This is basically the science project they are doing for the Environmental Studies class for those who are curious. 

http://www.ehow.com/about_6134291_sea-water-analysis.html

Their project is to test the quality of the water around Mako Island to write a report on their findings, and make a presentation, give it in front of the rest of the class; explain what people can do to keep the water clean and animal, plant life healthy. Don't worry, we are not going to write out the report/presentation. We can gloss over that part since I know you do not want to do school work for real. 

Haha The school requires they take ES because the town is really into keeping their home clean and teaching their children how to continue to do so. Okay so the islanders are tree huggers.