Alaska - Oceans (U.S. National Park Service)
According to scientific explanation, it's not two oceans but a glacier melting and the other is the offshore water of Gulf of Alaska. The melting. This paper was written as part of the Alaska Oceans Sciences Bowl . the gray silty water can be seen creating a plume in the Gulf of Alaska (Figure 2). When the Copper River reaches the ocean, it meets waters high in. The swirls of green are a phytoplankton bloom in the Gulf of California. The study of ocean color helps scientists gain a better understanding of phytoplankton and SeaWiFS - Patagonian Shelf Bloom 2 Kuring, SeaWiFS Project, image descriptions courtesy of James Acker, NASA GES DISC Oceans Data Team/SSAI.
However, as the database grows scientists are seeing that the contribution from Alaska's glaciers in the Gulf of Alaska form the largest contribution to rising sea level yet measured Arendt, et al.
Studies by Arendt have noted that between and Alaska's glaciers contributed about eight percent of the increased rate of sea level rise globally, which is two times the rate of contribution from Antarctic ice sheets, and seven times more than previously calculated in the USGS Benchmark study. The Copper River Basin in South-central Alaska and Canada is composed of both coastal and terrestrial glaciers, which both contribute to the high silt load of the Copper River.
The terrestrial glaciers add a different set of nutrients to the melt waters of the Copper River because they originate in the volcanic mountains of the Wrangell and St. Elias Ranges, where the coastal glaciers originate in the sedimentary Chugach Mountains Ahearn, The Copper River and Gulf of Alaska Twenty percent of the Copper River basin is covered in glaciers Mundy,and melting glaciers are creating an increased input of silt into the Copper River.
These glaciers reside in the Wrangell and Chugach Mountains, and are at the tributaries of the Copper River. Glacial silt contains high levels of iron, and when glaciers melt, iron is released into the tributary streams of the Copper River Campbell, The iron is then carried down to the mouth of the Copper River, where the gray silty water can be seen creating a plume in the Gulf of Alaska Figure 2.
When the Copper River reaches the ocean, it meets waters high in nitrate from upwelling. There are two types of upwelling that operate at the mouth of the Copper River: Both processes bring up many nutrients, including nitrate, to the mouth of the Copper. Coastal upwelling Figure 1 occurs along the Alaska Coastal Current.
It is fed from glacial runoff, snowmelt, and rainfall, and fueled by coastal winds. As wind blows the current along the coast from east to west, surface waters are blown out towards the ocean, and then pushed down under the thermocline.
The water displaced by the surface water is replaced by colder, deeper waters from beneath the thermocline. These cold waters are pushed back up the continental shelf and closer to shore, where they are then blown back out by wind and the cycle repeats. The deeper dense water brings up nutrients that were trapped on the continental shelf from decaying matter Barnes, This water is rich in nitrate because there is constant mixing at the plate boundary in the Gulf of Alaska Hales, Freshwater runoff makes the Alaska Coastal Current stronger; therefore, glaciers melting at a faster rate will strengthen it Mundy, Estuarine upwelling occurs when freshwater meets saltwater, or when a river meets the sea.
The freshwater that comes from the river is less dense and floats on top of the saltwater. There is a strong density gradient between the fresh and saltwater layers called the pycnocline.
However, the waves, wind, and tide cause mixing in the layers of water and can disrupt the pycnocline. Freshwater carries saltwater from below the pycnocline out to the ocean, and then more saltwater comes up from deep down to replace it. The deep saltwater is nitrate-rich because it has been traveling along the bottom of the ocean, where bacteria breaks down organic matter from decaying organisms. As the deep water rises, many nutrients are transported to the surface water at the head of the estuary.
This cycle repeats itself because all the organic matter is trapped in the estuary Barnes, The Copper River Plume and Dissolved Iron in the Gulf of Alaska Phytoplankton productivity is dependent on the availability of essential nutrients in euphotic surface waters. All growth is eventually limited by a factor such as nutrient availability, space, or predation. In the case of nutrient availability, this is called a limiting nutrient.
Phytoplankton populations are commonly limited by nitrate or iron. The majority of the Gulf of Alaska is a known high nutrient, low chlorophyll HNLC region, meaning it is rich in nutrients but has a low phytoplankton count. This apparent paradox is explained by the low quantity of iron, a micronutrient essential for photosynthesis. Iron in oceanic surface waters originates from terrestrial sediment that is transported by wind or rivers.
Iron has a residence time of about 80 days in surface water Ye, et al. Except for the occasional dust storm from the Copper River Delta, the open waters of the Gulf of Alaska do not have a significant source of particulate or dissolved iron. The Alaskan Coastal Current is nitrate-poor; however, it is rich in iron from freshwater runoff.
A major source of this runoff is the Copper River. The edge of the Copper River plume Figure 2 is where the iron-limited and nitrate-limited waters meet to create a nutrient-rich biological hotspot. Mixing between the subarctic eastern Alaskan Gyre and the Alaskan Coastal Current results in zones of high productivity in the northwestern Gulf of Alaska Figure 3. Bruland Research Lab a Projected Scenario Although greenhouse gases perform the essential function of capturing heat in the atmosphere to keep earth's temperature in a state of equilibrium, human activities such as the burning of fossil fuels are increasing the amount of CO2 emissions—strengthening the greenhouse effect and thus altering earth's heat equilibrium EPA, This shift began during the Industrial Revolution, when a sudden and continuous influx of CO2 emissions influenced earth's greenhouse process NOAA, The adverse effects of this shift are present in the retreat and melting of glaciers across both Alaska and the globe.
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As the amount of CO2 emissions in the atmosphere swells, more heat is trapped. This causes earth's temperature to rise, resulting in the melting and consequent retreat of glaciers.
Whereas a snow-covered glacier has albedo with the potential of reflecting up to 80 percent or more of earth's solar radiation, the melting of this snow causes the albedo to dramatically decrease to only 30 percent NASA, This decrease in albedo leads to the ground absorption of solar radiation and warming of "earth's surface and lower atmosphere," as the absence of snow fails to reflect such radiation back into space NASA,creating a positive feedback loop.
Glacial retreat causes mountainsides to erode, creating iron-rich sediment that is then deposited into nearby streams like those whose melt-water contributes to the Copper River.
As glaciers continue to melt as a result of global climate change, iron-rich sediment deposits continue to flow into the Copper River and the Gulf of Alaska. As most of the Gulf of Alaska currently experiences a low quantity of iron Campbell,an essential micronutrient for photosynthesis, the region is known for its low phytoplankton concentration. However, the rapid melting of glaciers that supply water and sediment to the Copper River will create an influx of iron into Alaska's Gulf and thus augment conditions necessary for phytoplankton growth.
The size of the Copper River plume is affected by how much freshwater is delivered to the mouth of the river Mundy, As glaciers melt at a faster rate due to climate change, there will be more glacial water transported to the mouth of the Copper River, thus bringing more iron down to the plume. Increased glacial melt will also cause a surge of water in the river, resulting in more landslides on the banks Bowersox.
Because increased freshwater runoff strengthens the Alaska Coastal Current, the current will become stronger and transport more nitrate to the plume. The town of Cordova, Alaska is dependant on the commercial fisheries in the Gulf of Alaska. Fifty percent of Cordova's jobs are directly related to commercial fishing Ecotrust athe sole basis of the town's economy. In view of the fact that phytoplankton are by far the most important primary producers in oceanic environments, commercially important species, and Cordova's economy, are ultimately dependant on phytoplankton populations.
Gulf Of Alaska, Where Two Oceans Meet But Never Mix
We predict that climate change will create a domino effect that will likely prove beneficial for Cordova's commercial fishing economy in the short-term, but will ultimately devastate the community's economy over a long period of time.
The warming of the planet will cause glaciers in the Copper River Watershed to melt, increasing the amount of iron necessary for phytoplankton production into the Gulf of Alaska.
An influx of iron will lead to an increase in both phytoplankton production and salmon population. This growth due to glacial melt will benefit Cordova's economy in the short-term by creating favorable fishing conditions for the commercial economy.
However, the problem arises when the glaciers of the Copper River cease to exist and no longer generate sediment. When the fundamental source of iron is eliminated, phytoplankton production and salmon population will considerably diminish—as will the overall flow of money generated from the Copper River fishing fleet.
Cordova's commercial fishing economy is currently experiencing the short-term benefits of the Copper River Plume's iron influx. As shown in Figure 4the biomass of zooplankton within the Gulf of Alaska increased during the s, an increase that is likely attributed to an increase in iron, the current limiting factor of the region. This occurrence may have also played a role in salmon population within the area. As zooplankton mass grew, Figure 5 shows that the biomass of all salmon species across Alaska, apart from the biomass of coho salmon, experienced growth as well.
Of these calculations, pink salmon exhibited the greatest increase statewide, topping the charts at about million pinks in and experiencing peaks at million pink salmon in,and Seeing as how these numbers represent statewide harvests, there is no direct correlation with how the Copper River Plume's iron influx played a role. However, as depicted in Figure 6the Prince William Sound's pink salmon harvest peaked at 24 million fish, nearly quadrupling the region's five-year average.
This spike in population can be attributed to the increase in zooplankton biomass as a result of the phytoplankton increase caused by the Copper River Plume's iron influx. If the glaciers at the tributaries of the Copper River continue to melt rapidly, more iron will flow down the river and congregate at its plume. This will create favorable conditions for phytoplankton and zooplankton production, provisions necessary for expanding Copper River salmon populations, and such harvests like that of the past season will occur more frequently over a short period of time.
However, when the imminent extinction of glaciers feeding the Copper River occurs, harvests such as those experienced in will become mere legend. In a community where 50 percent of "jobs are directly related to commercial fishing," "an additional 25 percent are indirectly dependent on the industry," and "half of all households have someone working in commercial harvesting or processing" Ecotrust athe majority of Cordova's economy and residents would be devastated if the salmon population dramatically declined.
Currently, there are commercial fishing permit holders living in Cordova Cordova District Fishermen Unitedand of these, there are around 80 to drift gillnet permits, which account for catching two thirds of the harvest Ecotrust Fisheries,being used in the Area E fisheries within the Prince William Sound ADFG b. Although these numbers may seem insignificant, the number of dependents reliant on the income of these permits is much greater.
When the industries indirectly related to these permit holders' income and the employment they provide are taken into account, the number of citizens affected by the commercial fishing industry heightens and the majority of Cordovan residents may experience financial affliction. The devastation of the fishing economy due to changes in iron input as a result of glacial reductions or potential absence, would affect permit holders, their dependents, and Cordovan residents alike.
Although this projection won't occur for about 50 years or more, commercial fishing embodies the livelihood of Cordova, and if it were brought to an end, the city of Cordova would experience a similar fate. Following the depletion of iron to the Copper Plume, the salmon run should eventually stabilize, but at a lower level.
The current, iron-infused fishery will become reminiscent of fisheries without such an iron source, similar to those in more southern locations, such as British Columbia or Washington State.
However, because it is currently unknown where salmon go after leaving their natal streams University of Washington it is perfectly possible that such fisheries also benefit from the Copper Plume.
If this is the case, and all salmon feed in the North Pacific, we can expect to see a decline in all Pacific salmon stocks. Before this stabilization occurs, there will be a temporary spike in the salmon population, following the iron spike that should coincide with the rapid melting of the ice sheets that feed the Copper River. In this increase, as well as in the drop that will follow, the current management system, which first allows a healthy escapement, then catches what is unnecessary in the spawning beds Ulmer and Knapp,should be sufficient to keep the population intact.
However, this form of management for a smaller run will result in a smaller catch, causing the fishermen to lose money. If this cycle continues long enough—or if we drop management and try to maintain a high catch rate—eventually there may not be enough money in fish to keep Cordova alive.
Proposed Management Plan We propose several forms of management to augment the nutrient supply, and subsequently, the salmon run. While these changes will not be enough to compensate for the nutrients supplied by the Copper Plume, they may help slow the decline and raise the level of eventual stabilization.
One of these solutions is to try to restore natural nutrient balance in the Copper River Watershed. Salmon returning to their spawning streams "provide marine-derived nutrients that support the web of life within the watershed" Ecotrust b. Wildlife thrives in icy waters and lush forests around this vast expanse of ice. Native Alutiiq relied on these resources to nurture a life entwined with the sea. Today, shrinking glaciers bear witness to the effects of our changing climate.
Thousands, hoping to ease the woes of economic depression, sold farms, dropped businesses and boarded ships to follow their dreams north.
Effects of melting glaciers on nutrient flux to the Gulf of Alaska
Today, the park commemorates the bravery of the stampeders who ventured north by protecting the trails, historic boomtowns and buildings of the Klondike Gold Rush era. Lake Clark National Park and Preserve Shoreline Miles Lake Clark National Park is a land of stunning beauty where volcanoes steam, salmon run, bears forage, craggy mountains reflect in shimmering turquoise lakes, and local people and culture still depend on the land and water of their home.
Solitude is found around every bend in the river and shoulder of a mountain. Venture into the park to become part of the wilderness. Elias is a vast national park that rises from the ocean all the way up to 18, ft. Park, and Switzerland combined!
Within this wild landscape, people continue to live off the land as they have done for centuries.