Autonomous Observation of Seasonal Carbonate Chemistry Dynamics in the Mid‐Atlantic Bight

Abstract

Ocean acidification alters the oceanic carbonate system, increasing potential for ecological, economic, and cultural losses. Historically, productive coastal oceans lack vertically resolved high-resolution carbonate system measurements on time scales relevant to organism ecology and life history. The recent development of a deep ion-sensitive field-effect transistor (ISFET)-based pH sensor system integrated into a Slocum glider has provided a platform for achieving high-resolution carbonate system profiles. From May 2018 to November 2019, seasonal deployments of the pH glider were conducted in the central Mid-Atlantic Bight. Simultaneous measurements from the glider's pH and salinity sensors enabled the derivation of total alkalinity and calculation of other carbonate system parameters including aragonite saturation state. Carbonate system parameters were then mapped against other variables, such as temperature, dissolved oxygen, and chlorophyll, over space and time. The seasonal dynamics of carbonate chemistry presented here provide a baseline to begin identifying drivers of acidification in this vital economic zone. Plain Language Summary Seawater chemistry affects the ability of organisms to survive in the ocean. Past monitoring of seawater chemistry has missed key times and locations that are important to natural life cycles. In order to fill in those gaps, we put a chemical sensor into a deep-sea robot that we can control from land. This robot, called a Slocum glider, glides from the top of the ocean down to 200-m depth and collects ocean chemistry data along the way. We used our Slocum glider to measure how seawater chemistry differs between seasons in the Mid-Atlantic, which will help us understand how organisms might be affected by water conditions.

Accurate spectrophotometric pH measurements made directly in the sample bottle using an aggregated dye perturbation approach

“…When TA is 400 μ mol kg −1 , the same bias in TA would lead to an error in |ΔpH/ΔT| of <0.005. Global (Bittig et al 2018; Carter et al 2018) or regional algorithms (Alin et al 2012; Takeshita et al 2015; Hirsh et al 2020; Wright‐Fairbanks et al 2020) that estimate TA from temperature and salinity have sufficient accuracy to constrain TA for the open ocean, so this source of temperature dependent error becomes negligible. Direct measurements for TA will likely be needed for environments with large freshwater influence such as estuaries or go through large biological modification from calcification such as on coral reefs.…”

Field Application of Automated Spectrophotometric Analyzer for High-Resolution In Situ Monitoring of pH in Dynamic Estuarine and Coastal Waters

“…Understanding spatial and temporal changes in pH in association with environmental variables is essential for a sustainable management of marine systems. Hydrodynamic and biogeochemical processes in coastal estuaries change rapidly from minutes to days, triggering acidification in the system (Xu et al, 2017;Wright-Fairbanks et al, 2020). Those sudden changes often cannot be resolved through sampling and analyses of discrete water samples.…”

The diadromous watersheds-ocean continuum: Managing diadromous fish as a community for ecosystem resilience

“…2022.1007599 as new pollutants (e.g., 6PPD-quinone and other chemicals found in urban watersheds and microplastics (Hiki et al, 2021;Johannessen et al, 2021;Parker et al, 2021). This needs to be assessed jointly with ocean acidification, warming, and changes in salinity (Huntington, 2010;Lynch et al, 2015;Le Bris et al, 2018;Wright-Fairbanks et al, 2020). Coastal habitats are often highly vulnerable to degradation (e.g., eutrophication and warming) due to increased watershed urbanization and agricultural use, and toxic episodes have already been observed in estuaries like the Chesapeake Bay (Brush et al, 2020;Malone and Newton, 2020).…”