Global warming is rapidly becoming an issue with the potential to permanently change the course of human history. As Al Gore stated in his speech to the National Sierra Club Convention in 2009, “The warnings about global warming have been extremely clear for a long time. We are facing a global climate crisis. It is deepening. We are entering a period of consequences”. The government and media have mainly been focusing on the “consequences” related to the rise in atmospheric CO2 levels, and have taken for granted the fact that the ocean absorbs almost 26% of the amount of CO2 released. This massive uptake of CO2 has definite consequences that could prove to be just as harmful as the effect of atmospheric CO2, but new studies also show the possibilities of marine adaptation.
The influx of anthropogenic CO2 in the ocean directly relates to an imbalance in the levels of calcium carbonate, as the equilibrium shifts towards bicarbonate and there are not adequate amounts of calcium carbonate. This imbalance was thought to directly impede the growth and health of calcifiers, such as crustaceans or mollusks, and while in the majority of cases this proved to be true, there were exceptions that are leading scientists to reform their ideas about the true effects of ocean acidification.
Mollusks, crustaceans, and other calcifiers rely on calcium carbonate as a building block for their shells and skeletons, and a decrease in the levels of this compound has been shown to decrease both the shell weight and the calcification levels in these organisms. However, in a study involving eighteen different calcifiers placed in conditions of high CO2, only ten displayed reduced rates of calcification, one showed no response, and seven actually showed net increases in their rates of calcification. This shows that a change in the levels of calcium carbonate clearly has a broad range of effects upon marine life, and can actually be beneficial in many cases.
Countering this study, however, is evidence that the organisms that “benefited” from a rise in CO2 levels were actually worse off in the long run. Mollusks in a low pH environment near an underwater vent volcano had a noticeably impaired metabolic system, and were much more vulnerable to predators than mollusks situated in normal environments. Also, in a study of the reaction of Amphiura filiformi, a type of brittlestar, to a decreased pH level, while the creatures’ metabolism and ability to calcify increased in this environment, it came at a cost of muscle wastage and the inability to sustain itself in this environment for the long term.
Overall, the increase of CO2 and the ocean’s consequent decreases in pH level clearly have a large effect on all marine life, but the mixed responses shown in studies reveal that more research is desperately needed. There is an underlying factor that connects each study, and this is the idea that the increase in CO2 will lead to sea life being less sustainable. Ocean acidification is the field which needs to be at the forefront in the struggle against global warming.
The oceans are an integral part of our world, covering approximately 71 percent of the earth’s surface. Ocean acidification is occurring in oceans all over the world, but is perhaps most troublesome in the waters closest to you and I. Coastal waters are used by humans every day both out of necessity and to have a little fun. Because of their close proximity to people, coastal ecosystems are put under a lot of stress before ocean acidification is even taken into effect. The acidity of the ocean’s coastal waters is already slightly higher than most other places due to pollution and runoff. When you put ocean acidification into the mix, organisms in coastal ecosystems will have a great deal of adapting to do in order to survive.
Bivalves, an important species to the ecosystem as well as to humans, have already been shown to have a negative reaction to increased acidity. Because the calcium carbonate needed to make their hard shells isn’t as readily available, bivalves are having a harder time reproducing and developing to maturity. Some species of lobsters, shrimp, and sea urchins are experiencing the same problems. While ocean acidification is affecting these species individually, it could have an even greater effect by harming organisms that make coastal habitats. Coral reefs are an integral part of coastal ecosystems, providing habitat for thousands of organisms. However, increased acidity and ocean temperatures are known to be extremely harmful to coral species. Without coral reefs, coastal ecosystems would lose valuable habitat and diversity.
Although it may seem cut-and-dry that ocean acidification is harmful to coastal ecosystems, there are many species not affected or positively affected by increased acidity. Some species of oysters, lobster, and crabs were actually found to thrive in the lower pH. This makes it reasonable to believe that other organisms might be able to adapt to the changes in acidity. Another species found to thrive in acidified waters is sea grass. Sea grass is another major habitat provider in coastal ecosystems. Because it thrives in the lower pH, it could possibly make up for some of the habitat loss of coral reefs.
It is quite difficult to argue the fact that coastal waters are becoming more and more acidic. In fact, the EPA has directed states to list areas of water where the acidity is increased as impaired. Throughout the United States coastlines, there are over 41,000 areas listed as impaired due to ocean acidification. While the fact of increased acidity is hard to argue, the future effects of this increase are quite vague. Humans need to be cautious either way, because losing the resources provided by coastal ecosystems would do serious economical and environmental damage.
When environmental problems having to do with the absorption of CO2 are mentioned, global warming immediately comes to mind. This may be due to the fact that people think it is the only environmental issue concerning CO2 that is relevant. What most are not aware of is that almost a quarter of all the anthropogenic carbon dioxide in the atmosphere is being absorbed into the oceans. This absorption of carbon dioxide into the oceans causes several changes in ocean chemistry including increases in CO2 concentration, decreases in pH, and decreases in calcium carbonate saturation. Naturally, the group most affected by all these changes, are the marine organisms, whose biological processes (respiration, CO2 fixation, uptake of growth nutrients, etc) are being negatively altered.
One such processes that is being affected, and not positively so, is the precipitation of calcium carbonate. When gradual seawater acidification is caused due to the absorption of fossil fuel carbon dioxide, calcification has been shown to slow down in come of the predominant calcifying groups (corals, cocolithopores, and foraminifera.) This is because when carbon dioxide is absorbed into the oceans, the water becomes more acidic, and thus its degree of saturation is reduced in regards to calcium carbonate (CaCO3.) Why is CaCO3 so important to marine organisms? It is the major constituent of many marine organisms’ protective shells, plates, and skeletons. In addition, the calcifying organisms include several different taxonomic groups and inhabit various ecological niches. Of those calcifying marine organisms that have been studied so far, most display either a slower rate of calcification or a decrease in total mass of CaCO3 per organism in response to the increase in CO2 levels and lower pH values in the sea water. In fact out of all observed biological effects of the acidification of ocean water, the most widely-observed and best known effect is the decrease in calcification/shell weight.
However, not all results pertaining to calcification due to ocean acidification are agreeable with this observation. A 60 d laboratory experiment done by Ries et. al. in 2009 investigated the effects of carbon dioxide induced ocean acidification on calcification in 18 benthic marine organisms from a broad range of taxa (crustacean, cnidarian, echinoidea, rhodophyta, cholorophyta, gastropoda, bivalvia, annelida. While in ten out of the eighteen species, reduced rates of net calcification were observed, in seven of the eighteen species, net calcification actually increased under the intermediate and even highest levels of carbon dioxide! The remaining species showed no change in net calcification. In another experiment by Langer et. al. in 2006, it was shown that that two of the most productive marine calcifying species (the coccolithophores Coccolithus pelagicus and Calcidiscus leptoporus) also did not follow the expected calcification results in response to ocean acidification. Thus, these diverse and varied results in response to ocean acidification demonstrate the differences between organisms when it comes to regulating pH at the site of calcification. Thus, even though there may be an overall trend in calcification in marine organisms as a result of increased CO2 levels in ocean water, the results are in fact quite varied.
Ries, J.B., A.L. Cogen, and D.C. McCorkle. 2009. Marine calcifiers exhibit mixed responses to CO2 induced ocean acidification. Geology 37(12): 1131-1134.
Langer G. et.al. 2006. Species-specific responses of calcifying algae to changing seawater carbonate chemistry. Geochemistry Geophysics Geosystems 7: Q09006.
Coral reefs constitute a very important component of many ecosystems across the world’s oceans. Although such reefs occupy less than one tenth of a percent of the oceans’ surface, these diverse ecosystems house twenty-five percent of the world’s marine organisms. The rigid structures that compose coral reefs are formed by a process known as calcification performed by polyps, small marine organisms, which then die and leave behind their calcified shells. However, with increasing carbon dioxide levels in the ocean, calcification can be negatively affected, thereby harming the whole of the world’s coral reef ecosystems.
Under normal conditions, the process of calcification begins with the combination of carbon dioxide and water to form carbonic acid. The carbonic acid subsequently dissociates into a hydrogen ion and a bicarbonate ion, which then breaks down into another hydrogen ion and a carbonate ion. Finally, calcium combines with the carbonate to form a hard calcium carbonate shell. However, when extra carbon dioxide comes into the process, the process shifts so that fewer quantities of calcium carbonate form, causing weaker, smaller calcium carbonate complexes to form reefs. These smaller, weaker reefs inherently cannot house as many organisms as their larger counterparts, and as the oceans continue to acidify, the reefs will continue to wane smaller and weaker. Ocean acidification also slows the growth of reefs, makes coral more susceptible to bleaching and disease, reduces the tolerance of reefs to ultraviolet radiation, and accelerates bioerosion; the combination of such negative effects on reef formation could lead to an eventual disappearance of the structures from the world’s oceans.
Multiple laboratory studies have shown substantial declines in reef growth associated with ocean acidification. In such studies, a doubling of the amount of atmospheric carbon dioxide has led to a decline of three to sixty percent in the rate of calcification. Likewise, calcification rates of brain corals in Bermuda have decreased by twenty-five percent during the last fifty years due in part to increasingly acidic ocean waters. In another study by the United States Geological survey, crustose coralline algae, another important part of reef building, also becomes much less effective in more acidic waters. In water tanks with decreased pH, crustose coralline algae covered ninety-two percent less area than in the tanks with normal ocean water. In addition, non-calcifying algae increased in area by fifty-two percent, showing its ability to outcompete the important crustose coralline algae in acidified ocean environments. A study at the University of Hawaii showed that dominance in reef building could shift from stony corals to fleshy algae in acidified oceans. This shift would lead to not only changes in the reefs themselves but also in neighboring coastlines, thereby drastically changing the ecosystems of the area.
Ocean acidification has many negative effects on coral and other crucial components of the calcification and the reef building process. Such adverse effects could lead to the eventual disappearance of reefs from the ocean, greatly impacting the lives of many marine organisms inhabiting reef-based ecosystems. Changes in reefs also cause changes in nearby coastlines, which will disturb the living conditions of even more organisms. If ocean acidification continues, the effects on coral reefs will snowball and disrupts a sizeable portion of the world’s marine organisms.
Carbon dioxide is a compound with extremely important biological connotations. It is a reactant in photosynthesis, the chemical process by which plants produce energy. Carbon dioxide is also, however, a byproduct of many industrial reactions, and the earth is struggling to try to find a place to put all this excess anthropogenic carbon dioxide. In particular, some of the carbon dioxide is being sopped up by the world’s oceans. Nonmetal oxides such as carbon dioxide are acid anhydrides in water, and as a result of this absorption, the oceans are becoming more acidic and the average pH of the earth’s oceans has dropped by a quantifiable margin. This phenomenon has aptly been entitled ocean acidification, and it has some rather grave implications. However, the additional carbon dioxide may, to some degree, improve the photosynthetic output of some marine plants, given the compound’s aforementioned role in the reaction.
Diatoms are unicellular algae that are significant producers in many marine food chains. The effects of ocean acidification on diatoms have been a hot topic of research within the past seven years given their importance. In one study, scientists bubbled varying levels of carbon dioxide into colonies of the coastal phytoplankton skeletonema costatum. The colony that received 350 ppm of carbon dioxide grew 1.6 times as much as the control group. A colony given 1000 ppm grew 2.1 times as much. The 1000 ppm culture produced more chlorophyll than the 350 ppm group, and the effectiveness of photosynthesis was enhanced by the additional carbon dioxide as well.
Another experimented conducted entailed the creation of an equilibrium of atmospheric carbon dioxide with bubbled aqueous carbon dioxide. When the carbon dioxide was made to be twice that of normal conditions, consumption increased by 27%. When the carbon dioxide was tripled, the diatoms’ consumption was 39% higher. Estimates say that such carbon dioxide consumption as that described here may in have kept atmospheric levels to 90% of what they would be otherwise since start of the industrial revolution. In yet another study, it was found that certain species of diatoms grow 20% faster when exposed to increased carbon dioxide.
This potentially positive consequence of the increase in atmospheric carbon dioxide is not nearly enough to outweigh the negative results of anthropogenic carbon dioxide. Some algae do not, in fact, benefit from increased levels of carbon dioxide. Zooxanthellae, for example, exist symbiotically with coral reefs. If the zooxanthellae colonies grow too large, then they will be doing so at the expense of their coral homes. Some species of phytoplankton may react poorly to the increased acidity. Then we must factor in things such as coral bleaching, coastal erosion, decalcification, and the loss of biodiversity. Indeed, for every possible upside that comes from ocean acidification, it seems that there are two potentially devastating ramifications.
Kleypas, Joan, Richard Feely, Jean-Pierre Gattuso, and Carol Turley. “FAQs about Ocean Acidification : OCB-OA.” Home : Mobile WHOI.edu. 6 Oct. 2010. Web. 05 Sept. 2011. <http://www.whoi.edu/OCB-OA/FAQs/>.
“Ocean Acidification (Effects on Marine Plants: Phytoplankton, Diatoms) — Summary.” CO2 Science. 7 July 2010. Web. 05 Sept. 2011. <http://www.co2science.org/subject/o/summaries/acidificationdiatoms.php>.
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.
In the past ten years, the rate of Americans who believe that environmentalists are alarmists has increased. I believe that the infinite problems, many of which result from different point source pollutants, have led the public to believe the importance of conservation is not high priority. The constant call for different environmental causes and the lack of drastic negative changes have led people to sh-luff off one’s responsibilities as a global citizen or expect someone else to do it instead of doing it oneself. The diminishing concern for protecting different natural habitats exemplifies tragedy of the commons. Unfortunately, this lack of concern is leading to more problems that are bigger which will need to be fixed in the future.
Ocean acidification is the decrease of pH due to the increase of carbon dioxide released from industrial sites. As a result of the gradual change of pH, there are numerous negative transformations occurring in the ocean. A prime example of this domino effect occurring would be the effect of ocean acidification on coral reefs.
Coral reefs are extremely susceptible to the effects of acidification due to the negative correlation between increased acidification and decreased rate of calcification. There are two main calcifying groups that are part of typical coral reefs: corals and calcifying macroalge. Both groups are extremely susceptible to changes in environment such as change in pH. The increased acidification has inhibited calcifying groups to produce at the typical rate. This decrease in calcification rates will negatively affect the skeletal growth of the reef-building organisms thus, stunting the growth rate of coral reefs and potentially causing the increase of erosion of pre-existing reefs. Despite the problem of the restricted growth of the coral reefs due to increased acidification, there is also the concern for the different organisms that are affected by reefs. Coral reefs, similar to any other environment, consist of interconnected species. Schools of fish use the reefs as barriers and the destruction of the reefs negatively affect the quantity of fish. With the diminishing amount of fish other organisms suffer, such as marine mammals. Therefore, not only is the physical reef itself affected but also the dependent organisms. Rather, multiple species dependent on this shrinking habitat are being harmfully impacted.
It is interesting to consider that if people were to eliminate (or reduce) the point source of water pollution the negative effects that go along with acidification would stop. Thus, as a whole ecosystem, coral reefs would not be as impacted in a harmful way. This would also minimize the amount of resources needed to devise new ways of raising different crops, which come from the assorted habitats that are being polluted, that humans are inclined to use/want.
Human activities have increased atmospheric concentrations of carbon dioxide by 36% during the past 200 years. One third of all anthropogenic CO2 has been absorbed by the oceans. But this has resulted in a pH reduction of ocean water by about 0.1 of a unit and significantly altered their carbonate chemistry. It is also predicted that the pH will decrease by 0.4 units by the end of the century.
When atmospheric carbon dioxide dissolves in seawater, carbonic acid forms. In order to reach equilibrium, carbonic acid disassociates into bicarbonate and then into carbonate ions, releasing two hydrogen ions in the process. Increased concentrations of hydrogen ions ([H+)] decrease pH, acidifying the ocean. To secrete their calcium carbonate shells, calcifying organisms, like oysters, need calcium ions and carbonate saturated waters. As pH decreases, carbonate turns into other forms of dissolved inorganic carbons, making it more difficult for the oysters to produce shells. To make matters worse, such conditions even promote the dissolution of the calcium carbonate shells. Hence retarded growth and abnormal shell development and maintenance are the most obvious threats for the oysters here. In addition, the oysters are also prone to dangers during their phases of fertilization and embryonic development. Carrying-over of impacts suffered during the larval phase into the juvenile phase is also a matter of concern.
Primarily, shells play an integral part in the oyster’s life by providing structure and protection. Underdeveloped shells, weak body-structure and such deformities lead to significantly increased mortality rates. Such decline can bring adverse effects in food web interactions as well as in the correlated ecosystem in general. This would also include a degradation of biogenic habitat structures formed by these ecosystem engineers. Besides, oysters represent a large part of worldwide aquaculture production. Hence, threat to their survival eventually threats the coastal biodiversity, ecosystem functioning as well as the socio-economic scenario.
Estuarine and coastal ecosystems are more susceptible to pH changes than open ocean environments. These ecosystems are less pH buffered due to different factors like naturally reduced alkalinity, lower salinity, freshwater input, upwelling, atmospheric deposition etc. A study, published in the Global Change Biology Magazine, investigated the synergistic effects of ocean acidification and temperature on the fertilization and embryonic development of the economically and ecologically important Sydney rock oyster. The impacts on both life-processes were deleterious.
As the partial pressure of dissolved carbon dioxide (pCO2) increased, fertilization significantly decreased. Same was the case when the temperature increased or decreased from the optimum temperature of 26 degrees Celsius. Also in embryonic development, as pCO2 increased, the percentage and size of the larvae decreased, in addition to a significant increase in the percentage of deformed larvae.
The results of this study suggest that predicted changes in ocean acidification and temperature over the next century may have severe implications for the distribution and abundance of this species of oyster as well as possible implications for the reproduction and development of other marine invertebrates.
Brian Gaylord, a biological oceanographer at the Bodega Marine Laboratory of the University of California at Davis, is investigating the consequences of increasing ocean acidity on the growth of larval and juvenile Olympia oysters native to the U.S. West Coast. His results strongly suggest that the effects of ocean acidification on oyster larvae persist well into the juvenile phase. He marks this as an ominous consequence for oyster populations.
However, the outcomes vary considerably with several different species of oysters. According to several studies, there is a significant pool of oyster species that suffer negligibly from ocean acidification. Miller et al. 2009 (PLOS ONE 4: 10.1371) found that oyster larvae appeared to grow, calcify and develop normally with no obvious deformities, despite conditions of significant aragonite undersaturation. These findings run counter to the expectations that aragonite shelled larvae should be especially prone to dissolution at high pCo2.
A study, by J. N. Havenhand and P. Schlegel at the Department of Marine Ecology at Tjärnö, University of Gothenburg in Sweden, reports the effects of near future levels of ocean acidiﬁcation on sperm swimming speed, sperm motility, and fertilization kinetics in a population of the Paciﬁc oyster Crassostrea gigas from western Sweden. These researchers found no signiﬁcant detrimental effect of ocean acidiﬁcation – a result that was well-supported by power analysis. Similar ﬁndings from Japan suggest that this may be a globally robust result, and hence emphasis is placed on the need for experiments on multiple populations from a species’ range. This group comes to the consensus that if we are to understand and predict the full consequences of ocean acidiﬁcation on marine organisms, our experiments need sufﬁcient statistical power to detect biologically meaningful effects. In other words, maximize the likelihood that non-signiﬁcant results are a reﬂection of no biological effect, and minimize the likelihood that such results are caused by insufﬁcient replication for the levels of variation present in the experimental system. The likely absence of signiﬁcant impact on a given species and process is every bit as important as ﬁnding signiﬁcant effects (negative or positive).
There are several claims, such as, ‘it is just a routine phase-change in ocean chemical field’, ‘this is just a part of natural selection’, ‘those endangered species are well safeguarded by internal homeostasis’, ‘it is going to bring positive shifts in oyster community composition’, that may have substantial base to imply an exaggeration in the predicted threats of ocean acidification. However, we should not get encouraged thinking that our carbon dioxide emissions are not doing much harm to the marine ecosystem. Globally, 85 percent of shellfish reefs have been lost, making oyster reefs one of the most severely threatened marine habitats on the planet (http://www.nsf.gov/news/news_summ.jsp?cntn_id=116767). Moreover, experienced and successful oyster farmers and hatchery operators have suffered badly and repeatedly in a continuous series of years in recent times (http://www.grist.org/food/2011-08-17-the-great-oyster-crash). Most of them confidently relate the influx of acidic ocean water to the greatly abnormal death rate of their oyster larvae. One thing that is certain is ocean acidification is not bringing considerable benefits to the planet and its inhabitants. And reducing carbon emissions into the atmosphere is an incontestable way of keeping ocean acidification from getting worse.
Osmoregulation/Buffering Capabilities in Multicellular Marine Species
Many species in the ocean have developed or simply been born with metabolic processes that help regulate the amount of acidity in their systems. According to the National Research Council, increased acid concentrations inside the cell membranes can stop vital cell processes such as DNA transcription or protein synthesis. With increased industrialization and global warming to facilitate the drop in ocean pH levels, these various forms of biological buffers are becoming vital to a species’ survival. In chemistry, a buffer is a substance that resists a slight change in pH. In living systems, buffering can be thought of as a form of osmoregulation, which is essentially the same thing as maintaining a balance in fluids and pressure. Many species attempt to keep the base-acid balance in their systems by excreting fluids. Others carry out osmoregulation on a much smaller level with ion channel pumps (Ocean Acidification). Regardless of the mechanism, most internal systems can determine when the internal pH has dropped to an unfavorable level and react appropriately.
Respiratory systems can function in two different ways. The standard is aerobic respiration, which is oxygen-dependent. Most organisms depend on aerobic respiration, because it is a much more direct and convenient path in metabolism. However, there is also anaerobic respiration, which is oxygen-independent respiration. Muscular systems are the primary ones to depend on anaerobic respiration, for they are most active when the amount of oxygen entering the body is limited. When the concentration of acid rises around an organism, it is much more difficult to carry out aerobic respiration. As a consequence, some species rely much more on anaerobic respiration. Take, for instance, the flatfish, a pelagic (an environment not too close to the coastline but not too deep in the ocean) fish species. The flatfish responded to the drop in pH levels by increasing the activity of the enzymes and the indicators in its muscular system. In fact, two key differences were seen. First, an indicator called LDH increased its activity (Somero). LDH is the indicator of anaerobic respiration. Second, an indicator called CS, which is for aerobic respiration, decreased in amount and activity (Somero). In other words, the flatfish has adapted by slightly shifted its respiratory activity from primarily oxygen-dependent to more oxygen-independent. This is extremely advantageous in that it allows the flatfish to continue its metabolic processes at a similar rate.
Another species that demonstrates osmoregulation in the presence of varied external conditions (including but not limited to increased acidity) is the seal. The seal is able to maintain appropriate water pressure as part of its electrolytic homeostasis. This is another way of saying that the seal’s hormones and systems help regulate fluid pressures. In fact, the renal systems (kidneys) of seals are able to use selective sodium or potassium pumps to exchange these protons for H+. This release of H+ will reduce the acidity of the internal membrane (Ortiz).
Many marine animals have adapted or have advantageous mechanisms that help them cope with the overall increases in acidity. At the core, these processes are nothing more than the simple homeostatic processes we carry out on a daily basis. However, despite life being able to get around ocean acidification right now, it will not always be this way. There may be a point where marine life simply cannot withstand the level of acidity. If we do not take efforts to reduce emissions, we will end up wiping out most of the ocean.
Ocean Acidification: a National Strategy to Meet the Challenges of a Changing Ocean. Washington, D.C.: National Academies, 2010. Print.
Ortiz, Rudy M. “Osmoregulation in Marine Mammals.” The Journal of Experimental Biology (2001): 1831-843. Print.
Somero, G. N. “SCALING OF ATP-SUPPLYING ENZYMES, MYOFIBRILLAR PROTEINS AND BUFFERING CAPACITY IN FISH MUSCLE: RELATIONSHIP TO LOCOMOTORY HABIT.” The Journal of Experimental Biology. 22 Nov. 1989. Web. <http://jeb.biologists.org/content/149/1/319.short>.
The ocean has absorbed carbon dioxide (CO2) from the atmosphere since the beginning of time. The ocean is known as a carbon dioxide sink because of its absorption capabilities. This has been viewed as a positive in the past few decades since global warming has become a pressing issue. The ocean absorbs CO2 from the atmosphere, which helps lessen the threat of global warming to the earth. Carbon dioxide levels have risen since the Industrial Revolution due to automobile emissions, cement production, industrial power plants and other contributing factors. Now, with the oceans absorbing absorbing about 1/3 of the earth’s carbon dioxide, the sea chemistry is being affected. The ocean cannot handle such high levels of CO2 as a result, its pH is becoming more acidic. This effect is known as ocean acidification.
Before the Industrial Revolution, the ocean’s pH levels were stable. Since then, the pH has dropped 0.1 units. Though this may seem like a relatively small change, the world’s ocean has a very high buffering, or acid neutralizing, ability so the fact that the pH has declined to this extent is very startling. PH levels are predicted to drop even more in the next century.
Like all ecosystems, marine ecosystems are comprised of a vast array of interactions between different species and different types of organisms (both alive and dead) and the physical environment. Therefore, a change in any of these aspects will lead to a plethora of changes throughout the rest of the ecosystem. Because of the sheer quantity of life present and the significant interactions between species, coral reefs are prime candidates to be affected greatly by ocean acidification. These reefs provide food and shelter to hundreds of thousands of marine organisms so when the reef is harmed by acidification, so are all of the organisms that interact with it. When global warming, one of the world’s most alarming environmental threats directly affects the coral reef, one of the ocean’s most important ecosystems, the ramifications are dire.
Coral reefs are created by large calcium carbonate colonies known as coral. These reef structures are the home and feeding grounds to a wide array of organisms. Coral reef ecosystems have been called “cradles of evolution” because more marine organisms evolve from coral reefs than from any other ecosystem.
Ocean acidification may actually alter the physical structure of coral reefs. Acidification affects the organisms that build the reef because it lowers calcification rates and pH, inhibiting the creature’s skeletal growth. Without these reef-building organisms, coral reefs cannot exist.
Aside from hindering the organisms that physically build the reefs, ocean acidification also increases the probability that existing reef structures may dissolve. Reef erosion is likely, given the vulnerability inevitable with increased acidification.
Acidification raises the possibility of coral mortality. It can cause coral bleaching, which can cause the coral to die. As the coral tries to survive and is in a weakened state, they become vulnerable to encroachment by other marine organisms. Some species can benefit from higher water acidity, like macroalgae. As these algae thrive, they block sunlight from getting to the coral and they may be abrasive to coral structures as they move through the water in the current. Both low light and abrasive contact can weaken the coral, or even kill the reef structure.
Dissolving and eroding coral reefs, as well as coral that is lost because of displacement by other organisms that can survive better in the high acidity all lead to what is known as “reef flattening”. This is a phenomenon that creates a loss in the “architectural complexity” of the reef. This affects all of the organisms that live within and rely on the reef as a key part of their survival methods. Reef flattening diminishes reef structure and habitats, and reduces organism populations and biodiversity.
Coral reefs are home to over 25% of all known species of fish and exhibit the highest biodiversity of any ecosystem in the entire ocean. Threats to coral reefs are a threat to thousands of other organisms, so as we see ocean acidification harming our world’s coral reefs, we should be very concerned. Ocean acidification does not mean that the oceans will die, but the survivors may be algae and jellyfish. For the ocean to be sustainable in its present form, with coral reefs the prominent sanctuaries for marine life, the pH of the ocean has to maintain acidity within relatively narrow boundaries. With the alarming increase in CO2 being absorbed into our great carbon dioxide sink known as the ocean, the coral reef is in jeopardy.
“Chapter 4.” Ocean Acidification: a National Strategy to Meet the Challenges of a Changing Ocean. Washington, D.C.: National Academies, 2010. Print.
Eilperin, Juliet. “Growing Acidity of Oceans May Kill Corals.” The Washington Post: National, World & D.C. Area News and Headlines – The Washington Post. 5 July 2006. Web. 04 Sept. 2011. <http://www.washingtonpost.com/wp-dyn/content/article/2006/07/04/AR2006070400772.html>