On 24 August, 2023, 10 community science organizations, the Connecticut Department of Energy and Environmental Protection (CT-DEEP) and the University of Connecticut collaborated to simultaneously sample total alkalinity in the embayments and rivers bordering Long Island Sound (LIS). Led by DMS PhD Candidate Lauren Barrett, the event was a regional repeat of the 2019 effort led across New England by the Northeast Coastal Acidification Network (NECAN, http://necan.org/ShellDay).

The participating groups sampled for total alkalinity (TA) and hydrographic variables such as salinity and temperature during low, mid-, and high tides, meaning the spatial variation in alkalinity across the Sound. Seawater alkalinity requires high precision, expensive instrumentation and a skilled analyst, and thus typical observations of TA in LIS conducted by a single or a few researchers require that spatially separate samples also have a temporal difference. However, TA varies across diel and tidal cycles, so the spatial and temporal difference is important to parse. The collaborative effort of Shell Day allowed for a spatial identification of TA trends in LIS without the confounding temporal variation.

Shell Day 2023 was a successful event. Despite some mild rain in the afternoon, community scientists weathered the storm and still provided high-quality samples, which are currently undergoing TA analysis at UConn. The results of this work will be interpreted in the context of open LIS data (available through the Vlahos lab at UConn) and the data collected during Shell Day 2019. This work will be presented to the LIS Science Technical and Advisory Committee (STAC) this fall as well as to the participating organizations at a meeting which is to be determined.