Accelerating thinning of Kenai Peninsula glaciers, Alaska

VanLooy, Jeffrey A.; Forster, R. R.; Ford, Andrew

doi:10.1029/2006gl028060

Cited by 34 publications

(24 citation statements)

References 19 publications

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“…It was important to examine the tolerance of the two primary Alaskan canopy-forming kelp species to natural sedimentation rates because this variable is predicted to change over the next decade with climatic changes (Svendsen et al 2002, VanLooy et al 2006). Both species reacted strongly but similarly to increases in sediments, indicating that there may be other factors that allow one species to become spatially or temporally dominant.…”

Section: Discussionmentioning

confidence: 99%

“…Sori of both species were collected in close proximity so that all sori at a site originated from equivalent environmental conditions. For Nereocystis, sori were gathered from floating blades at the surface melting in Alaska (VanLooy et al 2006), which probably increases the amount of glacially-discharged sediments that enters the nearshore environment. Spores within the water column can attach to suspended particles discharged by glacial and terrestrial runoff, preventing them from attaching to bottom substrate (Arakawa andMatsuike 1992, Arakawa 2005).…”

Section: Sorus Collection and Spore Releasementioning

confidence: 99%

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Susceptibility of Nereocystis luetkeana (Laminariales, Ochrophyta) and Eualaria fistulosa (Laminariales, Ochrophyta) spores to sedimentation

Deiman¹,

Iken²,

Konar³

2012

ALGAE

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The establishment of algal spores plays an essential role in adult kelp distribution and abundance patterns. Sedimentation is a key variable regulating algal spore settlement and success, possibly controlling species-specific dominance in situ. Laboratory experiments were used to determine spore attachment and survival rates of two Alaskan canopy-forming kelps, Nereocystis luetkeana (K. Mertens) Postels & Ruprecht and Eualaria fistulosa (Postels & Ruprecht) M. J. Wynne, to various types of sediment loading. Spore attachment for both species was significantly and similarly affected by three sediment treatments: suspended particles; settled sediment covering the substratum; and smothering of attached spores by settling sediment. Spore attachment decreased by approximately 90% at 420 mg sediment L -1, the highest sediment load tested here, under all three treatments for both species. These results suggest that increases in sedimentation may constrain the success of the spore stages, but sediment does not seem to be a likely factor explaining species-specific distribution patterns. However, while sedimentation affected spores of both species similarly, timing of spore release in relation to times of maximum sediment load in the water might differ for different species, possibly explaining kelp species distribution patterns.

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Section: Discussionmentioning

confidence: 99%

Section: Sorus Collection and Spore Releasementioning

confidence: 99%

Susceptibility of Nereocystis luetkeana (Laminariales, Ochrophyta) and Eualaria fistulosa (Laminariales, Ochrophyta) spores to sedimentation

Deiman¹,

Iken²,

Konar³

2012

ALGAE

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“…1). The Harding Icefield has been the site of both previous mass-balance 25 and glacial biota studies 10,41 . We supplemented data from an automated weather station (AWS; RAWS Harding Icefield station http://www.raws.dri.edu/cgi-bin/rawMAIN.pl?akAHAR) 210 m above and <3 km distant from our experimental study site (60.156029 • N 149.794006 • W) with three temperature sensors (Onset, model HOBO Pendant datalogger in radiation shield) maintained 2 m above the snow surface at the vertices of the experimental study site (Supplementary Fig.…”

Section: Methodsmentioning

confidence: 99%

“…1). Adjacent to the Gulf of Alaska, this rapidly thinning 25 network of >30 glaciers covers 1,890 km 2 and drains a snow-and ice-covered plateau, providing a potential model for ice sheets in Greenland and Antarctica.…”

mentioning

confidence: 99%

The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

et al. 2017

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A lack of liquid water limits life on glaciers worldwide but specialized microbes still colonize these environments. These microbes reduce surface albedo, which, in turn, could lead to warming and enhanced glacier melt. Here we present results from a replicated, controlled field experiment to quantify the impact of microbes on snowmelt in red-snow communities. Addition of nitrogen-phosphorous-potassium fertilizer increased alga cell counts nearly fourfold, to levels similar to nitrogen-phosphorusenriched lakes; water alone increased counts by half. The manipulated alga abundance explained a third of the observed variability in snowmelt. Using a normalized-di erence spectral index we estimated alga abundance from satellite imagery and calculated microbial contribution to snowmelt on an icefield of 1,900 km 2 . The red-snow area extended over about 700 km 2 , and in this area we determined that microbial communities were responsible for 17% of the total snowmelt there. Our results support hypotheses that snow-dwelling microbes increase glacier melt directly in a bio-geophysical feedback by lowering albedo and indirectly by exposing low-albedo glacier ice. Radiative forcing due to perennial populations of microbes may match that of non-living particulates at high latitudes. Their contribution to climate warming is likely to grow with increased melt and nutrient input.G lacier ablation is sensitive to changes in albedo 1 , with atmospheric 2,3 , hydrological 4 and ecological 5,6 consequences. Fresh snow reflects >90% of visible radiation, but during melt its grain size and water content increase, reducing albedo and further increasing snowmelt 1 . Impurities, including black carbon 3 , dust 4 , and resident microbes [7][8][9][10][11][12][13][14][15][16][17][18][19] , also lower albedo; however, microbes differ from non-living particulates in several critical ways. Perennial populations of photosynthetic microbes actively resurface following overwinter burial by snow 20 , and depend on liquid water and nutrients for survival and reproduction 13,14,[20][21][22] . This requirement for liquid water in a frozen environment imposes a selective force favouring a physiology that increases melt proximal to cell walls. The generation of meltwater through microbes' albedoreducing properties motivates an hypothesis of bio-geophysical feedback on glacial landscapes 13,16 , such as the Greenland ice sheet. This feedback hypothesis, whereby microbes increase because they produce needed meltwater, is an active research area [13][14][15][16][17][18][19] , yet field experiments testing its assumptions are absent.Glacier microbiomes are water-limited 21,22 , because ice is generally not metabolically available, and oligotrophic, because their nutrient content equals that of precipitation plus deposition by airborne dust, pollen, and so on, with only limited N-fixation by local cyanobacteria 21,22 . Moreover, rapidly percolating water through large-grained snow may exacerbate both water-and nutrient limitation for algae in supraglacial...

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“…I created linear models describing these biases and removed them from the elevation data where present (Figure 3.4). The standard deviation (± la) of the check patches represented the random error in the elevation data (VanLooy et al, 2006). I used Eq.…”

Section: Error Analysismentioning

confidence: 99%

Nine decades of glacier change in the Canadian Rocky Mountains.

Tennant¹

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Accelerating thinning of Kenai Peninsula glaciers, Alaska

Cited by 34 publications

References 19 publications

Susceptibility of Nereocystis luetkeana (Laminariales, Ochrophyta) and Eualaria fistulosa (Laminariales, Ochrophyta) spores to sedimentation

Susceptibility of Nereocystis luetkeana (Laminariales, Ochrophyta) and Eualaria fistulosa (Laminariales, Ochrophyta) spores to sedimentation

The role of microbes in snowmelt and radiative forcing on an Alaskan icefield

Nine decades of glacier change in the Canadian Rocky Mountains.

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