Do you think is really color of sea is blue. No its red if you see deep inside the sea the color of sea become red because we mankind made the color red of sea by killing of whales, sharks turtles. For our needs we makes worst condition for them  by throwing chemicals in sea and waste such as plastic bags, bottles. and killing them for such thinks like liver oil, skin and other things

Oil, which is also released from cruise ships, is a highly toxic substance that does tremendous damage to marine life.

for example, they eat plastic as  mistaken for food . The plastic fills their stomachs and causes difficulty with digestion and loss of appetite. Since it provides no nourishment, plastic debris can lead to starvation.

Due change In climate condition Acid rain causes a cascade of effects that harm or kill individual fish, reduce fish population numbers.

At last final we have to do something to make really  blue color of ocean means making good condition for water animals because their helpful for our ecosystem.