Abstract

Reduced sea ice has made a significant impact in the Arctic ecosystem. Organisms that depend on ice are particularly sensitive to the ice’s reduction. The Ivory Gull, because they are heavily dependent on the ice, could be a key indicator species to infer changes in the ice habitat. In addition to its reliance on the sea ice, the Ivory Gull has a high trophic level making it subject to bioaccumulation of chemicals that causes deterioration of their egg structures. This bioaccumulation, along with the reduction of sea ice, could be reasons for rapid decline in the populations of the Ivory Gull, a sign of some of the impacts occurring in the Arctic ecosystem (Miljeteig, 2009). Due to the current lack of data on the gull, more observations must be conducted in order to find a sufficient solution to help preserve this species. One way to make these observations would be to use Unmanned Aerial Vehicles (UAVs), as UAVs are capable of handling harsh temperatures, doing jobs that otherwise would endanger humans, observing animals without changing their natural behavioral patterns, and are gathering more accurate data to the likelihood of machines making more precise observations than human researchers (R. Bailey, Personal Communication, November 9, 2014). With the help of UAVs, the chances of knowing more about the Ivory Gull and finding new alternatives for seabirds and similar species in the face of environmental impacts due to sea ice reduction increases.

Introduction

Changes in the sea ice extent in the Arctic could strongly affect the organisms which inhabit that region. One effect it could have is changes to the Arctic food chain and the organisms that act as producers at the bottom of the food chain. Loss of the sea ice can cause changes in the blooming times of organisms like sea-ice algae and sub-ice plankton, which are the bottom of a chain that can lead all the way up to animals like polar bears and seabirds.

Organisms like the polar bears and the seabirds can also be affected by ice loss through increased human activity within the Arctic. The decrease in the sea ice extent allows for human activity in areas previously thought of as inaccessible. The increase in human activity in places where there previously was none could increase the amount of harmful material and impacts which could affect many organisms (Voss, 2014).

One particular organism that could be an indicator species for potential impacts due to changes in sea-ice extent is the Ivory Gull (Pagophila eburnea). The Ivory Gull, aside from being the northernmost breeding bird species, is also entirely dependant on the ice for all of its life stages. This makes the Ivory Gull highly vulnerable to environmental changes in the Arctic habitat. In 2002-2003, Canada showed an 80% decrease in population of the species (Miljeteig, 2009). The evident drop within population is alarming, bringing our attention towards the Ivory Gull. By looking at potential impacts the change in sea ice could have on the Ivory Gull, predictions can be made about future conditions for the Arctic and its inhabitants.

The Ice Sheet

Large changes in sea ice volume can be seen during the year. The Japan Aerospace Exploration Agency’s (JAXA) recorded data (1980 to present) shows an average difference of approximately two million km2 of Arctic sea ice extent throughout each year. The largest fluctuation in the range can be found from the beginning of August to the end of October. Water’s high latent heat capacity contributes to the lowest peak in ice extent, which happens in September. The heat accumulates in August when the temperature is at its annual peak and this results in a minimum ice extent in September. Since the melting of the ice is greatest between August and the end of October, there are implications that the temperature in the summer is increasing at a faster rate than any other time of the year. The increasing temperature anomaly seen in Figure 1 (above) shows temperature change has a strong inverse relationship with the ice extent as seen in Figure 2 (right).

Figure 1: Arctic-wide annual mean surface air temperatures (SAT) anomalies (UCAR, 2007).

 By noting the difference in the ice extent during the year, it is apparent that new winter ice forms every year. Although there is more new ice, that does not compensate for the great loss of ice caused by the warmer summers as seen in Figure 2. Organisms currently inhabiting the Arctic are being challenged more than organisms in the 1980s because the Arctic sea ice extent is changing more rapidly (Figure 2) due to increasing temperatures (Figure 1). Presently, the Ivory Gull is one of the organisms being affected by this physical change occurring in the Arctic.

Figure 2: Arctic September Sea Ice Extent: Observations and Model Runs. (NSIDC April 30, 2007.)

Future Sea Ice Model

In order to create an accurate sea ice model for the next fifty years, a graph which spans the course of thirty-three years (1979-2012, with five- year increments going from 1980-2005) was created using data from an article in the Journal of Statistical Distributions and Applications (Table 1).

Figure 3: Extrapolation using data from Arctic Sea Ice Extent from 1979 to 2064 in March and December (Journal of Statistical Distributions and Applications, 2014).

Table 1: Arctic Sea Ice Extent in March and September (Journal of Statistical Distributions and Applications, 2014)

This journal recorded the level of sea ice extent during those thirty-three years during the months of March and September, the times when the sea ice extent would be at its minimum and maximum. Using Excel, the team extrapolated this information from 2014 to 2064 to create a graph (Figure 3) for a 50-year model. Using the graph, it was determined that by September of 2064, the minimum level of ice coverage in the summer will have fallen to 0 km2. By March of 2064 however, the maximum ice coverage would be at 12 million km2 due to the formation of ice in the winter. The reason for this is that ice is melting at a faster rate than the rate at which the ice is forming.

Ivory Gull

The Ivory Gull was chosen as the indicator species for this paper for several reasons. The Ivory Gull is very sensitive to the ice dynamics of the Arctic environment. The Ivory Gull spends the entirety of its life on the sea ice habitat breeding, feeding, and wintering. Making the Ivory Gull highly vulnerable to changes within the environment; this vulnerability currently being experienced by the Ivory Gulls are experiencing currently and is estimated to continue in to the future due to the accelerating reduction in sea ice levels (Figure 3).

Diet

The Ivory Gull has diverse feeding habits. Their diet consists of small fish, supplemented by invertebrates. In the spring the seabirds are also known for scavenging carcasses and fecal matter, particularly sea mammal kills left on the ice by hunters (Bent, 1947). Due to the feeding habits of the Ivory Gulls they classified as scavengers. The Ivory Gull uses ice-free areas of the arctic water, otherwise known as polynyas, as their feeding grounds. However, many other animals also use polynas as their feeding grounds, which can cause the polynyas to become zones of contaminant transfer. Multiple contaminants, including mercury, have entered into the food web in polynyas through a chain of complex reactions. Because of this, the Ivory Gull is rapidly being impacted by the polluted environment through bioaccumulation of chemicals (Clayden, 2014).

The Ivory Gulls’ intake of mercury is most noticeable in the eggs. As mercury intake gradually increases, the eggs progressively become weaker. The bioaccumulation of mercury is not only detrimental towards the Ivory Gull, but also to mammals that prey on them. If the Ivory Gull persists in accumulating contaminants, the pollutants would cause more difficulty for adaptation, which in turn would affect the gulls’ overall survival (Birdlife International, Butchart, S., et al, 2014).

In addition to mercury, the Ivory Gull is effected by two major pollutants, dichlorodiphenyltrichloroethane (DDT) and polychlorinate biphenyl (PCB) (arkhive.org). DDT originates from insecticides, and PCB originates from fire retardants coated on wires. Both of these chemicals are hypothesized to have been introduced from rivers that flow into the Arctic Ocean (L. Bell, Personal Communication, November 7, 2014). The pollutants were mixed with food sources such as plankton. The plankton then work their way up the trophic levels and bioaccumulate in consumers, like the Ivory Gull. The bioaccumulation of PCB and DDT cause a thinning of the shell to the point where the shell cannot hold the yolk and the albumin. Miljeteig 2009) hypothesizes that mercury and PCBs are the root cause in Ivory Gull population decline. The Ivory Gull has suffered a steep decline in population largely due to the effect of increased pollutants on the biology of the bird (Miljeteig, 2009).

Behavior

The Ivory Gull feeds mostly by surface-plunging, dipping-to-surface, and surface-seizing on zooplankton, arctic cod, and shrimp. They also wade in shallow waters and scavenge on land (Planet of birds, 2014). The Ivory Gull is partially reliant on seals killed by polar bears which are a food source of these scavenger gulls. In the winter, part of their diet consist of feces, specifically that of polar bears, walrus, and seals (Divoky, 1976).

The Ivory Gull will not breed if the food sources are low. This is probably to ensure that neither the Ivory Gull nor its offspring perish during either the incubation or hatchling process (Birdlife International, 2014). The most common foods during the breeding season are fish and invertebrates, which would be fed to the young offspring. In years when there are adequate food sources, the Ivory Gull arrives at the breeding grounds from its wintering grounds while the snow is melting, usually between June and August. After the ground thaws it builds its nest using moss, grass, and lichen on flat ground or cliffs where both parents take turns incubating the clutch of one to two eggs. After two years, the Ivory Gull becomes mature (Planet of Birds, 2014).

Significance

The Ivory Gulls’ population plays a vital role in the Arctic ecosystem. This is especially true because it occupies a high trophic level. Stable populations of both the gulls and their prey are responsible for keeping the predator-prey relationship in balance so it does not tip in favor of either predators or prey. Without a balanced predator-prey relationship, organisms that are consumed by the Ivory Gull would, in theory, flourish. This would then affect the ecosystem, causing an imbalance in other organisms higher and lower in the food chain.

Predation

Mammals such as the polar bear and the arctic fox may benefit from the recession of sea ice relative to the Ivory Gull. As the Ivory Gull is pushed out of their typical range for foraging due to receding sea ice, it will venture into areas where it is more apt to be vulnerable to predators. Until the gull population declines, this food source will benefit the predators (Government of Canada, 2014). However, feeding on this gull may be dangerous for the predator’s health, since the gull might have ingested bioaccumulated harmful chemicals released by the melting sea ice (Arkive, 2008).

In addition to the threat of predatory animals, the people of Greenland, Norway, and Canada use the Ivory Gull for food. But with the significant decline of the species, these countries have set laws to regulate the hunting of the gull. With such small breeding grounds in Canada and Greenland, national governments’ protection efforts have become crucial for the gull’s survival. However, some hunters disregard these laws. Because of these poachers, governments of these countries need to lay down more severe regulations to maintain the Ivory Gulls’ population (Stenhouse, et al. 2004).

Effects on Ivory Gulls and Connection to other Organisms

If the ice continues to change at the rate which we have estimated in Figure 1, there will be many potential effects on the Ivory Gull population. As stated before, the Ivory Gull relies on the arctic ice environment for the entirety of its life. Because of this, a loss in the arctic ice would mean a loss of the living and breeding of the Ivory Gull and, furthermore, its hunting and wintering grounds.

The loss of any member of an ecosystem is bound to cause changes that would cause a ripple through the ecosystem. Our group inferred that because of their low population numbers and the fact that their diet mostly consists on small fish – occasionally supplemented with invertebrates and the remains of sea mammal kills – predictions about the overall effect on other organisms due to the loss of the Ivory Gull can be made (Bent, 1947). As mentioned before, some animals might even temporarily benefit through the loss of the Ivory Gulls as it would potentially tip the balance of the predator-prey relationship into their favor.

Alternative Steps and Solutions

Studying the Ivory Gull populations is arduous because individual gulls often use different colonies on a year-to-year basis and their locations are very remote. While there were successful aerial population surveys conducted previously, the actions of the gulls make it difficult to gather data on them (Gilchrist, 2005). In order for humans to aid in reversing the adverse effects of melting Arctic sea ice on Ivory Gulls, we must first better understand the bird itself. To do this, continual research from UAF and NOAA in the Arctic via Unmanned Aerial Vehicle (UAV) is recommended.

Using UAVs would be a good method to use in studying these birds for multiple reasons. First, after the initial cost of constructing a UAV that will withstand the harsh conditions of the Arctic region, equipment costs are relatively low compared to other methods. This will allow expenses to be better used in other areas of the study. By allowing machines to take the place of humans in the field, human inaccuracy could be reduced by having the surveys recorded with the use of technology. Digitally recorded surveys allow repeated population counts at a relatively low cost. Also, with UAVs taking the place of humans in the field, the possibility of any human casualties would be eliminated (R. Bailey, Personal Communication, November 9, 2014).

One important aspect of all observational studies is keeping the subject at hand undisturbed, before, during, and after the observation to avoid any bias in the results. Also, it is important to eliminate as much stress as possible on the specimen. A UAV will ensure that all necessary data is gathered while maintaining considerable distance from the specimen.

Conclusion

There is no denying that many changes have occurred within the Arctic in relation to the ice extent. If the trend and speed at which the sea ice is disappearing continues at the current rate, according to the model shown in Figure 1, it can be predicted that there will come a point when the Arctic sea ice will melt completely. The total disappearance of the sea ice would have many effects not only on human, but also on animal populations. For animals who only spend part of their life on the ice, this could mean many or few impacts. However, for animals like the Ivory Gull, who are dependent on the sea ice for all stages of life, the impacts could be much greater, because they would lose not only their nesting ground, but also their breeding, foraging, and wintering grounds (Marz, 2010). Therefore, we believe it is imperative that continued and thorough observations and population studies of the Ivory Gull be done as its health is a good indicator of the entire ecosystem.

With the help of UAVs, there is a chance that insightful observations could be made on mostly unstudied animals, such as the Ivory Gull. The cost of using UAVs, as mentioned before, can is relatively inexpensive after the initial cost of building, which can also be relatively inexpensive depending on the make and model. UAVs also offer a safer method of studying parts of the Arctic, and they can be used without causing an animal large amounts of stress or making them act outside of their normal behavioral patterns (R. Bailey, Personal Communication, November 9, 2014). By using UAVs, more accurate data may be gathered, and with more accurate data, the chance of helping organisms like the Ivory Gull to adapt to the potential impacts from increasing loss of Arctic sea ice will improve.

References

1. Bent, A.C. (1947) Life HIstory of North American Gulls and Terns. SmithsonianInstitution United States National Museum. Bulletin 113. Trenton, MA: WashingtonGovernment Printing Office.
2. BirdLife International (2014) Species factsheet: Pagophila eburnea. Downloaded from http://www.birdlife.org on October 23, 2014.
3. Blomqvist, S., & Elander, M. (1981). Sabine’s Gull (Xema sabini), Ross’s Gull(Rhodostethia rosea) and Ivory Gull (Pagophila eburnea) Gulls in the Arctic: A Review.Arctic Institute of North America. 34(2), 122-132.
4. Boertmann, D., Olsen, K., & Gilg, O. (2010). Ivory Gulls breeding on ice. Polar Record. 46(1), 86-88. doi:10.1017/S0032247409008626
5. Bogdal, C., Nikolic, D., Lüthi, M. P., Schenker, U., Scheringer, M., & Hungerbühler, K. (2010).Release of Legacy Pollutants from Melting Glaciers: Model Evidence and Conceptual Understanding. Environ. Sci. Technol. 44(11), 4063–4069 doi:10.1021/es903007h
6. Braune, B.M., Mallory, M.L., Gilchrist, H.G., Letcher, R.J. & Drouillard, K.G. (2007).Levels and trends of organochlorines and brominated flame retardants in Ivory Gull eggs from the Canadian Arctic, 1976 to 2004. Science of the Total Environment. 378: 403-417.
7. Braune, B.M., Mallory, M.L. & Gilchrist, H.G. 2006. Elevated mercury levels in adeclining population of Ivory Gulls in the Canadian Arctic. Marine Pollution Bulletin.52: 969-987.
8. Buckman A.H., Norstrom R.J., Hobson K.A., Karnovsky N.J., Duffe J., & Fisk A.T.(2004). Organochlorine contaminants in seven species of Arctic seabirds from northern Baffin Bay. Environ Pollut. 128(3), 327-38.
9. Chardine, J.W., Fontaine, A.J., Blokpoel, H., Mallory, M. and Hofmann, T. (2004). At-sea observations of Ivory Gulls (Pagophila eburnea) in the eastern Canadian high Arctic in 1993 and 2002 indicate a population decline. Polar Record. 40, 355-359. doi:10.1017/S0032247404003821.
10. Clayden, M.G., et al. (2014). Mercury bioaccumulation and biomagnification in a small Arctic polynya ecosystem. Science of the Total Environment. Article in Press.
11. Congdon, P. (2014). Modeling Changes in Arctic Sea Ice Cover: an application of generalized and inflated beta and gamma densities. Journal of Statistical Distributions and Applications. 1(3).
12. Divoky, G. J. (1976). The Pelagic Feeding Habits of Ivory and Ross’ Gulls. The Condor. 78(1), 85-90.
13. Environment Canada. (2014). Recovery Strategy for the Ivory Gull (Pagophila eburnea) in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. iv + 21pp.
14. Gilchrist, H.G., & M. Mallory. (2005). Declines in abundance and distribution of the ivory gull (Pagophila eburnea) in Arctic Canada. Biological Conservation. 121: 303-309.
15. Gilchrist, H.G., M. Mallory and F. Merkel. (2005). Can local ecological knowledge contribute to wildlife management? Case studies of migratory birds. Ecology and Society10(1): 20. [online] URL:http://www.ecologyandsociety.org/vol10/iss1/art20/
16. Gosling, S.N. (2013). The likelihood and potential impact of future change in the large-scale climate-earth system on ecosystem services. Environmental Science & Policy. 275: S15-S31.
17. Government of Canada. (2014, November 17). Species Profile: Ivory Gull. Retrieved November 29, 2014, from http://www.registrelep-sararegistry.gc.ca/species/speciesDetails_e.cfm?sid=50
18. Japanese Aerospace Exploration Agency. (2014, October). Arctic Sea Ice Extent. Arctic Sea-Ice Monitor. Retrieved October 23, 2014, from http://www.ijis.iarc.uaf.edu/en/home/seaice_extent.htm
19. JASMES -Climate. JAXA Satellite Monitoring for Environmental Studies. (2012). Sea Ice Extent Trends. Retrieved October 23, 2014, from http://kuroshio.eorc.jaxa.jp/JASMES/climate/index.html
20. Jiang, Y., Yang, E.J, Min, J.-O., Kang, S.-H., & Lee, S.H. (2013). Using pelagic ciliated microzooplankton communities as an indicator for monitoring environmental condition under impact of summer sea-ice reduction in western Arctic Ocean. Ecological Indicators. 34: 380-390.
21. Laxon, S.W., Giles, K.A., Ridout, A.L., Wingham, D.J., Willatt, R., Cullen, R., Kwok, R., Schweiger, A., Zhang, J., Haas, C., Hendricks, S., Krishfield, R., Kurtz, N., Farrell, S., & Davidson, M. (2013). CryoSat-2 estimates of Arctic sea ice thickness and volume. Geophysical Research Letters. 40:1-6.
22. Marz, S. (2010). Arctic Sea Ice Ecosystem: A summary of species that depend on and associate with sea ice and projected impacts from sea ice changes. Retrieved November 30, 2014, from http://www.caff.is/
23. Miljeteig C, Strøm H, Gavrilo MV, Volkov A, Jenssen BM, & Gabrielsen GW. (2009).High levels of contaminants in Ivory Gull Pagophila eburnea eggs from the Russian and Norwegian Arctic. Environ Sci Technol. 43(14), 5521-8.
24. National Audubon Society Birds. (2014). Ivory Gull (Pagophila eburnea). Retrieved October 18, 2014, from http://birds.audubon.org/species/ivogul
25. National Snow and Ice Data Center. (April 2, 2014). Arctic sea ice at fifth lowest annual maximum. NSIDC Arctic News and Analysis RSS. Retrieved October 18, 2014, from http://nsidc.org/arcticseaicenews/2014/04/arctic-sea-ice-at-fifth-lowest-annual-maximum/
26. National Snow and Ice Data Center. (April 30, 2007). Models Underestimate Loss of Arctic Sea Ice. NSIDC Arctic Newsroom. Retrieved October 18, 2014, from NationalSnow and Ice Data Center. http://nsidc.org/news/newsroom/20070430_StroeveGRL.html
27. UCAR University Corporation for Atmospheric Research. (April 30, 2007). Arctic Ice Retreating More Quickly Than Computer Models Project. NCAR News Release.
28. Norwegian Polar Institute. (n.d.). Ivory Gull (Pagophila eburnea). Retrieved October 18, 2014, from http://www.npolar.no/en/species/ivory-gull.html
29. Plowright, R. C., & Bateson, P. G. (1959). The breeding biology of the Ivory Gull in Spitsbergen. British Birds. 52(4), 21-24.
30. Renaud, W. E., & McLaren, P. L. (1982). Ivory Gull (Pagophila eburnea) Distribution in Late Summer and Autumn in Eastern Lancaster Sound and Western Baffin Bay. Arctic Institute of North America. 35(1), 141-148.
31. SeaWeb. Ocean Issues Brief – Ivory Gull. (2014). Retrieved October 18, 2014, from http://www.seaweb.org/resources/briefings/IvoryGull.php
32. Stenhouse, I.J. (2004) Canadian management plan for the Ivory Gull (Pagophila eburnea). Canadian Wildlife Service, St. John’s, NL.
33. Stern, G.A., Macdonald, R.W., Outridge, P.M., Wilson, S., Chetelat, J., Cole, A., Hintelmann, H., Loseto, L.L., Steffen, A., Wang, F., & Zdanowicz, C. (2012). How does climate change influence arctic mercury?. Science of the Total Environment. 414:22-42.
34. Trevena, A. J. & Jones, G. B. (2006). Dimethylsulphide and dimethylsulphonio- propionate in Antarctic sea ice and their release during sea ice melting. Marine Chemistry. 98(2-4), 210-222. doi:10.1016/j.marchem.2005.09.005
35. Varty, N., & Tanner, K. (2009). Background Document for Ivory Gull Pagophila eburnea. Ospar Commission. Retrieved October 18, 2014, from http://qsr2010.ospar.org/media/assessments/Species/P00410_Ivory_gull.pdf
36. Verboven, N., & Gabliensen, G. W. (2013). Status for contaminants in seabirds. BarentsPortal. Retrieved October 18, 2014, from http://barentsportal.com/barentsportal_v2.5/.php/en/2012-03-08-13-04-18/pollution/contaminants-in-seabirds/763-status-for-contaminants-in-seabirds
37. Voss, K. (2013). Arctic sea-ice loss has widespread effects on wildlife | Penn State University. Penn State News. Retrieved November 15, 2014, from http://news.psu.edu/story/283267/2013/08/01/research/arctic-sea-ice-loss-has-widespread-effects-wildlife