The Wrack

The Wrack is the Wells Reserve blog, our collective logbook on the web.

What's that Word: Eutrophication

Posted by Wells Reserve Contributor | July 13, 2006

Danger seeps from your garden.

Fertilizer causes tomatoes to ripen larger and plants to grow taller. But applying more than your plants need can have a devastating effect.

The rain washes your excess fertilizer, either manure or chemical, down the road and into the nearest water source. There, it mixes with water traveling from other gardens, farms, and power plants to create a stream of nitrogen and phosphorus. The stream pours directly into the marsh.

Algae in the marsh react to the extra nutrients almost immediately, and grow so rapidly that they create a large mass floating on the surface of the water. This prevents light from reaching the plants below. Submerged aquatic vegetation dies off and oxygen-consuming bacteria move in to feast on the dead plants. Dissolved oxygen levels plummet.

This process is known as eutrophication, when excess nutrients cause an algae bloom that leads to decreased dissolved oxygen.

Fish depend on the oxygen dissolved in the water to breathe. When oxygen levels decrease, most fish either die or leave the marsh to seek out areas where they do not face death by suffocation. At the same time, toxic algae growth explodes in an event known as red tide that forces local clam flats to shut down. Toxins from these algae are blown to land, where they irritate human respiratory problems. Local asthma attacks spike.

In the marsh itself, species diversity declines at an alarming rate. Even the birds flee. The estuary is devastated.

The cost to restore an estuary is enormous, and it comes out of your tax dollars and savings. It costs so much less, both in lives and dollars, to prevent eutrophication from getting out of control.

Help your local estuaries avoid this fate by minimizing the fertilizer you use in your garden. Take action!

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