Evaluating the physical and biogeochemical drivers of a reef community carbonate budget

Coral reef carbonate budgets are an important health metric that can indicate changes in community assemblages and reef complexity. In the Atlantic, a region-wide decline in coral cover and reef complexity has resulted in decreased carbonate production. This study investigated the carbonate budget of a Bermuda coral reef system within their northernmost extent in the Atlantic. Hydrochemistry and census-based approaches were used to quantify carbonate budgets. The water chemistry was evaluated using Eulerian flow respirometry to assess changes in total alkalinity between two fixed locations of known coral assemblages to estimate the net ecosystem calcification (NEC). For the census-based approach, the benthic community was quantified using orthophoto mosaics derived from video surveys. In this presentation, we compare the two approaches for measuring carbonate cycling and note the challenges in determining water residence time. These chemistry techniques are valuable in capturing temporal variability in NEC such as seasonality or changes due to disturbance events which may shift the coral community to a non-framework building taxa, reducing calcification rates. Bermuda’s reef system experiences higher seasonal variability in NEC and a reduced aragonite saturation state that limits the conditions for CaCO₃ precipitation compared to tropical regions. Studying the interactions and feedback between coral biogeochemical processes and oceanic carbonate chemistry changes is challenging but crucial to detect and predict carbon cycling changes in response to future climate change.

Presentation Preference: Poster

Primary Presenter: Shalimar Moreno, East Carolina University (morenosh20@students.ecu.edu)

Authors:

David Lagomasino, East Carolina University  (lagomasinod19@ecu.edu)

Yvonne Sawall, Arizona State University/Bermuda Institute of Ocean Sciences  (yvonne.sawall@bios.asu.edu)