Text and photos by Dr Kristina Beck
After several months of preparations, we were finally able to start our long-term cold-water coral experiment a month ago! Over the next year, we will investigate how cold-water corals cope with future environmental changes. In this experiment, we will study the combined effect of ocean acidification, warming, deoxygenation and food limitation on the cold-water coral species Lophelia pertusa. We will regularly measure the growth and respiration rates of the live corals and take samples to determine any changes in their energy reserves due to the different treatment conditions. In addition, we will also investigate the dissolution of dead coral skeletons because large parts of natural cold-water coral reefs are not covered with tissue. However, due to the complex three-dimensional framework of the reef, the dead coral skeletons provide important habitat and nursery grounds for other benthic and fish species.
We are conducting our experiment at the St Abbs marine station, where the experiment is set up in a cold room to keep the water temperature constant. The experimental tanks are constantly supplied with natural seawater. We have seven different treatments in this experiment with a total of 21 coral tanks.
Profilux computers (white boxes on the picture) are used to increase the temperature and reduce the seawater pH and oxygen concentration in order to reach the different treatment conditions. Carbon dioxide and nitrogen gases are used to lower the pH and oxygen levels, respectively. In order to be able to adjust all water parameters in the many coral tanks, we need a many probes to constantly measure the temperature, pH, salinity and oxygen concentration. In addition, any hoses are needed to bubble the gases into the coral tanks. That’s why you see so many cables and hoses on the pictures of the experimental setup.
Experiment set-up at the St Abbs marine station
We will soon start the first of a series of measurements and are very excited to gain first insights into how cold-water coral cope with changes in temperature, pH, oxygen and food availability – so stay tuned for the first results 🙂