Introducing a Novel in Situ Sensing Platform for Sustained Monitoring of Multi-Analyte Benthic Fluxes for Blue Economy Applications

Marine sediments play a crucial role in regulating several invaluable ecosystem services and blue economy outputs. However, sediments are highly prone to anthropogenic perturbations. Exchanges of dissolved analytes such as carbon, dissolved oxygen, and nutrients may critically control the health of coastal and deep marine ecosystems by regulating eutrophication, harmful algal blooms, hypoxia, and global carbon sequestration, among other phenomena. In conjunction with conventional field sampling, in situ sensing activities as part of sustained ocean observing networks provide valuable in situ data for a myriad of physical, chemical, and biological parameters. However, long-duration, in situ sediment monitoring is rarely implemented beyond fundamental oceanographic research. One type of sediment measurement, benthic fluxes, refers to monitoring exchanges of dissolved analytes between sediments and overlying waters and are thus highly relevant for ocean health. Conventional in situ benthic flux quantification techniques such as benthic chamber incubations generate only a single flux measurement per deployment per analyte and are not conducive for continuous ocean observing systems. Even more cutting-edge in situ technologies such as eddy correlation are limited with respect to analyte capabilities. A long-duration, sensor-agnostic benthic flux monitoring capacity could, however, pinpoint cause-and-effect relationships associated with ocean health, parameterize predictive models, inform ecosystem restoration planning and performance monitoring, as well as increase the efficiency of blue economy activities. In response, we present the Chamber ARray for Observing Sediment Exchanges Long-term (CAROSEL), a novel autonomous benthic lander platform developed specifically for monitoring, at sub-daily frequencies and over for long-durations, the in situ benthic fluxes of any relevant environmental analyte for which a commercially available sensor exists. While fundamentally based on conventional in situ benthic flux chamber incubation procedures, several unique features include a sensor-agnostic design, a compact form-factor allowing deployment from a small boat, and continuous time series monitoring of ambient water conditions and sediment-isolated biogeochemical processes. Ultimately, we envision this platform as an indispensable tool of global environmental monitoring and observation networks, facilitated by the exciting advancements of ocean technology into the future.