Record-setting algal bloom in Lake Erie caused by agricultural and meteorological trends consistent with expected future conditions

Document Type

Conference Paper/Presentation

Publication Date



In 2011, Lake Erie experienced the largest harmful algal bloom in its recorded history, with a peak intensity over three times greater than any previously observed bloom. Here we show that long-term trends in agricultural practices are consistent with increasing phosphorus loading to the western basin of the lake, and that these trends, coupled with meteorological conditions in spring 2011, produced record-breaking nutrient loads. An extended period of weak lake circulation then led to abnormally long residence times that incubated the bloom, and warm and quiescent conditions after bloom onset allowed algae to remain near the top of the water column and prevented flushing of nutrients from the system. We further find that all of these factors are consistent with expected future conditions. If a scientifically guided management plan to mitigate these impacts is not implemented, we can therefore expect this bloom to be a harbinger of future blooms in Lake Erie.

Publisher's Statement

© 2013 Michalak et al. Publisher's version of record: https://doi.org/10.1073/pnas.1216006110

Publication Title

Proceedings of the National Academy of Sciences of the United States of America