Relative importance of denitrification within the nitrogen budget of Red Sea coral holobionts

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Project Description

Nitrogen availability is a key limiting factor for primary production on many coral reefs. As such, benthic organisms such as corals adapted and evolved efficient uptake and (re)cycling of the available nitrogen. The microbiome of coral holobionts aids in this cycling of nitrogen by 1) creating de novo bioavailable nitrogen via fixation of atmospheric dinitrogen (N2) performed by so called diazotrophs, and 2) alleviating bioavailable nitrogen through denitrification. While the latter seems counterintuitive at first, the majority of energy for coral holobionts is produced by a symbiotic relationship with photosynthetic dinoflagellates of the family Symbiodiniaceae which need to be in a nitrogen-limited state to translocate their photosynthates to the coral host. As such, denitrification could benefit coral holobiont health by aiding in keeping Symbiodiniaceae in a nitrogen-limited state. Recent research suggests that N2 fixation and denitrification essentially cancel each other out in several Red Sea corals (Tilstra et al., 2019). In contrast, Glaze et al. (2021) recently provided evidence that the significance of denitrification in hard corals from the Great Barrier Reef is negligible relative to other coral holobiont associated N-cycling pathways. However, besides focusing on different reef locations (central Red Sea vs. Eastern Indo-Pacific), both studies utilized different methods for their assessment. While the former used an acetylene based method quantifying holobiont-wide fluxes, the latter used labelled isotopes suitable for targeted quantifications. As such, a comparison between both studies may be confounded. To accurately assess the significance of denitrification relative to other N-cycling pathways (e.g. N2 fixation) associated with Red Sea corals, a comparative analysis using both methods with a range of corals will be conducted.
Program - Marine Science
Division - Biological and Environmental Sciences and Engineering
Center Affiliation - Red Sea Research Center
Field of Study - Coral reef microbiology

About the
Researcher

Raquel Peixoto

Associate Professor, Marine Science

Raquel Peixoto
Prof. Peixoto's research has outlined the protocols and proved the concept that the manipulation of coral-associated microorganisms, using Beneficial Microorganisms for Corals (BMCs), is possible and can increase the host's resilience and resistance against environmental threats. This pioneering work has contributed to pave the way for new approaches to reveal and explore mechanisms of marine microbiology and symbiotic interactions. As a Beneficial Microbes for Marine Organisms network (BMMO) founder and chair, her goal is to keep promoting a powerful international platform where basic knowledge can be strengthened and transformed into products to be used for marine ecosystems and sustainable development, as part of her projects on coral reef protection, restoration and rehabilitation.

Desired Project Deliverables

To generate a dataset that can be used for the student's master thesis and one associated publication.

RECOMMENDED STUDENT ACADEMIC & RESEARCH BACKGROUND

Required academic background: last year of Master programme in Marine Sciences, Microbiology or related programmes
Required academic background: last year of Master programme in Marine Sciences, Microbiology or related programmes
Experience in molecular and/or physiological biology
Experience in molecular and/or physiological biology
Previous experience working in lab- and/or field-based experiments
Previous experience working in lab- and/or field-based experiments
Scientific writing skills
Scientific writing skills