Since 2011 the caribbean has seen a rapid increase in brown tide events, where large mats of sargassum inundate coastal areas

Preliminary data collected by caricoos suggests that sargassum inundation events may cause dramatic changes in carbonate chemistry significant enough to affect reef and ecosystem health. Despite significant increases in ocean acidification monitoring over the past decade, monitoring of carbonate chemistry in the US caribbean remains extremely limited. Many of the fixed buoys in the caribbean do not measure the biogeochemical variables needed to capture changes in water chemistry such as oxygen, CO2, and PH. In addition, existing buoys are in areas of high wave energy, where some extreme events (e.g. sargassum inundation) do not occur. Due to the high cost and complexity of conducting carbonate chemistry analysis most marine laboratories in the caribbean do not have the instruments required to conduct such analyses. This lack of monitoring has resulted in gaps in understanding of nearshore conditions, particularly during short-lived, highly impactful events such as sargassum inundation, which can threaten local species and ecosystems, including coral reefs. As such, there is a need to advance technology that is portable and produces high-quality data by defined ocean carbonate chemistry standards. This allows the local and broader ocean observing community to rapidly assess sensitive areas when and where observations are needed most. The ocean foundation (TOF), through its equisea initiative, has led international efforts to reduce the cost and complexity of ocean acidification monitoring. In partnership with the global ocean acidification observing network (GOA-on) and academic leaders, TOF created GOA-on in a box - a suite of monitoring equipment that enables users to collect weather quality ocean acidification data per GOA-ONS requirements. This system is highly modular, made of many constituent parts, to enable easy diagnosis of issues, maintenance, and repair. The ocean foundation will soon reach a milestone of deploying 22 of these systems to 17 countries, which has established observation programs at governmental ministries, academic institutions, and nonprofits. Yet, the system has not been leveraged to advance observations in data-limited regions of US waters, leading to an opportunity to refine the process and meet these needs. Likely due to the lengthy process of procuring each individual component of the system. The ocean foundation is the only institution to date that has purchased and shipped ystems. Other institutions have attempted to and then handed the process off to the ocean foundation due to complexity. TOF has partnered with DR. Burke hales of dakunalytics to create a new tool for low cost monitoring of ocean acidification, initializing development in 2020. The PCO to go is a low-cost handheld sensor that measures seawater PCO using a non-dispersive infrared (NDIR) sensor with an uncertainty of 15 PPM after correction and calibration. The sensor is made of off-the-shelf components that can be substituted if a supplier ceases making a particular item, enabling a predictable supply chain. The sensor provides more relevant carbonate chemistry data from both surface and sub-surface discrete samples than current similarly priced handheld PH sensors on the market. Over the past two years, this system has completed demonstration testing in hatchery and field settings (RL 6), but IT is not yet commercially available. Though the field components of this project are focused on characterizing the emerging threat of sargassum inundation, the PCO to go sensor has significant applications in aquaculture settings and in the maintenance of experimental carbonate chemistry conditions. As such the final design and operationalizing of the sensor will take into account uses by additional sectors, including aquaculture and biological experimentation. The project partners propose to build off T