| Marine Animal Forests (MAFs) are diverse benthic habitats, historically underestimated but ecologically vital. These underwater ecosystems mirror terrestrial forest, yet they uniquely rely on animals to construct intricate three-dimensional structures that serve as nurturing grounds and nurseries for various species. The main organisms composing these deep coral gardens are cold water corals (CWC), which are vital for ecosystem functioning and fisheries sustainability. Among the many threats these communities face, destructive fishing activities are the main one, since deploying nets in these deep ecosystems leads to seafloor erosion and high bycatch rates of CWC. Recently, numerous projects and initiatives have been developed, focusing on coral restoration that involves the rescue and transplantation of corals caught as bycatch. The ultimate goal is not restoring coral gardens on shallow depths by transplanting rescued gorgonians from deeper regions. The observation of these corals in such settings is, however, more feasible for scientific research. Nonetheless, this raises concerns about the corals’ adaptability, particularly to thermal changes, since shallower waters usually experience higher temperatures and fluctuations, which are increasing with climate change. Thus, studying the thermal performance of these bycaught gorgonians is vital. The current study aims to investigate and compare the thermal tolerance and plasticity of the four most common bycaught gorgonians of Sagres. Two lineages (purple and yellow) of Paramuricea grayi and two morphotypes (white and salmon) of Eunicella verrucosa. To achieve this goal, acute thermal stress assays were conducted, by exposing the corals to five temperature treatments ranging from 16°C to 25°C. For every temperature treatment, response parameters, including polyp activity, feeding capacity and respiration are analyzed. In addition, to account for potential differences in feeding due to polyp morphological differences, these are assessed as well in the four gorgonians. The study shows a strong effect of temperature on respiration, i.e. increase, coupled with decreasing polyp activity and feeding efficiency. These responses vary greatly not only between species, but also between lineages and morphotypes, indicating differences in their thermal plasticity, ranking from lower to higher tolerance: E. verrucosa (white)>P. grayi (purple)>E. verrucosa (salmon)>P. cf. grayi (yellow). Further research is still needed, e.g. longer-term temperature exposures to assess the effects on survival, growth, reproduction etc. However, these first results obtained here suggests that some of these gorgonians might be more viable candidates for transplantation on shallow depths. |