Roundup: Plant Life in Extreme Conditions, Freshwater in Tibet, and Alaskan Salmon

The Growth of Simple Plant Life in Extreme Conditions

From Polar Biology: “Aerial dispersal in the colonization of bare ground by lichens in the polar regions remains poorly understood. Potential colonists may arrive continually, although extreme abiotic conditions limit their viability. [The authors] investigated the vegetative dispersal of Antarctic macrolichens along a successional gradient (from 8.6–7.0 ka BP up to present) after glacial retreat on James Ross Island, in the Antarctic Peninsula region.“

Read more about the research here.

Olga Bohuslavová, one of the lead researchers on this project, speaking with Prince Charles (Source: Masaryk University).

 

Future Warming and Water Resource Availability in the Tibetan Plateau

From Earth Science Reviews: “Future climate warming is expected to have a significant effect on the operation of Earth and Ecological systems. A key concern in the future is water resource availability. In regions such as the Tibet Plateau (TP) lakes and glaciers appear to be highly sensitive to climate forcing and variations in the size and extent of these systems will have profound socio-economic and environmental consequences in South and Central Asia.”

Learn more about how these water sources will be affected here.

Qinghai Lake, China’s largest lake in China, located about 100 kilometers west of Xining (Source: Iwtt93/Flickr).

 

What Does Glacial Retreat in Alaska Mean for the Salmon Population?

From BioScience: “Glaciers cover 10 percent of our planet’s land surface, but as our climate warms, many glaciers are shrinking. As glacial retreat proceeds northward along the Pacific coast of the continental United States, through Canada, to Alaska, it is creating new stream habitat for salmon that has not existed in millennia. When and how will this new stream rollout happen? Where will salmon be distributed in the future?”

Find out what they discovered about the future of the salmon population here.

Alaskan salmon attempt to swim upstream (Source: Andrew E. Russell/Flickr).

 

Roundup: Harbor Seals, River Communities and Iceberg Melt

Glacial Habitats of Alaskan Harbor Seals

From Marine Mammal Science: “Harbor seals, Phoca vitulina, use diverse haul-out substrates including ice calved by tidewater glaciers. Numbers of seals at glacial and terrestrial haul-outs on the southeastern Kenai Peninsula, Alaska, were assessed using aerial, vessel, and video surveys. Mean annual abundance at glacial and terrestrial haul-outs differed temporally. From 2004 to 2011, numbers of seals counted during the molt increased 5.4%/yr at glacial haul-outs and 9%/yr at terrestrial haul-outs while numbers of pups increased 5.0%/yr at glacial sites and 1.5%/yr at terrestrial sites.”

Learn more about how harbor seals use glacial habitats here.

Lounging harbor seals (Source: Gregory “Slobirdr” Smith/Flickr).

 

River Invertebrate Biodiversity

From Nature Ecology & Evolution: “Global change threatens invertebrate biodiversity and its central role in numerous ecosystem functions and services. Functional trait analyses have been advocated to uncover global mechanisms behind biodiversity responses to environmental change, but the application of this approach for invertebrates is underdeveloped relative to other organism groups. From an evaluation of 363 records comprising >1.23 million invertebrates collected from rivers across nine biogeographic regions on three continents, consistent responses of community trait composition and diversity to replicated gradients of reduced glacier cover are demonstrated.”

Read more about the response of river invertebrates to decreasing glacier cover here.

River invertebrates, like this one here, were shown to respond reasonably predictably to decreasing glacier cover globally (Source: University of Leeds/Twitter).

 

Greenland’s Freshwater Budget

From Nature Geoscience: “Liquid freshwater fluxes from the Greenland ice sheet affect ocean water properties and circulation on local, regional and basin-wide scales, with associated biosphere effects. The exact impact, however, depends on the volume, timing, and location of freshwater releases, which are poorly known. In particular, the transformation of icebergs, which make up roughly 30–50% of the loss of the ice-sheet mass to liquid freshwater, is not well understood. Here we estimate the spatial and temporal distribution of the freshwater flux for the Helheim–Sermilik glacier–fjord system in southeast Greenland using an iceberg-melt model that resolves the subsurface iceberg melt. By estimating seasonal variations in all the freshwater sources, we confirm quantitatively that iceberg melt is the largest annual freshwater source in this system type.”

Discover more about the freshwater flux of iceberg melt from Greenland’s ice sheet here.

Satellite image of summer (left) and winter (right) fjord conditions for Helheim (H), Midgaard (M) and Fenris (F) glaciers (Source: Moon et al.).

Supercool water found near glaciers

Temperatures in Spitbergen, Norway may be below freezing, but the water around the Glacier Front isn’t frozen, researchers Eugene Morozov from Shirshov Institute of Oceanology, Aleksey Marchenko from the University Center in Svalbard, and Yu. D. Fomin from Moscow Institute of Physics and Technology, found,

This process of supercooling, also known as undercooling, happens when the temperature of a liquid or a gas drops below its freezing point without it becoming a solid. Experiments on Youtube show people taking liquid water out of their freezers, and pouring it on white plate under normal temperature. As the water hits the plate, it instantaneously turns into ice.

There are two methods for making water supercool. The first method, like the one show in Youtube videos, can only be achieved when water is extremely pure. Impure water has ‘nucleation sites,’ where water molecules gather and gradually solidify during the freezing process. People can make supercool water with a simple refrigerator and a bottle of pure water.

The other method relates to salinity and water pressure. Supercool water can occur under conditions of heat removal, different rates of heat and salt diffusion and rapid pressure decrease, chemists Valeria Molinero and Emily Moore in University of Utah found after much experimentation in 2011.

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Figure 1: Supercool water with no impurity. Source: BBC

With higher pressure, water will freeze at temperatures below 0 degree Celsius. In addition, higher salinity will also result in a lower freezing temperature. According to Figure 2, the freezing point will change depending on salinity and water pressure.

 

 

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Figure 2 Relationship between freezing point and Salinity/ Water Pressure. Source: London South Bank University

Previously, supercool water had only been created under laboratory conditions. However, the new findings from Eugene Morozov and his colleagues show that there is Glaciohydraulic supercooling water around the glacier that mixes and cools with high salinity and high pressure water.

The bottom of the glacier is approximately 15 m from the sea surface. The melt water (fresh water) flows from the glacier at a temperature of 0 C. After mixing with surrounding seawater with a temperature of – 1.8 C, melt water cools to temperatures lower than -1.8 C while ascending to the surface. As it surfaces, its temperature is close to the freezing point of seawater(-1.8 C). That temperature is lower than the freezing temperature of freshwater and its internal energy does not reach the equilibrium state required for freezing. This freshwater from glaciers cools to temperatures lower than freezing without becoming ice.

 

 

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Figure 3: Scheme showing freshwater flow from the glacier and measurement of water properties near the glacier front

The finding in Spitbergen is supported by research from Dr. Igor Dmitrenko, who works for Leibniz Institute of Marine Sciences at University of Kiel. He found that supercool water also exists in polynas, an area of open water surrounded by sea ice. However, this condition cannot be observed all the time since it cannot exist for an extended period. Supercooling water will transfer to the other states of water in a short time. It could play a crucial role in sea ice formation, researchers say.

“While frazil ice [needle-shaped ice fragments in water] formation in the Arctic was carefully examined over the past several years for the St. Lawrence Island and the Storfjord polynyas […] the processes controlling the sea ice growth due to supercooled water and frazil ice formation over the Siberian Arctic shelf remain poorly understood, owing to the scarce instrumental records and extreme climatic conditions,” Dmitrenko wrote in his study.  “From these considerations, supercooling might play a critical role in the shelf salt budget and sea ice production”

Check more information about glacier at Glacierhub.