors like hypoxia. Globally, 40-60% of kelp forests have disappeared in 50 years, with examples like dead forests in Norway due to turf algae invasion. Beyond carbon, kelp forests provide habitat for fish, supporting food security, and filter nutrients from agriculture and industry. They also have potential uses as animal feed to reduce methane emissions, as fertilizer, and in bioplastics. The episode concludes that while kelp forests are not a silver bullet for climate change, protecting existing ones is crucial for their ecosystem services and carbon storage potential.

Listen to the show on

Apple Podcasts Spotify

Play clips from this episode More from IQ - Wissenschaft und Forschung