Growth and respiration of the scleractinian cold-water coral Tethocyathus endesa

The recently discovered scleractinian coral Tethocyathus endesa (Cairns, Häussermann and Försterra, 2005) is a cold-water coral, thriving in the fjord Comau (Chile). It exhibits horizontal and vertical pH gradients resembling values forecasted for the end of this century by the recent IPCC-report (IPCC, 2014). Ongoing ocean acidification and global ocean warming might have harmful impacts on all calcifying organisms such as scleractinians. This study aims for a better understanding of the metabolic response of T. endesa in a changing ocean. Measured parameters were in situ growth rates and respiration rates as being two of the main factors that can be influenced by ocean acidification. In 2014, test corals were placed at two study sites (inside the fjord with low pH of 7.67 ± 0.05 and outside the fjord with higher pH of 7.87 ± 0.06). For each study site, ten specimens of T. endesa stayed at their place of origin to determine the general in situ long-term growth rates (one year) as well as to serve as a control for a cross- transplantation experiment. For the latter, additional ten specimens of T. endesa were exchanged to the other study site in 2014. One year later, growth rates were determined via buoyant weighing and respiration rates measured with the aid of optodes. So far there is only little knowledge about the in situ long-term growth rates and the respiration rates of cold-water corals. To the best of our knowledge this is the first study on the reaction of T. endesa towards a changing seawater pH. The findings of this study are therefore crucial to rate the ecological importance of T. endesa and its response to future condition