CYANOBACTERIAL BLOOMS IN AN OLIGOTROPHIC LAKE: MANIFESTATION OF NOT-SO-VISIBLE MULTI-DECADAL ECOSYSTEM CHANGES

Freshwater cyanobacterial blooms are often associated with eutrophy and high water temperature, but lakes that are considered oligotrophic by all three major indices (chlorophyll a, total phosphorus, and Secchi depth) have been affected by recurrent cyanobacterial blooms, including when the water temperature is < 15°C. Otsego Lake, NY, USA experienced recurrent blooms of toxigenic Microcystis aeruginosa for the first time in the summer of 2022, which took the local community by surprise while the lake had continuously been invaded by a variety of non-indigenous aquatic species. The effort to control further introductions had not been fully supported financially or in terms of lake user compliance. The most serious example is the serial invasions by zebra (2007) and quagga (2018) mussels, both of which quickly colonized the entire 16 km² lake. The altered food web structure and biogeochemical cycling as well as the unbalanced in-lake nitrogen to phosphorus (N:P) stoichiometry after successful P load reduction appear to be the main drivers that may be amplifying the effects of climate warming, reduced ice cover, and altered precipitation patterns. The Otsego Lake community is working towards a Nine Element Plan, a comprehensive lake and watershed management plan that includes both watershed and in-lake modeling, which will enable data-driven decisions for watershed management.

Primary Presenter: Kiyoko Yokota, State University of New York at Oneonta (kiyoko.yokota@oneonta.edu)

Authors:

Kiyoko Yokota, State University of New York at Oneonta  (Kiyoko.Yokota@oneonta.edu)