Arctic – BIOL3056 2016/17

Turmoil in the Tundra: the Cold Hard Truth

Posted on March 23, 2017 by Nikol Raykova

A harsh, cold land with no tree cover, temperatures averaging between -12 to -6 degrees Celsius, and enveloped in snow for the majority of the year (National Geographic, 2017).

Until the brief summer months bring warmth and plains become decorated with swathes of wildflowers. This is the tundra biome.

screen-shot-2017-03-22-at-22-35-14

Figure 1: Arctic animals

A home to many endearing (and endangered) animals like the Arctic fox, snowy owl, lemmings and grey-wolves (Figure 1) (National Geographic, 2017). But why should we care about some cold desolate place? The answer is simple yet complicated.

It comes down to the ever looming climate change disaster. The Arctic tundra has been recognised as one of the most vulnerable biomes to environmental change. Permafrost (permanently frozen ground) covers much of the tundra, with the top 30cm or so of it melting and refreezing with the changing seasons (NOAA, 2017). However, in the last few decades increasing global temperatures, and human developments have lead to more melting. This can have a negative effect on the ecosystem as the more permafrost that’s melted, along with the later arrival of the autumn freeze time means that shrubs and other vegetation, that couldn’t take root before, can now grow, potentially altering the habitat (Heijmans et al 2016).

screen-shot-2017-03-22-at-21-44-41

Figure 2. Different types of interactions within an Arctic tundra ecosystem. Solid lines = consumption between predator and prey between trophic levels (different parts of the food web Dotted lines = interaction between species in the same trophic level (same part of the food web) (Ims and Fuglei, 2005).

Northward expansion of Low Arctic trees and shrubs has been seen due to the warmer temperatures and longer growing seasons. This has other ecological consequences, like change in the biodiversity of an area if new species are introduced (Post et al., 2009). Overall ecosystem structure change has been recorded in multiple studies, including interaction between animal species (Hobbie et al 2017).

Although they may be cute and fluffy Arctic foxes are one of the key species within Arctic tundra ecosystems because they are a top predator, meaning they help control herbivore populations (Figure 2). It’s been seen that where abandoned Arctic fox dens are found, the productivity of that area (i.e. plant growth, number of insect and herbivores etc.) has increased (Killengreen et al., 2007).

A study by Ims and Fuglei, (2005) has shown that lemmings are also key players in the Arctic tundra. These rodents are a key prey species for a number of predators that rely on certain densities of lemming populations to allow them to reproduce, as they need sufficient amount of food. Lemmings breed during the winter season and undergo growth under the snow, leading to a peak in population density in spring. This means that with predicted warmer winters (hence less snow, and more rain) lemming peak times are very likely to alter, with population peaks happening during autumn (Putkonen and Roe, 2003). A change in the number of prey available, will impact predator numbers. Arctic fox and snowy owl numbers are likely to decrease as they will have lower reproductive rates during years when peak lemming populations occur autumn.

A change in the relationships between key species like this can have unprecedented effects on their communities and ecosystems. With a grim future ahead for cold-loving animals and ecosystems.

References

National Geographic, (2017). Explore the World’s Tundra. Available at: http://www.nationalgeographic.com/environment/habitats/tundra-biome/ [Accessed 17 Mar. 2017].

NOAA (2017). Arctic Change – Land: Permafrost. Available at: https://www.pmel.noaa.gov/arctic-zone/detect/land-permafrost.shtml [Accessed 17 Mar. 2017].

Post, E., Forchhammer, M. C., Bret-Harte, M. S., Callaghan, T. V., Christensen, T. R., Elberling, B., … & Ims, R. A. (2009). Ecological dynamics across the Arctic associated with recent climate change. Science, 325(5946), 1355-1358.

Ims, R. A., & Fuglei, E. V. A. (2005). Trophic interaction cycles in tundra ecosystems and the impact of climate change. Bioscience, 55(4), 311-322.

Killengreen, S. T., Ims, R. A., Yoccoz, N. G., Bråthen, K. A., Henden, J. A., & Schott, T. (2007). Structural characteristics of a low Arctic tundra ecosystem and the retreat of the Arctic fox. Biological Conservation, 135(4), 459-472.

Putkonen J, Roe G. 2003. Rain-on-snow events impact soil temperatures and affect ungulate survival. Geophysical Research Letters 30: 1188.

Heijmans, M. M. P. D., van Huissteden, J., Li, B., Wang, P., Limpens, J., Berendse, F., & Maximov, T. C. (2016). Can wet summers trigger permafrost collapse at a Siberian lowland tundra site?. INTERNATIONAL CONFERENCE ON PERMAFROST, 2016-06-20/2016-06-24

Hobbie, J. E., Shaver, G. R., Rastetter, E. B., Cherry, J. E., Goetz, S. J., Guay, K. C., … & Kling, G. W. (2017). Ecosystem responses to climate change at a Low Arctic and a High Arctic long-term research site. Ambio, 46(1), 160-173.

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Invasion of the Arctic: How warming temperatures have led to non-native species introduction

Posted on March 23, 2017 by Anonymous

Source: Animal Club (2017) Available from: http://elelur.com/mammals/arctic-fox.html — Arctic Fox (Animal Club, 2017. Available from: http://elelur.com/mammals/arctic-fox.html)

In the eyes of an arctic fox (Alopex lagopus), the temperatures of the tundra provide seamless living conditions. Their adaptations to low temperatures make their arctic habitats suitable for them to hunt, reproduce and in turn survive. However, their survival is threatened by increasing temperatures in the arctic, as it has become more suitable for red foxes (Vulpes Vulpes), too (Killengreen et al., 2007). As the red fox invades the territory of the arctic fox, they undergo competition for land and prey. Although this has not led to a direct decline in arctic fox numbers, it can have further impacts on food webs and community dynamics within the Arctic ecosystem (Gallant et al., 2012).

This is just an example of the new reality in the Arctic; ice is melting due to increased temperatures, and the ecosystem is changing vastly (Serreze et al., 2000). Many of us are aware that global temperatures are rising due to increased greenhouse gas emissions entering the atmosphere, however the rate of temperature change varies across the globe. Where average temperatures have increased by 0.4°C over the past 150 years, it is believed that warming in arctic regions has been almost 3 times higher (IPCC, 2014).

The increased warming creates an environment which is suitable for other, non-native species (Post et al., 2009) – such as the example of the Red Fox. Species towards the South of the Arctic have increased their range, placing pressure on the existing Arctic communities (Root et al., 2003). This ‘invasion’ is not limited to animal species; invasive species in the form of plant communities can also intrude on the ecosystem. For example, the warming has allowed shrub tundra to expand into a wider variety of habitats, and Boreal forest has begun to infringe on the tundra ecosystem (Hinzman et al., 2005).

Source: Animal Photgraphics (2017) Available from: http://alaskaphotographics.photoshelter.com/image/I00009qTaSPpYpaA — Arctic Ground Squirrel. (Animal Photgraphics, 2017. Available from: http://alaskaphotographics.photoshelter.com/image/I00009qTaSPpYpaA)

Another example is of the arctic ground squirrel (Urocitellus parryii), which acts as an ecosystem engineer through its key role in the food web (Wheeler, 2011). The arctic ground squirrel burrows into vegetated land as a mechanism for survival. The burrowing action also changes the composition of the soil, which is important for other ecological processes. However, as boreal, woody forests become more prominent than the easily accessible vegetation, the arctic ground squirrel loses its habitat (Donker & Krebs, 2011).

Figure 1. Predicted global surface temperature change, based on carbon emissions scenarios (IPCC, 2013).

The Arctic ecosystem is so complex that the full effects of climate change are not yet understood. This means that the invasive species described above have the potential to interrupt even more ecological processes and food webs. This could also affect human livelihood as we also rely on the stability of the food chain for survival. Furthermore, global warming is expected to cause temperatures to increase even more, dependent on emissions scenarios (Figure 1). This would cause the number of invasive species in both terrestrial and marine ecosystems to increase, threatening the existing communities to an even greater extent.

References

Donker, S. A., Krebs, C. J. (2011) Habitat Specific Distribution and Abundance of Arctic Ground Squirrels (Urocitellus parryii) in Southwest Yukon. Canadian Journal of Zoology, 89, 570-576.

Gallant, D., Slough, B. G., Reid, D. G., Berteaux, D. (2012) Arctic fox versus red fox in the warming Arctic: four decades of den surveys in north Yukon. Polar Biology, 35(9), 1421-1431.

Hinzman, L. D., Bettez, N. D., Bolton, W. R. et al. (2005) Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions. Climatic Change, 72(3), 251-298.

IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

IPCC (2014) Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, Switzerland, 151 pp.

Killengreen, S. T., Ims, R. A., Yoccoz, N. G., Brathen, K. A., Henden, J., Schott, T. (2007) Structural Characteristics of a Low Arctic Tundra Ecosystem and the Retreat of the Arctic Fox. Biological Conservation, 135(4), 459-472.

Post, E., Forchhammer, M. C., Bret-Harte, S. M. et al. (2009) Ecological Dynamics Across the Arctic Associated with Recent Climate Change. Science, 325(5946), 1355-1358.

Root, T. L., Price, J. T., Hall, K. R., Schneider, S. H., Rosenzweig, C., Pounds, J. A. (2003) Fingerprints of Global Warming on Wild Animals and Plants. Nature, 421, 57-60.

Serreze, M. C., Walsh, J. E., Chapin, F. S., III, Osterkamp, T., Dyurgerov, M., Romanovsky, V., Oechel. W. C., Morison, J., Zhang, T., Barry, R. G. (2000) Observational Evidence of Recent Change in the Northern High Latitude Environment. Climate Change, 46, 159-207.

Wheeler, H. C. (2011) Arctic Ground Squirrels Urocitellus parryii as Drivers and Indicators of Change in Northern Ecosystems. Mammal Review, 43, 238-255.

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From Sex to Starvation: Impacts of Decreasing Sea Ice on Arctic Communities

Posted on March 23, 2017 by James McWhirter

When you hear the word climate change, your mind immediately envisions a lonely polar bear swimming through a vast ocean looking for some lost ice on which to rest. If only it could be said that this was simply a dramatisation envisioned by climate change extremists in order to scare us into reducing our greenhouse emissions. If only…

Despite their constant denial, Fox News' can't say global warming isn't affecting their viewer ratings... (Mike Luckovich, 2015) — Despite their constant denial, Fox News’ can’t say global warming isn’t affecting their viewer ratings… (Image: Mike Luckovich, 2015)

Since the 1970’s, Arctic sea ice has decreased at a rate of 13.3% per decade, translating to loss of 13,500 square miles of sea ice coverage annually (Comiso et al., 2008). This drastic loss in sea ice coverage is having severely negative impacts on arctic animals that rely upon it for survival.

Sea ice extent (1970 - 2007) and projected decrease (2030 - 2100). (NOAA GFDL Model, n.d.) — Sea ice extent (1970 – 2007) and projected decrease (2030 – 2100). (Image: NOAA GFDL Model, n.d.)

Polar Bears:

Sea ice loss can be regarded as the main driver responsible for the 22% decrease in polar populations since 1987 (Derocher, 2004). Not only is the sea ice that is so necessary for them to hunt on disappearing, but their penile bones are fracturing during their most intimate moments.

While the function of a penis bone is still unknown (Simmons and Firman, 2013), many animals have them and it seems that chemical pollutants called PCBs may be having detrimental effects on the genitalia of polar bears. It is suggested that PCBs cause (Sonne et al., 2006; Sonne et al., 2015):

Smaller testes
Smaller penis bones
Lower calcium density in penis bones making them weaker

The loss of sea ice has accelerated the incidence of penile fracture as lowered foraging ability has led to skinnier bears, and therefore higher levels of circulating pollutants due to nutritional stress (Sonne et al., 2015).

Reduced reproductive success will have a severe impact on future populations.

“If it breaks, you probably won’t have a bear that can copulate” – Christian Sonne, 2015

Walruses:

Walruses are being forced to utilise sea ice in areas of greater depth where there is no food, or move onto solid land (Greenpeace, 2012). Thousands of deaths in beaching populations have been reported due to overcrowding and panic stampedes into the water (Chadwick and Fischbaik, 2008), which are particularly dangerous to young pups. A number of abandoned calves have been observed swimming in water with depths of 3000m, as mothers are forced to deeper waters due to lack of food at overcroweded beaches (Cooper et al, 2006).

Ice Seals:

Ice seals require sea ice for birthing, pup rearing and resting. As ice is melting earlier in the year, pups are unable to complete their 6 week nursing period due to the premature collapse of shelters, exposing them to the elements and predators (Greenpeace, 2012). In 2002, 75% of Harp seal pups died due to lack of ice (Carillo-Rubio, 2011).

Pup counts and the total number of Northern Fur Seal between 1978 and 2008. The decrease in total pup counts (000's) is notable. (COSEWIC Assessment and Status Report on the Northern Fur Seal in Canada, 2010) — Pup counts and the total number of Northern Fur Seal between 1978 and 2008 on St. Paul I island. The decrease in total pup counts (000’s) is notable. (COSEWIC Assessment and Status Report on the Northern Fur Seal in Canada, 2010)

Bowhead Whales:

Ice-free waters will potentially impact permanent marine mammals. Bowhead whales calve under sea ice as it provides a safe environment from Killer whales, their primary predators (Moore and Laidre, 2006). The future lack of sea ice is likely to increase predation on whale calves, decreasing the reproductive success of the species and decreasing global population. Increased exposure to the sun may also be detrimental as these whales are heat intolerant, and don’t have an ability to combat this.

This brief overview of some of the largest and most prevalent Arctic organisms provides a good indication of the fragility of the community assemblage present in this ecosystem.

Artists impression of the Arctic ecosystem and ultimately the organisms at risk from climate change (Image: Oceans North, The Pew Charitable Trust)

References:

Carillo-Rubio L (2011). Seals and their race against climate change. Climate Institute. www.climate.org/topics/ecosystems/seals-battle-climatechange.html [Accessed: 22/03/17]

Chadwick VJ & Fischbach AS (2008). US Geological Survey Factsheet 2008-3041. Pacific Walrus response to Arctic sea ice losses.

Cooper LW, Ashijian CJ, Smith SL, Codispoti LA, Grebmeier JM, Campbell RG & Sherr EB (2006). Rapid seasonal sea-ice retreat in the Arctic could be affecting Pacific walrus (Odobenus rosmarus divergens) recruitment. Aquatic Mammals, 32, 98–102.

Comiso J, Parkinson C, Gerston R, Stock L. (2008). Accelerated decline in the Arctic sea ice cover. Geophysical Research Letters. 35 (1), 41-49.

Derocher, A.E., Lunn, N.J., and Stirling, I. (2004). Polar bears in a warming climate. Integrative and Comparative Biology, 44, 163-176.

Greenpeace. (2012). Climate Change Impacts on Arctic Wildlife. Technical Report. (Review), 3-14.

Simmons L, Firman R. (2014). Experimental evidence for the evolution of the mammalian baculum by sexual selection. Evolution. 68 (1), 276-283.

Sonne C, Dyck M, Riget F, Jensen JE, Hyldstrup L, Letcher R . (2015). Penile density and globally used chemicals in Canadian and Greenland polar bears. Environment Research. 137 (1), 287-291.

Sonne C, Leifsson P, Dietz R, Born E. (2006). Xenoendocrine Pollutants May Reduce Size of Sexual Organs in East Greenland Polar Bears (Ursus maritimus). Environ. Sci. Technol., 40 (18), 5668–5674.

[Word Count: 500]

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In hot water: a planet surviving on thin ice.

Posted on March 22, 2017 by Katherine Turnbull

We’ve all seen it, the iconic lone polar bear stranded on the only ice in view. It has become the poster-boy for climate change (CC). CC is impacting almost every habitat on earth, but is the impact it’s having on Arctic organisms as bad as we’re made to believe?

The climate is changing. This mainly due to human’s releasing greenhouse gases into the atmosphere, causing the global phenomenon, CC. With increasing temperatures, melting ice stocks and changing ocean currents and weather, CC is one of the greatest challenge facing our generation (Steinfield et al., 2006).

The Arctic is expected to experience the most dramatic change out of any place on Earth (WWF, n.d). It is warming at twice the rate of the globe, a trend set to continue with global temperatures predicted to increase 1.4-5.8°C between 1990-2100 (Naware, 2015; Vihma, 2014). However, worryingly the so-far moderate warming has already impacted Arctic organisms; directly, through the immediate impacts, but also indirectly, by changing ecological interactions, such as predation and habitat distribution (Nahrgang et al., 2014). Heralding changing ecosystems and communities in the region.

It’s getting hot in here, shame polar bears can’t take off their clothes…

As temperature continues to rise, animals are moving poleward, to escape the heat or expand their territories (IPCC, 2007). This has caused ‘the clash of the animals’. For example, Red Foxes are migrating poleward placing their northern counterpart the Arctic Fox under threat (Post et al., 2009). The Red Fox is bigger and more aggressive, leading to a decline in populations of Arctic Foxes (Merchant, 2011). These invasions alter communities and carry threats of hybridization and increased disease (FAO, 2012). As the globe continues to warm, we will witness more unprecedented clashes like this…

Shame cuteness doesn't count for anything in nature right? Source: Foxesworld.com/ pintrest.com — **Shame cuteness doesn’t count for anything in nature right?** *Source: Foxesworld.com/ pintrest.com*

Increasing temperatures are altering the life-cycle events of birds, insects and plants. Bringing forward migration and reproduction. The Buff-breasted sandpiper is now nesting 10-days earlier due to increasing temperatures in the Arctic (Hattam, 2009).

‘If you meet a woman start talking about global warming, it’s a real icebreaker…’

The extent and thickness of ice coverage in the Arctic has reduced by 700,000m² compared to historical levels (1981-2010) (EPA, 2016). This has negatively impacted species that rely on the ice for prey, reproduction and predator avoidance (Post et al., 2009). This includes Walruses, who use sea ice to rest and reproduce, but now use land instead (Badore, 2014). This has been linked to decreasing populations, meaning it is so-far unclear if they will be able to successfully adapt. Changing extent and timing of sea ice formation impacts ecosystem resilience by affecting lower levels of the food chain, thereby impacting predators such as Polar Bears and Walruses who depend on them to survive (Derocher, 2004).

Walrus's resting on the beach instead of ice, their usual habitat, due to decreased ice stocks in the Arctic. Source: Walrus-world.com / Treehugger.com — **Walruses resting on the beach instead of ice, their usual habitat, due to decreased ice stocks in the Arctic.** *Source: Walrus-world.com / Treehugger.com*

So yes, the impacts are bad and possibly irreversible. The entire globe will be impacted through CC effecting the services the Arctic provides us with, such a climate regulation and natural resources (Post et al., 2009). So, what happens in the Arctic doesn’t just stay in the Arctic…

[Word count: 500]

References:

Badore, M. (2014). This is what it looks like when 35,000 walrus can’t find enough sea ice. [Online] [Last accessed: 20/03/2017] [Accessed at: http://www.treehugger.com/climate-change/what-it-looks-when-35000-walrus-cant-find-enough-sea-ice.html]

Derocher, A. (2004). Polar Bears in a Warming Climate. Integrative and Comparative Biology, 44(2), pp.163-176.

EPA. (2016). Climate Change Indicators: Arctic Sea Ice. [Online] [Last accessed: 19/03/2017] [Accessed at: https://www.epa.gov/climate-indicators/climate-change-indicators-arctic-sea-ice]

FAO. (2012). Wildlife in a changing climate. [Pdf]. [ Last accessed: 12/02/2017] [Accessed at:
http://www.fao.org/docrep/015/i2498e/i2498e.pdf]

Hattam, J. (2009). ‘Unsung’ Species Stressed by Climate Change Too. [Online]. [Last accessed: 20/03/2017] [Accessed at: http://www.treehugger.com/natural-sciences/unsung-species-stressed-by-climate-change-too.html]

IPCC. (2007). Climate Change 2007: Working Group II: Impacts, Adaptation and Vulnerability. [Online] [Last accessed: 18/02/2017] [Accessed at: https://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch1s1-3-5-2.html]

Merchant, B. (2011). Foxfight: Climate Change Causing Arctic & Red Foxes to Clash. [Online]. [Last accessed: 19/03/2017] [Accessed: http://www.treehugger.com/clean-technology/foxfight-climate-change-causing-arctic-red-foxes-to-clash.html]

Nahrgang, J., Varpe, Ø., Korshunova, E., Murzina, S., Hallanger, I., Vieweg, I. and Berge, J. (2014). Gender Specific Reproductive Strategies of an Arctic Key Species (Boreogadus saida) and Implications of Climate Change. PLoS ONE, 9(5), p.e98452.

Naware, R. (2015). 10 reasons why climate change in the Arctic affects us all. [Online]. [Last accessed: 11/03/2017] [Accessed at: https://www.earthhour.org/blog/10-reasons-why-climate-change-the-arctic-affects-us-all]

Post, E., Forchhammer, M., Bret-Harte, M., Callaghan, T., Christensen, T., Elberling, B., Fox, A., Gilg, O., Hik, D., Hoye, T., Ims, R., Jeppesen, E., Klein, D., Madsen, J., McGuire, A., Rysgaard, S., Schindler, D., Stirling, I., Tamstorf, M., Tyler, N., van der Wal, R., Welker, J., Wookey, P., Schmidt, N. and Aastrup, P. (2009). Ecological Dynamics Across the Arctic Associated with Recent Climate Change. Science, 325(5946), pp.1355-1358.

Schofield, O., Ducklow, H., Martinson, D., Meredith, M., Moline, M. and Fraser, W. (2010). How Do Polar Marine Ecosystems Respond to Rapid Climate Change? Science, 328(5985), pp.1520-1523.

Steinfeld, H. (2006). Livestock’s long shadow. 1st ed. Rome: Food and Agriculture Organization of the United Nations. Pp. xxi

Vihma, T. (2014). Effects of Arctic Sea Ice Decline on Weather and Climate: A Review. Surveys in Geophysics, 35(5), pp.1175-1214.

WWF. (N.d). Factsheet: Effects of climate change on arctic ecosystems. [Online]. [Last accessed: 10/03/2017] [Accessed at: https://c402277.ssl.cf1.rackcdn.com/publications/396/files/original/
Effects_of_Climate_Change_on_Arctic_Ecosystems_fact_sheet.pdf?1345753524]

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In hot water: a planet surviving on thin ice.

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