Cold and wet: Diatoms dominate the phytoplankton community during a year of anomalous weather in a Great Lakes estuary Mancuso, Jasmine L. Villar Argáiz, Manuel Diatoms Phytoplankton Climate change Extreme events Muskegon Lake Great Lakes estuary This research was funded by the Michigan Space Grant Consor-tium [NNX5AJ20H] , the Community Foundation for Muskegon County, the Grant Valley State University Presidential Research Grant, and the Michigan Chapter of the North American Lake Man-agement Society and Michigan Lakes and Streams Association Lake Research Student Grant to JLM. MV-A was supported by a Junta de Andalucia Award [P12-RNM 327] and an Universidad de Granada sabbatical aid. The authors thank Brian Scull and the Steinman Lab (Annis Water Resources Institute) for performing nutrient anal-yses and Muskegon Lake monitoring, respectively. The Muskegon lake Observatory project was supported by grants from EPA-Great Lakes Restoration Initiative [R5-GL2010-1] , Michigan Space Grant Consortium [NNX5AJ20H] , University of Michigan-Cooperative Institute for Great Lakes Research [NA12OAR4320071] , Community foundation for Muskegon County [20172151] , Edison Foundation [250695] , and the Annis Water Resources Institute to BAB. As sentinels of climate change and other anthropogenic forces, freshwater lakes are experiencing ecosystem disruptions at every level of the food web, beginning with the phytoplankton, a highly responsive group of organisms. Most studies regarding the effects of climate change on phytoplankton focus on a potential scenario in which temperatures continuously increase and droughts intersperse heavy precipitation events. Like much of the conterminous United States in 2019, the Muskegon River watershed (Michigan, USA) experienced record-breaking rainfall accompanied by unusually cool temperatures, affording an opportunity to explore how an alternate potential climate scenario may affect phytoplankton. We conducted biweekly sampling of environmental variables and phytoplankton in Muskegon Lake, a Great Lakes Area of Concern that connects to Lake Michigan. We compared environmental variables in 2019 to the previous eight years using long-term data from the Muskegon Lake Observatory buoy, and annual monitoring excursions provided historical phytoplankton data. Under cold and wet conditions, diatoms were the single dominant division throughout the entire growth season – an unprecedented scenario in Muskegon Lake. In 10 of the 13 biweekly sampling days in 2019, diatoms comprised over 75% of the phytoplankton community in the lake by count, indicating that the spring diatom bloom persisted through the fall. Additionally, phytoplankton seasonal succession and abundance patterns typically seen in this lake were absent. In a world experiencing reduced predictability, increased variability, and regional climate anomalies, studying periods of extreme weather events may offer insight into how natural systems will be affected and respond under future climate scenarios. 2021-10-27T10:55:03Z 2021-10-27T10:55:03Z 2021-07-22 journal article Jasmine L. Mancuso... [et al.]. Cold and wet: Diatoms dominate the phytoplankton community during a year of anomalous weather in a Great Lakes estuary, Journal of Great Lakes Research, Volume 47, Issue 5, 2021, Pages 1305-1315, ISSN 0380-1330, [https://doi.org/10.1016/j.jglr.2021.07.003] http://hdl.handle.net/10481/71136 10.1016/j.jglr.2021.07.003 eng http://creativecommons.org/licenses/by/3.0/es/ open access Atribución 3.0 España Elsevier