Algal blooms happen when too many chemicals containing nitrogen are washed into freshwater areas. Nitrogen is an important chemical for algae growth, but when algae becomes too concentrated, it can reduce oxygen levels for the other organisms. What are the effects of increased algal blooms on ecosystems?

increased algal blooms on an ecosystem, causes a NEGATIVE effect to the organisms of the system.

Explanation:

Algal blooms occurs when algae, a microscopic algae- like photosynthetic organism, over grows in fresh, salt or brackish waters. The over growth of these algae can occur due to climatic changes, naturally or as a result of human activities.

When it over grows in an area, it can cause the following NEGATIVE effects to the ecosystem which includes:

- it can reduce the oxygen content of the water body thereby harming the fish and other aquatic organisms.

- some of the algae releases toxins into the water body making it unfit for a source of water for drinking,

- the toxins can also work their way through the food web impacting mammals, birds and other wildlife that feeds on glasses shellfish or fish tinted with the toxins. I hope this helps, thanks!

the answer is c) an oak tree