2-C 2021 RI C-AIM Research Symposium

Seasonal and -Related Bacterioplankton Dynamics in Narragansett Bay, RI

Zachary Pimentel1, Alexa Sterling1, Tatiana Rynearson2, Bethany Jenkins1, Ying Zhang1

1University of Rhode Island, Kingston, RI 2Graduate School of Oceanography, University of Rhode Island, Narragansett, RI

Bacteria play critical roles in the functioning of marine ecosystems, from impacts to biogeochemical cycles to both benefcial and detrimental interactions with other organisms. However, little is known about the dynamics, including the taxonomic identity, of the resident bacterial communities in Narragansett Bay (NBay), RI. Here, free-living (FL) and particle-associated (PA) bacterial communities have been profled with weekly samples for one year at the NBay Long-Term Time Series using 16S rRNA community profling. Comparisons have revealed that the FL and PA communities are distinct at all points throughout the year; however, they followed similar seasonal patterns. In addition, FL and PA community dynamics were compared in response to a historically large algal bloom, dominated by , that occurred in NBay in the winter of 2018 (with peak a greater than 60 µg/L).

While decreased alpha diversity was observed in response to the bloom in both communities, differences were observed in taxa that responded to the bloom; for example, Dokdonia, Reinekea, and SAR92 increased in relative abundance in the FL community after the bloom while Loktanella and Aquibacter responded in the PA community. Further investigations of the FL community dynamics are underway to analyze microbial interactions under seasonal perturbations and algal bloom-related dynamics. Increasing our knowledge of bacterial community structure and function in NBay will bring further insights into modeling their contributions to various ecological and economic processes in NBay.