Spatial and temporal patterns in microcystin toxins in Lake of the Woods surface waters

ABSTRACTZastepa A, Watson SB, Kling H, Kotak B. 2017. Spatial and temporal patterns in microcystin toxins in Lake of the Woods surface waters. Lake Reserve Manag. 33:433–443.Lake of the Woods (LOW) is a complex system, with limited exchange between its multiple basins and strong spatial variance in physicochemical conditions and susceptibility to cyanobacterial blooms (cHABs). Nutrient input from tributaries has contributed to a highly productive southern basin with widespread cHABs, which are also present in some northern sub-basins. To date, there is no systematic lake-wide assessment of spatial and temporal patterns of microcystins (MCs) in relation to cyanobacterial taxa along physicochemical gradients. To achieve this, surface waters were sampled June to September in 2006, 2008–2010, and 2014–2015 offshore, inshore, and along developed shorelines. Offshore MC measured by ELISA and PPIA was consistently low despite high chlorophyll-a (Chl-a) (e.g. 0.7 µg MC-LR equivalents/L; 126 µg/L Chl-a), with only...