Reports out of the Gulf of Mexico come at us every day: the status of the well head closure, wildlife death counts, weather effects. Many of these reports conflict. As we start day 100 of the BP leak, we're still not sure how much oil has actually passed from the underground reservoir into the aquatic ecosystem, or how much wildlife has been killed. The government reports one estimate; independent researchers another. And the reports now being issued on dissolved oxygen concentrations in the water in the Gulf show another series of discrepancies.
To the average person, much like the conflicting arguments on climate change, this can be very confusing and frustrating. Why aren't the scientists on both sides of the fence coming up with the same conclusions? After all, they're sampling the same waters! How is it, for example, that researchers from the University of California at Santa Barbara or University of Georgia at Athens can state with confidence that oxygen levels in parts of the Gulf have dropped 30% to 50% since the leak began, but government researchers claim the changes are minimal?
The answer lies in a combination of Research Methods and Data Interpretation. Dissolved oxygen (the oxygen aquatic animals rely on to breathe) is measured through the use of specialized equipment that can detect the concentrations in the water at parts per million. This equipment typically has a sensitive membrane that allows oxygen to pass through. Unfortunately, much like the gills on a fish, this membrane is sensitive to the clogging nature of oil. So, while independent researchers are confident that their equipment is functioning properly, doubt is still cast on the reliability of their data. To confound this, other researchers have used different methods of calculation (such as Winkler titrations) and are coming up with different results.
Complicating matters further, not all of the researchers are sampling in the same areas. Many independent researchers argue that the data suggesting low oxygen changes is coming from areas close to the well head where the population of oil-consuming organisms have not increased. (The reduction of oxygen is the result of a bloom in these populations, much like a seasonal algal bloom in a lake.)
Even if all of the data did come out similar, though, there would still be much to argue about. An event of this magnitude is, fortunately, something that we don't encounter often, which means that the long-term effects are hard to determine for certain. Scientists in the Gulf have been using modeling techniques based on knowledge from smaller spills to make educated guesses, but every ecosystem is different. The currents, weather patterns, and wildlife of the Gulf of Mexico, for example, is very different from that of Prince William Sound, Alaska.
As the clean-up efforts and monitoring continue (and they likely will for years), it's important to remind ourselves that science is not a series of facts that are determined simply, but a process of discovery that includes a significant element of human influence and input from multiple sources. Only time will tell what the realities of the situation are. In the meantime, it's important for as much reliable information to be gathered as possible to add to the repository of data.
Do you deal with research methods or data interpretation in your classroom or work? What do you think of the discrepancies scientists in the Gulf are showing? How would you explain this to a non-scientist?