Which of the following processes most likely played the greatest role in the formation of the famous “blue caves” in greece?

wind erosion
human intervention
water erosion
volcanic activity

The answer to the first one is barometer.

When a lake, river or other aquatic  system  becomes  eutrophic, it can have serious negative effects on other organisms like fish, birds and even people.if an algal bloom is so bad that it causes wide-spread death  in  the  water, the organisms that die will all sink to the bottom and start to decompose.