Posted on EPOCA: 30 Apr 2013
Ocean acidification has been a hot topic in Willapa since 2005, but the implications that ocean acidification has on marine ecosystems is global in scope. A study done by Havenhand et al. (2008) found that gametes and larvae of sea urchins are negatively impacted by -0.4 pH units (the upper limit of predictions for 2100). The effects included significant reductions in sperm speed and motility. These species are commonly found in the southern inshore waters of Australia. It is interesting to note, that this is a future projected analysis, thus, these affects are not occurring momentarily. A study done by Anthony et al. (2008) found that an increase of CO2 induces coral bleaching, and productivity. Furthermore, the same study found that ocean acidification impacts bleaching and productivity more than it impacts calcification. Similarly to Havenhand et al (2008), this study also manipulated CO2 levels to simulate IPCC’s projected increases for 2100.
Not all studies have found similar results; a study done in Plymouth Sound, UK (Wood et al. 2008) found that the brittle star has shown to have an increase in the rate of calcification due to ocean acidification. This does come at a cost; the same study found that although calcification and metabolism rates improved, the test subjects showed a decrease in arm muscle mass. Although there was a trade off that could detrimentally affect the brittle star (loss of muscle mass can negatively impact feeding and predator avoidance), it is almost refreshing to read about a study that contradicted the common literature and media.
In terms of ocean acidification, the results from our study were quite inconclusive. We did not find any significant increase of pH levels as a function of time (1991 to 2012). This could either be due to our lack of past data (perhaps our timeline is too short to fully show the effects) or because ocean acidification is not the only reason for the recent decrease in natural oyster set. Most studies that have recently tested implications of ocean acidification on marine species have not used observational analysis from current ocean pH levels, but have instead projected future estimations of pH levels on species and tested how they would react. Thus, these laboratory manipulations and earth systems models help shed light on what (may) happen in the future, but the current effects are either unobservable, inconclusive or both.
Ocean acidification is a topic that spans spatially and temporally in research. The effects that ocean acidification are projected to have are not localized, but instead encompass much of the globe. Furthermore, most of the studies that have been done use future projected outcomes instead of those, which are based on past and current values (a method that we chose to use). Reasons to look into the future are numerous (perhaps they want to induce human behavioral changes or they want to simply prepare for what is to come), nonetheless, although our data was local and current, the implications extend globally and into the future.
Anthony, K. R. N., D. I. Kline, Guillermo Diaz-Pulido, S. Dove, and O. Hoegh-Guldberg. “Ocean acidification causes bleaching and productivity loss in coral reef builders.” Proceedings of the National Academy of Sciences 105, no. 45 (2008): 17442-17446. http://www.pnas.org/content/105/45/17442.long
Havenhand, Jon N., Fenina-Raphaela Buttler, Michael C. Thorndyke, and Jane E. Williamson. “Near-future levels of ocean acidification reduce fertilization success in a sea urchin.” Current Biology 18, no. 15 (2008): R651-R652. http://www.sciencedirect.com/science/article/pii/S0960982208007355
Wood, Hannah L., John I. Spicer, and Stephen Widdicombe. “Ocean acidification may increase calcification rates, but at a cost.” Proceedings of the Royal Society B: Biological Sciences 275, no. 1644 (2008): 1767-1773 http://www.ncbi.nlm.nih.gov/pmc/articles/pmc2587798/
Kara Batdorff, Situating the Global Environment, Lewis & Clark College Environmental Studies Program, 28 April 2013. Article.