The role of inorganic nutrients in bleaching tolerance and energy metabolism in scleractinian corals.

• Grant number: 24/21922-8
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2025
• End date: February 28, 2027
• Field of knowledge: Biological Sciences - Zoology - Physiology of Recent Groups
• Principal Investigator: Samuel Coelho de Faria
• Grantee: Beatriz Nazar
• 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 are ecosystems characterized by their high biodiversity and by the establishment of relevant ecological relationships with other organisms, such as Symbiodiniaceae dinoflagellates, which mutually benefit from the recycling of metabolic subproducts or from the acquisition of photosynthetic products. Such symbiosis is a regular subject of many climate change researches, mainly using coral species from Caribbean Sea and Indo-Pacific Ocean as experimental models. However, these regions exhibit a coastal water regime which differs from the South Atlantic one. In this scenario, the project's main goal is to analyze the energy metabolism and the bleaching tolerance of scleractinian corals in different inorganic nutrient availability scenarios, specially nitrate and phosphate. Thus, we hypothesize (i) low nitrate and phosphate concentrations maintain symbiosis integrity, oxidative/energy metabolic state and calcification rate; (ii) high nitrate concentrations with limited phosphate concentrations promote coral bleaching, compromising photosynthesis, metabolism and growth. Differently, (iii) high phosphate concentration is protective against high nitrate concentrations. Furthermore, (iv) increased temperatures promote a greater physiological impact than nitrate/phosphate imbalanced rates. Hence, Mussismilia hispida was selected because of its wide distribution throughout the Brazilian coast. Colonies (N = 6) from Alcatrazes Archipelago will be fragmented, acclimated and subjected to different nutritional treatments, followed by the exposure to temperatures which simulate the elevated thermal scenario predicted for 2100, according to projections from Intergovernmental Panel on Climate Change (IPCC). Organismal and biochemical parameters will be analyzed to assess metabolic and photosynthetic performance, which will contribute to understanding the coral bleaching tolerance.