Western Alaska Research Articles

Storekeeper perspectives on improving dietary intake in 12 rural remote western Alaska communities: the “Got Neqpiaq?” project

ABSTRACT Low intake of fruits and vegetables and high intake of sugar-sweetened beverages persists as a public health concern in rural remote Alaska Native (AN) communities. Conducting key informant interviews with 22 storekeepers in 12 communities in the Yukon-Kuskokwim region of Alaska, we explored potential factors impeding or facilitating dietary change towards healthier food choices. We selected these sites as part of a multi-level intervention aimed at introducing more traditional AN subsistence foods, increasing fruit and vegetable intake, and decreasing SSB consumption among young children enrolled in Head Start (preschool) programmes (Clinicaltrials.gov #NCT03601299). Storekeepers in these communities agreed that seasonality and flight schedules were primary factors determining commercial foods’ availability. Several storekeepers noted that federal food assistance programmes that specify which food items may be purchased with funds received from the programme and community policies that set limits on less healthy items promote customer purchases of healthier products. The fact that storekeepers are comfortable enforcing government assistance programme guidelines, company policies, and tribal resolutions suggests an important role storekeepers play in improving nutritional intake in their communities.

Cretaceous to Oligocene magmatic and tectonic evolution of the western Alaska Range: Insights from U-Pb and 40Ar/39Ar geochronology

AbstractNew U-Pb and 40Ar/39Ar ages integrated with geologic mapping and observations across the western Alaska Range constrain the distribution and tectonic setting of Cretaceous to Oligocene magmatism along an evolving accretionary plate margin in south-central Alaska. These rocks were emplaced across basement domains that include Neoproterozoic to Jurassic carbonate and siliciclastic strata of the Farewell terrane, Triassic and Jurassic plutonic and volcanic rocks of the Peninsular terrane, and Jurassic and Cretaceous siliciclastic strata of the Kahiltna assemblage. Plutonic rocks of different ages also host economic mineralization including intrusion-related Au, porphyry Cu-Mo-Au, polymetallic veins and skarns, and peralkaline intrusion-related rare-earth elements. The oldest intrusive suites were emplaced ca. 104–80 Ma into the Peninsular terrane only prior to final accretion. Deformation of the northern Kahiltna succession and underlying Farewell terrane occurred at ca. 97 Ma, and more widespread deformation ca. 80 Ma involved south-vergent folding and thrusting of the Kahiltna assemblage that records collisional accretion of the Peninsular-Wrangellia terrane and juxtaposition of sediment wedges formed on the inboard and outboard terranes. More widespread magmatism ca. 75–55 Ma occurred in two general pulses, each having distinct styles of localized deformation. Circa 75–65 Ma plutons were emplaced in a transpressional setting and stitch the accreted Peninsular and Wrangellia terranes to the Farewell terrane. Circa 65–55 Ma magmatism occurred across the entire range and extends for more than 200 km inboard from the inferred position of the continental margin. The Paleocene plutonic suite generally reflects shallower emplacement depths relative to older suites and is associated with more abundant andesitic to rhyolitic volcanic rocks. Deformation ca. 58–56 Ma was concentrated along two high-strain zones, the most prominent of which is 1 km wide, strikes east-northeast, and accommodated dextral oblique motion. Emplacement of widespread intermediate to mafic dikes ca. 59–51 Ma occurred before a notable magmatic lull from ca. 51–44 Ma reflecting a late Paleocene to early Eocene slab window. Magmatism resumed ca. 44 Ma, recording the transition from slab window to renewed subduction that formed the Aleutian-Meshik arc to the southwest. In the western Alaska Range, Eocene magmatism included emplacement of the elongate north-south Merrill Pass pluton and large volumes of ca. 44–37 Ma andesitic flows, tuffs, and lahar deposits. Finally, a latest Eocene to Oligocene magmatic pulse involved emplacement of a compositionally variable but spatially concentrated suite of magmas ranging from gabbro to peralkaline granite ca. 35–26 Ma, followed by waning magmatism that coincided with initiation of Yakutat shallow-slab subduction. Cretaceous to Oligocene magmatism throughout the western Alaska Range collectively records terrane accretion, translation, and integration together with evolving subduction dynamics that have shaped the southern Alaska margin since the middle Mesozoic.

Shifts in the wintering distribution and abundance of emperor geese in Alaska

For wildlife species that winter at northern latitudes, harsh overwinter conditions can play an important role in population dynamics. Recent changes in global temperatures have resulted in distributional shifts of wildlife species, as well as amelioration of winter climates in northern landscapes. The emperor goose (Anser canagicus), an endemic migratory bird of the Bering Sea region, winters across a large area of the subarctic, with potential differences in migration strategies and costs among individuals. As a long-standing species of conservation concern due to decreased population size, understanding the response of emperor geese to changing conditions has become critical to on-going management. We sought to evaluate changes in wintering distribution and arrival/departure dates over time, by comparing spatial and temporal patterns of wintering emperor geese from 2015 to 2017 (using geolocator data) to satellite telemetry data collected from 1999 to 2004. Further, we quantified changes in spatial patterns of winter abundance by comparing historical and contemporary aerial and ground surveys at three island complexes encompassing most of their winter distribution. Our results indicate that emperor geese are arriving at wintering areas earlier and spending more time at these areas than in the past. Our comparisons among historical aerial and ground surveys suggests that increasing numbers of emperor geese are wintering closer to breeding areas in western Alaska; a change likely related to increasing habitat availability due to shifting environmental conditions. Our results also showed that fewer emperor geese are using an area in the core of their wintering range, suggesting either decreased habitat quality or a reduction in migration distance via alternative wintering locations. Overall, our study highlights a rapid response to apparent habitat change likely due to warming temperatures and a reduction in ice cover and emphasizes the importance of understanding complex interactions among migration distance, the environment, and habitat in interpreting site selection.

Using electronic dental records to establish a surveillance system for dental decay in rural Western Alaska.

Previous surveys have demonstrated high rates of early childhood caries (ECC) in the Alaska Native (AN) population of western Alaska. There are many challenges to providing dental care in this road-less Yukon-Kuskokwim Delta region. The regional Tribal Health Organization implemented an electronic dental record (EDR) system in the late 1990s. We explored use of the EDR to establish an oral health surveillance system in children. We contracted with EDR software developers to implement calculation of a summary count of decayed (d), missing (m) or filled (f) primary (dmft) score for each individual. We calculated the yearly average dmft scores for 2011-2019 for children aged 3 and 5 years with a comprehensive exam in a given year. We also assessed the number of children undergoing full mouth dental rehabilitation (FMDR). We used US census data population estimates for these age groups to calculate rates. Over the 9-year period, 2,427 3-year-old children (47 percent of all 3-year olds over this period), received a comprehensive exam; increasing from 24 percent in 2011 to 62 percent in 2019. Their average dmft score over the 9-years was 6.4 with a significant annual decline over this period. Seventy percent of AN children who turned 6 between 2015 and 2019 had received at least one FMDR. An oral health surveillance system has been established in western Alaska using the Electronic Dental Record. High rates of ECC and FMDR were observed. This surveillance system will allow assessments of ECC prevalence and impact of dental interventions.

Headwater Catchments Govern Biogeochemistry in America's Largest Free‐Flowing River Network

AbstractRiverine chemistry reflects both watershed conditions and instream processing, both of which vary across river networks, yet little is known about the scales at which watershed attributes regulate biogeochemical constituents. We used spatial stream network (SSN) models to quantify both watershed and instream effects on streamwater constituents in the Kuskokwim River (western Alaska), the largest free‐flowing river in the United States. We assessed chemical constituents spanning from labile nutrients (nitrate [NO3−] and orthophosphate [PO43−]) to biologically and chemically conservative tracers (calcium [Ca2+], strontium [Sr2+], and Sr isotopes [87Sr/86Sr]). We also examined the behavior of dissolved organic carbon (DOC) relative to these constituents to understand whether bulk DOC behaved conservatively in a large boreal river network, where future changes in DOC and nutrient loading are expected under a shifting climate. We derived watershed spatial covariates comprising land cover, geology, and geomorphic characteristics at 14 different spatial extents based on stream order and relative to position in the river network to understand the effect of distant and proximal watershed attributes on streamwater constituents. For all constituents but 87Sr/86Sr, watershed attributes in low‐order headwater catchments yielded the best predictive ability for streamwater constituent concentrations across the entire network. Spatial patterning for conservative tracers and bulk DOC showed strong spatial autocorrelation, whereas PO43− and NO3− exhibited spatial patchiness indicative of instream processing. Our work shows that headwater streams are disproportionately important contributors to network‐wide biogeochemical constituents supporting aquatic food webs and that conservation and management of aquatic systems should include these small and often remote watershed areas.

Healthy Pregnancies Project: Cluster Randomized Controlled Trial of a Community Intervention to Reduce Tobacco Use among Alaska Native Women.

Substantial gaps remain in the evidence base for prenatal tobacco use interventions among Indigenous women. Using a cluster randomized controlled trial (RCT), the Healthy Pregnancies Project evaluated a community-level intervention for Alaska Native (AN) women in rural western Alaska. Sixteen villages were randomly assigned to usual care (control, n = 8 villages) or usual care plus a community-level intervention delivered by local AN “Native Sisters” (n = 8 villages). Outcomes were tobacco use rate at delivery and at 2 and 6 months postpartum, with biochemical confirmation obtained at 6 months. The program had high reach, enrolling 73% of all eligible women screened. Of the 352 participants, 67% used tobacco at baseline. No significant differences emerged between study groups on follow-up in tobacco use rates. More intervention than control participants made a quit attempt at 2 months postpartum (70% vs. 51%, respectively, p = 0.012). Participants in both study groups reported the program helped to raise awareness of healthy pregnancies in the study villages. This trial supports the reach of a community-level intervention, but not its efficacy for reducing tobacco use during pregnancy or postpartum. Efforts to sustain early quit attempts appear warranted. The community involvement, and reported impact on raising awareness of the importance of healthy pregnancies, supports the value of the research program in this community.

Density‐dependent effects of eastern Kamchatka pink salmon (Oncorhynchus gorbuscha) and Japanese chum salmon (O. keta) on age‐specific growth of western Alaska chum salmon

AbstractHatcheries release >4.5 billion juvenile Pacific salmon (Oncorhynchus spp.) into the North Pacific Ocean annually, raising concerns about competition with wild salmon populations. We used retrospective scale analysis to investigate how the growth of chum salmon (O. keta) from western Alaska is affected by the abundance of chum salmon from Japanese hatcheries and wild pink salmon (O. gorbuscha) from the Russian Far East. Over nearly five decades, the growth of Kuskokwim River chum salmon was negatively correlated with the abundance of Japanese hatchery chum salmon after accounting for the effects of sex and spring/summer sea‐surface temperature in the Bering Sea. An effect of wild eastern Kamchatka pink salmon abundance on the growth of Kuskokwim River salmon was detectable but modest compared to the intraspecific competitive effect. A decrease in Japanese hatchery chum salmon releases in 2011–2013 was not associated with increased growth of Bering Sea chum salmon. However, the abundance of wild chum salmon from the Russian Far East increased during that time, possibly obscuring reduced competition with hatchery chum salmon. Our results support previous evidence that chum salmon are affected by intraspecific competition, and to a lesser extent interspecific competition, in the North Pacific, underscoring that the effects of salmon hatchery production transcend national boundaries.

Nomenclature changes in the "Entolomatoid fungi of western North America and Alaska" (Largent 1994)

Nomenclatural omissions and orthographic errors in my 1994 monograph are corrected. The three genera Calliderma, Clitopiloides, and Fibropilus were validly published in 1994 as stat. nov. based on infrageneric names, and their extraterritorial basionym type species are proposed here as Ca. callidermum comb. nov., Cl. cyathus comb. nov., and F. fumosifolius comb. nov. Names originally proposed as provisional are validated as Leptonia cyanea comb. nov., L. cyanea var. occidentalis var. nov., and Inocephalus appressus sp. nov. Nolanea names that were illegitimate later homonyms are proposed as N. undatomarginata comb. nov. and N. papillatoides comb. nov., based on published replacement names. The published validation of the invalid 1994 name "Leptonia violacea" is indicated, and seven orthographic epithet corrections are listed

Gendering human capital development in Western Alaska

This article posits that conventional human capital development theory as applied to economic development lacks a consideration of cultural context. In developing regions of the world, life decisions at the postsecondary educational level are often less driven by individual choices and “rational” cost–benefit analyses and more by the continuing importance of family, community, and place‐based values. Results from an examination of postsecondary educational outcomes among rural, coastal peoples of Western Alaska demonstrate how human capital development stimulated through a regional economic development program is gendered: More women than men are pursuing higher education. They are often motivated by a desire to “give back” to both their families and their communities. The study also finds a lack of participation in formal vocational training programs despite the applicability of vocational skills to resource extraction–based industries in rural Alaska. Policy recommendations include economic development organizations creating value in postsecondary educational pathways that most benefit Bering Sea communities, such as those both in caring labor and in the skilled trades. This focus could help validate rural Alaskan commitments to family, community, and sense of place.

A characteristic periglacial landform: Automated recognition and delineation of cryoplanation terraces in eastern Beringia

AbstractAutomated recognition and delineation of specific landforms and their constituent elements ranks among the most active areas of contemporary geomorphological research. This study contributes to that literature by applying semi‐ and fully automated recognition procedures to upland periglacial geomorphic landscapes. The Cryoplanation Terrace semi‐Automated Recognition (CTAR) algorithm utilizes basic terrain parameters to identify locations of cryoplanation terraces (CTs) from the high‐resolution ArcticDEM. Using a multistep process, candidate areas are identified based on morphometric characteristics. CTAR uses terrain derivatives to search ridges, hills, and mountains for flat areas bounded by abrupt breaks in slope. Because CTs are found exclusively in upland periglacial environments, some locations require that low‐lying areas be filtered out. To assess accuracy, CTAR was tested at five local study sites distributed across eastern Beringia, each containing multiple CTs delimited manually in a previous study. CTAR performed well, with an overall accuracy of 90%. A strong linear relationship exists between the size of CTAR‐delimited terraces and those identified in a previous study through air‐photo interpretation. In addition to identifying nearly all of the CTs in the five study areas, a fully automated version of the algorithm (GEE‐CTAR), implemented in Google Earth Engine, identified nearly 8,000 previously unmapped potential CTs in the Seward Peninsula region of western Alaska. The ability to identify CTs from digital elevation models provides a useful tool for recognizing and delineating upland periglacial topography. Objective recognition of large erosional landform elements created by periglacial processes is a critical step in developing the field of periglacial geomorphometry.

A Block Model of Present‐Day Kinematics of Alaska and Western Canada

AbstractWe present an updated GPS velocity field for Alaska and western Canada and use it to develop the first regionally comprehensive tectonic block model for the area based on modern geodetic data. The greatest tectonic influences along the southern margin are the translation, collision, and flat slab subduction of the Yakutat block and subduction of the Pacific plate. Northward directed velocities surrounding the Yakutat collisional front are consistent with indenter‐related deformation while southcentral Alaska is undergoing a counterclockwise rotation. Westerly velocities in western Alaska and along the Aleutian forearc suggest that crustal material is escaping into the Bering Sea region. The majority of relative plate motion is taken up along major boundary faults, but right‐lateral strike‐slip faults in interior and western Alaska accommodate part of the motion. Escape tectonics in western Alaska extends as far north as the Kaltag fault. We observe significant motion relative to North America in every part of Alaska, including the North Slope. Evidence of localized right‐lateral shear between the Totschunda and Fairweather faults suggests that strain transfer into interior Alaska has moved away from the eastern Denali‐Chatham Strait system to a more direct corridor. Observed deformation in southcentral Alaska indicates that locked portions of the Yakutat flat slab extend further east and north than previously estimated.

Evaluation of methods for spawner–recruit analysis in mixed-stock Pacific salmon fisheries

Salmon populations harvested in mixed-stock fisheries can exhibit genotypic, behavioral, and life history diversity that can lead to heterogeneity in population productivity and size. Methods to quantify this heterogeneity among populations in mixed-stock fisheries are not well-established but are critical to assessing harvest–biodiversity trade-offs when setting harvest policies. We developed an integrated, age-structured, state-space model that allows for more complete use of available data and sharing of information than simpler methods. We compared a suite of state-space models of varying structural complexity to simpler regression-based approaches and, as an example case, fitted them to data from 13 Chinook salmon (Oncorhynchus tshawytscha) populations in the Kuskokwim drainage in western Alaska. We found biological and policy conclusions were largely consistent among state-space models but differed strongly from regression-based approaches. Simulation trials illustrated our state-space models were largely unbiased with respect to spawner–recruit parameters, abundance states, and derived biological reference points, whereas the regression-based approaches showed substantial bias. These findings suggest our state-space model shows promise for informing harvest policy evaluations of harvest–biodiversity trade-offs in mixed-stock salmon fisheries.

A Review of the Western Canadian and Alaskan Species of Corticaria Marsham, 1802 (Coleoptera: Latridiidae): Descriptions of New Species and Taxonomic Notes on Other North American Species

The western Canadian and Alaskan species of CorticariaMarsham, 1802 are reviewed. After this review, there are 29 species recognized from western Canada and Alaska. The following are reported for the first time from North America: Corticaria kabakovi Saluk, new continent record; and for the first time from Canada: Corticaria arctophila Fall, Corticaria cavicauda Fall, Corticaria fulva (Comolli), Corticaria inconspicua Wollaston, Corticaria planula Fall, and Corticaria prionodera LeConte, new country records. Twelve new species are described from Canada: Corticaria alta Hammond and Chambers, Corticaria arborea Hammond and Chambers, Corticaria bousqueti Hammond and Chambers, Corticaria cylindracea Hammond and Chambers, Corticaria langori Hammond and Chambers, Corticaria maritima Hammond and Chambers, Corticaria montana Hammond and Chambers, Corticaria pseudofennica Hammond and Chambers, Corticaria pseudoincerta Hammond and Chambers, Corticaria pseudopinetorum Hammond and Chambers, Corticaria pseudovicollis Hammond and Chambers, and Corticaria pseudotsuga Hammond and Chambers. An additional two new species are described from Montana: Corticaria andrewsi Hammond and Chambers and Corticaria aspera Hammond and Chambers. After examination of North American type material the following nomenclatural and taxonomic changes are proposed: Corticaria dentigera LeConte is placed in synonymy with Corticaria rubripes Mannerheim, new synonymy; Corticaria grossa LeConte is taken out of synonymy with Corticaria pubescens (Gyllenhal) and instead is placed in synonymy with Corticaria punctulata Marsham, new synonymy; Corticaria valida Fall is placed in synonymy with Corticaria aphictoides Reitter, new synonymy; Corticaria varicolor Fall is placed in synonymy with Corticaria impressa (Olivier), new synonymy; Corticaria falliHetschko, 1929, should be adopted in lieu of Corticaria cribricollisFall, 1899, as the latter is a junior primary homonym of Corticaria cribricollisFairmaire, 1863; and the following names are declared nomina dubia until type specimens can be located: Corticaria canaliculataMannerheim, 1853; Corticaria columbiaFall, 1899; Corticaria salpingoidesMotschulsky, 1867; and Corticaria spinulosaMannerheim, 1852. A key to the Canadian and Alaskan fauna and discussion of all current North American species is provided.

Three-dimensional shape and structure of the Susitna basin, south-central Alaska, from geophysical data

AbstractWe use gravity, magnetic, seismic reflection, well, and outcrop data to determine the three-dimensional shape and structural features of south-central Alaska’s Susitna basin. This basin is located within the Aleutian-Alaskan convergent margin region and is expected to show effects of regional subduction zone processes. Aeromagnetic data, when filtered to highlight anomalies associated with sources within the upper few kilometers, show numerous linear northeast-trending highs and some linear north-trending highs. Comparisons to seismic reflection and well data show that these highs correspond to areas where late Paleocene to early Eocene volcanic layers have been locally uplifted due to folding and/or faulting. The combined magnetic and seismic reflection data suggest that the linear highs represent northeast-trending folds and north-striking faults. Several lines of evidence suggest that the northeast-trending folds formed during the middle Eocene to early Miocene and may have continued to be active in the Pliocene. The north-striking faults, which in some areas appear to cut the northeast-trending folds, show evidence of Neogene and probable modern movement. Gravity data facilitate estimates of the shape and depth of the basin. This was accomplished by separating the observed gravity anomaly into two components—one representing low-density sedimentary fill within the basin and one representing density heterogeneities within the underlying crystalline basement. We then used the basin anomaly, seismic reflection data, and well data to estimate the depth of the basin. Together, the magnetic, gravity, and reflection seismic analyses reveal an asymmetric basin comprising sedimentary rock over 4 km thick with steep, fault-bounded sides to the southwest, west, and north and a mostly gentle rise toward the east. Relations to the broader tectonic regime are suggested by fold axis orientations within the Susitna basin and neighboring Cook Inlet basin, which are roughly parallel to the easternmost part of the Alaska-Aleutian trench and associated Wadati-Benioff zone as it trends from northeast to north-northeast to northeast. An alignment between forearc basin folds and the subduction zone trench has been observed at other convergent margins, attributed to strain partitioning generated by regional rheologic variations that are associated with the subducting plate and arc magmatism. The asymmetric shape of the basin, especially its gentle rise to the east, may reflect uplift associated with flat-slab subduction of the Yakutat microplate, consistent with previous work that suggested Yakutat influence on the nearby Talkeetna Mountains and western Alaska Range. Yakutat subduction may also have contributed to Neogene and later reverse slip along north-striking faults within the Susitna basin.

Incorporating harvest–population diversity trade-offs into harvest policy analyses of salmon management in large river basins

Accounting for population diversity can be critical to the sustainable management of mixed-stock fisheries because harvest rates that can be sustained by productive populations may come at the cost of overfishing less productive ones. While these harvest–diversity trade-offs are well-recognized, their consequences for harvest policy performance are not often explicitly evaluated in contemporary fisheries management. We use closed-loop simulations to evaluate the ability of alternative harvest policies to meet population diversity and fishery objectives for one of the largest subsistence Chinook salmon (Oncorhynchus tshawytscha) fisheries in the world (Kuskokwim River Basin in western Alaska). We found clear evidence of population diversity that resulted in asymmetric trade-offs among fishery and conservation objectives whereby policies that forgo relatively small amounts of harvest result in relatively large increases in equitable access to Chinook and elimination of risk of weak stock extirpation. The performance of alternative harvest policies, and the magnitude of trade-offs, were sensitive to regime shifts and uncertainty in the drivers of recruitment variation. However, we found that harvest policies that prioritized meeting minimum subsistence needs were unlikely to jeopardize long-term sustainability.

Is subarctic forest advance able to keep pace with climate change?

Recent climate warming and scenarios for further warming have led to expectations of rapid movement of ecological boundaries. Here we focus on the circumarctic forest-tundra ecotone (FTE), which represents an important bioclimatic zone with feedbacks from forest advance and corresponding tundra disappearance (up to 50% loss predicted this century) driving widespread ecological and climatic changes. We address FTE advance and climate history relations over the 20th century, using FTE response data from 151 sites across the circumarctic area and site-specific climate data. Specifically, we investigate spatial uniformity of FTE advance, statistical associations with 20th century climate trends, and whether advance rates match climate change velocities (CCVs). Study sites diverged into four regions (Eastern Canada; Central and Western Canada and Alaska; Siberia; and Western Eurasia) based on their climate history, although all were characterized by similar qualitative patterns of behaviour (with about half of the sites showing advancing behaviour). The main associations between climate trend variables and behaviour indicate the importance of precipitation rather than temperature for both qualitative and quantitative behaviours, and the importance of non-growing season as well as growing season months. Poleward latitudinal advance rates differed significantly among regions, being smallest in Eastern Canada (~10m/year) and largest in Western Eurasia (~100m/year). These rates were 1-2 orders of magnitude smaller than expected if vegetation distribution remained in equilibrium with climate. The many biotic and abiotic factors influencing FTE behaviour make poleward advance rates matching predicted 21st century CCVs (~103 -104 m/year) unlikely. The lack of empirical evidence for swift forest relocation and the discrepancy between CCV and FTE response contradict equilibrium model-based assumptions and warrant caution when assessing global-change-related biotic and abiotic implications, including land-atmosphere feedbacks and carbon sequestration.

The interactive effect of competition and climate on growth of boreal tree species in western Canada and Alaska

Understanding interactions between competition and climate in relation to their effects on individual tree growth is crucial to the development of climate-sensitive growth models required for modelling boreal forest succession in a changing climate. We used data from permanent growth and yield sample plots in western Canada and Alaska to investigate the impact of competition within a regional gradient of climatic conditions for lodgepole pine (Pinus contorta Douglas ex Loudon), jack pine (Pinus banksiana Lamb.), trembling aspen (Populus tremuloides Michx.), balsam poplar (Populus balsamifera L.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.). We characterized the effects of competition (basal area of spruce–fir, deciduous, and pine trees larger than the focal tree) and climate (mean annual temperature and precipitation) and their interactions on basal area growth of individual trees using linear mixed-effects models. Our results indicated that intraspecific competition had stronger effects on growth than interspecific competition and climate. Moreover, significant interactions between intraspecific competition and climate suggest that an increase in intraspecific competition will lead to a reduction in tree growth for warmer regions (lodgepole pine, trembling aspen, balsam poplar, and white spruce) and wetter regions (jack pine). The manner in which interspecific competition altered tree growth responses to climate was variable, depending on tree species and competition type. These results indicate that the relationships between growth and climate may differ according to the degree of competition and the structure of the stand.

ASLO 2020 Award Winners

<scp>ASLO</scp> 2020 Award Winners

Long‐term research and hierarchical models reveal consistent fitness costs of being the last egg in a clutch

Maintenance of phenotypic heterogeneity in the face of strong selection is an important component of evolutionary ecology, as are the consequences of such heterogeneity. Organisms may experience diminishing returns of increased reproductive allocation as clutch or litter size increases, affecting current and residual reproductive success. Given existing uncertainty regarding trade‐offs between the quantity and quality of offspring, we sought to examine the potential for diminishing returns on increased reproductive allocation in a long‐lived species of goose, with a particular emphasis on the effect of position in the laying sequence on offspring quality.To better understand the effects of maternal allocation on offspring survival and growth, we estimated the effects of egg size, timing of breeding, inter‐ and intra‐annual variation, and position in the laying sequence on gosling survival and growth rates of black brant Branta bernicla nigricans breeding in western Alaska from 1987 to 2007.We found that gosling growth rates and survival decreased with position in the laying sequence, regardless of clutch size. Mean egg volume of the clutch a gosling originated from had a positive effect on gosling survival (β = 0.095, 95% CRI: 0.024, 0.165) and gosling growth rates (β = 0.626, 95% CRI: 0.469, 0.738). Gosling survival (β = −0.146, 95% CRI: −0.214, −0.079) and growth rates (β = −1.286, 95% CRI: −1.435, −1.132) were negatively related to hatching date.These findings indicate substantial heterogeneity in offspring quality associated with their position in the laying sequence. They also potentially suggest a trade‐off mechanism for females whose total reproductive investment is governed by pre‐breeding state.

Novel insights into serodiagnosis and epidemiology of Erysipelothrix rhusiopathiae, a newly recognized pathogen in muskoxen (Ovibos moschatus).

Muskoxen are a key species of Arctic ecosystems and are important for food security and socio-economic well-being of many Indigenous communities in the Arctic and Subarctic. Between 2009 and 2014, the bacterium Erysipelothrix rhusiopathiae was isolated for the first time in this species in association with multiple mortality events in Canada and Alaska, raising questions regarding the spatiotemporal occurrence of the pathogen and its potential impact on muskox populations. We adapted a commercial porcine E. rhusiopathiae enzyme-linked immunosorbent assay to test 958 blood samples that were collected from muskoxen from seven regions in Alaska and the Canadian Arctic between 1976 and 2017. The cut-off between negative and positive results was established using mixture-distribution analysis, a data-driven approach. Based on 818 samples for which a serological status could be determined and with complete information, we calculated trends in sample seroprevalences in population time-series and compared them with population trends in the investigated regions. Overall, 219/818 (27.8%, 95% Confidence Interval: 24.7-31.0) samples were classified as positive for exposure to E. rhusiopathiae. There were large variations between years and regions. Seropositive animals were found among the earliest serum samples tested; 1976 in Alaska and 1991 in Canada. In Alaskan muskoxen, sample seroprevalence increased after 2000 and, in two regions, peak seroprevalences occurred simultaneously with population declines. In one of these regions, concurrent unusual mortalities were observed and E. rhusiopathiae was isolated from muskox carcasses. In Canada, there was an increase in sample seroprevalence in two muskox populations following known mortality events that had been attributed to E. rhusiopathiae. Our results indicate widespread exposure of muskoxen to E. rhusiopathiae in western Canada and Alaska. Although not new to the Arctic, we documented an increased exposure to the pathogen in several regions concurrent with population declines. Understanding causes for the apparent increased occurrence of this pathogen and its association with large scale mortality events for muskoxen is critical to evaluate the implications for wildlife and wildlife-dependent human populations in the Arctic.