Algal Blooms May Have Threatened These Ancient Cities

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Since the 1990s, Lake Erie has been swamped with blooms that turn its waters a bright green color. The drinking water of millions of people was threatened by the plague in 2011. Similar blooms will become more frequent in the future according to experts.

A body of water can grow out of control if there is excess nitrogen and phosphorus in it. The dead zones created by the algal blooms are caused by greedily consuming the environment and blocking sunlight from reaching underwater plants. Some harmful algal blooms are produced by a type of algae called cyanobacteria that produce harmful toxins.

Lake Erie's algal blooms flare up when rainfall washes the nutrients left behind by human activity into connecting streams. Climate change makes storms more common in the spring and summer, which is why freshwater ecosystems around the world share a similar risk.