Mitigation Strategies

Mitigation Strategies and Solutions

SCI/275

October 2, 2011

Mitigation Strategies and Solutions

The largest oxygen-depleted waters in the United States, and the second largest in the world, is the northern Gulf of Mexico. Analyses of sedimentary records suggest that hypoxia in this area has intensified since the 1950s, and that hypoxia began in the 1970s (JUSTIĆ, BIERMAN, SCAVIA, & HETLAND, 2007). The extent of the hypoxic zone, has been monitored in mid-summer since 1985, and has increased from 6,900 km2 in 1985-1992 to 15,733 km2 in 1993-2009, with a peak of 22,000 km2 in 2002 (Rabalais, Turner, Justić, Dortch, & Wiseman, 1999)[3, 4]. In the past 5 years, the hypoxic zone has averaged 15,620 km2. The expansion of the Gulf’s hypoxic zone in recent decades has been related to increases in nitrate loading, and a growing scientific conclusion (Rabalais, Turner, Sen Gupta, Boesch, Chapman, & Murrell, 2007)supports the hypoxia in this region is linked to

eutrophication.

Hypoxia is an environmental phenomenon where the concentration of dissolved oxygen in the water column decreases to a level that can no longer support living aquatic organisms (What is hypoxia?, 2011). Hypoxia occurs naturally in many of the world’s marine environments and have existed throughout time. There are several different causes of hypoxia two of the biggest are eutrophication and  stratification. Eutrophication is a syndrome of ecosystem responses to human activities that fertilize water bodies with nitrogen and phosphorus, often leading to changes in animal and plant population and degradation of water and habitat quality (Cloern, 2007). Stratification occurs when environmental factor such as temperature and salinity are not uniform from top to bottom and causes the bottom layer to be deprived of oxygen (What is hypoxia?, 2011).

The main cause of the eutrophication in the Gulf is runoff from the Mississippi River. To better understand what happens in...