Working Group: Coral Adaptation to Extremes

In the tropics, we are exploring natural gradients, in the coral reefs of the Andaman Sea, where for instance cooling by internal waves protected corals during a severe bleaching event in 2010. In addition, corals that thrive in an environment influenced by internal waves were more resilient to thermal stress and thus prepared for such extreme events and possibly also for future ocean warming. A topic that is also being investigated as part of the current DFG Priority Programme SPP2299 (Tropical Climate Variability & Coral Reefs). Within the SPP2299, our project focusses on the ability of internal waves to protect reefs and thus contribute to the sustainability of reefs in the future. It is in line with another SPP2299 project that aims to reconstruct the thermal variability and stress events since the Little Ice Age in the same area and whether internal waves have also helped to protect against heat stress in the past (PI: Thomas Felis @ MARUM).

We also utilise other strong gradients of environmental variability along the reefs from the shoreline to the reef slope. We study the coral genets of different coral species from intertidal to subtidal habitat to explore intra- and interspecific phenotypic variations. The aim is to better understand the interaction between local environmental conditions, coral phenotypes and reef structure and what this can tell us about the future of coral reefs.

Environmental fluctuations also play a role in the fitness of cold-water corals, and at the limits of their distribution this can cause additional stress and have a negative impact on their metabolism and presumably their fitness. This also means that their fatty acid balance is affected and lipid reserves are likely to be more depleted than in habitats with less environmental variability. Despite their remoteness, the Patagonian fjords are subject to anthropogenic pressures from intensive aquaculture, but the impact on neighbouring benthic communities is less well understood, including the potential impact on the diverse and dense cold-water coral reefs in this region. While we are interested in assessing the health of corals in the region along natural physico-chemical environmental gradients, we have recently begun to investigate the role of aquaculture and whether it contributes to shifts in coral-associated bacterial taxa and what problems this may pose for coral health. The Comau Fjord in Patagonia, Chile, is an ideal system to study these issues, which also has implications for other fjord systems in the region.