Ecophysiological response of Chilean Desmophyllum dianthus to Mediterranean environmental conditions

Student: 
Sophia Kleemeier

The cold-water coral Desmophyllum dianthus thrives in mostly oceans of the world and is thus one of the most widespread scleractinians. Since the environmental conditions in the various habitats this coral inhabits differ greatly, the question arises whether the distribution is mainly evolutionary (adaptation to different environmental conditions) or whether the species has a high acclimation potential that enables it to colonize new habitats in a relatively short time. To test the acclimation potential (phenotypic plasticity), D. dianthus specimens from Chilean Comau Fjord were exposed to conditions prevailing in the Mediterranean Sea. Using an uni- and bifactorial approach, I tested the single effect of elevated temperature (12 °C) and the interactive effect of elevated temperature and salinity (38 [PSU scale]) on polyp expansion, respiration, and growth of the corals. While polyp expansion, as well as respiration rates, were not affected by the increase in temperature and by its combination with high salinity, an increase in growth of 140 % was recorded, stimulated by increased salinity and the associated increased aragonite saturation. Consequently, the species has a great phenotypic plasticity, which explains the cosmopolitan distribution of D. dianthus.