Organismal Metabolism and Their Drivers in Coral Reefs

The two most important and fundamental processes describing coral reef ecosystem functioning are photosynthesis (primary production) and calcification (reef growth). They determine energy flow, carbon cycling and habitat provision (calcium carbonate structures) in reefs. The MABEE lab addresses research questions that relate to the temporal and spatial dynamics of reef organism and reef community metabolism under in-situ or near-natural conditions. The strong seasonal environmental fluctuations in Bermuda and the long-standing ocean time series BATS provide an ideal framework to study the capacity for metabolic adjustments in corals and other reef organisms. 

Eddy Reef (NSF-funded #2123697, since 2021, lead-PI: Sawall). 

The main goal of the project is to understand the impact of mesoscale eddies on coral performance, in particular on coral calcification. Mesoscale eddies are sporadically occurring large-circulating current patterns in the ocean that can create substantial vertical water mixing. Their effect on coral reefs is so far largely unexplored. This project (1) assesses the physical and biogeochemical changes of reef waters that occur during eddies, (2) determines how these biogeochemical changes affect coral performance and (3) systematically explore long-term eddy impacts on corals (several decades) through the examination of oceanic time-series data and coral skeleton proxy records. We use moored sensors (SeapHOx, SeaBird), automated water samplers (RAS-500, McLane), and a custom-built incubation chamber setup (BIO-REPORT) to address these questions. 

Co-PIs: Damian Grundle (ASU) and Nathalie Goodkin (AMNH, USA)

Lab participants and others: Roderick Bakker, Xinya Calhoun, Julia LeBlanc and undergraduate student interns  

Collaborators: Peter Gaube (Univ. of Washington)

Organism metabolism, coral heterotrophy and nutrient fluxes 

All living organisms and their environment are in constant exchange of components, including O2, CO2, nutrients, and a range of inorganic and organic carbon compounds. To measure these processes, we constructed an innovative fully automated in-situ incubation chamber setup (BIO-RESORT), together with engineers at GEOMAR Helmholtz Center for Ocean Research, Kiel, Germany. The BIO-RESORT allows continuous measurements of metabolic rates in 6 units simultaneously for up to one week at a time. Next to photosynthesis and respiration rate measurements (with O2 sensors), automated water samplers connected to each incubation chamber allow determining rates of, for example, calcification and nutrient uptake / release.

Further research efforts are currently directed towards improving our understanding of coral energy gain via autotrophy and heterotrophy. Those include (1) refined measurements of gross photosynthesis (GP) and daytime respiration of corals on a diurnal and seasonal scale and (2) the exploration of new approaches to improve coral heterotrophy quantification (in collaboration with Leocadio Blanco-Bercial, BIOS). (In-situ) coral heterotrophy and its contribution to the coral’s energy budget and nutrition is a so far poorly explored, although its significance may increase under climate change driven environmental stress.

Coral Reef Airborne Laboratory (CORAL) & light-use-efficiencies (NASA-funded, 2016 – 2019, Lead-PI: Eric Hochberg, BIOS)  

Advancements in understanding in-situ organism metabolic rates via innovative incubation chambers (BIOS Cawthorn Research Innovation Fund, 2020 - 2021, PI: Y Sawall; co-PI: Tim Noyes (BIOS), collaborator: Michael Bender (Princeton)

Improving reef calcification measurements and exploring dynamics of reef functioning, 2017 - 2019, BIOS Cawthorn Research Innovation Fund. PIs: Y Sawall, EJ Hochberg, N Bates.