Water Quality for Healthy Beaches and Shellfish Beds

Dead Zone
The Gulf of Mexico contains an area simply referred to as the Dead Zone. This area is hypoxic; there is not enough oxygen in the water to sustain life especially bottom-dwelling animals like clams, lobsters and oysters. It is located off the Louisiana and Texas coasts and is approximately the size of New Jersey. The Dead Zone forms each spring when spring rains cause runoffs into the Mississippi River containing chemical nutrients primarily from fertilizers. It breaks-up or disappears with the tropical storms and hurricanes that usually occur during the summer and fall.

Pathogens
A pathogen is a microorganism such as bacteria, viruses, protozoans, algae and fungi that are capable of causing diseases.  These organisms are naturally occurring and can be found in the Gulf of Mexico.  One of the pathogens that can be found in the Gulf of Mexico is a bacterium called Vibrio vulnificus. Each year there are people who are affected by Vibrio by either eating raw or undercooked shellfish or by entering the body through a cut or wound. Symptoms include skin ulcerations, fever, vomiting, diarrhea, abdominal pain, and can lead to death. Vibrio is more prevalent during summer months when the water is warmer.
  
Harmful Algal Blooms
Algae are microscopic plants that live in fresh and salt water. An algal bloom occurs when conditions are right for the algae to grow faster than other types of algae. A harmful algal bloom (HAB) occurs when specific species of algae create an algal bloom that produces toxins that are harmful to plants and animals. An example of this is Red Tide, which gets its name form the red discoloration of the water due to the large number of algal cells.  
 
HABS are caused by an increase in nutrients such as nitrogen and phosphorous in the water. These are typically found in fertilizers used on lawns and eventually wind up in the rivers and stream that drain into the Gulf of Mexico. In addition, they are created when there is a change in their environment such as water quality, temperature, nutrients, sunlight and other factors. 

These toxins kill fish by paralyzing their gills and making it impossible to breathe. It also accumulates in oysters, clams and scallops. If someone eats shellfish that contain these toxins they may experience neurologic and gastrointestinal symptoms called neurotoxic shellfish poisoning. The toxins can also become air borne and as a result cause eye, nose and throat irritation along with more severe issues like asthma attacks.     

Mercury
Mercury is a heavy metal which can be found naturally in rocks and soil and is discharged by some industries, wastewater treatment facilities and power plants. Once it enters the water system it becomes methylmercury which is highly toxic and can build up in fish. At high concentrations it is considered a health risk.  Federal and state health departments provide fish-consumption advisories to limit the amount of mercury consumed by the general public and specifically pregnant women, nursing mothers and children.