Question

When fertilizers run off farmland into streams and ponds, the nitrogen content of the water increases. this can lead to rapid growth of algae in a process called eutrophication. how can this process affect other organisms in the water? question 1 options: oxygen is used up as algae is decomposed, reducing the amount available to other organisms. the water becomes better able to support aerobic organisms. the algae provide food for fishes and other organisms, leading to decreased algae populations. the extra nitrogen provides additional food for the other organisms, increasing their population?

Answer 1

The correct answer is: oxygen is used up as algae is decomposed, reducing the amount available to other organisms. Algae require nutrients to grow, and it is well known that in many rivers, algal growth is limited by one particular nutrient, most often phosphates or nitrates. This means, as soon as there is a sizable input of nutrients into a river or lake, the algae population will grow exponentially. This dramatically changes the trophic status of a river or lake. However, the algal population will eventually exhaust the supply of nutrients, and the vast biomass of algae that grew over a short period of time will all die at the same time due to lack of nutrients. As you know, rotting organic matter uses up oxygen. This results in an anoxic aquatic environment that can kill all the other organisms living in that environment.