explain why amphibians are good early warning devices for water pollution.

Because when the water gets bad they start to die. So then we know that the water is bad

If there are no living amphibians in a water source that probably means that the water is polluted. This is because they probably moved or they all died because of the pollution.

Hope this helps stay safe and have a great day! :

depression is an ongoing sadness\lack of motivation. you feel and feel like its never going to get better. you're so sad to the point you think of death.

anxiety is an ongoing feeling of paranoia\ feeling like everyone is watching you and making fun of you. you get nervous easily and feel like the room is spinning.  

yes, they cause death every year. its a long, exhausting battle. only few make it through as sad as it sounds.

explanation:

answer; /// i believe the answer is (phenylketonuria);