Tidal flooding's role in the spread of eelgrass wasting disease: Laboratory experiments

Zostera marina, a prominent New England eelgrass, is an integral part of the region's marine and coastal ecosystems as it sequesters carbon, filters the water to improve clarity, and provides food and shelter for various marine species. Over the past century however, New England's eelgrass has been decimated by frequent epidemics of eelgrass wasting disease (EWD) leading to a staggering decrease in the region's eelgrass since the 1930s and the decline of various species once prevalent across New England. This study explores whether areas most susceptible to EWD transmission are areas that experience more intense tidal flooding periods on average as noted by larger changes in volumetric flow rate and stronger currents. We employ an open-channel flume, ultraviolet fluorescent paste, and true-to-size eelgrass models while utilizing field condition flow rate data obtained from buoys in regions historically containing eelgrass. Additionally, we apply corresponding Reynolds numbers to replicate how a diseased eelgrass plant infects other eelgrass in the meadow. Results reveal the effects of unidirectional turbulent flow, monami waves, and swiftly changing flow rates on EWD transmission of plants proximal to the highly diseased plant.