Agriculture and the ocean

By: Grace Helmke

The ocean does not take credit where credit is due. It sustains all life on earth. Without it, humanity would cease to exist. Oxygen would slowly dissipate, temperatures would drop to astronomically low levels, jobs would be lost, and coastal economies would be suffering.

Even so, there is complete disregard for the ocean and its inhabitants. Agriculture, amongst many other things, is one of the greatest plagues our oceans have ever seen; contributing to the complete eradication of life in many areas of our ocean. 

What are dead zones? 

Human activity has created areas in the ocean known as “dead zones,” which are regions where less oxygen is dissolved due to lack of marine habitation. Dead zones occur in areas that are unusually high in nutrients such as nitrogen and phosphorus. This dramatic increase causes large scale red tides, which are harmful algal blooms that are toxic to all forms of life. It can become deadly to fish and birds, and can cause severe illness in humans. The red tides will die off after using up all the oxygen in the area, sinking to the bottom to decompose, leaving a barren environment in its wake. 

Causes of dead zones 

While dead zones can be created naturally, man has significantly impacted their frequency and extremity. Overfishing, global warming, and urbanization can all cause dead zones, but one of the most significant causes of dead zones is the industry of agriculture.

Animal manure and commercial fertilizer runoff makes its way into waterways, and empties out into the ocean. Both manure and fertilizer contain phosphorus and nitrogen, the two chemical nutrients which, when built up, can cause algal blooms. The environmental protection agency suggests that around 335 million tons of animal waste is produced by livestock every year.

If a farm doesnt have the correct system to deal with waste, it ends up in the waterways. In 2011, The Economic Research Service, of the USDA, stated that 22 million tons of fertilizers were used in crops in the United States. According to Edf.org, about 50 percent of fertilizer is actually taken up by the crops themselves. The rest ends up in waterways. 

Dead zones around the world 

The biggest dead zone in the world is in the Arabian Sea, right between the nations of Oman and Iran. It covers almost 63,7000 square miles of the Gulf of Oman (equivalent to the size of Florida). The cause is a combination of overfishing and a buildup of phosphorus and nitrogen from the agricultural industry. 

The famed waterway, the Mississippi, is a significant carrier of nitrogen and phosphorus. Midwest farming operations have produced so much chemical population that they have created the second largest dead zone in the world. The Mississippi carries the chemicals through the nation, and empties them out into the Gulf of Mexico. Its area varies in size, but can cover up to 7,000 square miles. 

Effects 

The effects of dead zones can be incredibly detrimental to a region’s economy. Many coastal cities rely on their seafood industry, and biodiversity, to bring in tourists. In addition, many locals work in commercial fishing. If the fish disappear from the ocean, they have no job. 

What can be done to prevent dead zones? 

  1. Buying organic: Organic farms are prohibited from using fertilizer or pesticides on crops. Supporting organic methods of farming is a great way of contributing to a cleaner ocean. 
  2. Buffers: Planting trees, shrubs, and grasses would help reduce the amount of nutrients making their way into the ocean. The plants absorb nutrients, keeping it away from bodies of water.
  3. Animal waste systems: Implementing animal waste systems in farms would help to reduce the amount of phosphorus and nitrogen being released into oceans. 

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