Convection occurs in earths (asthenosphere/lithosphere) where rocks are hot enough to (be ridged/bend easily) please help with both :)

The correct answer would be lost aquila

Physical systems is the answer

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.