Roundup: Antarctic Soils, Himalayan Glacial Vulnerability, and Lake Pastahué 

Impacts on Prokaryotes in Antarctic Soils

From Antarctic Science: “The soil microbiome was investigated at environmentally distinct locations on King George Island in the South Shetland Islands (Antarctic Peninsula) … the taxonomic analysis revealed 20 bacterial and archaeal phyla, among which Proteobacteria (29.6%), Actinobacteria (25.3%), Bacteroidetes (15.8%), Cyanobacteria (11.2%), Acidobacteria (4.9%) and Verrucomicrobia (4.5%) comprised most of the microbiome.”

Read more about how deglaciation and human impacts affect prokaryotic communities in Antarctic soils here.

King George Island, Antarctica (Source: Acaro/Creative Commons).

 

Borehole Thermometry and Vulnerability of Himalayan Glaciers

From Nature Scientific Reports: “From boreholes drilled in the glacier’s ablation area, we measured a minimum ice temperature of −3.3 °C, and even the coldest ice we measured was 2 °C warmer than the mean annual air temperature. Our results indicate that high-elevation Himalayan glaciers are vulnerable to even minor atmospheric warming.”

Read more about Himalayan glacial vulnerability due to complex surface topography and seasonal variations here.

Bhagirathi Peaks, Garhwal Himalaya (Source: Richard Haley/Flickr).

 

Record of Environmental Change in Lake Pastahué

From SAGE Journals: “The aim of this study was to reconstruct the environmental and climatic history of the last 1000 years of Lake Pastahué through a multi-proxy sediment core analysis … the variations observed since the beginning of the 20th century could be the result of the combined effect of anthropogenic activities and the increase in temperature recorded in south-central Chile and Patagonia.”

Read more about documenting paleo records on Lake Pastahué here.

Lake Pastahué, Chile (Source: Pablo Acevedo).
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Glacier Retreat Exposes New Breeding Ground for Kelp Gulls in Antarctica

Glacier retreat caused by anthropogenic climate change is often in the news because of its impacts on sea level rise and shrinking habitats. However, a recent study published by Lee et al. in the Journal of Ethology has found that glacier retreat on King George Island could have a positive impact on kelp gulls, exposing new ground with suitable breeding sites.

Kelp gulls have a large range in the southern Hemisphere (Source: Yuri Hutflesz / Creative Commons).
Kelp gulls have a large range in the southern Hemisphere (Source: Yuri Hutflesz/Creative Commons).

The kelp gull, Larus dominicanus, breeds on coasts and islands throughout the Southern Hemisphere, as detailed on the IUCN Red List. It has a large range, from subantarctic islands and the Antarctic peninsula to coastal areas of Australia, Africa and South America. Breeding occurs between September and January, with nests usually built on bare soil, rocks or mud in well-vegetated sites.

King George Island, the largest of the South Shetland islands, is part of the kelp gull’s range. It can be found off the coast of the Antarctic peninsula and is a nesting ground for seabird species during the summer months. Numerous research stations are located on the island, and its coasts are home to a variety of wildlife, such as elephant and leopard seals, and Adelie and Gentoo penguins.

A map of Barton Peninsula on King George Island (Source: NOAA).
A map of Barton Peninsula on King George Island (Source: NOAA).

Research has shown that breeding nests of kelp gulls have been recorded in ice-free areas of King George Island since the 1970s. Studies of Gentoo penguin populations  also suggest that rapid glacier retreat could give species that favor ice-free environments a chance to expand their habitats. As such, Lee et al. used a combination of satellite photographs and field observations of kelp gull nests in newly exposed locations to study possible correlations between glacier retreat and nest distribution in the Barton Peninsula on King George Island.

Based on eight different satellite images, Lee et al. determined that glaciers on the Barton Peninsula have retreated 200-300m from the coast since 1989, exposing an area of approximately 96,000 square kilometers. Within this area, they found up to 34 kelp gull breeding nests between 2012 and 2016, along with evidence that kelp gulls have been breeding on newly exposed ground for decades.

A map of the study site showing the extent of glacier retreat and locations of kelp gull nests (Source: Lee et al.).
A map of the study site showing the extent of glacier retreat and locations of kelp gull nests (Source: Lee et al.).

As the glaciers on the Barton peninsula retreat inland, moraine surfaces made up of glacial soil and rock debris are left on the coast. Rocks within these moraines provide shelter from harsh Antarctic coastal winds, reducing the stress to the gulls arising from these winds. This makes the exposed areas more attractive for breeding.

Previous studies have suggested that kelp gulls select nest sites in favorable locations with rock and vegetation cover, and kelp gull populations are known to nest in neighboring areas like Potter Peninsula and Admiralty Bay. In this study, kelp gull nests were found between 40-50cm away from the rocks, suggesting that a combination of rocks and vegetation present on the moraines help to create favorable nesting conditions.

The rocky moraines left on the coast by retreating glaciers are suitable breeding ground for kelp gulls (Source: Acaro / Creative Commons).
The rocky moraines left on the coast by retreating glaciers are suitable breeding ground for kelp gulls (Source: Acaro/Creative Commons).

These gulls probably originated from neighboring kelp gull populations, such as those on King George Island or the Nelson Islands. Continued retreat of glaciers on King George Island could expose larger areas of suitable breeding ground, attracting more gulls from neighboring islands and increasing kelp gull populations.

Anthropogenic climate change and glacier retreat have many adverse effects, but research like this sheds light on the ways in which some species might benefit in unexpected ways.

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Roundup: Porcupine Glacier, Patterned Ground and Ciliates

Roundup: Glacier Calving, Ciliates and the Alps

 

A calving event in Porcupine Glacier shows rapid retreat

From the American Geophysical Union: “Porcupine Glacier is a 20 km long outlet glacier of an icefield in the Hoodoo Mountains of Northern British Columbia that terminates in an expanding proglacial lake. During 2016 the glacier had a 1.2 square kilometer iceberg break off, leading to a retreat of 1.7 km in one year. This is an unusually large iceberg to calve off in a proglacial lake, the largest ever seen in British Columbia or Alaska… The retreat of this glacier is similar to a number of other glaciers in the area: Great Glacier, Chickamin Glacier, South Sawyer Glacier and Bromley Glacier. The retreat is driven by an increase in snowline/equilibrium line elevations which in 2016 is at 1700 m, similar to that on South Sawyer Glacier in 2016.”

Learn more about the retreat of Porcupine glacier, and view satellite images here.

A glacier in Kenai National Park, where Porcupine glacier is located
A glacier in Kenai National Park, where Porcupine glacier is located (Source: Dubhe/Wikimedia Commons)

 

Patterned ground exposed by glacier retreat in the Alps

From the Biology and Fertility of Soils: “Patterned ground (PG) is one of the most evident expressions of cryogenic processes affecting periglacial soils, where macroscopic, repeated variations in soil morphology seem to be associated with small-scale edaphic [impacted by soil] and vegetation gradients, potentially influencing also microbial communities. While for high-latitude environments only few studies on PG microbiology are available, the alpine context, where PG features are rarer, is almost unexplored under this point of view… These first results support the hypothesis that microbial ecology in alpine, periglacial ecosystems is driven by a complex series of environmental factors, such as lithology [study of the general physical characteristics of rocks], altitude, and cryogenic activity, acting simultaneously on community shaping both in terms of diversity and abundance.”

Learn more about glacier retreat in the Italian Alps here.

Glaciers in the Italian Alps
Glaciers in the Italian Alps (Source: Glac01 /Wikimedia Commons)

 

Microorganisms found in glacial meltwater streams

From Polar Biology: “Microbial communities living in microbial mats are known to constitute early indicators of ecosystem disturbance, but little is known about their response to environmental factors in the Antarctic. This paper presents the first major study on ciliates [single-celled animals bearing cilia] from microbial mats in streams on King George Island (Antarctica)… Samples of microbial mats for ciliate analysis were collected from three streams fed by Ecology Glacier. The species richness, abundance, and biomass of ciliates differed significantly between the stations studied, with the lowest numbers in the middle course of the stream and the highest numbers in the microhabitats closest to the glacier and at the site where the stream empties into the pond. Variables that significantly explained the variance in ciliate communities in the transects investigated were total organic carbon, total nitrogen, temperature, dissolved oxygen, and conductivity.”

Learn more about the ciliates here.

One of the glaciers on King George Island
One of the glaciers on King George Island (Source: Acaro/Wikimedia Commons).
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Polar Ecology in Flux Due to Climate Change

Glacial melting and rising ocean temperatures are affecting the feeding, breeding and dispersion patterns of species, such as krill, cod, seals and  polar bears, in the polar regions, according to two recently published research articles. This climatic shift could create an imbalance in the regional ecology and negatively impact numerous species as the effects of climate change worsen.

The first article reflects on how a threat to a key species in Antarctica may shake up the food chain, while the other considers how a changing habitat in the Arctic could skew the population trends of several interconnected species and create a systemic imbalance in the ecosystem.

Glacier-originated melt-water creek carrying large amounts of particles. (Source: V. Fuentes/Nature)

After a nine-year study of krill in Potters Cove, a small section of King George Island off the coast of Antarctica, a team of South American and European marine biologists published their research this past June in the scientific journal Nature.

Krill are shrimp-like sea creatures that feed mostly on plankton.  Since they extract their food from the water by filtering it through fine combs, they are known as filter feeders.  Krill are found in all oceans and are an abundant food source for many marine organisms.  In the polar regions, predators such as whales often rely on krill as their only consistent food source.

The authors of this first piece found that a destruction of the krill population could extend undermine the Antarctic food web that relies on the presence of the small creatures.

 The study launched after stacks of dead krill washed ashore at Potters Cove in 2002, lining the coast. The article’s nine authors, Verónica Fuentes, Gastón Alurralde, Bettina Meyer, Gastón E. Aguirre, Antonio Canepa, Anne-Cathrin Wölfl, H. Christian Hass, Gabriela N. Williams and Irene R. Schloss, suggest the first observed  and subsequent stranding incidents are connected to large volumes of particulate matter dumped into the ocean by melting glaciers. The high level of tiny rock particles carried by the glacial melt water may have clogged the digestive system of filter feeders like krill.

The researchers conducted a series of experiments in which they exposed captive krill to water with varying amounts of particulates. The krill’s feeding, nutrient absorption and general performance were all significantly inhibited after 24 hours of exposure to concentrations of particles similar to those found in the plums of glacial runoff.

Stranded krill along the southern shore of Potters Cove, King George Island (Source: V. Fuentes/Nature).

Although krill are mobile creatures and can usually avoid harmful environments, exposure to the highly concentrated particles interfered with their ability to absorb nutrients from their food.  The krill became weak, which resulted in their inability to fight local ocean currents and their subsequent demise.

About 90 percent of King George Island is covered in glaciers that are melting and discharging particles into the surrounding marine ecosystem, according to the article.  Similarly, an overwhelming majority of the 244 glacier fronts, a location where a glacier meets the sea, studied on the West Antarctic Peninsula have retreated over the last several decades, which suggests that high particulate count from glacial meltwater may be occurring in other parts of Antarctica.

Since much of the Antarctic coast is not monitored and most dead krill sink to the bottom of the ocean, the authors caution that these stranding events likely represent a small fraction of the episodes.  

In another recent study on climate change’s impacts on wildlife, scientific researchers with the Norwegian Polar Institute focus their attention on the high Arctic archipelago of Svalbard, Norway.  They found that glacial melting and changes in sea ice have impacted numerous land and sea animals in the Arctic. These shifts have the potential to influence more creatures. The study, by Sebastien Descamps and his coauthors, was published this May in the scientific journal Global Change Biology.

Tidewater glacier in Greenland, taken from helicopter (Source: Brocken Inaglory/CC)

Some species, such as the pink-footed goose, are benefiting from the warming Arctic climate, however. Lower levels of spring snow cover and earlier melting has expanded the time for its breeding and the area of available breeding grounds, which will likely lead to an increase in the geese population.  

However, the success or the overpopulation of one species can cause an imbalance in the ecosystem and negatively affect numerous other organisms.  As the authors explain, “An extreme increase in a herbivore population [like the geese] has the potential to affect the state of Svalbard’s vegetation substantially, with possible cascading consequences for other herbivorous species and their associated predators.”

The authors conclude, “even though a few species are benefiting from a warming climate, most Arctic endemic species in Svalbard are experiencing negative consequences induced by the warming environment.”

Polar bears and the Arctic ringed seal are among the species which are suffering the impacts of a warming Arctic.  Seals breed on sea ice and depend on snow accumulation on the ice in order to form lairs for their pups.  The snow lairs provide protection from the harsh winter and predators.  As ocean temperature warms and the season of sea ice formation shortens, there is less time for accumulation of snow.  Thus, many seals are giving birth on bare ice, which leads to a much higher pup mortality rate.

Weddell seals (Source: changehali/CC).

This  article also points out that tidewater glaciers have become increasingly important foraging areas for several species, including seals, seabirds and whales.  Additionally, these creatures’ presence makes the glacier fronts fruitful hunting grounds for polar bears. Icebergs drifting near the glacier fronts create valuable resting areas in the hunting grounds for many of these animals.

The authors hypothesize that the increase in icebergs calved from the glacier fronts could counterbalance the ecological loss resulting from the disappearance of sea ice. Yet this may only offer a brief reprieve for the Arctic species that depend on the ice.  

“Continued warming is expected to reduce the number of tidewater glaciers and also the overall length of calving fronts around the Svalbard Archipelago.  Thus, these important foraging hotspots for Svalbard’s marine mammals and seabirds will gradually become fewer and will likely eventually disappear,” wrote the authors.

Taken together, these two recent articles show that glacier retreat, as well as other forms of loss of ice, have negative impacts on high-latitude ecosystems, both in the Arctic or in Antarctica. There are strong similarities between these two cases, distant from each other in spatial terms but close to each other in their shared vulnerabilities.

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