Linking hydrodynamics to harmful algal blooms on the coast of Maine

Bailey, Taylor; Ross, Lauren; Smith, Sean; Cronin, Hanna; Dineen, Maeve

From the abstract: "Harmful algal blooms (HABs) associated with the toxic diatom Pseudo-nitzschia (PN) have appeared in the coastal waters of Maine in recent years. The blooms are alarming because they produce the neurotoxin domoic acid (DA) that can lead to amnesic shellfish poisoning (ASP), a potentially fatal illness when infected shellfish are consumed by humans. Despite this, knowledge of the environmental and hydrodynamic conditions that influence HAB occurrence and transport in marine waters is limited. The gaps in knowledge surrounding HABs influences shellfish harvesting closure decisions when PN is detected, adversely affecting the livelihood of aquaculture farmers and fishermen who rely on harvesting for income. This stakeholder driven research aims to support a more advanced scientific basis for closure decisions by investigating factors that influence HABs through measurements and hydrodynamic modeling of the Frenchman Bay estuary system. By drawing correlations between observational water quality data and measured levels of DA in shellfish meats, this work will help to identify conditions that cause HABs in the Gulf of Maine. Preliminary results suggest a correlation between precipitation events and bloom occurrence, which will be linked to hydrodynamic conditions from model hindcasts of the year 2016, the most severe year of ASP events in Maine. These findings will inform the development of a hydrodynamic forecasting model of Frenchman Bay, which is currently underway. The model will serve as a tool to inform management decisions surrounding bloom events and to advance understanding of HAB development and transport in marine waters."