Dead Zone

Suffocating waters

Coastal animals around the world are spending more time in or around waters with too little oxygen
 By Cecile LeBlanc

 March 29, 2012

 http://www.sciencenewsforkids.org/2012/03/suffocating-waters/
What is a death zone? What do they do and how are they caused? Since the human race existed air pollution just as much as water pollution has been happening. What is the longest you can hol your breath, probably from about 15seconds- likely less than 1 minute, and now imagine being stuck at the bottom of the sea, in the so called death zones and not being able to get out, more specifically swimm away from. Fish and crabs are just some of the examples of the trapped innocent sea inhabitants, the reson why these deaths zones are called death zones is due to the lack of oxygen.
"Since 1994, he and the World Resources Institute in Washington,D.C., have identified and mapped 479 dead zones around the world. That’s more than nine times as many as scientists knew about 50 years ago." - From Suffocating Water
The nutrients released into the water take too much oxygen from the fish is suggested, these would for example come from big rivers which come from smaller tributaries picking washing through farms and dirt, and all of this is originated due to rainfall.
"Phytoplankton are tiny one-celled plants and plant-like organisms such as algae. They float in the water. Individual phytoplankton are too small to see without a microscope. But they can grow by the millions to form “blooms” in the ocean that are visible from space."- From article Suffocating Water.
These are most likely to start death zones.Zooplanktons graze on the phytoplankton keeping the number down, however if too much of it is made the planktons won't be able to keep up.
 
"As phytoplankton die, they fall to the ocean floor. So does zooplankton poop. Bacteria — small, single-celled organisms — feed on both. To break down these wastes, the growing populations of bacteria will need oxygen ."
This means that since they need all the oxygen they take it away from the other sea animals.
Since the bacteria needs the oxygen, new oxygen will arrive as waves and ocean currents bring the new water, they will bring oxygen because waves also grab oxygen from the atmosphere. When this ocean mixing stops and no more oxygen is brought in, death zones will develop. When freshwater is dumped into salty sea water it is heated by teh sun and stays atop due to its light weight, when no storm or stong winds arrive to mix the water up it will stay divided into freshwater and salty water which will limit the oxygen level,Hypoxia is what scientists call the state of having low oxygen

Jellyfish and fast swimming fish are able to escape this torture however the snails and animals that have created a firm home will slowly die, still these dead zperiods last for only about a few weeks or months until the ocean mixing hapen again, one of the best known places for Hypoxia would be at the Gulf of Mexico.
Surprisingly not every death zones are caused by humans, they are caused by winds that push the water away from the shores and bring cold water to the shores where oxygen can drop to 0. It is predicted that natural death zones will continue, "One theory as to why: Climate change is producing warmer layers of upper water that trap colder water below. These layers reduce ocean water mixing."- From article Suffocating Water
Scientists are trying to find a way to reduce the amount of nutriens entering the waters. Since the 1980s people have been careful to decreasing the amout of nutries entering the bays. Diaz, one of the scientists says death zones don't have to be permanent, we just have to watch we are doing and how we could chage it. Since then 55 dead zones have started improving.

I choose to read this article because I wanted to read about something I had not yet read about. I found it very interesting because it is an issue all around the world, I learned that waves absorb oxygen just as much as the nutriens do. I would recommend anyone to read this because it is educative and has a lot of new information.