Seeing the photos from the record-breaking algal bloom on Lake Erie in 2011 was like dÃ©jÃ vu for me. I grew up in the Great Lakes region in the 1960s and 1970s and remember the days when Lake Erie was declared ‘dead.’
I later learned that the green scum that plagued the lake during summer months was a sign that the lake was actually overly alive. It gained its morbid reputation because when blooms of the tiny plant-like organisms die-off, the decomposition process consumes oxygen. In extreme cases, it creates an unpleasant, smelly mess and literally sucks the oxygen from the water.
With anoxic conditions like these, walleye pike and yellow perch alike turn belly-up and die or gasp for breath at the surface, unable to syphon oxygen from the water that flows through their gills.
Algae gets a bad rap sometimes, a reputation not always deserved. Many varieties of algae are beneficial to lakes, providing the basis of the food chain that supports the entire ecosystem. Other types, like cyanobacteria, produce toxins that are harmful to humans and can even cause death to animals that consume it. Large blooms, even non-toxic ones, affect ecosystem health.
Too much phosphorus, an essential element for plant growth, is the usual culprit in triggering algal blooms in lakes. It washes into lakes from agricultural runoff, sewage treatment plants, lawn fertilizer, water treatment plants, and septic systems. At the right water temperature, the more phosphorus there is in the water, the more algal growth you get.
Lake Erie suffered from toxic algae blooms in the 1970s, but with a major effort to reduce phosphorus loading, the blooms disappeared for nearly two decades. By the mid 1990s, conditions began to deteriorate again. When I sailed across the lake in late summer 2004, an algae bloom stretched from the Erie Islands to the western shore.
For more information, contact Elizabeth.Turner@noaa.gov.