Answer:
<em>Organisms that are eaten by the mayfly will increase.</em>
<em>Organisms that eat mayfly will decrease at first.</em>
<em>Organisms that eat mayfly would consume more of other organisms in their diet</em>
Explanation:
her get killed or they will migrate from the stream that is polluted. The population of the organisms on which the mayfly larva fed would increase as it will have a lesser number of predators now.
On the other hand, the organisms which fed on the mayfly would decrease at first as they will have a lesser amount of food available. They might find another source of food in order to survive. 
 
        
             
        
        
        
<span>D. That they variable is staying the same.
Hope this helps (:
-Payshence xoxo</span>
        
             
        
        
        
Scientists carry out several researches to understand the cause and reason behind the natural phenomena happening around us. While carrying out an experiment, the scientist need to refer to various research papers and research articles to plan and follow the protocol of the experiment accordingly. 
Going through the background studies lead to greater insight and knowledge about the subject. It broadens our mind and way of thinking. It makes us more logical and precise towards our work.