Potter's lake used to be the nicest lake in the area. but these days the water is green with algae, and the lake is choked with weeds all summer long. as a result, people can no longer swim in it. experts have determined the cause of the problem. fertilizers from yards and farms have been running into the lake. they cause algae and weeds to grow out of control. they also kill birds and fish.

Oceans produce approximately 80 percent of the oxygen our planet needs to support animal life. pollution that reaches the ocean through dumping, oil leaks, runoff, and other processes interferes with that oxygen production and poses a real threat to the oxygen content in our atmosphere. if the oxygen content decreases, it is likely that carbon dioxide will increase. this could have dramatic consequences for life as we know it. which does this passage indicate causes a decrease of oxygen in the atmosphere?