Question

Complete this sentence. Excess ____________ from human activities can cause harmful algal blooms (HABs), such as red tide, that produce toxic effects on aquatic species, marine mammals, and birds, as well as on the humans who eat them.
Nitrogen
Carbon
Salt
Heat

Answer 1

Answer:  Nitrogen

Explanation:

Harmful algal blooms can occur in lakes, reservoirs, rivers, ponds, bays and coastal waters, and the toxins they produce can be harmful to human health and aquatic life. Harmful algal blooms are mainly the result of a type of algae called cyanobacteria, also known as blue-green algae.

Answer 2

The answer is nitrogen, nitrogen helps algae grow and when it grows in excess it takes away the dissolved oxygen from the water which kills off fish, which puts more nitrogen in the water making algae grow even more until it snowballs and destroys the aforementioned ecosystem.