In addition to heating the seas, falling pH values of the water also threaten many living things in the ocean. Corals may be the best example for this: they bleach if it is too warm for them for a long time and they build up their lime scaffolding worse when it gets too acidic. According to a study by Jan Taucher from the Geomar Helmholtz Center for Marine Research in Kiel and his team in "Nature", even pebbles are increasingly having problems if the sea continues to ensure. So far, they have been considered rather robust because their cell sleeves are made of silicon dioxide.
Kiesel algae are among the most important organisms in the ocean: they form the basis of many food networks and withdraw the atmosphere with its sheer mass large amounts of carbon dioxide. In this way, they contribute significantly to the still existing lowering effect of the oceans. Kiesel algae or diatomes provide around 40 percent of the production of vegetable biomass in the sea. When you die, you put huge amounts of carbon into the deep sea.
Due to the decreasing pH values, the silicon shells of diatoms are now dissolving more slowly, which is why dead diatoms sink into deeper water layers than before, before they dissolve chemically. The silica that is released is therefore available to a lesser extent than before in the upper, light-rich water layers, where, however, new generations of diatoms need it for their shells.
This has long -term consequences: "We expect a loss of up to ten percent of pebbles until the end of this century," says Jan Taucher: "But it is important to think over 2100. Climate change will not stop abruptly, and global effects in particular need some time until they become clearly visible. Depending on the amount of emissions, our model in the study predicts a loss of up to 27 percent silica in surface water and an ocean case decline of the pebbles of up to 26 percent by 2200 - more than a quarter of the current inventory. «The consequences for the Food networks are not yet foreseeable.
For their study, the working group experimented with so-called mesocosms in various regions from the subtropics to the Arctic: large-volume, oversized test tubes in the ocean with a capacity of several tens of thousands of liters, in which changes in environmental conditions in a closed, but otherwise natural ecosystem can be studied. They then enriched the water with carbon dioxide, as is expected for future climate scenarios.
