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An update onHarmful Algal Blooms in
Lake Erie
Thomas BridgemanUniversity of Toledo
June 11, 2014
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Anabaena Aphanizomenon
Planktothrix
Microcystis
Lyngbya
Common Harmful “Algae” (Cyanobacteria)
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Focus on Phosphorus• High Phosphorus concentration leads to
- high algal biomass- dominance by cyanobacteria
(Kalff 2001)
Diatoms
Green algae
Golden algae
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1970s-1990s: Phosphorus controls led to Recovery
Conroy & Culver 2005
Alg
ae
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Mid-1990s: Return to eutrophic conditions and harmful algal blooms
Conroy & Culver 2005
Alg
aeA
lgae
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Field Methods (2002-2014) 6 sites sampled
biweekly 112 um mesh
plankton net Nutrients
West Sister IslandMaumee Bay
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Annual estimate of Microcystis
2002
2009
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2003: Return of HABs in Lake Erie
August 2002
August 2003
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Microcystis in Lake ErieAll years following 2002 have had moderate to intense Microcystis
blooms. The bloom of 2011 was the largest bloom ever recorded.
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2011 bloom from the Space Station
Michalak et al. 2013
2003
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2013 Microcystis open water bloom
2013 open water bloom was second only to 2011 over last 12 years
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West Sister IslandMaumee Bay
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2013 Microcystis Maumee Bay
More Microcystis in Maumee Bay and south shore areas in 2013
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October 2, 2013
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Effects of 2013 Bloom
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Mixed plankton After 1 Hour After 1 Day
HABs mixed downward may cause more problems for water utilities
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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?
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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 HABs over 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.
Summary