One more thing to worry about!
Global warming is a very publicized issue, however there are many off-shooting issues that are not given their fair share of the public limelight. Ocean warming and acidification is an increasing problem, as 30% of the carbon dioxide which we (humans) produce is absorbed by the sea! So, not only is the sea being warmed but it is becoming less basic as the extra carbon dioxide dissolves in to the sea to form carbonic acid, which then interacts with chemicals in the sea and is slowly overcoming the buffering power of the sea.
One offshoot of the oceanographic warming/acidification issue is species having access to areas of the benthic (sea bed in water of depth <100m) which were previously inaccessible to them. These warmer water animals usually have faster metabolisms and greater propensity to fast movement than cold-water animals. One specific example of this is the advancement of shell crushing (durophagous) king crabs up the sea shelf surrounding the Antarctic. King crabs have heavily calcified chelae (claws), and are fiercesome predators, however they cannot survive in water below a certain temperature and so have been kept off the benthic area for physiological reasons, and nothing else. Now the water temperature is on the increase, the area of seabed available to the crabs is slowly increasing.
For the past 40 million years, roughly, the animals living on the Arctic Peninsula have lived in a habitat where there are very few durophagous predators and so these animals have devolved any sort of protection they once had prior to the Eocene period. They have adapted to live in an incredibly cold climate by developing very slow metabolisms, and some species, for example various isopods, are now gigantic. These specialties are a huge benefit to life on the Antarctic Peninsula as it currently is, however, if the king crabs invade the area then none of the indigenous species stand any chance of survival and there may be a mass extermination of the original animals as the population of the crabs will no doubt explode given their newfound access to a brand new source of food, in an environment in which they themselves are relatively free from predation. This invasion will obviously radically change the food chains of the Antarctic waters and will contribute to the gradual homogenization of the global marine population as certain species monopolize on the changes that are currently taking place globally.
If we, humans, wish to conserve anything of the incredible, diverse and beautiful seas that we take so much for granted, we have to start acting radically, and most importantly, soon! Once alien species have taken over it can be nearly impossible to restore the ecosystem to its previous state so clearly the aim has to be not to create the environment where an invasion can happen in the first place.
Based on the work done by Aronson, R.B., S. Thatje, A. Clarke, L.S. Peck, D.B. Blake, C.D. Wilga, and B.A. Seibel. 2007. Climate change and invasibility of the Antarctic benthos. Annual Review of Ecology, Evolution, and Systematics 38: 129-154.
The Loss of Coral Reefs
The increased acidification of the world’s oceans is beginning to pose a great threat to the many life forms that inhabit them. One ecosystem in which this threat is particularly prevalent is the coral reefs. Between the broad array of corals and sponges that make up reefs and the many other organisms that depend on reefs for shelter, they are the most biodiverse ecosystem in the ocean. However, based on some models these reefs may lose a great deal of that amazing biodiversity in the near future.
The base of the problem of ocean acidification comes from the vast amount of CO2 that is being absorbed by seawater. Once the CO2 is in the seawater it quickly goes through a series of chemical reactions creating carbonic acid and bicarbonate. In the creation of these two compounds the carbonate ion (CO32-) is removed from the calcium carbonate (CaCO3), which was previously present in the seawater. This process can be observed by measuring the pH of the water, as the amount of carbonic acid in the ocean increases, the pH of the seawater drops. Since the dawn of the Industrial Revolution the amount of CO2 in the air has been rapidly increasing, this has caused the average pH of the ocean surface to drop from 8.2 to 8.1. While 0.1 may seem like an insignificantly small number, there has not been a change in ocean pH this intense in hundreds of thousands of years (Ocean Studies Board). Since corals rely on taking calcium carbonate from the water and the drop in pH has reduced the concentration of calcium carbonate in the water, this change is having a negative impact on the reefs. Studies show that important groups of reef building corals begin to struggle and in some cases die as they attempt to carry on the calcification process. After observing the CO2 seeps in Milne Bay, Papua New Guinea a group of scientists concluded that falling pH causes a decrease of up to 40% in coral diversity with mainly boulder corals surviving. The same group found that if the pH of the ocean falls below 7.7, all reef growth will come to a halt (Katharina E. Fabricius). Another experiment predicts that by the middle of the century seawater conditions will cause many coral groups to have calcification rates 10-50% less than the pre-industrial average (Joan A. Kleypas and Kimberly Yates). The coral reefs of the world are on the brink of destruction if the current trend of ocean acidification continues.
When people talk about the effects of the huge amounts of CO2 that people produce every day the destruction of coral reefs is rarely at the forefront of the discussion. After my research I would argue that coral reefs should be a huge part of the argument about CO2 and global warming. Coral reefs are the most vibrant, diverse, and arguably important ecosystem in the oceans which happen to take up most of the Earth’s surface. Considering ocean acidification and rising water temperatures these reefs are undoubtedly in danger that people cannot continue to ignore. Whether we like it or not humans rely on sea-life as a supply of food and coral reefs are just the first ecosystem in a long line that we could lose if we stand by and do nothing.
Fabiricius, Katharina E. “Ocean Acidification and Coral Reefs.” PhysOrg.com – Science News, Technology, Physics, Nanotechnology, Space Science, Earth Science, Medicine. Nature Climate Change, 29 May 2011. Web. 04 Sept. 2011. .
Kleypas, Joan A., and Kimberly K. Yates. “Coral Reefs and Ocean Acidification.” Oceanography 22.4 (2009). The Oceanographic Society. Web. 4 Sept. 2011. .
Ocean Studies Board. Ocean Acidification: a National Strategy to Meet the Challenges of a Changing Ocean. Washington, D.C.: National Academies, 2010. Print.