Near-record 'dead zone' forecast off US Gulf coast, threatening fish

James Marshall
June 12, 2019

A near record-sized "dead zone" of oxygen-starved water could form in the Gulf of Mexico this summer, threatening its huge stocks of marine life, researchers said. The buildup happens every summer, but researchers predict this year the dead zone could be as large as 8,766 square miles - roughly the size of the Commonwealth of MA.

When this excess of nutrients-particularly nitrogen and phosphorus-enters the Gulf it fuels a rapid increase in the growth of certain types of algae, otherwise known as an algal bloom.

Scientists say that the annually recurring phenomenon is caused by excessive nutrient pollution-originating from human activity in farms and urban areas-which drain into the Mississippi River Basin and eventually get washed into the Gulf. NOAA stresses that the actual size of the dead zone could differ from their estimates due to the effects of significant climate events, such as hurricanes and tropical storms.

A task force of federal, tribal and state agencies from 12 of the 31 states that make up the Mississippi River watershed set a goal almost two decades ago of reducing the dead zone from an average of about 5,800 square miles to an average of 1,900. When this plant material decomposes in the bottom layer of the Gulf, it results in carbon dioxide, which depletes the oxygen levels in the water.

An oxygen-sapping, fish-killing swath of algae is headed to Gulf of Mexico this summer.

This year, the low-oxygen area is likely to cover about 7,800 square miles - roughly the size of Massachusetts, NOAA said.

The predictions for the size of the dead zone are based on computer models that make calculations based on typical weather conditions for the summer months.

It will be measured during an annual July cruise by Nancy Rabalais of the Louisiana Universities Marine Consortium. The record was 8,776 sq. miles set in 2017. "The unusually high Mississippi River discharge in May controls the size of this zone, which will likely be the second largest zone since systematic measurements began in 1985".

A task force of federal, tribal and state agencies from 12 of the 31 states that make up the Mississippi River watershed set a goal almost two decades ago of reducing the dead zone from an average of about 5,800 square miles to an average of 1,900.

This story clarifies that NOAA forecast is an area roughly the size of the land in MA and removes incorrect reference to the size of Turkey.

This story was reported from Los Angeles.

Other reports by Click Lancashire

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