Students in Arctic Research (STAR) | Research Report

Introduction

Global climate change has a dramatic effect on the Arctic ecosystem. It alters the ice pack and produces more or less desirable living conditions for all marine life, including the algae that lives embedded in the ice. As the entire food chain stems from the algae, any fluctuation in its abundance or condition is magnified in each step of the food chain. The ice-pack provides a habitat for a large majority of species which comprise the Arctic marine food chain, and fluctuations in the "behavior" of the ice-pack (such as less "good ice," a smaller surface area during warmer seasons) may result in drastic fluctuations in the arctic food chain, and in a change in global weather patterns. The Arctic is a sensitivity indicator of global climate change. Measurable changes in Arctic systems may indicate future significant climatic and ecological perturbations here in Maine.

Background

During the summer of 1998, I was privileged to assume the role of a student researcher aboard the United States Coast Guard Cutter Polar Sea for the Arctic West Section (AWS) 1998 cruise. This opportunity arose when I expressed an interest in the Arctic ecosystem to my biology teacher Mr. Tim Buckley, who was a member of the Teachers Experiencing the Arctic (TEA) program, and had previously sailed on the Polar Sea in 1996. Mr. Buckley was searching for a student interested in participating in a month long voyage through the Arctic Ocean, and conducting research on the pack ice with an elite team of scientists. I jumped at the chance somewhat blindly, not knowing what to expect, or what to get out of the experience - but being quite sure that the outcome would be positive.

The National Science Foundation, and the Arctic Research Consortium of the United States (ARCUS) were driving forces behind the TEA program, and suggested that the student to take part in the program might be somewhat familiar with the Arctic climate. Since I had been living in Barrow, Alaska for the past year, I had learned the fundamentals of life above 70°N latitude - the blowing wind, blistering cold, the two month-long night, the unsetting sun, and how to deal with polar bears. This knowledge base played a key role in the appreciation of the month that I was to spend aboard Polar Sea.

Mr. Buckley and I boarded the icebreaker on June 1st in Nome, Alaska, where we joined with 17 other scientists studying various elements of the arctic ice-pack. The team that Mr. Buckley and I were directly involved with consisted of Mr. Terry Tucker and Mr. Bill Bosworth from the Cold Regions Research and Engineering Lab (CRREL) branch of the Army Corps of Engineers in Hanover, New Hampshire. Their research involved correlation of the presence of algae and sediment in a variety of types of sea ice. The purpose of this research was to develop an understanding of the role of sea-ice in the redistribution of near-shore elements (USCG 1998).

The other teams focused on the climatic aspects of the Arctic, on the benthic ecosystems, and the carbon cycle. Combined, the scientists aboard Polar Sea were mapping the relationships between the different steps of the ecological "life cycle" of the Arctic

Polar Sea's science mission started from Nome, AK, where it proceeded through the Bering Strait into the Chuckchi Sea, and around Cape Lisburne. It continued north to 73.6°N latitude, into the Beaufort Sea. The true ice-edge was reached at around 70.5°N latitude, which we stayed in until our departure to Barrow, AK on June 25.

Methodology

During the cruise, our team collected data on various stops, or "science stations" along the way. A total of 21 stations were sampled during the time I spent on board - 12 of which included "ice ops," (ice operations) where we would be transported onto the ice to collect data. Our team collected data only at ice ops stations.

A typical ice ops station occurred when Polar Sea was parked in the most efficient way to transport scientists from the ship to the ice. There were typically four scientists and two bear-watches venturing out onto the ice, with two sleds to transport instruments and boxed ice-cores. Personnel and equipment were lowered on a hanging platform from the ship's deck to the ice by a crane. Alternate means of transportation included boats and helicopters.

Once we were on the ice, we established 50 - 100 meter transects, where we drilled ice-cores every 5 meters. The placement and length of the transects were determined in part by means of drilling efficiency, where obstacles such as thin and ridged ice were avoided. Transect placement was also based on the likely algae concentration of the ice, and we searched for areas that appeared to have distinct traces of it. The ROV (Remotely Operated Vehicle) was of great use in finding places of high Melosira concentration. The ROV was sent underwater, retrieving live video data under the ice. We would place noticeable stakes through the ice (placed along the transect), and the ROV operator would radio to us telling us if there was any visible algae. If there were visible colonies, then that spot along the transect would be drilled.

At each sample point along the transect, we would drill two cores. The cores were 10 cm in diameter, and their length depended on the thickness of the ice-floe. One was a goal to get the entire width of the floe cored, so as to provide an accurate profile of the floe's properties. That was the main reason for avoiding ridged (where two ice floes have pushed up against each other, forming ridges) or rafted ice (where an ice floe has overrun another, thrusting over the top and forming two layers) .

Once the first core was "pulled," it was set on a wooden plank, where a small hole was drilled every 10 cm starting at 5 cm below the top of the core (the holes following at 15 cm, 25 cm, etc.) for the entire length. Core temperature was then taken with a digital thermometer at each drilled hole. Once the temperatures were recorded, the core would be placed in a "core-tube" container for storage, later to be analyzed for ice structure.

The second core was pulled, and again placed onto the wooden plank. This core was then sectioned every 10 cm by means of handsaw, leaving us with 10 cm chunks to be placed in sample bags to be analyzed later. Observations of visible algae and sediment content were noted, as well as observations relating to the age of the ice (first year vs. multi-year), and whether or not the ice is rafted or ridged. After the coring procedure, we spent the rest of our time collecting sediment from the ice surface. This consisted of scraping varying portions of mud-like materials from the snow, and vacuuming sediment from the bottoms of melt-ponds using a turkey baster. The samples were placed in Tupperware containers, and given to Mr. Tucker.

Once the ice ops were completed, we boarded Polar Sea. The cores stored in the core-tubes were then brought to the "cold lab" for structural analysis. The cold lab is a cooled laboratory suited for working with temperature-sensitive samples, which was important for properly analyzing the ice core structure. The cores were removed from their tubes, and sectioned lengthwise into thin slices (known as "thin sections"). The thin sections were then placed on a polarized light-table, to make the ice crystals composing the ice much easier to see. These sections were then analyzed to determine whether they were of a granular structure (typically snow or ice that was formed during turbulent weather conditions - such as a fall freeze-up), or columnar structure (long, well-formed vertical ice crystals comprising the ice - a component of multi-year ice). Changes from granular to columnar or vice versa were noted, as well as bands of either structure through the core.

The cores that were divided into 10 cm sections were brought to the "dry lab," or the laboratory with conventional laboratory facilities, and were left to melt. Once the core sections had completely melted, the salinity was taken for each sample. Following this, additional tests beyond the scope of the focus of this project were conducted on the samples.

Results

Data analyses show that out of the 22 cores taken, 8 (36.4%) had traces of algae. From the eight cores containing the algae, the average temperature was -1.1°C in the section of the core with algae, and the temperature range was -0.8°C to -1.4°C. The average salinity in the algae-containing sections of the cores was 2.8â, and the salinity range was 1.2â to 4â. Algae appeared 87.5% of the time in columnar ice, and 12.5% of the time in granular ice. All algae was found inhabiting the bottom 10 cm of each core with the only exceptions found in a core with strong evidence of ice-floe rafting. The average depth of the ice containing algae was 103 cm. There was no algae in cores that contained sediment.

Figure 1 summarizes all data collected. The values for salinity and temperature are averages taken from the 10cm sections of the cores they represent.

Figure 2 is a graph displaying the relationship between ice algae and latitude. This graph shows that most algae was found between 71° and 72°N, but this is biased by a single floe that was laden with algae at one of the stations.

Figure 3 is a graph displaying the presence of algae in columnar ice vs. the presence of algae in granular ice. There was a much higher percentage of algae found in columnar ice.

Figure1: Summary of Data Collected

Figure 2: A graph representing the abundance of algae at different stations.

Figure 3: A graph representing the presence of algae in columnar ice vs. the amount of algae present in granular ice.

According to the data, there was a strong relationship between the depth of the core to the temperature and salinity. The average core exhibited results such as the core in Figure 4. The temperature was inversely proportional to the depth - the greater the depth, the lower the temperature. The salinity was directly proportional to the depth - the greater the depth, the higher the salinity.

Figure 4: Taken from cores 155-1 (temperature) and 155-3a (salinity)

Discussion

Ice algae are very light-sensitive organisms, and our data imply that ice conditions are very influential on the abundance of algae. Ice algae, or Melosira arctica is a member of the "Golden Brown Algae," division Chrysophyta, subdivision Diatomaceae (Bacillariopyceae). It is found primarily in mats on the underside of sea-ice attached to the well-formed ice crystals, staying there until released into the water column by disruption of the ice to which it is attached. Melosira often forms large mats in the spring due to the increased sunlight, and forms diatomic shells in the fall when the sunlight is almost 100% decreased. Melosira inhabits the very lower portions of the ice-floes normally, suggesting that around 100cm of ice offers a light filter substantial for their photosynthetic needs. But many factors can vary the amount of light reaching bottom of the floe, which will in turn alter the Melosira population - resulting in positive or negative fluctuations.

Figure 5: A photograph of Melosira (University of Minnesota, 1998)

To determine the factors, it is necessary to evaluate the system ideal for Melosira. The results show that algae are found in primarily in the bottom 10cm of a floe. The ideal conditions for algal growth in the lowest ten centimeters are columnar ice and salinity between 1.2â and 4â. The temperature would be between -0.8°C and -1.4°C.

One of the first factors that could drastically change the algae population, would be a change in the atmospheric conditions. A change such as this would cause a slight melting in the column of ice, resulting in deteriorated columnar ice. The Melosira may prefer the columnar ice for its structural stability, but the way in which light passes through may play a large part in Melosira's preference. Since the columnar ice crystals have more uniform edges, the light travels through more directly. If the crystals were to melt, and form granular crystals, then the increased diffraction would lessen the amount of light getting to the algae.

Warming ice can have other effects on Melosira too. Since the brine particles trapped in the ice are heavier than the water molecules, they tend to drain to the bottom of the ice, leaving a nice gradation (as observed in figure 3) of increasing salinity as the depth increases. The warmer the ice becomes, the greater the rate of brine drainage. Under circumstances where the ice is warmed considerably, the brine will form channels through the ice as it migrates downwards towards the water. These channels introduce new means of obstruction for the light on its path to the algae, and also introduce pockets of air to the structure of the ice.

Ice entrained sediment is another source of sunlight interference in the ice column. The sediment is black, and on the average composed of 5.32% sand, 32.71% silt, and 61.97% clay (Meese, 1994). The sediment is found on and in the ice, due to a number of causes. Hurricanes off the coastlines Japan and Russia will churn up sediment from the ocean bottom into the water column, where it is swept into the Bearing Strait, and frozen in ice. Shore-fast ice often churns up beach sand, and occasionally chunks are brought out to sea.

This sediment found on the ice, due to its black color, absorbs the heat emanated from the sun, and slowly melts the ice around it. The sediment will literally eat through the ice, and in large quantities also inhibits the amount of sunlight getting to the algae. The results show that no Melosira was found coexisting with sediment in the same core, which suggests that sediment is detrimental to algae population. Observations showed that in dirty areas, occasional colonies of dead algae were found, but none living.

With the sensitivity of algae to specific environmental conditions, it is not surprising that algae is found in only 16% of the polar ice-pack (Tucker, 1998). Algae, being a primary producer, is the basis for the entire arctic marine food chain. Melosira is the source of food for zooplankton, which feed the whales, and fish. The fish feed marine mammals, seals, walrus, and whales, which ultimately feed the Iñupiat Eskimos, and polar bears. Melosira, when not eaten by the zooplankton, tends to secrete a membrane that develops into a diatomic shell. The alga then goes into a "dormant" phase, where it sinks to the ocean floor. When on the ocean floor, the algae feed the benthic organisms such as sea cucumbers and brittle stars. These organisms then feed certain fish, and marine mammals (such as walruses and seals), which feed the polar bears, and which feed the Iñupiat as well.

The Arctic marine food chain depends largely on the abundance of algae, and any fluctuation in its abundance can have a magnified effect in each link of the chain. Fluctuations of algae's abundance arise from changes in ice-conditions, which are typically caused by weather changes. Fluctuations in algae population stemming from changing ice-conditions reverberate all the way to the top of the food chain. High order predators such as polar bears are sensitivity indicators of subtle climate changes. A rise or fall in temperature can drastically alter the population of polar bears by increasing or decreasing the amount of ice, or by affecting the food supply. It may reduce the population by a decrease in the algae concentration, causing more and more dramatic declines in populations of dependent species.

Due to algae's dependence on ice-conditions, and the food chain's dependence on algae, the health of the ecosystem can be measured in part by the effects of climate on the ice. These data indicate that any change in climate will have an effect on this dynamic system, and the effects are more often than not (in the short term) negative. But effect of climate change on the polar ice-pack are not only biological. A warming climate that melts the ice-pack also impacts the polar ice caps on Greenland and Antarctica. Rapid sea-level rise associated with increased rates of ice-cap melting has global implications. A large increase in fresh water added to the ocean may disrupt the ocean circulation patterns which would have a major effect on climate. The impacts of global warming are magnified by the rate at which climate change occurs.

Global warming may be caused by the building concentration of CO2 in our atmosphere. The CO2 is trapping the heat in our atmosphere (i.e. the "greenhouse effect") causing a warming of our atmosphere that can partly be contributed to natural global warming, but is also partly human induced. The industrial fumes and automobile exhausts being spilled into the air, are intensifying the greenhouse effect - causing unprecedented temperature changes during this century.

Many effects of the global warming process can be seen in the form of recurrent weather patterns, such as El Niño due to the increasing amounts of water evaporating from the ocean. A similarly immediate threat from global warming is threatening Maine's coastline.

The intensifying storminess in conjunction with the rising sea-level, is causing increasing erosion on Maine coastlines. Maine coastal villages are being threatened by erosion, as storms impact beaches and coastal development. In the long term, it threatens more than Maine's economy, it threatens the very land that coastal communities are built on.

An event that may cause sea-level to eventually rise, was the collapse of a portion of the Ross Ice Shelf in Antarctica. In theory, since the ice-shelf was submerged anyway, it's break away did not effect the sea-level dramatically, but the open water it exposed may contribute to increasingly warm climate changes, and the threatening collapse of more major Antarctic ice-shelves.

Since the ice-pack acts as a temperature buffer for the ocean, a sudden amount of open water can completely throw off the climatic balance, and start an intensifying cycle of conditions that will exist long after the open water has refrozen. Small factors such as this are causing minor climatic changes that are combining to produce the drastic effects that will end up being the fate of the east coast of the United States.

On a biological standpoint, the collapse of these ice-shelves, and the gradual melting of the polar ice-cap and glaciers, will have a direct effect on worldwide marine ecosystems. Since many organisms are very sensitive to changes in their environment, even slight changes in salinity and temperature can have drastic effects on their population. And by adding sudden, large quantities of fresh water to the ocean, many organisms may not be able to adapt fast enough to the decreased salinity before it is able to reach equilibrium. Events such as this could easily effect the Maine fishing industry. The population fluctuations of the organisms that fisherman rely on, will have resulted from fluctuations in the food chain that they are a part of, if not directly.

A warming climate could also contribute to fluctuations in species' migratory habits, which would also have an effect on Maine. The endangered Right Whale (Eubalaena glacialis) relies on the resources provided by the edge of the polar ice cap in the summer, and in the winter stays near the eastern and western coasts of the United States, the Maine coast acting one of their winter retreats. If the ice-edge were to retreat due to a warming climate, then the distances for the migrating whales would grow to be much greater, causing longer migratory periods, and shorter periods of rest. This could prove inefficient and too draining for the animals, and reduce their populations even more.

The Right Whale, when summering in the Arctic, will not only be affected by the retreating pack-ice, but will also be affected by the food chain fluctuations caused by the changes in ice-conditions. Since the Right Whale relies on filter-feeding zooplankton, and the zooplankton rely on ice algae, decreases in the amount of algae will have an effect on the whales.

Such is the case for other migratory animals that play parts in multiple ecosystems. King Eider ducks (Somateria spectabilis) are known for their massive flocks to and from the Arctic. They commonly migrate to the ice-pack for the Arctic summer, and come as far south as New England. Other migratory birds summering in the Arctic include: the Snow Bunting (Plectrophenax nivalis), the Lapland Longspur (Calcarius lapponicus), and the Oldsquaw (Clangula hyemalis) among others.

This is why studying the Arctic can be so beneficial to understanding the environment we live in. Climatic effects on biota can be observed in the Arctic far before they can be observed anywhere else, and can help us predict the types of changes that will be taking place in our environment.

Conclusion

By observing the population of Melosira in the polar ice-pack, we not only are able to make educated predictions about the health of the Arctic ecosystems, but we are also able to predict the success of migratory animals in Maine. Since Melosira populations serve as a primary indicator of both changes in ice-conditions, and changes in the Arctic marine ecosystem, the health of animals reliant on the arctic can be predicted. With algae as an indicator of changes in ice-conditions, observing the reaction of the pack-ice to global climate change allows us to make predictions about the health of marine ecosystems in general - based on the salinity and temperature relationships between the ice-pack and the ocean. The rate at which Maine's coastlines will erode based on oceanic conditions will be an invaluable resource. The combined effects of intensified storm surges and rising sea level are being felt in Maine's coastal communities, as beaches are washing away, and ocean-front development is threatened.

Ice algae and its dependence on ice-conditions may be used as a proxy of the effects of global change in Maine and the rest of the world. The Arctic can be used as an exaggerated model depicting what will eventually happen elsewhere. The Arctic ecosystem's strong dependence on its environment shows how subtle environmental changes can have drastic effects. These effects can be expected to show up in a delayed manner everywhere else in the world, which is what makes the algae in the Arctic such an invaluable indicator.

References

• Gow, A. J., Tucker, W.B. (September, 1991). Physical and dynamic properties of sea ice in the polar oceans. Monograph 91-1. U.S. Army Corps of Engineers Cold Regions Research & Engineering Laboratory.
• Horner, R. Sckley, S.F., Dieckmann, G.S., (1992). Ecology of sea ice biota. Polar Biology. 12: 417-427.
• Lopez, B. (1986). Arctic Dreams. New York: Charles Scribner's Sons.
• Meese, D.A., Reimntz, E., Tucker, W.B., Gow, A.J., Bischof, J., Darby, D. (1997).
• Evidence for radionuclide transport by sea ice. The Science of the Total Environment, 202, 267-278.
• Peterson, R.T. (1980). A Field Guide to the Birds East of the Rockies. (4th ed.). Boston Houghton Mifflin.
• Udvardy, M.D. (1997). The Audubon Society Field Guide to North American Birds: Western Region. New York: Alfred A. Knopf.
• United States Coast Guard, (27 April - 18 July). Arctic West Summer 1998 Cruise Report. Polar Icebreaker Cruise Reports, COMDTINST 16155.2B.
• Witness the Arctic Program (August, 1998) Chronicles of the Arctic System Science Research, 6 (2), 1-23.

World Wide Web Sites:

• www.antarctica.com - Antarctica.com
• www.biosci.cbs.umn.edu - University of Minnesota
• www.arcus.org - Arctic Research Consortium of the United States
• www.crrel.asace.army.gov - Cold Regions Research and Engineering Lab
• www.oz.net/~polarsea - Polar Sea