Search

Oil and gas exploration and development is expanding across the Arctic Coastal Plain (ACP) of Alaska, USA. To examine the effects of industrial development on greater white‐fronted geese (Anser albifrons), we monitored nests and nesting behavior within a 4‐km2 study area within 4 km of gravel roads and pads during pre‐development, construction, and operation activities at a new oil development in the National Petroleum Reserve‐Alaska in 2013−2019. We examined distribution, incubation constancy, and nest survival in relation to distance to gravel roads or pads, year and status of development, presence of an ice road the previous winter, and land cover type. Nest density increased throughout the study period, which was consistent with surveys of this species in other regions of the ACP. There was no direct evidence that oil extraction infrastructure and the associated human activity adversely influenced the abundance, distribution, or daily nest survival of greater white‐fronted goose nests. Geese avoided nesting in the alignments of ice roads from the previous winter, and land cover type influenced their nest distribution. Nest age and incubation constancy were important predictors of daily nest survival. The incubation constancy of successful nesters (98.5 ± 0.1% [SE]) was significantly greater than for failed nesters (94.7 ± 0.6%) for all years combined and tended to be greater during the pre‐construction and construction years of 2014 and 2015, compared to when oilfield operations began in 2017 and 2019. Greater‐white fronted geese appear to be tolerant of some levels of industrial activities and the presence of gravel roads did not have a significant effect on nest distribution, incubation constancy, or nest survival. We recommend, however, that indirect effects from ice roads should be explicitly considered in impact assessments because white‐fronted geese avoid nesting in the footprints of the previous winter's ice roads and pads. [ABSTRACT FROM AUTHOR]

Moose management throughout much of Alaska and Canada relies on aerial count data, which are commonly collected using the geospatial population estimator (GSPE) protocol. The GSPE uses a model‐based analytical approach and finite‐population block kriging to estimate abundance from a collection of sampled survey units. Widespread implementation and well‐documented analytical software have resulted in reliable estimates of moose abundance, density, and composition across a large proportion of their range. Analysis is conducted almost exclusively using the GSPE software, which fits a fixed model structure to data collected within a single year. The downside of this approach to analysis is that the fixed model structure is inefficient for estimation, leading to more field effort than would otherwise be necessary to achieve a desired level of estimator precision. We developed a more easily modified and flexible Bayesian spatial general additive model approach (BSG) that accommodates spatial and temporal covariates (e.g., habitat characteristics, trend), multiple survey events, prior information, and incomplete detection. Using a series of 6 GSPE surveys conducted in Yukon‐Charley Rivers National Preserve, Alaska, USA, from 2003–2019, we established the equivalence of the 2 approaches under similar model structures. We then extended the BSG to demonstrate how a more comprehensive approach to analysis can affect estimator precision and be used to assess ecological relationships. The precision of annual abundance estimators from the BSG were improved by an average of 43% over those based on the standard GSPE analysis, highlighting the very real costs of assuming a fixed (i.e., suboptimal) model structure. The population increased at a rate of 2.3%/year (95% CrI = 0.8–3.8%), and the increase was largely explained by a parallel increase in wildfire extent (i.e., high quality moose habitat). These results suggest that our approach could be used to increase estimator efficiency or decrease future survey costs without any modifications to the basic protocol. While modification of the GSPE software is possible, practitioners may find the BSG approach more convenient for quickly developing model structures for a particular application, thereby allowing them to extract more information from existing and future datasets. [ABSTRACT FROM AUTHOR]

Climate change will lead to more frequent and more severe fires in some areas of boreal forests, affecting the distribution and availability of late‐successional forest communities. These forest communities help to protect globally significant carbon reserves beneath permafrost layers and provide habitat for many animal species, including forest‐dwelling caribou. Many caribou populations are declining, yet the mechanisms by which changing fire regimes could affect caribou declines are poorly understood. We analyzed resource selection of 686 GPS‐collared female caribou from three ecotypes and 15 populations in a ~600,000 km2 region of northwest Canada and eastern Alaska. These populations span a wide gradient of fire frequency but experience low levels of human‐caused habitat disturbance. We used a mixed‐effects modeling framework to characterize caribou resource selection in response to burns at different seasons and spatiotemporal scales, and to test for functional responses in resource selection to burn availability. We also tested mechanisms driving observed selection patterns using burn severity and lichen cover data. Caribou avoided burns more strongly during winter relative to summer and at larger spatiotemporal scales relative to smaller scales. During the winter, caribou consistently avoided burns at both spatiotemporal scales as burn availability increased, indicating little evidence of a functional response. However, they decreased their avoidance of burns during summer as burn availability increased. Burn availability explained more variation in caribou selection for burns than ecotype. Within burns, caribou strongly avoided severely burned areas in winter, and this avoidance lasted nearly 30 years after a fire. Caribou within burns also selected higher cover of terrestrial lichen (an important caribou food source). We found a negative relationship between burn severity and lichen cover, confirming that caribou avoidance of burns was consistent with lower lichen abundance. Consistent winter avoidance of burns and severely burned areas suggests that caribou will experience increasing winter habitat loss as fire frequency and severity increase. Our results highlight the potential for climate‐induced alteration of natural disturbance regimes to affect boreal biodiversity through habitat loss. We suggest that management strategies prioritizing protection of core winter range habitat with lower burn probabilities would provide important climate‐change refugia for caribou. [ABSTRACT FROM AUTHOR]

In this study, we investigated how Little Brown Myotis (Myotis lucifugus), North America's northernmost bat species, adjusted to variable spring and autumn conditions and very little darkness during the boreal summer. We recorded bat activity around Anchorage and the lower Matanuska-Susitna Valley, Alaska. Initiation of bat activity in the spring varied among years and was affected by minimum nightly temperatures in late April and, to a lesser extent, precipitation. Cessation of bat activity in the autumn was consistent among years, with a weak association with early-October minimum temperature. During summer, bat activity was highest on warm, clear nights, but was reduced by wind or rain. Bat activity was positively related to open water and forest cover and negatively related to human development. Most bat activity occurred between sunset and sunrise, even during very short nights in mid-summer. Although there was some activity prior to sunset, bat activity after sunrise was very rare. Pre-sunset bat activity was almost exclusively at sites with high forest cover. After sunset, moderately forested sites were also used, but sites with little forest cover were rarely used before or after sunset. [ABSTRACT FROM AUTHOR]

Aim: As within‐species genomic data have been shown useful in interpreting broader biogeographic trends, we analysed the mode of population genomic isolation involved in a well‐studied intertidal genomic cline to better understand the mechanisms maintaining it. These results were interpreted in the context of spatial variation in habitat use and availability as well as likely fitness consequences for hybridization between the two lineages. Location: Pacific coast of North America. Taxon: Arthropods (Class Maxillopoda, Order Sessilia, Family Balanidae; Balanus glandula). Methods: Genotype‐by‐sequencing approaches were used to generate single‐nucleotide polymorphism markers across sites sampled between southern Alaska and Southern California. Inference using standard population genomic methods, including analysis of population structure, inbreeding and linkage disequilibrium, was used to identify the steepest transitions across the largest number of loci examined. These data were put in the context of observed population density and habitat availability. Results: We show that the majority of markers analysed show strong clinal transitions in a very narrow portion of the California coast. Patterns of linkage disequilibrium among markers, along with prior evidence of variation in reproductive potential by latitude and by mitochondrial lineage, suggest some reproductive isolation among the northern and southern lineages of B. glandula that are concordant with the drop in population density and habitat availability in central California. Main Conclusions: A significant clinal transition in genomic diversity is stronger and more localized than previously recognized and exhibits statistical patterns suggesting that the lineages are reproductively and phenotypically distinct in ways that may be ecologically important. As this species has been used to infer process in coastal biogeography, further study of concordant patterns will be important for advancing our understanding of this region. [ABSTRACT FROM AUTHOR]

Anadromous Pacific salmon are semelparous, and resource subsidies from spawning adults (marine-derived nutrients, or MDN) benefit juvenile salmonids rearing in freshwater. However, it remains unclear how MDN assimilation relates to spawner abundance within a watershed. To address this, we examined seasonal, watershed-scale patterns of MDN assimilation in rearing coho (Oncorhynchus kisutch) and Chinook (O. tshawytscha) salmon and compared it with spawner biomass and landscape features in a western Alaska watershed with contrasting structural complexity in two sub-drainages. Adult salmon biomass density was estimated from escapement and spawner distribution data, and MDN assimilation in juvenile salmon was estimated via stable isotopes. In the North River, MDN assimilation was lowest in early summer, prior to annual spawning migrations, increased after spawning, and peaked in late winter. In the more complex mainstem Unalakleet River, MDN assimilation was higher but varied minimally from summer through fall before increasing in late fall and winter. Summer MDN assimilation, prior to salmon spawning, was primarily a function of habitat complexity, where MDN was highest in sloughs and the more complex mainstem river. After salmon spawned, fall MDN assimilation was a function of adult pink and Chinook salmon biomass as well as MDN assimilation that occurred prior to spawning (that is, summer MDN), but unrelated to total summer biomass (all salmon species biomass combined). Thus, MDN assimilation by juvenile salmon in the fall was a function of species-specific adult spawner abundance but seasonal patterns of MDN assimilation were masked in complex habitat where summer MDN assimilation remained high. [ABSTRACT FROM AUTHOR]

In this analysis, five eastern Gulf of Alaska (eGOA) inshore study sites from the North Pacific Research Board's (NPRB) Gulf of Alaska Integrated Ecosystem Research Program (GOAIERP: http://www.nprb.org/gulf-of-alaska-project) were characterized using multiple Geographic Information System (GIS) physical measurements including water volume, surface area, and shoreline length. These eGOA sites include three small bays (Islas Bay, Torch Bay and Graves Harbor), a large semi-protected body of water (Salisbury Sound), and a large bay (Whale Bay). These measurements provide quantitative metrics of study sites that may aid in the interpretation of biological differences among the sites. The analysis is similar to a previously published study of five central Gulf of Alaska (cGOA) sites that also included three small bays, an unprotected body of water, and a large bay. In addition, this analysis included new measures of the surface area of lakes within each sites' watershed, and the amount of nearby shallow (< 200 m) continental shelf area. Multivariate analyses were used to examine similarities among the cGOA and eGOA sites and suggested that location and size were both important grouping factors, with the cGOA and eGOA small bays forming unique groups. The cGOA non-bay and large-bay sites were the most distinct locations. It appears that there is some link between geographic location and physical similarity of study sites chosen for the GOAIERP. [ABSTRACT FROM AUTHOR]

Understanding bird distributions outside of the breeding season may help to identify important criteria for winter refuge. We surveyed marine birds in Prince William Sound, Alaska, USA over nine winters from 2007 to 2016. Our objectives were twofold: to examine the seasonal patterns of piscivorous species overwintering in Prince William Sound, and to explore the relationships between spatial covariates and bird distributions, accounting for inherent spatial structure. We used hurdle models to examine nine species groups of piscivorous seabirds: loons, grebes, cormorants, mergansers, large gulls, small gulls, kittiwakes, Brachyramphus murrelets, and murres. Seven groups showed pronounced seasonal patterns. The models with the most support identified water depth and distance to shore as key environmental covariates, while habitat type, wave exposure, sea surface temperature and seafloor slope had less support. Environmental associations are consistent with the available knowledge of forage fish distribution during this time, but studies that address habitat associations of prey fish in winter could strengthen our understanding of processes in Prince William Sound. [ABSTRACT FROM AUTHOR]

Very little is known about the range and ecology of the Little Brown Bat ( Myotis lucifugus) in Alaska and how the species continues to persist in a region where temperatures fall below their predicted threshold for winter survival. Establishing a baseline of current distribution is critical to monitoring potential population shifts. We hypothesized that persistence of the Little Brown Bat in interior and northern Alaska is dependent on the ability of bats to gain sufficient mass over a short summer with limited darkness, and on the availability of human structures for roosting in areas where temperatures are likely too low for roosting in natural structures. To describe the roosting ecology of bats in interior and northern Alaska, we combined traditional ecological knowledge, outreach through citizen science, and sampling using roost studies and telemetry. Activity outside of the roost was positively related to length of time between sunset and sunrise. Fat gained through summer in interior Alaska constituted 21% of body mass in fall prior to dispersal. Radio-tracked bats migrated short distances (<100 km) to areas where human structures were the most likely hibernacula. We conclude that Little Brown Bats use human structures to offset the constraints of cold temperatures and short foraging seasons in interior Alaska. [ABSTRACT FROM AUTHOR]

This study describes phenetic characteristics and examines the life history of anadromous Arctic lamprey Lethenteron camtschaticum and freshwater-resident Alaskan brook lamprey Lethenteron alaskense in two tributaries of the middle Yukon River, Alaska. Larval lampreys could not be identified to species using pigmentation density patterns or trunk myomere counts, but adults could be identified to species based on colouration, body size and oral-disc dentition. Although larvae were patchily distributed in both rivers, there was a greater proportion of sample locations where Lethenteron spp. were absent in upper reaches than in middle and lower reaches. Relative abundance, density and median and maximum total length ( LT) of larvae were highly variable among sampling locations. Current velocity, substratum type and coarse woody debris were most strongly correlated with larval Lethenteron spp. density; velocity and substratum size was negatively correlated, whereas woody debris was positively correlated. Water depth, dissolved oxygen levels and specific conductance did not influence habitat selection. Length-frequency distributions, diet composition (organic detritus ≥ 98%), assimilation efficiency (>70%) and gut fullness (<0·2 mg diet ash-free dry mass) were similar for larvae, regardless of river or sampling location. These results increase understanding of Lethenteron spp. biology and ecology in interior Alaska drainages and add to the existing literature on Lethenteron spp. life history. [ABSTRACT FROM AUTHOR]

Despite changes in shrub cover and weather patterns associated with climate change in the Arctic, little is known about the breeding requirements of most passerines tied to northern regions. We investigated the nesting biology and nest habitat characteristics of Smith's Longspurs (Calcarius pictus} in 2 study areas in the Brooks Range of Alaska, USA. First, we examined variation in nesting phenology in relation to local temperatures. We then characterized nesting habitat and analyzed nest-site selection for a subset of nests (n = 86) in comparison with paired random points. Finally, we estimated the daily survival rate of 257 nests found in 2007-2013 with respect to both habitat characteristics and weather variables. Nest initiation was delayed in years with snow events, heavy rain, and freezing temperatures early in the breeding season. Nests were typically found in open, low-shrub tundra, and never among tall shrubs (mean shrub height at nests = 26.8 ± 6.7 cm). We observed weak nest-site selection patterns. Considering the similarity between nest sites and paired random points, coupled with the unique social mating system of Smith's Longspurs, we suggest that habitat selection may occur at the neighborhood scale and not at the nest-site scale. The best approximating model explaining nest survival suggested a positive relationship with the numbers of days above 21 °C that an individual nest experienced; there was little support for models containing habitat variables. The daily nest survival rate was high (0.972-0.982) compared with that of most passerines in forested or grassland habitats, but similar to that of passerines nesting on tundra. Considering their high nesting success and ability to delay nest initiation during inclement weather, Smith's Longspurs may be resilient to predicted changes in weather regimes on the breeding grounds. Thus, the greatest threat to breeding Smith's Longspurs associated with climate change may be the loss of low-shrub habitat types, which could significantly change the characteristics of breeding areas. [ABSTRACT FROM AUTHOR]

Primary producers form the base of food webs but also affect other ecosystem characteristics, such as habitat structure, light availability, and microclimate. Here, we examine changes caused by 5-30+ years of nutrient addition and resulting increases in net primary productivity (NPP) in tundra, streams, and lakes in northern Alaska. The Arctic provides an important opportunity to examine how ecosystems characterized by low diversity and low productivity respond to release from nutrient limitation. We review how responses of algae and plants affect light availability, perennial biotic structures available for consumers, oxygen levels, and temperature. Sometimes, responses were similar across all three ecosystems; e.g., increased NPP significantly reduced light to the substrate following fertilization. Perennial biotic structures increased in tundra and streams but not in lakes, and provided important new habitat niches for consumers as well as other producers. Oxygen and temperature responses also differed. Life history traits (e.g., longevity) of the primary producers along with the fate of detritus drove the responses and recovery. As global change persists and nutrients become more available in the Arctic and elsewhere, incorporating these factors as response variables will enable better prediction of ecosystem changes and feedbacks in this biome and others. [ABSTRACT FROM AUTHOR]

Moose Alces alces are large and conspicuous animals valued for wildlife watching and hunting opportunities. However, near urban areas they can cause collisions with vehicles and damage to garden and ornamental plants. We studied a population of adult female moose that lives in and around both urban and industrial development on an active Army and Air Force base adjacent to Anchorage, Alaska, to evaluate nutrition and diet, map habitat quality, and model how habitat development affects the number of moose the landscape can support. Population density was moderate and hunter harvest was high in our study area, so we hypothesized that moose in our study area would be in similar condition to other healthy populations in Alaska. We also hypothesized that, in our study area, shrublands would support more moose than any other habitat type and that areas disturbed for urban development would be crucial to maintaining the local moose population. Rump fat depths, blood chemistries, and pregnancy rates in November and March for moose in our study area were consistent with populations in good to moderate condition. Microhistology of composite fecal samples indicated that willows Salix spp. dominated the summer diet, whereas the winter diet was divided among willows, birch Betula spp., and cottonwood Populus balsamifera. Low concentrations of available nitrogen in winter stems limited the number of moose that could be supported in our study area. Shrublands were the most valuable habitat type for moose, theoretically supporting 11–81 times more moose per hectare than any other habitat type. Shrublands were more concentrated within the developed portion of our study area than the surrounding undeveloped portions of the military base; and the access to shrublands in clearings, greenbelts, and parks sustains the productivity of this moose population despite the many disturbances of an urbanized landscape. Our habitat values can be used to model potential impacts of habitat modification on the number of moose the landscape can support. [ABSTRACT FROM AUTHOR]

Climate warming is affecting the Arctic in multiple ways, including via increased dominance of deciduous shrubs. Although many studies have focused on how this vegetation shift is altering nutrient cycling and energy balance, few have explicitly considered effects on tundra fauna, such as the millions of migratory songbirds that breed in northern regions every year. To understand how increasing deciduous shrub dominance may alter breeding songbird habitat, we quantified vegetation and arthropod community characteristics in both graminoid and shrub dominated tundra. We combined measurements of preferred nest site characteristics for Lapland longspurs ( Calcarius lapponicus) and Gambel's White-crowned sparrows ( Zonotrichia leucophrys gambelii) with modeled predictions for the distribution of plant community types in the Alaskan arctic foothills region for the year 2050. Lapland longspur nests were found in sedge-dominated tussock tundra where shrub height does not exceed 20 cm, whereas White-crowned sparrows nested only under shrubs between 20 cm and 1 m in height, with no preference for shrub species. Shrub canopies had higher canopy-dwelling arthropod availability (i.e. small flies and spiders) but lower ground-dwelling arthropod availability (i.e. large spiders and beetles). Since flies are the birds' preferred prey, increasing shrubs may result in a net enhancement in preferred prey availability. Acknowledging the coarse resolution of existing tundra vegetation models, we predict that by 2050 there will be a northward shift in current White-crowned sparrow habitat range and a 20-60% increase in their preferred habitat extent, while Lapland longspur habitat extent will be equivalently reduced. Our findings can be used to make first approximations of future habitat change for species with similar nesting requirements. However, we contend that as exemplified by this study's findings, existing tundra modeling tools cannot yet simulate the fine-scale habitat characteristics that are critical to accurately predicting future habitat extent for many wildlife species. [ABSTRACT FROM AUTHOR]

Nursery areas for juvenile fishes are often important for determining recruitment in marine populations by providing habitats that can maximize growth and thereby minimize mortality. Pacific ocean perch (POP, Sebastes alutus) have an extended juvenile period where they inhabit rocky nursery habitats. We examined POP nursery areas to link growth potential to recruitment. Juvenile POP were captured from nursery areas in 2004 and 2008, and estimated growth rates ranged from −0.19 to 0.60 g day−1 based on differences in size between June and August. Predicted growth rates from a bioenergetics model ranged from 0.05 to 0.49 g day−1 and were not significantly different than observed. Substrate preferences and the distribution of their preferred habitats were utilized to predict the extent of juvenile POP nursery habitat in the Gulf of Alaska. Based on densities of fish observed on underwater video transects and the spatial extent of nursery areas, we predicted 278 and 290 million juvenile POP were produced in 2004 and 2008. Growth potential for juvenile POP was reconstructed using the bioenergetics model, spring zooplankton bloom timing and duration and bottom water temperature for 1982-2008. When a single outlying recruitment year in 1986 was removed, growth potential experienced by juvenile POP in nursery areas was significantly correlated to the recruitment time-series from the stock assessment, explaining ∼30% of the variability. This research highlights the potential to predict recruitment using habitat-based methods and provides a potential mechanism for explaining some of the POP recruitment variability observed for this population. [ABSTRACT FROM AUTHOR]

Abstract: Red king crab, Paralithodes camtschaticus, an important fishery species in Alaska, exhibits cannibalism both within and among age classes. Cannibalism in crab species can be an important determinant of recruitment success, and this might be especially important in king crab because year-0 and year-1 crab occupy the same habitat types in the wild. In this study we used laboratory experiments to determine the predator functional response, or the effect of prey density on predation rates of year-1 crab preying on year-0 crab in three different habitat types: Sand, which was unstructured soft sediment, Whole Shell, which was whole clam valves, and Shell Hash, which was smaller pieces of crushed shell. We also examined how predator density (one or two predators) affects the functional response. The data was fit to Type I, or density independent, Type II, or inversely density dependent, and Type III, or density dependent, functional response models and the best fit model was chosen using Akaike''s information criterion. The functional response was a Type II in all habitat types; however, the predation rate was lower at all prey densities in the Whole Shell habitat than in Shell Hash and Sand. The functional response was a Type II at both predator densities as well. The presence of a second predator decreased both the attack rate and the handling time, resulting in slightly lower predation rates at low prey densities, and slightly higher predation rates at high prey densities when compared to the single predator treatment. This indicates a low level of predator interference. This work has implications for potential stock enhancement activities, as year-1 crab could inhibit enhancement success though cannibalism of introduced year-0 crab, especially given the destabilizing nature of the Type II functional response. A potential solution would be to enhance a given area only every other year to give previous cohorts a chance to start podding in less complex habitats. Future work should examine whether the presence of alternative prey changes the functional response to a Type III, as this would give year-0 crabs a low‐density refuge from predation. [Copyright &y& Elsevier]

Habitat conditions and nutrient reserve levels during spring migration have been suggested as important factors affecting population declines in waterfowl, emphasizing the need to identify key sites used during spring and understand habitat features and resource availability at stopover sites. We used satellite telemetry to identify stopover sites used by surf scoters migrating through southeast Alaska during spring. We then contrasted habitat features of these sites to those of random sites to determine habitat attributes corresponding to use by migrating scoters. We identified 14 stopover sites based on use by satellite tagged surf scoters from several wintering sites. We identified Lynn Canal as a particularly important stopover site for surf scoters originating throughout the Pacific winter range; approximately half of tagged coastally migrating surf scoters used this site, many for extended periods. Stopover sites were farther from the mainland coast and closer to herring spawn sites than random sites, whereas physical shoreline habitat attributes were generally poor predictors of site use. The geography and resource availability within southeast Alaska provides unique and potentially critical stopover habitat for spring migrating surf scoters. Our work identifies specific sites and habitat resources that deserve conservation and management consideration. Aggregations of birds are vulnerable to human activity impacts such as contaminant spills and resource management decisions. This information is of value to agencies and organizations responsible for emergency response planning, herring fisheries management, and bird and ecosystem conservation. [ABSTRACT FROM AUTHOR]

The article presents a study on determining whether the patterns in body size, condition, and cub recruitment of polar bears in the southern Beaufort of Alaska were related to the availability of preferred sea ice habitats It explores whether these measures and habitat availability exhibited trends over time, between 1982 and 2006. It shows that the size and condition of most sex/age classes exhibited positive relationships with the annual availability of preferred sea ice habitats.

Increasing demand for backcountry recreation opportunities during winter (e.g., snowshoeing, helicopter-assisted skiing, snowmobiling) in steep, high-elevation terrain has elevated concern about disturbance to brown bears (Ursus arctos) denning on the Kenai Peninsula, Alaska, USA. To help identify areas where such conflicts might occur, we developed a spatially explicit model to predict potential den habitat. The model indicated brown bears selected locations for den sites with steep slopes, away from roads and trails. Den sites were associated with habitat high in elevation and away from potential human contact. We then compared areas with the highest probability of providing den habitat with patterns of snowmobile and nonmotorized recreation on a portion of the Kenai Peninsula. We found limited overlap between the 2 recreation activities and potential den habitat for brown bears. At the landscape scale, however, backcountry skiing overlapped more high-quality den habitat than did snowmobile riding. Our results may be used by land management agencies to identify potential conflict sites and to minimize the potential effects of recreation activities on brown bears in dens. [ABSTRACT FROM AUTHOR]

The article presents a study that examines the seafloor disturbance and damage to corals and sponges due to fishing practices in the Aleutian Archipelago in Alaska. It says that video of seafloor were collected through Delta, a two-person submarine and the Jason II which is a remotely operated vehicle. It mentions that video transects reveal the overall damage of 14% and 22% in corals and sponge respectively. It suggests that most of the seafloor disturbances and damage occur in areas where commercial fishing frequently occur. It also suggests that conservation of coral and sponge habitat requires a greater concern.

Yeung, C., and McConnaughey, R. A. 2008. Using acoustic backscatter from a sidescan sonar to explain fish and invertebrate distributions: a case study in Bristol Bay, Alaska. – ICES Journal of Marine Science, 65: 242–254.Environmental variables that are ecologically relevant and easily measured over large areas are useful for modelling species distributions and habitats. Continuous acoustic, sonar-backscatter data convey information about physical properties of the seabed, and hence could be a valuable addition to that suite of variables. We tested the potential utility of acoustic backscatter for improving habitat models of marine species using data from a pilot sidescan-sonar survey. Raw digital-backscatter data were processed with QTC SIDEVIEW and CLAMS software. Resultant acoustic variables—Q-values (Q1, Q2, and Q3), representing the first three principal components of the data derived from image analysis of backscatter echoes, and a complexity metric (compx) measuring the variance of Q-values in a geographic area—were used in multiple linear regression to model individual species abundance from bottom-trawl survey data. Habitat models for flathead sole (Hippoglossoides elassodon), Pacific cod (Gadus macrocephalus), walleye pollock (Theragra chalcogramma), red king crab (Paralithodes camtschaticus), basket star (Gorgonocephalus eucnemis), and sponges (Porifera) included acoustic variables as significant predictors. For these six taxa, full models explained 67–86% of variability in abundance, with 9–54% of that total contributed by the acoustic predictors, suggesting that acoustic data could advance habitat research for some bottom-associated marine species. [ABSTRACT FROM PUBLISHER]

We compared winter diets of Western Arctic Herd Caribou (Rangifer tarandus) from 1995/1996 and 2005 using microhistological fecal analysis on samples collected at paired permanent vegetation transects. Changes in the diets of Caribou followed the same trends as vegetative changes documented in long-term studies in northwestern Alaska. Lichens were significantly less prevalent on the landscape and in the winter diets of Caribou between 1995/1996 and 2005, while graminoids (grasses and sedges) were significantly more prevalent. Dramatic changes are forecasted for Arctic ecosystems under global warming scenarios which may continue the trend of declining lichens in northwestem Alaska and in the diet of Western Arctic Herd Caribou. The question of whether or not the altered diet will affect the population dynamics of this herd remains unresolved. [ABSTRACT FROM AUTHOR]

For a comprehensive bird inventory of Yukon-Charley Rivers National Preserve, Alaska, we stratified the 1 million hectare study area by large, physiographically defined regions known as ecological units. Point-count data from the bird inventory were used to test the ability of the ecological units to differentiate bird assemblages, and compare the effectiveness of ecological units to fine-scale vegetation types. The ecological units were a synthesis of geology, landforms, soils, and vegetation mapped at a scale of 1:250,000; the vegetation types were based on vegetation within 50 m of the sample points. Nonparametric multivariate statistical tests showed that ecological units and vegetation types had similar success in differentiating bird assemblages, despite their different scales and conceptual bases. Analyses of individual bird species showed that both ecological units and vegetation types provide useful and complementary information about bird habitat selection. Ecological units have several advantages over vegetation types as sample-area strata: they are stable over time, logistically easier to sample in a large road- less study area, and they allow one to obtain a larger bird sample size through inclusion of birds detected at greater distances. [ABSTRACT FROM AUTHOR]

We examined the effect of large (potentially piscivorous) lake trout ( Salvelinus namaycush) on the dietary habits of small lake trout in an arctic lake. We hypothesized that large lake trout constrain the foraging of small lake trout, thus, in the absence of large lake trout, small lake trout will shift their diet from littoral to more abundant prey offshore. We tested this hypothesis using samples from a removal experiment where all lake trout large enough to be susceptible to gill nets were removed from a small arctic Alaskan lake during 1988–1989. We examined size at age and conducted stomach content and stable isotope analyses of lake trout collected during removal (1988), early recovery (1990), and late recovery (1999) portions of the study. Lake trout grew more quickly following removal. All lake trout fed on a variety of prey, but stomach analyses provided little information on segregation of diet between size classes. δ15N and δ13C analyses showed that small lake trout shifted their diet after large lake trout were removed, apparently toward more reliance on offshore zooplankton, which also implies a habitat shift to open water. Thus, we conclude that large lake trout are restricting the dietary habits of small lake trout, a restriction that was removed in an exploited population. [ABSTRACT FROM AUTHOR]

King Eiders (Somateria spectabilis) breeding in western Canada and Alaska molt wing feathers and spend the winter in remote areas of the Bering Sea, precluding direct observation. To characterize timing of migration and habitat used by King Eiders during the nonbreeding period, we collected location data for 60 individuals (27 females and 33 males) over three years from satellite telemetry and utilized oceanographic information obtained by remote sensing. Male King Eiders dispersed from breeding areas, arrived at wing molt sites, and dispersed from wing molt sites earlier than females in all years. Males arriving earlier at wing molt sites molted flight feathers at higher latitudes. Distributions of molt and winter locations did not differ by sex or among years. Of the variables considered for analysis, distance to shore, water depth, and salinity appeared to best describe King Eider habitat throughout the nonbreeding period. King Eiders were located closer to shore, in shallower water with lower salinity than random locations. During the winter, lower ice concentrations were also associated with King Eider locations. This study provides some of the first large-scale descriptions of King Eider migration and habitat outside the breeding season. [ABSTRACT FROM AUTHOR]

A unique feature of the benthic habitat in the Aleutian Islands is the presence of a highly diverse and abundant coral and sponge community. These communities likely provide important habitat for a variety of fish and invertebrate species. Summaries of historical data and recent direct observations with a submersible indicate that the Aleutian Islands may harbour the highest diversity and abundance of coldwater corals in the world. There are 69 documented taxa (species and subspecies) of coral in the Aleutians of which 25 are endemic. Within the Aleutian Islands, there is an increase in diversity of corals west of about longitude 169°W. This shift in diversity is consistent with the hypothesis of an ecological boundary in the vicinity of Samalga Pass. Given the endemism and high diversity and abundance of corals in the Aleutians, there is evidence that this region is the evolutionary centre of origin for some taxa of coldwater corals. [ABSTRACT FROM AUTHOR]

We assessed antler size of Alaskan moose (Alces alces gigas) with respect to the geographic region and dominant vegetation community (taiga or tundra) from which they were harvested from 1968 to 1983. Our retrospective analysis indicated that moose from the Copper River Delta and Alaska Peninsula possessed the largest antlers, whereas those from southeast Alaska, USA, had the smallest antlers. Delta flood plains of the Copper River offer a rich food supply for moose, and browse on the Alaska Peninsula also is plentiful; both areas have mild maritime climates and longer growing seasons than tundra and taiga habitats in interior Alaska7mdash;large antlers in those moose populations likely were the result of superior nutrition. After controlling for age, antlers of moose from tundra communities were significantly larger than those inhabiting taiga. Willows (Salix spp.), which are an important food for moose, dominate braided rivers and associated riparian areas in tundra habitat, and provide a high-quality and stable food supply over time. Fire and subsequent successional changes dominate taiga landscapes, which results in a variable food supply that is sometimes low in quality and quantity. Again, forage abundance and quality likely play important roles in determining antler size for populations of Alaskan moose inhabiting those plant communities. Nonetheless, antlers of A. a. gigas from taiga regions in Alaska, USA, were larger than those of A. a. andersoni from similar habitat in northeastern Minnesota, USA, and Saskatchewan, Canada. In addition, moose from tundra habitat on the Seward Peninsula, Alaska, which have colonized that area within the last ∼30 years from the boreal forest, possessed antlers intermediate in size between moose inhabiting taiga and tundra. Moreover, moose from forested areas of southeast Alaska, which have a unique mitochrondial DNA haplotype from other subspecies of moose, also had comparatively smaller antlers than other moose in Alaska. Those outcomes indicated that differences in antler size likely have a genetic in addition to a nutritional basis. We hypothesize that differences in antler size of Alaskan moose in relation to habitat may have genetic as well as nutritional underpinnings related to openness of habitat, but more research is needed. Finally, our results on antler morphology, in concert with information on pelage coloration and recent data on genetics, do not support hypotheses concerning a double migration, or eastern and western races of moose, forwarded to explain morphological variation in moose inhabiting the New World. Likewise, we reject the hypothesis that ecotypical differences are primarily responsible for morphological variation in subspecies of moose inhabiting North America. [ABSTRACT FROM AUTHOR]

We investigated the pelagic habitat requirements of Arctic larval fish and the effects of interannual variability of ocean conditions on their distribution. We examined the distribution of larval Arctic cod, Bering flounder, yellowfin sole and capelin in the Chukchi and northern Bering seas during two years with different oceanographic conditions. We found that despite marked changes in water mass distribution, the distributions of larval fishes were not significantly different between the two years. In both years, Arctic cod and Bering flounder were found in cold, high salinity shelf waters advected from the south and influenced by winter cooling (Chukchi Winter Water and Anadyr Water mix). Yellowfin sole and capelin distributions were also similar from year-to-year but they were only found in warm, low salinity Alaska Coastal Water. The cold, high salinity water masses had elevated large copepod biomass, and the Alaska Coastal Water had elevated small copepod biomass. Thus, we propose that these water masses provided different but nonetheless potentially profitable foraging habitat for the four species of larval fishes. We conclude by suggesting that the timing and location of spawning of these species has evolved such that larval offspring are distributed in suitable foraging habitat despite interannual variability in ocean conditions. This study provides a baseline of Arctic larval fish distribution and insight into the degree of climate variability that might be expected to impact early life history stages of larval fish. Our results also increase the knowledge of the mechanistic links between oceanography and the early life history of fish. Because growth and survival of early life stages of fish often drives population change, our results contribute to the understanding of the impacts of climate change on Arctic fish populations. [ABSTRACT FROM AUTHOR]

Tracking and understanding variation in pathogens such as Batrachochytrium dendrobatidis (Bd), the agent of amphibian chytridiomycosis which has caused population declines globally, is a priority for many land managers. However, relatively little sampling of amphibian communities has occurred at high latitudes. We used skin swabs collected during 2005-2017 from boreal toads Anaxyrus boreas (n = 248), in southeast Alaska (USA; primarily in and near Klondike Gold Rush National Historical Park [KLGO]) and northwest British Columbia (Canada) to determine how Bd prevalence varied across life stages, habitat characteristics, local species richness, and time. Across all years, Bd prevalence peaked in June and was >3 times greater for adult toads (37.5%) vs. juveniles and metamorphs (11.2%). Bd prevalence for toads in the KLGO area, where other amphibian species are rare or absent, was highest from river habitats (55.0%), followed by human-modified upland wetlands (32.3%) and natural upland wetlands (12.7%)-the same rank-order these habitats are used for toad breeding. None of the 12 Columbia spotted frogs Rana luteiventris or 2 wood frogs R. sylvatica from the study area tested Bd-positive, although all were from an area of low host density where Bd has not been detected. Prevalence of Bd on toads in the KLGO area decreased during 2005-2015. This trend from a largely single-species system may be encouraging or concerning, depending on how Bd is affecting vital rates, and emphasizes the need to understand effects of pathogens before translating disease prevalence into management actions.

Standard techniques for estimating size of home range for semiaquatic mammals usually result in overestimating area because unused tractsof land and water are incorporated into calculations. For River Otters (Lutra canadensis) that inhabited a narrow strip of habitat along the terrestrial-marine interface, linear length of shoreline previously was used as a measure of home-range size. Although that method produced a conservative estimate, selection of data points using that procedure did not provide any measure of probability or indication of core areas. We used the adaptive-kernel estimator and Geographic Information System (GIS) for calculating linear length of home ranges for River Otters inhabiting a marine environment and assessed the effect of reducing the bandwidth size on those home-range estimates. Using locations collected from four otters in Ester Passage, Prince William Sound, Alaska, USA, during summer 1991, we determined that adaptive kernel with 100% and 95%a density contours resulted in a larger estimate than that produced by the previously used method. Decreasing bandwidth did not significantly alter the estimated linear distances of home range. In addition, the use of density contours of 65% delineated core areas; therefore, this technique provided a tool with which researches can to test hypotheses such as seasonal shifts in size and location of home ranges in relation to resource availability and distribution. Our technique may be useful for estimating home ranges of other animals approximating a linear distribution of locations. [ABSTRACT FROM AUTHOR]