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.
        
                    
             
        
        
        
QUESTION 1
Which of the following genetic techniques does NOT use labelled DNA probes?
        
             
        
        
        
The answer is TRUE because the process of a fish need to be in freshwater at its first parts of the growing process of a fish.
        
             
        
        
        
2 and 3 Becuase both undergo photosynthesis, which is only a think plants do. Hope this helps.