Toxoplasma is a parasite that lives in what?

The parasite can live in the environment for many months and contaminate soil, water, fruits and vegetables, sandboxes, grass where animals graze for food, litter boxes, or any place where an infected cat may have defecated. Toxoplasmosis is an infection caused by a microscopic parasite called Toxoplasma gondii.

The population decreases.

Explanation:

Flood has a very adverse effect on the population of both adult and juvenile trout that lives in the streams because the trouts which has less than one year age are not good swimmers so they can't with stand with the fast flow of water during flood condition so the population of both adult and juvenile trout decreases in that stream in which flood occurs.