Unlike their tropical cousins, cold-water corals live in cool waters, primarily with temperatures in the single digits Celsius. Here – for example, in the depths of Norwegian and Chilean fjords – they play an important part in the marine ecosystem, offering many fish species a place to hide and breed. AWI researchers recently spent several months investigating how three different life stages of the cold-water coral Caryphyllia huinayensis are responding to climate-change-induced environmental influences. In this regard, ocean acidification, warming waters, and reduced food availability were taken into account. The six-month-long experiment in a controlled aquarium setting allowed the experts to test the effects of various combinations of negative influences. In contrast, past studies have chiefly focused on mature cold-water corals and the influence of respective individual environmental parameters.
“We found that the different life stages react differently to changed environmental conditions,” explains AWI expert Kristina Beck, first author of the study. “Under simulated future environmental conditions, we observed higher mortality among the mature corals, and slowed growth among the young corals. Taken together, these two effects threaten the future of entire populations: Higher mortality means that fewer corals live long enough to reproduce. And due to slowed growth, the young corals only reproduce much later.”