Annual Time Series of Psuedo-Nitzschia and Domoic Acid Production in Narragansett Bay, RI, USA

Parameters: Chlorophyll

Congratulations to Alexa Sterling who was awarded a Travel Stipend for her presentation at the 2019 ASLO Aquatic Sciences Meeting featuring our Trilogy and 10AU Fluorometers.

Abstract

Some strains of the diatom Pseudo-nitzschia produce the neurotoxin domoic acid (DA) which can bioaccumulate in shellfish. Toxic shellfish consumption has deleterious impacts on higher trophic levels including mortality in marine animals and amnesic shellfish poisoning in humans. In 2016 and 2017, DA toxicity closed shellfish harvest in Narragansett Bay (NB), Rhode Island, USA. While Pseudo-nitzschia have been detected in NB for over 50 years, these were the first DA closures in RI, threatening local economies and potentially human health. It is unknown what instigated these recent toxic events in NB: whether a changing environmental factor altered the physiology of Pseudo-nitzschia strains present or new DA-producing strain(s) were introduced to the NB ecosystem. In order to investigate, we conducted year-long sampling of NB from Sept. 2017 - 2018 at several sites including the NB mouths and inner regions. DNA from biomass collected on filters (> 5.0 um) was extracted and amplified using diatom-specific primers in order to track community composition. Cell-associated DA was quantified, with accompanying environmental metadata (e.g. nutrients, temperature, and pH). Low DA concentrations were detected throughout, with the highest peaks in Sept. and Jun. at NB mouths. There is one Pseudo-nitzschia sequence dominant in the winter, and a higher diversity of sequences in the summer months. This analysis will assist in identifying strains responsible for DA production in NB and help identify ecological factors that may correlate with elevated DA. >>View Presentation

Author: Alexa Sterling

Institution: University of Rhode Island, Narragansett Bay, Rhode Island, USA