Biochemical adaptations in stony corals: effects of depth and bleaching on the enzyme kinetics of metabolism and calcification

• Grant number: 24/22207-0
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2026
• End date: December 31, 2028
• Field of knowledge: Biological Sciences - Zoology - Physiology of Recent Groups
• Principal Investigator: Samuel Coelho de Faria
• Grantee: Leonardo Milani Fabri
• Host Institution: Centro de Biologia Marinha (CEBIMAR). Universidade de São Paulo (USP). São Sebastião , SP, Brazil
• Associated research grant: 22/03105-7 - Using the phylogenetic past to predict climate impacts: ecophysiology of symbiosis and accelerated evolution to coral reef conservation, AP.PNGP.PI

Abstract

Coral reefs harbor a vast diversity of marine life and provide numerous ecosystem services on a global scale, including fisheries, coastal protection, tourism, and sources for biochemical and pharmaceutical compounds. However, these ecosystems are particularly vulnerable to climate change, especially rising ocean temperatures and decreasing oceanic pH. In addition to warm, shallow-water reefs, there are also reefs in deep, cold waters, although these have received less attention from the scientific community. Coral reefs are primarily formed by the exoskeletons of stony corals, which precipitate aragonite through a highly regulated and energy-demanding biomineralization (calcification) process. In corals, this energy mainly derives from glucose, which can be obtained through autotrophy (in zooxanthellate corals that maintain a mutualistic relationship with dinoflagellates) or predation, and is subsequently metabolized via aerobic or anaerobic pathways. Despite their ecological importance, calcification and coral metabolism at the enzymatic level remain poorly understood. This project aims to investigate the effect of depth on the kinetics and biochemistry of key enzymes involved in fundamental metabolic processes, such as lactate dehydrogenase (LDH, a marker of anaerobic metabolism), citrate synthase (CS, aerobic metabolism), and plasma membrane (Ca²¿)-ATPase (PMCA, a proxy for the calcification process [i.e. growth]) in azooxanthellate coral species distributed across shallow (4 m) and deep waters (~1,000 m). The lower activities of PMCA and CS in deep-sea corals may be adaptations to the occupied environment. Additionally, the project will experimentally simulate heatwaves to evaluate the effect of bleaching (i.e., the expulsion of zooxanthellae) on the kinetics of energy metabolism and calcification in zooxanthellate corals, hypothesizing a decrease in the activity of all three enzymes (LDH, CS, and PMCA) in response to reduced energy availability. (AU)