Scientists fear lower layers of the ocean willl be devoid of marine life because of the 'dead zone' (Gally/Getty)

While floodwaters continue to wreck havoc in Mississippi, US, scientists have warned of a 'dead zone' in the Gulf of Mexico as well.

A 'dead zone' refers to an area in the ocean with low oxygen levels or hypoxia which threatens the local ecology.

In the Gulf of Mexico, a half billion dollar industry is at stake as well. The Gulf of Mexico is home to a commercial fishing industry valued at more than $600m. It also hosts a recreational fishing community worth $1bn more which sees 22 million fishing trips annually.

This is a regular occurrence in the Gulf of Mexico, but this year's affected area is expected to exceed that of 2002 when more than 8,400 square miles were affected due to high levels of nitrogen in the water.

Nitrogen levels are around one third above normal levels.

A record late-winter and spring-rainfall swelled the Mississippi River to a height of almost 48 feet in Memphis, causing the flow rate of the Mississippi to almost double.

Flooded farm fields, have channeled the nitrogen from farm chemicals into the waters.

These nutrient-rich waters pouring into the Gulf encourage the growth of tiny marine phytoplankton which feed on the chemicals before dying, decaying and sinking to the bottom of the sea.

Here they are consumed by bacteria which absorb much of the oxygen in the water causing a condition known as hypoxia.

It is these lower layers of the ocean, between five and 35 metres, which scientists fear will be devoid of marine life.

Although floodwaters are expected to decrease, it may be some time before the Gulf of Mexico, its marine life and fishing communities begins to improve.

Source: Al Jazeera and agencies