Community structuring, phylogeography, and ecological traits from the Brazilian scleractinian endosymbiont zooxanthellae

• Grant number: 22/10482-1
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: September 01, 2022
• End date: February 28, 2026
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Marcelo Visentini Kitahara
• Grantee: Amana Guedes Garrido
• Host Institution: Centro de Biologia Marinha (CEBIMAR). Universidade de São Paulo (USP). São Sebastião , SP, Brazil
• Associated research grant: 21/06866-6 - Integrating tools and disciplines to understand the future of Southwestern Atlantic shallow-water corals in a changing planet, AP.JP2
• Associated scholarship(s): 23/14580-0 - Coral holobionts under different nutrient availabilities and heat stress, BE.EP.PD

Abstract

Since their debut in shallow waters (circa 240 Mya), the vast majority of scleractinian corals have established a symbiotic relationship with photosynthetic dinoflagellates of the family Symbiodiniaceae. These endosymbionts, commonly known as zooxanthellae, assist corals in their nutrient production through photosynthetic activities, typically averaging densities of 1-5x106, per square centimeter of coral tissue. In brief, the zooxanthellae provide fixed carbon compounds to the coral host and, in return, the host coral polyp provides a protected environment and a steady supply of carbon dioxide for the zooxanthellae photosynthesis. However, the millions of years that such a relationship has endured turned most shallow-water corals dependent on the zooxanthellae's energy supply. Due to this relationship, corals and, therefore, shallow-water coral reefs are particularly sensitive to increasing temperatures as their symbiosis with zooxanthellae suffers a breakdown when temperatures are anomalously high. The breakage of this symbiotic relationship, termed "coral bleaching" (as corals tissue becomes transparent when zooxanthellae are lost - exposing corals' white skeleton), reduces the performance of the coral host and has become more frequent and widespread in the past decades. These mass bleaching events (where most of the coral assemblage bleaches in a particular locality), are often associated with widespread coral mortality and, for those that survive, depressed colony growth and reproduction have been detected. On top of that, the increase in frequency and strength of ocean thermal anomalies in the last few years is resulting in more pervasive bleaching events. Nevertheless, there is growing evidence indicating that patterns of bleaching as well as bleaching susceptibility are far from homogeneous in terms of taxa and also locations. In Brazil, several localities are being affected by climate change but, our corals have been purported to have a higher resistance as heterotrophy appears to be more widespread in our more turbid waters. Furthermore, the zooxanthellae population/community structure within the coral is dynamic, and field experiments have indicated turn- over in the endosymbiont zooxanthella community that improved hosts' susceptibility to ocean warming at a particular place and time. Therefore, the postdoc candidate will, together with the associated researcher from the main proposal, co-lead this complementary research, which will enable us to further understand the holobiont fitness/adaptation in time of increasing anthropogenic-related impacts. To achieve that, in situ zooxanthellae community profile from the Brazilian corals will be determined, and in situ and ex situ experiments will test the zooxanthellae community potential turnover due to ocean warming. The postdoc activities include assisting with sampling, planning and executing transplant experiments, DNA/RNA extractions, and library preparation for NGS sequencing, data analysis, and writing. Besides being the first effort to sequence genomic and transcriptomic data from Brazilian corals, the project will generate unprecedented data that will serve as a baseline for future investigations and help to answer several questions within small and large evolutionary scales. A master's scholarship will assist the postdoc along with the project. (AU)