For seagrass meadows the impacts could be severe
Two thirds of the earth's surface is covered by water. Oceans play an important role to us humans - they are food sources, heat stores, trade routes and one of the most important stores of carbon dioxide (CO2). In particular, seagrass meadows along the coasts absorb a lot of CO2, but this ecosystem is sensitive to the effects of climate change and could lose much of its storage function. Angela Stevenson, a postdoc in the "Marine Evolutionary Ecology" research unit at GEOMAR in Kiel, is examining the condition of seagrass meadows along the German Baltic Sea coast to find out how they can help to reduce CO2 emissions.
What is special about seagrass meadows?
Coastal vegetated systems, like seagrass meadows, mangrove forests and salt marshes, play an important role in the global carbon budget due to their exceptional ability to capture and store organic carbon below ground. Burial rates here are 30 to 50 fold greater than that of forests on land. In the Baltic Sea, seagrass meadows are vast. We have a total area of approximately 285 km2 of these habitats.
How can one imagine seagrass meadows?
Seagrasses are marine plants that live at depths of about 1 to 8 meters in German coastal waters, and slightly deeper elsewhere around the world. They have roots and root stocks, so called rhizomes, below ground, and shoots and leaves above ground. Like other plants, they need light to survive and take up CO2 during photosynthesis. It is the seagrass’ dense canopy that distinguish it from other plants in terms of enhanced carbon storage: the canopy increases particle capture from the water column and reduces water flow along the seafloor, efficiently lowering loosening up of sediments and hence protecting buried carbon. The plant’s intricate below-ground network of roots and rhizomes is not easily displaced, and their muddy sediments enhance low oxygen levels that inhibit microbial activity and thus remineralization of buried organic carbon. This process further increases longterm organic carbon burial efficiency.