A Sea Change was a great documentary in terms of presenting the dangers of ocean acidification to a general audience. Because the writers stayed away from the complicated science of ocean acidification, viewers are able to see the negative effects of it without being confused by the specifics. However, by simplifying everything the writers ended up with logical fallacies throughout the film. Whether on purpose or not, using these fallacies makes it difficult for viewers to have a thorough understanding of the situation.

One fallacy used extensively attacks both the emotion and logic of viewers. Pteropods are talked about frequently, and Sven makes sure to point out how beautiful and majestic they are. By showing how these small, fragile creatures are so negatively affected by ocean acidification, the writers take advantage of peoples’ soft spot for helpless animals. After getting to viewers’ emotions, the film continues to talk about pteropods and how they are a major part of salmon’s diet. A major chain reaction affecting salmon is talked about, going after viewers again because salmon are a much larger part of our lives than pteropods. However, the film fails to discuss the studies that show how salmon have adapted to eating other food sources in places where pteropod populations are diminished. By leaving these studies out, the film makes the loss of pteropods seem more destructive to our own lives.

Another thing the film oversimplifies multiple times is how much it would cost to fix the CO₂ problem in America. Throughout the documentary, Sven is very interested in why nothing significant has been done to lessen our carbon emissions. According to multiple scientists, it would only take 2% of the GDP to solve the CO₂ problems we are currently facing. When thrown out as a small percentage, this task seems much more attainable. However, what some people might not know is that the United State’s GDP for 2010 was roughly 14.5 trillion dollars. Simple math tells us that two percent of 14.5 trillion is approximately 290 billion dollars. With the economy and national debt the way it is, coming up with that much money in a responsible way would be very difficult to do. The scientists, and in turn the writers, would like people to believe it is much easier to solve the emissions problem than it actually is.

Overall, A Sea Change did a great job of outlining the present and potential problems caused by ocean acidification. The writers were definitely trying to present the movie to the average viewer, and by doing this used rhetorical fallacies quite often. Whether they did this on purpose is debatable, but considering the tone of the movie it is hard to believe it occurred accidentally. It is an informative movie for anyone interested in the ocean acidification topic, but some discretion is needed when accepting everything that is said.

The Effects of Ocean Acidification on Pteropods

While there is a wide range of negative effects expected in the future due to ocean acidification, there are some cases that have much more potential fallout than others. One of these cases is plankton. Plankton plays a crucial role in food webs, and therefore any damage done to plankton species will have a ripple effect that spreads throughout the ecosystem. A prime example of plankton that is at risk due to ocean acidification is the pteropod. While much uncertainty remains regarding the severity of future damage to pteropods, the prospect of a losing a key part of the food web is frightening. The ocean’s changing chemistry will inhibit pteropods’ ability to grow and survive, subsequently creating imbalance (decreasing biodiversity) among the various plankton species and creating problems further up the food chain.

Pteropods are snail-like plankton that float through ocean waters consuming smaller plankton. They, like many other marine organisms, rely on the process of calcification to grow their shells (which consist of aragonite and calcium carbonate). Thus, the saturation of carbonate ions in the water is vital to their survival. The increased amount of carbon dioxide in ocean water has shifted the chemical equilibrium such that there is a decreasing concentration of carbonate ions. Studies have shown that pteropods tend to have a slower rate of calcification when placed in water with a high concentration of carbon dioxide. To make matters worse, the decrease in carbonate ions also pushes the saturation horizon closer to the surface of the ocean, reducing the amount of water that pteropods are able to inhabit (calcium carbonite and aragonite will dissolve if placed below the saturation horizon). In addition to problems with building shells, pteropods face a few other potential roadblocks due to ocean acidification. First, they might have to adjust to a new diet; phytoplankton, pteropods’ main food source, will also be negatively affected by ocean acidification, and therefore pteropods could potentially have to deal with either a lack of phytoplankton or a change in what types of phytoplankton they are limited to consuming. Second, they, like many other marine organisms, will have to work harder to regulate bodily processes. The changes in pH of ocean water make it more difficult for pteropods to maintain the proper internal pH; acclimating to the new environment requires energy (which could be put towards other important processes). The combination of all of these roadblocks puts pteropods at risk.

Unfortunately, the risk extends beyond just pteropods. Ocean acidification ultimately threatens the balance of existing plankton species. Studies have shown that some species of plankton are less susceptible to changing ocean chemistry than others; this means that there will be winners and losers amongst plankton species over the next series of decades, resulting in a decrease in biodiversity. This, in turn, will send waves up the food chain. For example, pteropods make up a major part of the diets of certain types of salmon in the arctic (over 60% in some cases), so a decrease in the pteropod population could potentially do serious damage those salmon populations. Possibilities such as this are frightening, especially when considering that it is just one example of what ocean acidification is capable of changing; the situation that pteropods face is a mere microcosm of what could happen to the ocean’s ecosystem as a whole.

Sources:

Websites:

http://www.up.ethz.ch/education/term_paper/blank_termpaper_fs07_final.pdf

http://en.wikipedia.org/wiki/Zooplankton

http://en.wikipedia.org/wiki/Pteropoda

Book:

National Research Council. Ocean acidification: a national strategy to meet the challenges of a changing ocean. Washington, D.C: National Academies Press, 2010. Print.