Ocean and fishery pollution

Introduction

History

General Information

The Chesapeake Bay watershed is 64,000 square miles and has 11,600 miles of tidal shoreline, including tidal wetlands and islands. The watershed encompasses parts of six states. Approximately 17 million people live in the watershed; about 10 million people live along its shores or near them.

Formed about 12,000 years ago as glaciers melted and flooded the Susquehanna River valley, the Chesapeake Bay is North America's largest estuary and the world's third largest.

Chesapeake Bay is approximately 200 miles long and runs north-south from the mouth of the Susquehanna River to the Atlantic Ocean. Chesapeake Bay's headwaters begin at Cooperstown, N.Y., home to the Baseball Hall of Fame.

More than 500 million pounds of seafood is harvested from the Bay every year. The Bay supports 3,600 species of plant and animal life, including more than 300 fish species and 2,700 plant types.

Algal Blooms

What is Eutrophication?

“Eutrophication is the enrichment of an ecosystem with chemical nutrients, typically compounds containing nitrogen, phosphorus, or both.” <ref>“Eutrophication”. Science Daily. 1995-2009 http://www.sciencedaily.com/articles/e/eutrophication.htm</ref> Phosphorus and nitrogen are limiting factors in natural marine and aquatic ecosystems. When quantities of these elements are released into aquatic ecosystems, algal blooms often form in response. Although eutrophication sometimes occurs naturally in marine ecosystems, many problems with eutrophication along coastlines and within smaller bodies of water like bays, lakes and rivers have been attributed human activities.

What are Algal Blooms?

Algal blooms are the “rapid excessive growth of algae, generally caused by high nutrient levels and favorable conditions. [They can] result in deoxygenation of the water mass when the algae die, leading to the death of aquatic flora and fauna” often known as creating hypoxic zones. Algal blooms can occur in both saltwater and freshwater environments although they may be more prevalent in salt water ecosystems. Because of the variety species of algae that live in these two distinct environments, algal blooms vary in color ranging from green to a yellow-brown to a red (which is more commonly known as a red tide).

How do Algal Blooms affect the Ecosystems of the Chesapeake Bay?

For the Chesapeake Bay, many of the sources of nutrient pollution come from: farm fertilizer runoff (both manure and chemical fertilizer), farm pesticide runoff, and air pollution. “Air pollution from vehicles, industries, gas-powered lawn tools and other emitting sources contribute nearly one-third of the total nitrogen load to the Chesapeake's waterways.” In 2008 alone the Chesapeake Bay absorbed 13.8 million pounds of phosphorus and 291 million pounds of nitrogen. 38% of the total nitrogen content in the Chesapeake Bay comes from agricultural practices while 45% of the total phosphorus content in the Chesapeake Bay comes from agricultural origins. Algal blooms triggered by these pollutants create problems in the Chesapeake Bay in that they block the sunlight from reaching underwater grasses which provide food for birds and shelter for fish and crabs. Algal blooms also absorb the oxygen in the water, thus creating hypoxic zones where no species can effectively live and degrading the biodiversity of the ecosystem.