News and views, and history and humor, about the lake I love.

"I can hear my granddad's stories of the storms out on Lake Erie, where vessels and cargos and fortunes, and sailors' lives were lost." ~ James Taylor, Millworker

Monday, August 8, 2011

What's It All About, Algae? Meet the Dead Zone!

Algae bloom is represented by green color seen in the western basin.  European Space Agency/NOAA Photo
As reported in Sunday's Toledo Blade, a huge bloom of potentially toxic microcystis algae, which has reared its ugly head almost annually since 1995 after more than a 20-year absence, has been visible from space since at least July 22. European Space Agency satellite photos (one example shown above) show it fanning out toward the Lake Erie islands.

Although the lakes always have small, natural concentrations of algae, heavy spring rain and near-record phosphorus runoff from farms and sewage networks, combined with dry, intense heat and stagnant air of recent weeks, are the likely driving forces behind the bloom.

A Lake Erie Harmful Algal Bloom Bulletin issued by NOAA on July 28 said the microcystis concentration in the algae is 500 times greater than the World Health Organization’s standard (20 micrograms per liter) for recreational water.
Not all microcystis contains the deadly toxin microcystin. It is not known how much, if any, of the current bloom has that toxin. If it does, the potential health effects are serious.

Algae choked beach on Catawba Island
But problems associated with phosphorus runoff are not confined to Lake Erie's Western Basin. Stand by for The Dead Zone. No, I'm not referring to the Dead Zone of the Stephen King novel, nor do I mean the movie or TV series of the same name. No I'm referring to the dead zone in Lake Erie.

In recent decades, the bottom waters in the Central Basin of Lake Erie have become anoxic in the late summer. Anoxic means without oxygen. Aquatic creatures, including fish and bottom-dwelling animals, need oxygen in the water to live or they suffocate. The fish may be able to swim to better waters, but most of the other animals cannot. Commercial fishermen of the Central Basin are all too familiar with the dead zone.

The reasons for this annual dead zone were, at first, unclear. So, in June 2002, the U.S. Environmental Protection Agency in cooperation with many universities and other agencies in the United States and Canada, began an intensive special study to determine the cause of the oxygen depletion in Central Lake Erie.
The study concluded that while the unique configuration of Lake Erie's Central Basin is largely responsible for the problem, too many nutrients, especially phosphorus, make the problem much worse. Most of the excess phosphorus comes from human activities, including sewage treatment plants and agriculture. This animation gives a simplified explanation of how oxygen depletion develops:

video

The EPA monitors oxygen depletion levels in Lake Erie by taking samplings and doing surveys, primarily from its vessel, Lake Guardian, the only self-contained, non-polluting research vessel on the Great Lakes.

The problems of algae blooms in western Lake Erie and the dead zone in the central basin of the lake are going to be with us for the foreseeable future. These problems are going to require solutions - and vigilance. At a time when funding is becoming scarcer by the year and some politicians suggest killing or at least gutting the EPA and other environmental agencies, the answers are not going to be easy to come by.

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