This paper was written as part of the 2009 Alaska Oceans Sciences Bowl high school competition. The conclusions in this report are solely those of the student authors.
Projected Effects of Ocean Acidification on the Marine Ecosystem and Social Structure of Kodiak
In the North Pacific Ocean, the Gulf of Alaska holds some signs of ocean acidification. An increasing of atmospheric carbon dioxide (CO2) and reducing ocean pH and calcium carbonate (CaCO3) availability will in turn reduce the survival and density of the plankton. To research ocean acidification we interviewed some local scientists and we researched ocean acidification and its effects on plankton, crustaceans, fish, humans, and marine mammals. We found that plankton would be affected by the lack of calcium carbonate in the water, and that the ocean would dissolve their shells if it became more acidic. Crustaceans and fish are affected indirectly by the food sources of these animals being depleted and directly by crustacean's shells being dissolved and the fish having trouble breathing. Kodiak's fishery is affected by migration of the fish and lessened food source of fish which all in turn decreases the number of workers and profit. Marine mammals are at the top of the food chain so they are affected by the population changes of the trophic levels below them, and by the increase of noise in the ocean which leads to injury of the echolocation system and the lack of food source.
Ocean acidification is the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of anthropogenic carbon dioxide (CO2) from the atmosphere. Ocean acidification takes place when CO2 in the atmosphere comes into contact with the ocean. Then, the ocean absorbs the CO2 by forming HCO3 and H+ ions. The H+ plus ions decrease the pH of the water. These ions bond with the calcium carbonate in the water. This in turn, takes away calcium carbonate that crustaceans use to create and maintain their shells.
Ocean acidification affects many different fisheries in Kodiak. One of the fisheries that are affected is the crab fishery. The crab fishery will be affected because crustaceans eat plankton, which is affected by ocean acidification. In addition, the crustaceans are, as already noted, affected by the loss of calcium carbonate. Also Kodiak is reliant on the pink salmon fishery. The pink salmon's diet is made up partly of pteropods. Pteropods are a kind of plankton. These pteropods are extremely susceptible to acidification.
In this paper, we will discuss questions pertaining to all subjects mentioned above.
- How will ocean acidification affect plankton?
- How will in turn crustaceans and salmon be affected?
- How will the salmon and crab fishery be affected?
- What are some social impacts on Kodiak?
In the first question, we addressed plankton. Plankton are the base of many food chains. They are essential to pink salmon, and crustaceans. If plankton were affected by ocean acidification, then many food chains would collapse. This in turn would greatly affect the fisheries of Kodiak and the surrounding villages.
In the second question, we will discuss how salmon and crustaceans will be affected by the acidification of the ocean. Scientists are just beginning to study ocean acidification and the aspect of global climate change. It has been proven that crustaceans need a certain level of calcium carbonate in the water to survive. The increasingly acidic nature of the ocean has and continues to wear away the shells of the crustaceans. This fact has formed the basis of the belief that the fisheries will suffer.
In the third question, we will discuss how the fisheries of salmon and crabs are affected. Crustaceans and salmon support the main fisheries of Kodiak. These fisheries are the set net fishery, the seine fishery, the trawl fishery, and the crab pot fishery.
Lastly, in the fourth question, we addressed the social impacts on Kodiak. If the fisheries were affected in a way that was not recoverable, then the social structure of Kodiak would change drastically. Many families in the villages of Kodiak Island rely heavily on the fishery as their only means of support. The economy of Alaska is already suffering, but to add the failing fisheries on behalf of ocean acidification would spell disaster for many Alaskans way of life.
To obtain our information we interviewed some local scientists about the affects of ocean acidification. We talked to Bob Foy, the lead scientist at the Kodiak Fishery Research Center. He is currently studying the affects of ocean acidification of crustaceans and other marine life. We asked him the following questions:
- What ocean acidification research are you aware of around Kodiak?
- How do you think ocean acidification could affect marine life and fisheries? In Kodiak?
- How could ocean acidification impact crab populations and fisheries in Kodiak?
We then obtained our information from other scientists we interviewed. We talked to Sarah Persellin about how ocean acidification affects the shells and survival rates of crabs and plankton. We asked her the following questions:
- How does ocean acidification affect the crab larvae?
- Do you think that it is already affecting survival of crab in the ocean around Kodiak?
- What consequences do you expect for marine life and fisheries around Kodiak?
Following our previous discussions, we interviewed Kally Spalinger of the Alaska Department of Fish & Game in Kodiak, reviewing statistical data analysis. We asked her the following questions:
- Would you expect the people who bring in the currency to have as substantial of a salary as from recent years with more fishermen?
- Do you believe there are any changes in the populations of crab and salmon, resulting from a possible imbalance in their diets from smaller life forms?
- Has there been an increase of suicide rates over the last two decades, and if so, has it been discussed over any identifiable factors?
Finally, we had an exclusive interview with Michael Horton, a mental health clinician from the Kodiak Area Native Association. This interview was the only one not done with a scientist. These were the questions we asked him:
- Only a mere seven years following the discovery of global warming, it was found that the Bristol Bay suicide rate increased substantially, possibly due to ocean acidification and its effect on the food chain. Do you believe there may be some correlation and if so, would it impact Kodiak as well?
- Has there been an observable social impact over the last two decades, and if so, has it been discussed? Are there any identifiable factors?
Results and Discussion
Plankton is the life blood of many food chains. If plankton was affected by ocean acidification, as noted above, many food chains would collapse. Plankton are drifting animals, bacteria, and plants in the ocean. The bottom of the food chain consists of phytoplankton. Phytoplankton are plants, but some of them have shells that need calcium carbonate for maintenance. One example of phytoplankton is a coccolithophore. These organisms need calcium carbonate to make their shells.
Zooplankton are animals that feed on phytoplankton or prey on other zooplankton. Many zooplankton are crustaceans so they need calcium carbonate as well. The lack of calcium carbonate will affect these organisms in a number of ways. The animals will not be able to build their shells as easily as they had been able to before. Also, the acidity will dissolve their shells, which will put stress on the organism. Lastly, the mortality rates of all types of crustaceous plankton will increase, thus shrinking the population of plankton. Pteropods are small planktonic snails. These organisms will also be affected because they have calcium carbonate shells.
As ocean acidification increases, the decreasing pH will affect the shells of crab and their larvae. This includes: tanner crab, king crab, snow crab, and Dungeness crab. The decrease in pH will result in the decrease of the crab's ability to survive in the ocean. This happens because the crab's shells are intolerant to acidic water, so the acidity will reduce the strength of the shells. In Kodiak, there was a study on how the acidic oceans affect the crabs and plankton shells. In the first year the scientists found out that the shells of the crabs and plankton have grown weaker and the weights of the organisms were less. With the decreasing of pH, the decrease in survival rates of crabs not only affects their populations but also the food chain. As the crab larvae mortality rate rises and the levels of calcium carbonate in the ocean decrease, the crab population will suffer as well as the organisms that depend on crustaceans for a food source.
Many organisms will be affected indirectly by the loss of plankton and crab larvae. An example of this is the pink salmon. The pink salmon's diet is made up of copepods and pteropods. As noted above, these are zooplankton and affected by the acidification.
Fish that feed on plankton will also be affected by ocean acidification. They will be affected because the plankton population will decrease. The lack of plankton will cause the fish to migrate to not ideal habitats. The fish will use more energy traveling and trying to find food, so they will not have the energy to reproduce. Also, the juveniles will not have the energy to grow as quickly.
When fish breathe, they take in oxygen from the water near by. The increasingly acidic water will irritate the fish, and cause them to have trouble breathing. This in turn will cause the fish to expend more energy trying to breathe and not reproducing, eating, and growing.
Many scientists are under the impression that the fishery will suffer because of ocean acidification. According to the 2000 census of Kodiak, Alaska, the population was approximately 14,000 individuals with a 7.6% poverty rate. Although the highest population of poverty lies within the city limits of Kodiak, the suicide rate lies almost entirely within the six remote outlying villages of Kodiak Island. All over Kodiak, fisheries is the top profession and the rates of success for fishing vary greatly. However, the remote locations of the outlying villages are factors in rates of depression and suicide. When the shells of crustaceans are deteriorated and the populations decrease because of the acidic waters, the food chain is altogether affected negatively. When the food does not make it to salmon and crab in certain populated areas, they will shift to search for new sources of food. This will cause fishermen who are familiar with their given areas of harvest to have fruitless seasons. Thus, depression and anxiety will fall in with the mix of the overall solitude in the fishing villages, and may lead to the unfortunate suicide rates. Why suicide is less common in Kodiak proper is attributed to the city's commercial ties and the higher magnitude of professions available. Fortunately, it was studied by the Kodiak Area Native Association that suicide rates are on a decline. Attributed to the decrease of alcohol and cocaine, their research has not found a correlation to a climate change or scarce harvests. As found by Kelly Spalinger, many fishermen have expanded into multiple fisheries, often due to the scarceness of caches.
Gaylord Nelson introduced the first actual and legitimate evidence of a climate shift and ocean acidification in 1970. Since then, coincidentally, suicide rates of Alaska have been increasing dramatically. According to research and analysis conducted by the Bristol Bay Corporation in Alaska, it was found that from 1977 to 1982, 84 individuals, mostly minority natives, committed suicide. In all probability, the seven years since the original discovery of determined human–affected climate shift, the slight increase in temperature was the most likely candidate for the reason that the fisheries resources decreased in that region.
When salmon and crustaceans are negatively affected, the whole economy suffers and social impact hits very hard. According to statistics, natives hold the majority of the suicides, especially in ancient native villages, particularly ones on Kodiak Island, where fishing is the communities' main source of industry. This, of course, is often attributed to the common element of seclusion and poverty, which of course are ideal conditions for suicidal individuals. According to Kally Spalinger, the king crab population of Kodiak has been very low, staying at a constant rate with no sign of recovery. The interesting part of this is that as young creatures, king crab feed upon crustaceans. If crustaceans are unavailable, then the probability of starvation becomes much higher. Therefore, the possible acidification and its effect on crustaceans may be attributed to the low king crab population.
Marine mammals will be affected by ocean acidification in different ways than crustaceous plankton and fish. They are affected indirectly through the food chain and directly through the corruption of echolocation. Some marine mammals eat crustaceous plankton. Others eat plants, fishes, sea cucumbers, octopi, squids, and other marine mammals. All of these animals are affected in some way by the loss of plankton.
Figure 1 shows that all animals that marine mammals prey on are either directly connected or indirectly connected to the loss of plankton. As noted above, you can see that plankton is essential to the oceanic ecosystem.
Some marine mammals use echolocation to find food, and navigate the ocean. As the ocean's pH decreases, the water becomes noisier and noisier. This makes it more difficult for the animals to travel in the ocean and makes hunting for food harder. If the echolocation system of the marine mammals was scrambled, then the animals would crash into boats or beach themselves by accident. This will cause the already–endangered marine mammals to become extinct.
In our research of ocean acidification, we found that ocean acidification affects many different kinds of organisms. We did not include in our paper the effects of ocean acidification on land animals other than humans. Ocean acidification affects the entire biosphere. The increased CO2 in the atmosphere is what will cause ocean acidification. As inhabitants of this planet, it is our duty to solve the problem of ocean acidification by decreasing our greenhouse gas emissions.
Kodiak will be affected profoundly by ocean acidification. Kodiak's main industry is fishing, and if ocean acidification affects the fishery, then Kodiak's economy will be negatively affected. If this would happen, then Kodiak's people who spent their lives near the ocean and work on the ocean, will lose their jobs and that would affect the other jobs on the island. Eventually the town's population would shrink, and the industry would disappear. This is why we must solve the problem of ocean acidification.
We would like to thank Mr. Lauscher and Mrs. Switgard!
- Keith C. Hester, Edward T. Peltzer, William J. Kirkwood, and Peter G. Brewer. 2008. Unanticipated consequences of ocean acidification: A noisier ocean at lower pH. Geophysical Research Letters, Vol. 35, L19601.
Scientists from Kodiak, Alaska
- Dr. Robert Foy, Director Kodiak Laboratory. Alaska Fisheries Science Center. NOAA fisheries. 301 Research Court Kodiak, AK 99615
- Sarah Persellin, Scientists at Kodiak Laboratory. Alaska Fisheries Science Center. NOAA fisheries. 301 Research Court Kodiak, AK 99615
- Kally Spalinger, Crab management biologist, Alaska Department of Fish and Game. 211 Mission Road, Kodiak, AK 99615
- Michael Horton, Mental health clinician. Kodiak Area Native Association. 3449 E. Rezanof Dr. Kodiak, AK 99615