Cyanobacteria Blooms in Upper Klamath Lake

ESR 575 Limnology

November 23, 2009

Lauren Senkyr

Upper Klamath Lake

Oregon’s largest lake

Oregon’s largest lake:

•Volume ~ 536 x 1036

•Surface area ~275 km2

•Shallow, hypereutrophic

•Avg. depth 2.2 m

•Mean depth 2 m

•Max. depth 15.2 m

Management issues

ESA listed suckers

Water diversions

Agriculture- nutrient inputs + water useDams along Klamath River

↑ Phosphorus↑ Algal Blooms

↑ pH

↑ Unionized Ammonia

↓ Dissolved Oxygen

↓ Algal Blooms

↑ Nutrient Loading

Fish Die-offs

Cycle of Water Quality Degradation in Upper Klamath Lake

Cyanobacteria• “Blue green algae”• Aphanizomenon flos-aquae

dominant June-October• 1st appearance 1933• Collapse causes anoxic conditions that lead to

fish kills • Commercially harvested

• 1 toxic species in UKL (Microcystis aeruginosa)

Basic Biology of AFA

•Does not grow in pH < 7.1, water temperature < 11 degrees C

Yamamoto and Nakahara, Limnology (2005)

Current Conditions in Upper Klamath Lake Favor AFA

Eilers et. al. 2004

•High pH

•High water temperatures

Internal P Loading

• Internal load ~2/3 Total P in Upper Klamath Lake

• Decrease in total P in top

2 cm of sediment before/

after bloom

(Simon et. al. 2009)

The Role of Wind

• Very strong relationship between climate and water quality in Upper Klamath Lake

• ↑ wind speeds = ↓ water column stability

• Wind induced mixing of sediments= increased nutrient availability

• (Kann and Welch 2005)

Impacts of altered hydrology• Sedimentation• Nutrient retention• Greater internal loading• Wind control

accentuated by lower water levels

Eilers. E

t. al. 2004

Implications for wetland restoration and dam removal?

http://www.nature.org/wherewework/northamerica/states/oregon/about/art25169.html#