Probabilistic forecast of microcystin toxin using satellite remote sensing, in situ observations and numerical modeling Environmental Modelling & Software

Lake Erie has experienced a resurgence of cyanobacterial harmful algal blooms (CHABs) since the early 2000's dominated by Microcystis aeruginosa, which produce toxins known as microcystins. We develop an approach to predict the spatially- and temporally-resolved probability of exceeding a public health advisory (PHA) level (6 μg/L) of microcystins in the western basin of Lake Erie that would be suitable for use in a forecast system, consisting of 1) an existing HAB chlorophyll forecast system, 2) a toxin-chlorophyll-a relationship that is updated weekly from observations, and 3) a statistical model relating observed relative frequency of exceeding the PHA to model predictions over a hindcast period. We evaluate the system's performance and the system's useful level of skill. This novel approach to a CHAB toxin forecast system could provide a decision support tool to Lake Erie stakeholders, and the approach may be adapted to other systems.