Which independent variable affected the organism’s health positively in each of the trials? Why do you think this occurred?

Please see below  

Explanation:

The variable that had the most affect was the salinity. The sea animals have a tough time trying to survive under highly saline sea water, as this upsets their internal environment as well, in turn affecting their bodily functions and overall health too. The reason behind this was probably that they were used to an environment of high levels of salinity and low levels of light.