A device for reaming holes in ice

A device for reaming holes cored through ice sheets is described. Its advantage being that its operation is possible while lines to equipment below the ice, such as used in in situ productivity studies in lakes, remain in place, without damage. This device was designed to maintain the dimensions of a SIPRE ice auger hole, similar devices of differing dimensions would serve to maintain other hole diameters.     

Bionic Design and Finite Element Analysis of Elbow in Ice Transportation Cooling System

With the increase in mining depth, mine heat harm has appeared to be more prominent. The mine heat harm could be resolvedor reduced by ice refrigeration. Thus, ice transportation through pipeline becomes a critical problem; typically flowresistance occurs in the elbow. In the present study, according to the analysis of the surface morphology of fish scale, abiomimetic functional surface structure for the interior wall of elbow is designed. Based on the theory of liquid-solid two phaseflow, a CFD numerical simulation of ice-water mixture flowing through the elbow is carried out using finite element method.Conventional experiments of pressure drop and flow resistance for both bionic and common elbows are conducted to test theeffect of the bionic elbow on flow resistance reduction. It is found that with the increase in the ice mass fraction in the ice-watermixture, the effect of bionic elbow on resistance reduction becomes more obvious.     

Ice crystals formed in tissue during cryosurgery. II. Electron microscopy

Tissues frozen by means of a cryosurgical probe have been examined by electron microscopy following techniques designed to preserve the ice crystal spaces.Ice crystals appeared similar whether tissues were quenched or not following cryosurgery and the various techniques of dehydration resulted in similar ice crystal architecture.Ice crystal spaces in the area deep to the freezing probe were intracellular both in epithelium and muscle although in the muscle zone some fibers contained large and others small crystal spaces. It is suggested that this might be due to variations in the local blood supply.At the periphery of the frozen area ice crystals were usually extracellular producing gross distortion of the cells which, however, retained intracellular structural integrity. These results are consistent with the belief of many workers that intracellular ice is lethal while extracellular ice is not, but no evidence of penetration of cell membrane by ice crystals was seen.     

Numerical investigations of transient heat transfer characteristics and vitrification tendencies in ultra-fast cell cooling processes

During freezing, cells are often damaged directly or indirectly by ice formation. Vitrification is an alternative approach to cryopreservation that avoids ice formation. The common method to achieve vitrification is to use relatively high concentrations of cryoprotectant agents (CPA) in combination with a relatively slow cooling rate. However, high concentrations of CPAs have potentially damaging toxic and/or osmotic effects on cells. Therefore, establishing methods to achieve vitrification with lower concentrations of CPAs through ultra-fast cooling rates would be advantageous in these aspects. These ultra-fast cooling rates can be realized by a cooling system with an ultra-high heat transfer coefficient (h) between the sample and coolant. The oscillating motion heat pipe (OHP), a novel cooling device utilizing the pressure change to excite the oscillation motion of the liquid plugs and vapor bubbles, can significantly increase h and may fulfill this aim. The current investigation was designed to numerically study the effects of different values of h on the transient heat transfer characteristics and vitrification tendencies of the cell suspension during the cooling processes in an ultra-thin straw (100 microm in diameter). The transient temperature distribution, the cooling rate and the volume ratio (x) of the ice quantity to the maximum crystallizable ice of the suspension were calculated. From these numerical results, it is concluded that the ultra-high h (>10(4) W/m2 K) obtained by OHPs could facilitate vitrification by efficiently decreasing x as well as the time to pass through the dangerous temperature region where the maximum ice formation happens. For comparison, OHPs can decrease both of the parameters to less than 20% of those from the widely used open pulled straw methods. Therefore, the OHP method will be a promising approach to improving vitrification tendencies of CPA solutions and could also decrease the required concentration of CPAs for vitrification, both of which are of great importance for the successful cryopreservation of cells by vitrification.     

We Scream for Nano Ice Cream

There is a wide range of new products emerging from nanotechnology, and “nano ice cream” is an easy one that you can use to teach topics from surface area to volume applications. In this activity, students learn how ice cream can be made smoother and creamier tasting through nanoscience. By using liquid nitrogen to cool the cream mixture, students can sample nano ice cream and investigate how decreasing the size of the ice crystal affects the taste and texture of the ice cream.     

Sea‐ice loss boosts visual search: fish foraging and changing pelagic interactions in polar oceans

Light is a central driver of biological processes and systems. Receding sea ice changes the lightscape of high‐latitude oceans and more light will penetrate into the sea. This affects bottom‐up control through primary productivity and top‐down control through vision‐based foraging. We model effects of sea‐ice shading on visual search to develop a mechanistic understanding of how climate‐driven sea‐ice retreat affects predator–prey interactions. We adapt a prey encounter model for ice‐covered waters, where prey‐detection performance of planktivorous fish depends on the light cycle. We use hindcast sea‐ice concentrations (past 35 years) and compare with a future no‐ice scenario to project visual range along two south–north transects with different sea‐ice distributions and seasonality, one through the Bering Sea and one through the Barents Sea. The transect approach captures the transition from sub‐Arctic to Arctic ecosystems and allows for comparison of latitudinal differences between longitudes. We find that past sea‐ice retreat has increased visual search at a rate of 2.7% to 4.2% per decade from the long‐term mean; and for high latitudes, we predict a 16‐fold increase in clearance rate. Top‐down control is therefore predicted to intensify. Ecological and evolutionary consequences for polar marine communities and energy flows would follow, possibly also as tipping points and regime shifts. We expect species distributions to track the receding ice‐edge, and in particular expect species with large migratory capacity to make foraging forays into high‐latitude oceans. However, the extreme seasonality in photoperiod of high‐latitude oceans may counteract such shifts and rather act as a zoogeographical filter limiting poleward range expansion. The provided mechanistic insights are relevant for pelagic ecosystems globally, including lakes where shifted distributions are seldom possible but where predator–prey consequences would be much related. As part of the discussion on photoperiodic implications for high‐latitude range shifts, we provide a short review of studies linking physical drivers to latitudinal extent.     

An ice-binding protein from an Antarctic sea ice bacterium

An Antarctic sea ice bacterium of the Gram-negative genus Colwellia, strain SLW05, produces an extracellular substance that changes the morphology of growing ice. The active substance was identified as a approximately 25-kDa protein that was purified through its affinity for ice. The full gene sequence was determined and was found to encode a 253-amino acid protein with a calculated molecular mass of 26,350 Da. The predicted amino acid sequence is similar to predicted sequences of ice-binding proteins recently found in two species of sea ice diatoms and a species of snow mold. A recombinant ice-binding protein showed ice-binding activity and ice recrystallization inhibition activity. The protein is much smaller than bacterial ice-nucleating proteins and antifreeze proteins that have been previously described. The function of the protein is unknown but it may act as an ice recrystallization inhibitor to protect membranes in the frozen state.     

Sympagic macro-fauna from multiyear sea-ice near Svalbard

Summary The object of the present investigation was to map the distribution and abundance of sympagic fauna (= ice fauna) (>350 m) within the perennial sea ice zone near Svalbard and to study relations between the sympagic fauna and the age and history of its ice substrate. The sampling took place in July/August 1986 and September 1988 using SCUBA-operated sampling gear (suction samplers, plankton nets with especially designed frames for sampling at the sea-ice/seawater interface, and underwater cameras). The amphipods Apherusa glacialis, Onisimus sp., and Gammarus wilkitzkii were the most conspicuous sympagic species both years. Scattered individuals of the amphipods Gammaracanthus loricatus, Weyprechtia penguis and the polychaete Harmathoinae indet. were also recorded. A. glacialis was the most numerous and contributed near 65% of the collected specimens in both years, with a maximum density exceeding 2000 individuals/m². However, G. wilkitzkii was on average larger, and contributed most to the biomass (1986: 80%; 1988: 77%). The average biomass of sympagic fauna in 1986 and 1988 was estimated to be 4.7 g/m² and 8.3 g/m² respectively. Biomass values reported here are ten to hundred times higher than what is found within the seasonal sea ice zone. Autochthonous sympagic species, like A. glacialis, Onisimus sp. and G. wilkitzkii, have a permanent association with ice. The seasonal sea ice zone will thus have to be recolonized every year resulting in lower densities compared to multiyear ice. It is suggested that the speed of the ice leaving the Polar Basin through the Fram Strait is too high for the sympagic fauna to remain its position in the sea ice zone. The result is an annual loss in the order of 7^*10⁵ tons of sympagic fauna from the perennial sea ice zone.     

Mechanism of initiation of intracellular ice formation

Intracellular ice crystallization was studied by the method of cryomicroscopy in the systems modeling a biological suspension, such as erythrocyte concentrates. Initiation of crystallization by extracellular ice through hydrophilic channels has been shown to be the most probable mechanism of intracellular ice formation.     

Determining the Ice-binding Planes of Antifreeze Proteins by Fluorescence-based Ice Plane Affinity

Antifreeze proteins (AFPs) are expressed in a variety of cold-hardy organisms to prevent or slow internal ice growth. AFPs bind to specific planes of ice through their ice-binding surfaces. Fluorescence-based ice plane affinity (FIPA) analysis is a modified technique used to determine the ice planes to which the AFPs bind. FIPA is based on the original ice-etching method for determining AFP-bound ice-planes. It produces clearer images in a shortened experimental time. In FIPA analysis, AFPs are fluorescently labeled with a chimeric tag or a covalent dye then slowly incorporated into a macroscopic single ice crystal, which has been preformed into a hemisphere and oriented to determine the a- and c-axes. The AFP-bound ice hemisphere is imaged under UV light to visualize AFP-bound planes using filters to block out nonspecific light. Fluorescent labeling of the AFPs allows real-time monitoring of AFP adsorption into ice. The labels have been found not to influence the planes to which AFPs bind. FIPA analysis also introduces the option to bind more than one differently tagged AFP on the same single ice crystal to help differentiate their binding planes. These applications of FIPA are helping to advance our understanding of how AFPs bind to ice to halt its growth and why many AFP-producing organisms express multiple AFP isoforms.     

Bacterial recovery from ancient glacial ice

Ice that forms the bottom 18 m of a 308 m ice core drilled from the Guliya ice cap on the Qinghan-Tibetan plateau in Western China is over 750000 years old and is the oldest glacial ice known to date. Fourteen bacterial isolates have been recovered from samples of this ice from approximately 296 m below the surface (mbs). Based on 16S rDNA sequences, these are members of the alpha- and beta-proteobacterial, actinobacterial and low-G + C Gram-positive bacterial lineages. 16S rDNA molecules have also been amplified directly, cloned and sequenced from the ice-core melt water. These originated from Pseudomonas and Acinetobacter gamma-proteobacterial species. These results demonstrate that bacteria can be recovered from water ice that has frozen for time periods relevant to biological survival through terrestrial ice ages or during interplanetary transport.     

The timing of sea ice formation and exposure to photosynthetically active radiation along the Western Antarctic Peninsula

Understanding the flow of solar energy into ecosystems is fundamental to understanding ecosystem productivity and dynamics. To gain a better understanding of this fundamental process in the Antarctic winter sea ice, we produced a model that estimates the time-integrated exposure of seasonal Antarctic sea ice to PAR through the use of remotely sensed sea ice concentrations, sea ice movement and spatially distributed PAR calculations that account for cloud cover and have applied this model over the past three decades. The resulting spatially distributed estimates of sea ice exposure to PAR by mid-winter are evaluated in context of changes in the timing of sea ice formation that have been documented along the Western Antarctic Peninsula (WAP) region and its potential effects on the variation (seasonal and inter-annual) in the accumulation of sea ice algae in this region. The analysis shows the ice pack is likely to have large inter-annual variations (10–100 fold) in productivity throughout the autumn to winter transition in the sea ice along the WAP. Moreover, the pack ice is likely to have spatial structure in regards to biological processes that cannot be determined from analysis of sea ice concentration information alone. The resulting inter-annual variations in winter processes are likely to affect the dynamics of Antarctic krill (Euphausia superba).     

Cloning and expression of afpA, a gene encoding an antifreeze protein from the arctic plant growth-promoting rhizobacterium Pseudomonas putida GR12-2

The Arctic plant growth-promoting rhizobacterium Pseudomonas putida GR12-2 secretes an antifreeze protein (AFP) that promotes survival at subzero temperatures. The AFP is unusual in that it also exhibits a low level of ice nucleation activity. A DNA fragment with an open reading frame encoding 473 amino acids was cloned by PCR and inverse PCR using primers designed from partial amino acid sequences of the isolated AFP. The predicted gene product, AfpA, had a molecular mass of 47.3 kDa, a pI of 3.51, and no previously known function. Although AfpA is a secreted protein, it lacked an N-terminal signal peptide and was shown by sequence analysis to have two possible secretion systems: a hemolysin-like, calcium-binding secretion domain and a type V autotransporter domain found in gram-negative bacteria. Expression of afpA in Escherichia coli yielded an intracellular 72-kDa protein modified with both sugars and lipids that exhibited lower levels of antifreeze and ice nucleation activities than the native protein. The 164-kDa AFP previously purified from P. putida GR12-2 was a lipoglycoprotein, and the carbohydrate was required for ice nucleation activity. Therefore, the recombinant protein may not have been properly posttranslationally modified. The AfpA sequence was most similar to cell wall-associated proteins and less similar to ice nucleation proteins (INPs). Hydropathy plots revealed that the amino acid sequence of AfpA was more hydrophobic than those of the INPs in the domain that forms the ice template, thus suggesting that AFPs and INPs interact differently with ice. To our knowledge, this is the first gene encoding a protein with both antifreeze and ice nucleation activities to be isolated and characterized.     

A collapsible opening-closing net for zooplankton sampling through ice

The English umbrella net is a new-design vertical closing netdeveloped to sample zooplankton populations in under-ice environments.Operating on the principle of an umbrella, this wide-mouth netfits through a hole drilled in sea ice and expands below theice to sample the water column. A messenger-activated releasecloses the net for a discrete sample and collapses the frameso that it can be retrieved back through the hole in the ice.Nets of this design were used for extensive sampling on Fletcher'sIce Island (T-3) in the Arctic Ocean.     

Aerial surveys for Antarctic minke whales (Balaenoptera bonaerensis) reveal sea ice dependent distribution patterns

This study investigates the distribution of Antarctic minke whales (AMW) in relation to sea ice concentration and variations therein. Information on AMW densities in the sea ice‐covered parts of the Southern Ocean is required to contextualize abundance estimates obtained from circumpolar shipboard surveys in open waters, suggesting a 30% decline in AMW abundance. Conventional line‐transect shipboard surveys for density estimation are impossible in ice‐covered regions, therefore we used icebreaker‐supported helicopter surveys to obtain information on AMW densities along gradients of 0%–100% of ice concentration. We conducted five helicopter surveys in the Southern Ocean, between 2006 and 2013. Distance sampling data, satellite‐derived sea‐ice data, and bathymetric parameters were used in generalized additive models (GAMs) to produce predictions on how the density of AMWs varied over space and time, and with environmental covariates. Ice concentration, distance to the ice edge and distance from the shelf break were found to describe the distribution of AMWs. Highest densities were predicted at the ice edge and through to medium ice concentrations. Medium densities were found up to 500 km into the ice edge in all concentrations of ice. Very low numbers of AMWs were found in the ice‐free waters of the West Antarctic Peninsula (WAP). A consistent relationship between AMW distribution and sea ice concentration weakens the support for the hypothesis that varying numbers of AMWs in ice‐covered waters were responsible for observed changes in estimated abundance. The potential decline in AMW abundance stresses the need for conservation measures and further studies into the AMW population status. Very low numbers of AMWs recorded in the ice‐free waters along the WAP support the hypothesis that this species is strongly dependent on sea ice and that forecasted sea ice changes have the potential of heavily impacting AMWs.     

Seasonal variation in freeze tolerance and ice content of the tree frog Hyla versicolor

Freeze tolerance and ice content of Hyla versicolor showed pronounced variation between summer (June) and winter (December). Summer frogs survived freezing at -3 degrees C for up to 9 hr and ice accumulation up to 50% of their total body water. A time course of ice formation indicated that an equilibrium level was reached in approximately 15 hr. Thus, the lethal ice content was less than the equilibrium ice content for these conditions (63.1%). A second group was induced to enter an overwintering condition by holding them through the summer and then subjecting them to a progressive reduction in temperature and photoperiod for 2 months. These frogs survived freezing for 48 hr at -3 degrees C. Their equilibrium ice content at this temperature was significantly lower (52.5%) than comparably treated summer animals. In the winter acclimatized group, frozen frogs had substantially higher blood glucose levels than unfrozen frogs (22.7 mumol/ml vs. 1.33 mumol/ml), but glycerol levels were not elevated after freezing. Freezing frogs conditioned for overwintering at -7 degrees C resulted in a higher equilibrium ice content (62.6%), but none survived. It is evident that in preparation for overwintering, frogs reduce the amount of ice formed at a given subzero temperature, but there is little indication of a substantial change in the total amount of ice tolerated.     

Identification of the sea ice diatom biomarker IP25 in Arctic benthic macrofauna: direct evidence for a sea ice diatom diet in Arctic heterotrophs

Currently, the impact of declining seasonal sea ice extent in the Arctic on polar food webs remains uncertain. Previously, a range of proxy techniques has been employed to determine links between sea ice or phytoplankton primary production and the Arctic marine food web, although it is accepted that such approaches have their limitations. Here, we propose a novel approach to tracing sea ice primary production through Arctic food webs using the sea ice diatom biomarker, IP₂₅. Various benthic macrofaunal specimens were collected between March and May 2008 from Franklin Bay in the Amundsen Gulf, Arctic Canada, as part of the International Polar Year–Circumpolar Flaw Lead system study. Each specimen was analysed for the presence of the sea ice diatom biomarker IP₂₅ in order to provide evidence for feeding by benthic organisms on sea ice algae. IP₂₅ was found in nineteen out of the twenty-one specimens analysed, often as the most abundant of the highly branched isoprenoid biomarkers detected. The stable isotope composition of IP₂₅ (δ¹³C = −17.1 ± 0.5‰) in the sea urchin (Strongylocentrotus sp.) specimens was similar to that reported previously for this biomarker in Arctic sea ice, sedimenting particles and sediments. It is concluded that detection of IP₂₅ in Arctic benthic macrofauna represents a novel approach to providing convincing evidence for feeding on sea ice algae. It is also proposed that analysis of IP₂₅ may be used to trace trophic transfer of sea ice algal-derived organic matter through Arctic food webs in the future.     

Polar bears in a warming climate

Polar bears (Ursus maritimus) live throughout the ice-coveredwaters of the circumpolar Arctic, particularly in near shoreannual ice over the continental shelf where biological productivityis highest. However, to a large degree under scenarios predictedby climate change models, these preferred sea ice habitats willbe substantially altered. Spatial and temporal sea ice changeswill lead to shifts in trophic interactions involving polarbears through reduced availability and abundance of their mainprey: seals. In the short term, climatic warming may improvebear and seal habitats in higher latitudes over continentalshelves if currently thick multiyear ice is replaced by annualice with more leads, making it more suitable for seals. A cascadeof impacts beginning with reduced sea ice will be manifestedin reduced adipose stores leading to lowered reproductive ratesbecause females will have less fat to invest in cubs duringthe winter fast. Non-pregnant bears may have to fast on landor offshore on the remaining multiyear ice through progressivelylonger periods of open water while they await freeze-up anda return to hunting seals. As sea ice thins, and becomes morefractured and labile, it is likely to move more in responseto winds and currents so that polar bears will need to walkor swim more and thus use greater amounts of energy to maintaincontact with the remaining preferred habitats. The effects ofclimate change are likely to show large geographic, temporaland even individual differences and be highly variable, makingit difficult to develop adequate monitoring and research programs.All ursids show behavioural plasticity but given the rapid paceof ecological change in the Arctic, the long generation time,and the highly specialised nature of polar bears, it is unlikelythat polar bears will survive as a species if the sea ice disappearscompletely as has been predicted by some.     

Environmental Predictors of Ice Seal Presence in the Bering Sea

Ice seals overwintering in the Bering Sea are challenged with foraging, finding mates, and maintaining breathing holes in a dark and ice covered environment. Due to the difficulty of studying these species in their natural environment, very little is known about how the seals navigate under ice. Here we identify specific environmental parameters, including components of the ambient background sound, that are predictive of ice seal presence in the Bering Sea. Multi-year mooring deployments provided synoptic time series of acoustic and oceanographic parameters from which environmental parameters predictive of species presence were identified through a series of mixed models. Ice cover and 10 kHz sound level were significant predictors of seal presence, with 40 kHz sound and prey presence (combined with ice cover) as potential predictors as well. Ice seal presence showed a strong positive correlation with ice cover and a negative association with 10 kHz environmental sound. On average, there was a 20–30 dB difference between sound levels during solid ice conditions compared to open water or melting conditions, providing a salient acoustic gradient between open water and solid ice conditions by which ice seals could orient. By constantly assessing the acoustic environment associated with the seasonal ice movement in the Bering Sea, it is possible that ice seals could utilize aspects of the soundscape to gauge their safe distance to open water or the ice edge by orienting in the direction of higher sound levels indicative of open water, especially in the frequency range above 1 kHz. In rapidly changing Arctic and sub-Arctic environments, the seasonal ice conditions and soundscapes are likely to change which may impact the ability of animals using ice presence and cues to successfully function during the winter breeding season.     

The physico-chemical characterization of a boiling stable antifreeze protein from a perennial grass (Lolium perenne)

We have characterized a cold-induced, boiling stable antifreeze protein. This highly active ice recrystallization inhibition protein shows a much lower thermal hysteresis effect and displays binding behavior that is uncharacteristic of any AFP from fish or insects. Ice-binding studies show it binds to the (1 0 1 0) plane of ice and FTIR studies reveal that it has an unusual type of highly beta-sheeted secondary structure. Ice-binding studies of both glycosylated and nonglycosylated expressed forms indicate that it adsorbs to ice through the protein backbone. These results are discussed in light of the currently proposed mechanisms of AFP action.