Near-Record Sea Life ‘Dead Zone’ Predicted in Gulf of Mexico

 

Scientists in the United States have predicted a near-record area of oxygen-starved water to appear in the Gulf¹ of Mexico this summer.

The National Oceanic and Atmospheric² Administration, or NOAA, describes the area as a “dead zone” containing little to no oxygen. Such an area can be deadly to fish and other sea life.

NOAA scientists reported the 2019 dead zone area could spread to more than 20,000 square kilometers. The Gulf of Mexico sits along the southern coast of the United States. The dead zone covers an area off the coasts of Louisiana and Texas.

The 2019 prediction is near the record 22,700 square kilometers set in 2017. It is also much larger than the five-year average of 14,944 square kilometers for the Gulf of Mexico, NOAA noted³.

Dead zones are formed in other areas of the U.S. and the world. But the one that forms in the Gulf of Mexico is the second largest on Earth, NOAA says. The largest exists in the Baltic Sea.

Many things can play a part in forming dead zones, also called hypoxic zones. Physical, chemical and biological causes can be involved. However, NOAA reports that the biggest cause is nutrient⁴ pollution from human activities.

Nutrients⁵, including chemical fertilizers from farms, can pollute water that runs off land into rivers and coastal⁶ areas that feed into the Gulf of Mexico. The nutrients can cause an explosion in the population of algae⁷, which then dies, sinks and breaks down in the water. This process takes large amounts of oxygen, greatly reducing the supply available to healthy sea life.

Nancy Rabalais is an ocean ecologist with Louisiana State University. She told National Geographic⁸ magazine that a lot of the sea creatures begin to leave when the oxygen supply drops too low.

“When the oxygen is below two parts per million, any shrimp⁹, crabs¹⁰, and fish that can swim away, will swim away,” Rabalais said. Sea life that has settled on the bottom and cannot swim away will be nearly completely destroyed, she added.

NOAA said the larger dead zone this year was caused by heavy spring rainfall in parts of the Mississippi River Basin. The Mississippi River flows into the Gulf.

Scientists had predicted last month that widespread flooding would make a large dead zone likely this year. Weather experts have warned that more extreme rainfall is expected to continue if overall temperatures keep rising.

This could worsen the problems with nutrient runoff, especially from agriculture-related chemicals. “The best way to solve the issue is to limit the nutrients at their source,” says Rabalais. “Once they're in the river, there's no good way to reduce them.”

Don Scavia is a former ecologist who studied ocean conservation issues at the University of Michigan. He agrees that dead zones are likely to keep growing if steps are not taken to reduce the nutrient flow. “We will never reach the dead zone reduction target [of 4,920 square kilometers] until more serious actions are taken to reduce the loss of Midwest fertilizers into the Mississippi River system,” Scavia said in a statement.

I’m Bryan Lynn.

Words in This Story

algae – n. simple plants that have no leaves or stems¹¹ and that grow in or near water

source – n. where something comes from

1 gulf   

n.海湾；深渊，鸿沟；分歧，隔阂

参考例句：

• The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
• There is a gulf between the two cities.这两座城市间有个海湾。

2 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

3 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

4 nutrient   

adj.营养的，滋养的；n.营养物，营养品

参考例句：

• Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
• The roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。

5 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

6 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

7 algae   

n.水藻，海藻

参考例句：

• Most algae live in water.多数藻类生长在水中。
• Algae grow and spread quickly in the lake.湖中水藻滋蔓。

8 geographic   

adj.地理学的，地理的

参考例句：

• The city's success owes much to its geographic position. 这座城市的成功很大程度上归功于它的地理位置。 来自《简明英汉词典》
• Environmental problems pay no heed to these geographic lines. 环境问题并不理会这些地理界限。 来自英汉非文学 - 环境法 - 环境法

9 shrimp   

n.虾，小虾；矮小的人

参考例句：

• When the shrimp farm is built it will block the stream.一旦养虾场建起来，将会截断这条河流。
• When it comes to seafood,I like shrimp the best.说到海鲜，我最喜欢虾。

10 crabs   

n.蟹( crab的名词复数 )；阴虱寄生病；蟹肉v.捕蟹( crab的第三人称单数 )

参考例句：

• As we walked along the seashore we saw lots of tiny crabs. 我们在海岸上散步时看到很多小蟹。 来自《简明英汉词典》
• The fish and crabs scavenge for decaying tissue. 鱼和蟹搜寻腐烂的组织为食。 来自《简明英汉词典》

11 stems   

n.（花草的）茎( stem的名词复数 )；词干；（高脚酒杯的）脚；烟斗柄v.遏制[阻止]（液体的流动等）( stem的第三人称单数 )；封堵；遏止

参考例句：

• The present wave of strikes stems from discontent among the lower-paid. 当前的罢工浪潮起因于低工资雇员们的不满情绪。 来自《简明英汉词典》
• Her interest in flowers stems from her childhood in the country. 她对花卉的兴趣产生于她在乡下度过的童年时代。 来自《简明英汉词典》