Background: Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. The nitrogen is a fertilizer in the water bodies. Since there is a lot of nitrogen it causes algae to grow out of control. Figure below shows a pond covered with algae. Algae may use up so much oxygen in the water that nothing else can grow. Soon, even the algae die out. Decomposers break down the dead tissue and use up all the oxygen in the water. This creates a dead zone. A dead zone is an area in a body of water where nothing grows because there is too little oxygen. There is a large dead zone in the Gulf of Mexico. You can see it Figure below .

Situation: Mark's grandparents owned some land in the country and he remembered fishing there when he was young. Mark decided to go visit the place and do some fishing. He was disappointed when he got there and saw the pond covered in algae. Since he had come all this way he decided to try fishing anyway but didn't catch any fish all day.

Question: what caused the algae to grow too much nitrogen or too much oxygen?

Situation: Mark's grandparents owned some land in the country and he remembered fishing there when he was young. Mark decided to go visit the place and do some fishing. He was disappointed when he got there and saw the pond covered in algae and there were very few fish. Since he had come all this way he decided to try fishing anyway but didn't catch any fish all day.

Question: What was killing the fish?

Situation: Mark's grandparents owned some land in the country and he remembered fishing there when he was young. Mark decided to go visit the place and do some fishing. He was disappointed when he got there and saw the pond covered in algae and there were very few fish. Since he had come all this way he decided to try fishing anyway but didn't catch any fish all day.

Question: If Mark came back next year would there be more or less fish?

Situation: Mark's grandparents owned some land in the country and he remembered fishing there when he was young. Mark decided to go visit the place and do some fishing. He was disappointed when he got there and saw the pond covered in algae and there were very few fish. Since he had come all this way he decided to try fishing anyway but didn't catch any fish all day.

Question: Is there too much nitrogen or to much oxygen in the water?

Situation: Mark's grandparents owned some land in the country and he remembered fishing there when he was young. Mark decided to go visit the place and do some fishing. He was disappointed when he got there and saw the pond covered in algae and there were very few fish. Since he had come all this way he decided to try fishing anyway but didn't catch any fish all day.

Question: Will the algea keep growing or eventually die?

Situation: Mark's grandparents owned some land in the country and he remembered fishing there when he was young. Mark decided to go visit the place and do some fishing. He was disappointed when he got there and saw the pond covered in algae and there were very few fish. Since he had come all this way he decided to try fishing anyway but didn't catch any fish all day.

Question: If the algae dies will the oxygen increase or decrease?

Situation: As mark walked along the field he saw a small pond and walked over to it.  As Mark looked around at the wide open farm land he wondered why none fished there. Once he was closer noticed that the pond was completely covered with algae.

Question: Is there too much oxygen or nitrogen in the water?

Situation: As mark walked along the field he saw a small pond and walked over to it.  As Mark looked around at the wide open farm land he wondered why none fished there. Once he was closer noticed that the pond was completely covered with algae.

Question: Is the algea consuming the oxygen or carbondioxide?

Situation: As mark walked along the field he saw a small pond and walked over to it.  As Mark looked around at the wide open farm land he wondered why none fished there. Once he was closer noticed that the pond was completely covered with algae.

Question: will decomposser use up the oxygen or carbondioxide?

Situation: As mark walked along the field he saw a small pond and walked over to it.  As Mark looked around at the wide open farm land he wondered why none fished there. Once he was closer noticed that the pond was completely covered with algae.

Question: Does a lot of algea benefit or harm fish?

Situation: As mark walked along the field he saw a small pond and walked over to it.  As Mark looked around at the wide open farm land he wondered why none fished there. Once he was closer noticed that the pond was completely covered with algae.

Question: Is the water habitable or uninhabitable?

Situation: Mark had been fishing all morning and only caught one fish. He was disappointed because he remembers catching a lot of fish here as a child. There was a lot more algae than back then but other wise the area looked pretty much the same, dotted with lots of small farms.

Question: Was there more or less nitrogen in the water than when Mark was a child.

Situation: Mark had been fishing all morning and only caught one fish. He was disappointed because he remembers catching a lot of fish here as a child. There was a lot more algae than back then but other wise the area looked pretty much the same, dotted with lots of small farms.

Question: Was there more or less oxygen in the water than when Mark was a child.

Situation: Mark had been fishing all morning and only caught one fish. He was disappointed because he remembers catching a lot of fish here as a child. There was a lot more algae than back then but other wise the area looked pretty much the same, dotted with lots of small farms.

Question: Is the pond able to support more or less fish than in the past?

Situation: Mark had been fishing all morning and only caught one fish. He was disappointed because he remembers catching a lot of fish here as a child. There was a lot more algae than back then but other wise the area looked pretty much the same, dotted with lots of small farms.

Question: If the algea dies will the oxygen level increase or decrease?

Situation: Mark had been fishing all morning and only caught one fish. He was disappointed because he remembers catching a lot of fish here as a child. There was a lot more algae than back then but other wise the area looked pretty much the same, dotted with lots of small farms.

Question: Is the pond able to support more or less algae than in the past?