Humans do not eat the algae directly from the ocean, so how can we still be
affected by it?

it could affect the environment.

Explanation:

The sea life we eat could be affected which affects us humans.

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.