Western Arctic Research Webinar
When: Friday April 19 at 1:30 pm EST (Quebec-Ontario time)
Link in Gotomeeting to register: https://www1.gotomeeting.com/register/937288792
Webinar ID: 937288792
APECS Canada is organizing a Western Arctic research webinar (web-based seminar). The format will be similar to other conference seminar series. Six speakers, from differing research backgrounds, will present a 15 minute presentation using power point. This will then be followed by a 5-10 minute question period.
Our Speakers:
Gabrielle Gascon
Three-dimensional changes of the stratigraphy of the accumulation area of the Devon Ice Cap, Nunavut, Canada, during a period of climate warming
To document climate-driven changes in the firn stratigraphy and snow facies distribution within the accumulation area of the Devon Ice Cap, Nunavut, 500MHz ground-penetrating radar (GPR) surveys were conducted along a 40-km transect in each spring from 2007 to 2012. These GPR surveys were supplemented by 36 firn cores, and four 190 m by 100 m GPR grid surveys. The upper limit of the superimposed ice zone migrated from ~1430 m a.s.l. in spring 2007 to ~1520 m a.s.l. in spring 2012, a horizontal displacement of ~14.5 km. The upper limit of the wet snow zone migrated from ~1520 m a.s.l. in 2007 to ~1640 m a.s.l. in 2012, a horizontal distance of ~4.5 km. Much of this change was attributable to the growth of a thick ice body within the firn layer, which developed by upwards accretion over an initial, widespread ice layer formed during summer 2005. This ice body thickened by between 0.5 and 4.5 m over the study period, and filled much of the pore volume in the upper part of the firn, reducing both vertical percolation of meltwater into deeper sections of the firn and the water storage potential of much of the firn body.
Falk Huettmann
Status, overview and strategic conservation management (Marxan) of the three poles: How do we fit in?
Most of the snow and ice is located at the three poles (Arctic, Antarctic and Hindu-Kush Himalaya); this has major repercussions in many dimensions. While spatially and culturally apart, the three poles
still have much in common, and when globalization and climate change unfold further. Based on a synthesis and best available data, here I provide an overview (biodiversity, cultural, economic and synergistically) dealing with the status of each pole, and how they act in concert. While attention is put on wilderness attributes, here
it will be presented how polar governance and human well-being is affected. I conclude with a first polar-wide Strategic Conservation Management approach that includes terrestrial and marine/freshwater systems using Marxan and which allows to prioritize efforts globally, instead of just isolated pieces that ignore the wider context, e.g. for protecting the world's atmosphere.
Emily Choy
Identifying the offshore diet of the eastern Beaufort Sea belugas and the energetic effects of climate change.
As the most abundant Arctic cetacean with a circumpolar distribution, beluga whales (Delphinapterus leucas) are potential indicator species for Arctic climate change. The Beaufort Sea beluga population is one of the world's largest and is an important traditional food to the subsistent lifestyle of people from the Inuvialuit Settlement Region. During the summer, belugas migrate from the Bering to the Beaufort Sea and segregate by sex, reproductive status, and size into different habitats based on sea ice concentration. The differences in habitat use are defined largely by beluga len and predict their diets and exposure to mercury. Comparison of fatty acid profiles have revealed Arctic cod (Boreogadus saida), a sea ice associated fish, to be an important prey, but the contribution of other prey to the diet of Beaufort Sea belugas remains unknown. Changes in sea ice as a result of climate change may have affect prey availability to belugas. My first objective is to identify the seasonal and offshore diet of the Beaufort Sea beluga population. I will collect and survey the abundance and distribution of prey species in the offshore pelagic ecosystem of the Beaufort Sea using a fish trawling program anticipated to receive support from the Beaufort Regional Environmental Assessment. Beluga tissues will be sampled during summer subsistence hunts and information on sex, physical condition, and life stage will be recorded. Stomach contents of belugas, stable isotopes, and fatty acid profiles will be used to establish food web linkages and determine prey contribution to beluga diet. My second objective is to study the diving energetics of belugas and create a bioenergetics model of energetic requirements. My overall objective will be to provide a better description of diet for future comparisons to assess the impacts of climate change on the Beaufort Sea beluga population and marine ecosystem.
Adam Houben
Permafrost thaw slump effects on tundra lake limnology and Hg cycling in a warnming Arctic.
Accelerated warming in Canada's western arctic has led to increased thermokarst activity in tundra lakes, resulting in catastrophic shoreline collapse via retrogressive thaw slumping, east of the Mackenzie Delta, Inuvik, NT. The influx of thaw slump melt-waters causes dramatic physico-chemical increases in lake water clarity and ionic strength, associated with lower dissolved organic carbon concentrations (DOC). This is contrary to reported DOC increases in other thermokarst lake-rich regions experiencing warming environments, also having implications for enhancing Hg bioavailability. We aim to describe limnological drivers affecting primary production and mercury availability in tundra lakes affected by thaw slumps. Through a paired-lake study design of thaw slump-affected lakes and undisturbed reference lakes, we demonstrate that thaw slump events are the dominant agents of change in this region. Water column macronutrients (N and P), phytoplankton production (Chl-a), and Hg, are also reduced proportionately to the scale of thermokarst degradation. However, algal bioconcentration factors suggest that remaining mercury is potentially more available for uptake in lakes with greater thaw slump activity. Ongoing research will further elucidate the net balance of these Hg sources and fates to ultimately determine the toxicological impacts of thaw slumps on freshwater foodwebs. With estimates of up to 7 million square kilometres of permafrost thaw over the next century, the delineation of net Hg toxicity in thaw slump-affected tundra lakes will become increasingly important.
Louise Chavarie
An exceptional case of Lake Trout polymorphism: the coexistence of multiple shallow-water forms in Great Bear Lake, NT.
Intraspecific morphological variation, ranging from subtle to large enough to result in misidentification, is commonly observed among fishes in recently glaciated lakes of the Canadian Arctic. A UPGMA cluster analysis of 558 Lake Trout distinguished three different morphs that co-exist in the shallow waters of Great Bear Lake, NT. A fourth distinct albeit rarer morph has also been identified from other collections. We combined classical morphometric/meristic measures with shape analysis (geometric morphometrics) to quantify morphological differences among adult and juvenile shallow-water Lake Trout from Great Bear Lake. The most important differences among adult morphotypes are associated with variation in head and fin measurements, whereas body shape variation is less distinctive. These patterns are consistent with many evolutionary adaptations in fish that involve traits associated with feeding and swimming. However, no consistent patterns of variation were found among juveniles, suggesting that divergence develops at later stage. Due to the large size and complex morphometry of Great Bear Lake, we also examined to determine patterns across different regions of the lake. Within a single morphotype, morphological variation, including body shape differences, was found to vary among lake areas.
Kristen Peck
Eating off of the same plate: interactions between a small mammal and invertebrate herbivores
Choosing among available food resources is a complicated business. On top of choosing among nutritional gains or the risk of eating, other foragers may indirectly influence the same food patch. Herbivores (plant-eaters) include a diversity of distantly-related organisms, dispersed in time and space but which may commonly interact through their shared food sources. We demonstrated such an interaction with a model alpine species, the collared pika (Ochotona collaris), and invertebrate herbivores in Southwest Yukon. To prepare for the long alpine winter, these small mammals cache food piles under rocks during the summer to eat in the winter. Their food choices are extremely limited to areas directly around their rocky territories, forcing them to interact with any other herbivores foraging in their food patches. By observing the food selected by pikas, we saw that pikas changed their selection if the food had been previously grazed by invertebrate herbivores. Then, by manipulating an insect herbivore, we experimentally showed that pikas seemed to prefer the food previously grazed by the insect. Why pikas prefer previously eaten food is not known, but the interaction between these species suggests that many unknown interactions between herbivores remain to be discovered.
