A dense growth of plant life in a aquatic ecosystem which many animals living there die(due to lack of enough oxygen present in water) and the ecosystem gets completely disrupted.
Eutrophication excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life.
D because kg is mass and cubic cm is volume which Density = Mass / Volume
You can use the translucent test, lipids leave a translucent trace when smouldered on paper
or you can just use sudan III solution