Abstract
Cold-water corals are important bioengineers that provide structural habitat for a diverse species community. About 70% of the presently known scleractinian cold-water corals are expected to be exposed to corrosive waters by the end of this century due to ocean acidification. At the same time, the corals will experience a steady warming of their environment. Studies on the sensitivity of cold-water corals to climate change mainly concentrated on single stressors in short-term incubation approaches, thus not accounting for possible long-term acclimatisation and the interactive effects of multiple stressors. Besides, preceding studies did not test for possible compensatory effects of a change in food availability. In this study a multifactorial long-term experiment (6 months) was conducted with end-of-the-century scenarios of elevated pCO2 and temperature levels in order to examine the acclimatisation potential of the cosmopolitan cold-water coral Lophelia pertusa to future climate change related threats. For the first time multiple ocean change impacts including the role of the nutritional status were tested on L. pertusa with regard to growth, “fitness,” and survival. Our results show that while L. pertusa is capable of calcifying under elevated CO2 and temperature, its condition (fitness) is more strongly influenced by food availability rather than changes in seawater chemistry. Whereas growth rates increased at elevated temperature (+4°C), they decreased under elevated CO2 concentrations (~800 μatm). No difference in net growth was detected when corals were exposed to the combination of increased CO2 and temperature compared to ambient conditions. A 10-fold higher food supply stimulated growth under elevated temperature, which was not observed in the combined treatment. This indicates that increased food supply does not compensate for adverse effects of ocean acidification and underlines the importance of considering the nutritional status in studies investigating organism responses under environmental changes.
Highlights
The cold-water coral Lophelia pertusa is one of six widespread azooxanthellate scleractinian coral species that are known to be capable of building large three-dimensional reef frameworks (Roberts et al, 2009)
Under elevated temperature of 12◦C, growth rates were increased compared to ambient temperature of 8◦C and were in the lower range of rates estimated by Orejas et al (2011) with the same technique for Mediterranean Lophelia pertusa grown for 3 months at the same temperature, which is typical for Mediterranean cold-water coral sites
Several studies have shown that cold-water corals are able to sustain positive growth under ocean acidification and/or warming, but net calcification rates of L. pertusa exposed to Ar-undersaturated conditions often decreased close to zero or even became negative (i.e., Lunden et al, 2014; Hennige et al, 2015) as was likewise observed in the elevated pCO2 treatment of the present study
Summary
The cold-water coral Lophelia pertusa is one of six widespread azooxanthellate scleractinian coral species that are known to be capable of building large three-dimensional reef frameworks (Roberts et al, 2009). This ecologically important species is found throughout the world’s oceans and forms structural habitat for a variety of fishes and other invertebrates. Climate change has already caused an increase of global mean sea surface temperature of 0.56–0.92◦C in the last 100 years and a further increase of ∼3–4◦C is projected until the end of this century (IPCC, 2014)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
