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An update on Harmful Algal Blooms in Lake Erie. Thomas Bridgeman University of Toledo June 11, 2014. Common Harmful “Algae” (Cyanobacteria). Anabaena. Microcystis. Aphanizomenon. Planktothrix. Lyngbya. Focus on Phosphorus High Phosphorus concentration leads to
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An update onHarmful Algal Blooms in Lake Erie • Thomas Bridgeman • University of Toledo • June 11, 2014
Common Harmful “Algae” (Cyanobacteria) Anabaena Microcystis Aphanizomenon Planktothrix Lyngbya
Focus on Phosphorus • High Phosphorus concentration leads to • - high algal biomass • - dominance by cyanobacteria Golden algae Diatoms Green algae (Kalff 2001)
1970s-1990s: Phosphorus controls led to Recovery Algae Conroy & Culver 2005
Mid-1990s: Return to eutrophic conditions and harmful algal blooms Algae Algae Conroy & Culver 2005
Field Methods (2002-2014) • 6 sites sampled biweekly • 112 um mesh plankton net • Nutrients West Sister Island Maumee Bay
Annual estimate of Microcystis 2009 2002
2003: Return of HABs in Lake Erie August 2002 August 2003
Microcystis in Lake Erie All years following 2002 have had moderate to intense Microcystis blooms. The bloom of 2011 was the largest bloom ever recorded.
2011 bloom from the Space Station 2003 Michalak et al. 2013
2013 Microcystis open waterbloom 2013 open water bloom was second only to 2011 over last 12 years
West Sister Island Maumee Bay
2013 Microcystis Maumee Bay More Microcystis in Maumee Bay and south shore areas in 2013
HABsmixed downward may cause more problems for water utilities After 1 Hour After 1 Day Mixed plankton
Recent Development • Modeling study (Obenour et al., in review) indicates Lake Erie has become increasingly susceptible to HABs. • i.e. less P required to cause a bloom now than in 2002. • Seed in sediments? • Climate change?
Summary • Although the annual size of HABs may be somewhat predictable, the effect (on utilities and beaches) is less so. • Weather-driven water circulation patterns • Vertical water mixing patterns • L. Erie may have become more susceptible to HABsover the past decade. • Although a reduction in P loading would have an immediate beneficial effect, it may take several years of low P loading before Lake Erie “heals” completely.