Background: Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. Nitrogen is a fertilizer in the water. Since there is a lot of nitrogen, it causes algae to grow out of control. Pictured below is a pond covered with algae ( Figure below ). Algae use up carbon dioxide in the water. After the algae die, decomposers break down the dead tissue. The decomposers 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 ( Figure below ). The U.S. states outlined on the map have rivers that drain into the Gulf of Mexico. The rivers drain vast agricultural lands. The water carries fertilizer from these areas into the Gulf.

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: Was the oxygen level high or low in the pond?

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: Was the nitrogen level high or low in the pond?

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: What is growing out of control?

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: What is using up all the oxygen?

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: Will the oxygen increase or decrease when the algae dies?

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: What are the fish have too much or not enough oxygen?

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: Will decomposers use oxygen or make oxygen?

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: Will the remaining fish survive or die off

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: Will the pond recover or become a dead zone?

Situation: Mark bought a piece of land that had once been part of a farm. He knew there was a small pond on the land and hoped he could fish there. But when he went to see it he was surprised to see it was completely covered in algae. There were few if any fish in the pond. A neighbor told him that the previous owner had tried stocking fish but they had died.

Question: Will killing the algae hurt or help?

Situation: Josh had always enjoyed fishing in the pond on his property. Recently someone bought a couple of acres of land near him and started farming it. The land had not been farmed in a long time and one of the first things his new neighbor did was spread fertilizer. Josh new noticed that there was a lot more algae growing in his pond.

Question: Will oxygen increase or decrease in the pond?

Situation: Josh had always enjoyed fishing in the pond on his property. Recently someone bought a couple of acres of land near him and started farming it. The land had not been farmed in a long time and one of the first things his new neighbor did was spread fertilizer. Josh new noticed that there was a lot more algae growing in his pond.

Question: Have nitrogen levels increased or decreased in the pond?

Situation: Josh had always enjoyed fishing in the pond on his property. Recently someone bought a couple of acres of land near him and started farming it. The land had not been farmed in a long time and one of the first things his new neighbor did was spread fertilizer. Josh new noticed that there was a lot more algae growing in his pond.

Question: Does the algae use carbondioxide or oxygen?

Situation: Josh had always enjoyed fishing in the pond on his property. Recently someone bought a couple of acres of land near him and started farming it. The land had not been farmed in a long time and one of the first things his new neighbor did was spread fertilizer. Josh new noticed that there was a lot more algae growing in his pond.

Question: Will there be more or less fish in the pond in the future?

Situation: Josh had always enjoyed fishing in the pond on his property. Recently someone bought a couple of acres of land near him and started farming it. The land had not been farmed in a long time and one of the first things his new neighbor did was spread fertilizer. Josh new noticed that there was a lot more algae growing in his pond.

Question: Where is the nitrogen likely coming from?

Situation: Josh had always enjoyed fishing in the pond on his property. Recently someone bought a couple of acres of land near him and started farming it. The land had not been farmed in a long time and one of the first things his new neighbor did was spread fertilizer. Josh new noticed that there was a lot more algae growing in his pond.

Question: What will take the oxygen from the water algae or decomposers??

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: Is the algea using all the oxygen or the carbon dioxide?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: What will decomposers eat?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: What will decomposers use up oxygen or nitrogen?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: Was the nitrogon level low or high before the rain?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: Was the nitrogon level low or high after the rain?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: Will there be more or less fish as the algea spreads?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: Will there be more or less fish when the algea dies?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: What did the rain wash into the pond nitrogen or carbon?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: Is the algea beneficial or harmful?

Situation: The community park had a pond in its center. The pond had always been a popular place for fishing. Recently it had rained a lot and Mark noticed that there was a lot of algae growing on the pond.

Question: Is nitrogen beneficial or harmful to the pond?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond should mat choose for the picnic?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond would have good fishing?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond would have no or poor fishing?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond has a high nitrogen level?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond has a low nitrogen level?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond is most likely to be down strem from a farm?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond is least likely to be down strem from a farm?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond is least likely to have low oxygen levels?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond is most likely to have low oxygen levels?

Situation: Mat was planning the company picnic. He was told he could pick between two locations A and B. He knew that several people had expressed interest in fishing and both locations had ponds that had been popular fishing areas years ago. Mat decided he would go visit each pond and see we would be best. Pond A had clear water with lots of plant life. Matt noticed a turtle going into the water. Pond B was completely covered in algae and he did not see any wildlife around the pond.

Question: Which pond is most likely to have good fishing?