A comparative physiology to the causes of coral reef conservation: does trophic plasticity drives tolerance against climate changes?

Abstract

Physiological mechanisms, ecological processes and phylogenetic history are associated with biogeographic patterns and tolerance to climate changes, which includes ocean warming and acidification. The most diverse marine environment - the coral reefs - have been suffering with bleaching and decreasing on calcification rates, especially scleractinian coral species occupying oligotrophic, tropical environments, such as the Pacific Ocean and the Caribbean Sea. Nevertheless, 0.01% occupy the South Atlantic, whose waters show greater turbidity as consequence of higher sedimentation and organic matter. Thus, a physiological comparative evaluation of bleaching and calcification concerning trophic ecology is imperative for understanding the climatic effects in the coral reef fauna, whether related to the physicochemical nature of oceans and/or to the phylogenetic history. Selected ecophysiological traits will be evaluated in 12 scleractinian coral species from South Atlantic, East Pacific and Caribbean Sea, under natural and simulated conditions of increasing temperature and acidification, using comparative methods. It is hypothesized here that: (i) heterotrophy is prominent in the species distributed along the coast of Brazil, unlike photosynthesis; (ii) Brazilian species are more tolerant to bleaching and reduction in calcification rates due to the prominent heterotrophy; and that (iii) the evolution of trophic plasticity was driven by physicochemical nature of the oceans. The findings could underpin future management plans against climate changes, especially for the Brazilian fauna owing the particular environmental characteristics and emblematic endemism, still scarce of studies. (AU)