Award: OCE-1316047

The ability of coral reef ecosystems to "build reefs" is determined by their ability ro deposit calcium carbonate over time. This ?net calcification?, is a key process that is fundamental for coral reef health. Ocean acidification is thought to reduce net calcification rates on coral reefs by lowering seawater pH, making it either harder for corals to deposit skeletons, or easier for existing skeletons to dissolve. However, the tools to measure net calcification rates in the field are time and labor intensive, usually requiring collection of water samples and returning them to the lab for analysis using sophisticated instrumentation. This limits our ability to detect and study how ocean acidification is impacting coral reefs in the natural world. In this project, we developed the Benthic Ecosystem Acidification Measurement System (BEAMS), a fully autonomous system that measures in situ net calcification rates in coral reefs. BEAMS utilizes chemical sensors to measure net calcification rates at ~15 minute intervals for weeks to months. We tested and validated this new method on Palmyra Atoll, a pristine coral reef atoll in the central Pacific. Surprisingly, we found no relationship between seawater pH and net calcification rates over a 2 week period, highlighting the importance of making in situ measurements to accurately assess the impacts of ocean acidification on net calcification. We have deployed BEAMS in over a dozen reefs worldwide, and are currently working on adapting the method for other coastal ecosystems. Last Modified: 09/24/2018 Submitted by: Jennifer E Smith