Marine Policy
Volume 34, Issue 3, May 2010, Pages 367-374

doi:10.1016/j.marpol.2009.08.006

How is the the world’s oceans related to economics? How can an assessment of an economy prevent unprecedented impacts and help mitigate many factors that contribute to ocean related problems? J.T Kidlow, The National Ocean Economics Program, and A. Mcllgorn, The University of new England and Southern Cross University, have researched the importance of estimating the ocean as a contributor to modern economies.  Until 1990, many nations have not formally conducted an evaluation of the effects the ocean has on its economy. Kidlow conducted an evaluation of ocean industry sectors, based off APEC’s industry sectors, and concluded that the U.S.A’s GDP, is directly effected from the following ocean industries: oil and gas; fisheries/living resources; shipping; marine construction; and marine tourism. Kudlow reasearch in 2009, based off data in 2004,  list that the ocean is 138billion dollar contributor to the U.S economy, not including environmental and ecosytem stocks that arent direct goods and services. Kudlow presents data that could be useful to policy makers in the determination of ocean and marine ecosystem preservation.

With the increasing amount of CO2 being absorbed into the oceans, one can only imagine the impact it is and will have, and the breadth and depth of the effects of ocean acidification. Effects on surface water chemistry, calcification, various biological processes, and coral reef growth provide an idea of the breadth of impacts, but observing something specific, like phytoplankton, can be used to show the depth of negative effects.

The basis behind ocean acidification is that the ocean is becoming more acidic as a result of increased CO2 levels, which are being absorbed from the emissions in the atmosphere. Acids have higher concentrations of H+ ions, and this is exactly what is happening as CO2 is absorbed into the ocean: there are more H+ ions. Essentially, the CO2 combines with water to form carbonic acid (H2CO3). This carbonic acid then breaks down, forming bicarbonate (HCO3) and a remaining H+ ion, the ion found in acids.

Of course a more acidic environment could prove detrimental to ecosystems and organisms alike simply because of a change in the environment. But as we see, a decreased pH will even have effects on nutrient acquisition, and it starts with the nutrients themselves. The nutrients taken in by organisms are essentially chemical compounds. And because we have changed the chemistry of the ocean, it makes sense that the compounds themselves, which are taken in by organisms, are now also changed. Iron, among many trace metals, is an essential element for different biological processes. Unfortunately, a decreased pH causes dissolved iron to less bioavailable, and as low iron levels limit primary production in Phytoplankton, they now experience a limiting growth factor.

Other nutrients, such as phosphate, exhibit similar behavior in regards to their chemical form as result of a change in pH. These elements can bind to organic compounds, and the rate and type of binding occur relative to the pH. So Phytoplankton will have to use enzymes to biochemically remove the phosphate from the organic compound. It so happens that the enzymatic activity is also affected by the pH, and the enzymes which cleave phosphate or other nutrients from the organic compounds are located externally; they are directly affected with the pH change.

Additional to the nutrients being altered, increased CO2 levels increase Phytoplankton synthesis and primary production, and has been shown in various studies. Further studies have shown that the composition of what Phytoplankton produce in higher CO2 levels have greater carbon to nitrogen rations (C:N). A higher organic carbon ratio can mean the Phytoplankton have higher nutritional values, and since our Phytoplankton are at the bottom of the sea trophic levels, consumers can potentially expect an increased growth and reproduction rate.  Looking at a study on bottom-up affects on trophic levels, we see that if trophic level 1 is increased, above trophic levels experience increases relative to the ratio of change in trophic level 1. If Phytoplankton encounter increased nutritional values, above trophic levels will reach a new population density equilibrium, as reproductions can also be affected at higher trophic levels.

However, other studies argue that even after comparing eight different species of phytoplankton, a decrease in pH, even to the predicted pH for the end of the century (7.8), showed neither an increase or decrease in growth or production rates. This is not to dismiss our theoretical situation where consumers reach a new population density equilibrium, but to note that sufficient studies are not yet available and to show that predications of what ocean acidification can do are fairly difficult, as the potential impacts cover a large scope.

Bibliography

Berge e al. “Effect of Lowered PH on Marine Phytoplankton Growth Rates.” MARINE ECOLOGY PROGRESS SERIES 416 (2010): 79-91. 14 Oct. 2010. Web. 4 Sept. 2011. <http://www.int-res.com/articles/meps2010/416/m416p079.pdf>.

Devaraj, Maurice S. THREE TANK MODEL: A Top down or Bottom up Dominance Analysis. Journal of Theoretics. Web. 4 Sept. 2011. www.journaloftheoretics.com/Link/Papers/ TDBU.pdf