An update onHarmful Algal Blooms in

Lake Erie

Thomas BridgemanUniversity of Toledo

June 11, 2014

Anabaena Aphanizomenon

Planktothrix

Microcystis

Lyngbya

Common Harmful “Algae” (Cyanobacteria)

Focus on Phosphorus• High Phosphorus concentration leads to

- high algal biomass- dominance by cyanobacteria

(Kalff 2001)

Diatoms

Green algae

Golden algae

1970s-1990s: Phosphorus controls led to Recovery

Conroy & Culver 2005

Alg

ae

Mid-1990s: Return to eutrophic conditions and harmful algal blooms

Conroy & Culver 2005

Alg

aeA

lgae

Field Methods (2002-2014) 6 sites sampled

biweekly 112 um mesh

plankton net Nutrients

West Sister IslandMaumee Bay

Annual estimate of Microcystis

2002

2009

2003: Return of HABs in Lake Erie

August 2002

August 2003

Microcystis in Lake ErieAll 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

Michalak et al. 2013

2003

2013 Microcystis open water bloom

2013 open water bloom was second only to 2011 over last 12 years

West Sister IslandMaumee Bay

2013 Microcystis Maumee Bay

More Microcystis in Maumee Bay and south shore areas in 2013

October 2, 2013

Effects of 2013 Bloom

Mixed plankton After 1 Hour After 1 Day

HABs mixed downward may cause more problems for water utilities

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?

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