Evidence for a survival-driven traveling wave in a keystone boreal predator population.

Cyclical population dynamics are a common phenomenon in populations worldwide, yet the spatial organization of these cycles remains poorly understood. In this study, we investigated the spatial form and timing of a population collapse from 2018 to 2022 in Canada lynx (Lynx canadensis) across the northwest boreal forest. We analyzed survival, reproduction, and dispersal data from 143 individual global positioning system (GPS) collared lynx from populations across five study sites spanning interior Alaska to determine whether lynx displayed characteristics of a population wave following a concurrent wave in snowshoe hare (Lepus americanus) abundance. Reproductive rates declined across the study sites; however, site-level reproduction declined first in our easternmost study sites, supporting the idea of a population wave. Despite a clear increase in percent of dispersing lynx, there was no evidence of directional bias in dispersal following a hare population wave. Analysis did show increasingly poor survival for lynx dispersing to the east compared to combined resident and westward dispersal. This pattern is consistent with a survival-mediated population wave in lynx as the driver of the theorized population wave. The combination of these factors supports the idea of a hierarchical response to snowshoe hare population declines with a drop in lynx reproduction followed by increased dispersal, and finally reduced survival. All of this evidence is consistent with the expected characteristics of a population undergoing a traveling wave and supports the hypothesis that lynx presence may facilitate and mirror the underlying wave patterns in snowshoe hare.

Effect of a multicarbohydrase containing α-galactosidase in sow lactating diets with varying energy density.

Sow productivity improvements are associated with high energetic demand due to increasing prolificity. The reproductive life and longevity of sows, and the readiness for weaning of the offspring may be impaired when sows loose significant body weight (BW) during lactation. The impact of a multicarbohydrase containing α-galactosidase on a low energy dense lactation diet was evaluated in this study. Two-hundred and eight sows (208 ±â€…25.2 kg) were blocked by parity and BW to one of four treatments, in which a corn-soybean meal diet was formulated to have varying levels of added fat (0, 1.5%, and 3%) to titrate an energy density model. A fourth treatment replicated the 0% added fat formulation with enzyme supplementation at 250 g/tonne. Sows were weighed individually on entry, post-farrow (by calculation) and at weaning. Daily feed intakes (ADFI) and caloric intake were used for calculation of sow feed efficiency (FE) and caloric efficiency. Litter performance was characterized at birth, and size was standardized within 24h of farrow and within treatment to ensure uniform litter sizes. Average wean weight and pre-weaning mortality were determined. Piglets were weighted individually to study litter weight distribution. Data was analyzed as a randomized completely block design, using sow as the experimental unit, treatment as the main effect, and standardized average weight and litter sizes as covariates where appropriate. Although sows fed a multicarbohydrase had lower standardized litter size (P < 0.001), average wean weight was higher in this group and equivalent to the 3% added fat treatment. Enzyme supplementation tended to reduce the proportion of light weight pigs (BW < 4.1kg) within the litter, when compared with the 0% added fat diet (P < 0.1). The multicarbohydrase tended to increased sow ADFI (P < 0.10), although sows from all treatments had equivalent caloric intakes during lactation (P > 0.1). Enzyme supplementation yielded significant improvements in sow FE (P < 0.01), similar to the 3% added fat group. Thus, the carbohydrase degrading enzyme tested in this study improved the efficiency of sows, while increasing average wean weights of the offspring, suggesting an improvement in nutrient digestion and/or metabolic efficiency from typical lactation diets.

An evaluation of an employment pilot to support forensic mental health service users into work and vocational activities.

BACKGROUND: Few employment programmes exist to support forensic service users with severe mental health problems and a criminal history. Little is known about how best to achieve this. The Employment and Social Inclusion Project (ESIP) was developed and piloted to support forensic service users into employment and vocational activities. AIMS: This pilot service evaluation aimed to assess the number of service users who secured employment/vocational activities and explored services users' and staff experiences. METHOD: Quantitative data were collected to record the characteristics of participating service users and how many secured employment and engaged in vocational activities. Eighteen qualitative interviews were conducted with service users and staff. RESULTS: Fifty-seven service users engaged with the project, most were men (93.0%) and previously employed (82.5%). Four service users (7.0%) secured paid competitive employment. Eight (14.0%) gained other paid employment. Tailored one-to-one support to increase skills and build confidence was an important feature of the project. Creation of a painting and decorating programme offered training and paid/flexible work. CONCLUSIONS: This exploratory project achieved some success in assisting forensic service users into paid employment. Further research to identify what works well for this important group will be of great value.

Trophic dynamics of shrinking Subarctic lakes: naturally eutrophic waters impart resilience to rising nutrient and major ion concentrations.

Shrinking lakes were recently observed for several Arctic and Subarctic regions due to increased evaporation and permafrost degradation. Along with lake drawdown, these processes often boost aquatic chemical concentrations, potentially impacting trophic dynamics. In particular, elevated chemical levels may impact primary productivity, which may in turn influence populations of primary and secondary consumers. We examined trophic dynamics of 18 shrinking lakes of the Yukon Flats, Alaska, that had experienced pronounced increases in nutrient (>200 % total nitrogen, >100 % total phosphorus) and ion concentrations (>100 % for four major ions combined) from 1985-1989 to 2010-2012, versus 37 stable lakes with relatively little chemical change over the same period. We found that phytoplankton stocks, as indexed by chlorophyll concentrations, remained unchanged in both shrinking and stable lakes from the 1980s to 2010s. Moving up the trophic ladder, we found significant changes in invertebrate abundance across decades, including decreased abundance of five of six groups examined. However, these decadal losses in invertebrate abundance were not limited to shrinking lakes, occurring in lakes with stable surface areas as well. At the top of the food web, we observed that probabilities of lake occupancy for ten waterbird species, including adults and chicks, remained unchanged from the period 1985-1989 to 2010-2012. Overall, our study lakes displayed a high degree of resilience to multi-trophic cascades caused by rising chemical concentrations. This resilience was likely due to their naturally high fertility, such that further nutrient inputs had little impact on waters already near peak production.

Pronounced chemical response of Subarctic lakes to climate-driven losses in surface area.

Losses in lake area have been observed for several Arctic and Subarctic regions in recent decades, with unknown consequences for lake ecosystems. These reductions are primarily attributed to two climate-sensitive mechanisms, both of which may also cause changes in water chemistry: (i) increased imbalance of evaporation relative to inflow, whereby increased evaporation and decreased inflow act to concentrate solutes into smaller volumes; and (ii) accelerated permafrost degradation, which enhances sublacustrine drainage while simultaneously leaching previously frozen solutes into lakes. We documented changes in nutrients [total nitrogen (TN), total phosphorus (TP)] and ions (calcium, chloride, magnesium, sodium) over a 25 year interval in shrinking, stable, and expanding Subarctic lakes of the Yukon Flats, Alaska. Concentrations of all six solutes increased in shrinking lakes from 1985-1989 to 2010-2012, while simultaneously undergoing little change in stable or expanding lakes. This created a present-day pattern, much weaker or absent in the 1980s, in which shrinking lakes had higher solute concentrations than their stable or expanding counterparts. An imbalanced evaporation-to-inflow ratio (E/I) was the most likely mechanism behind such changes; all four ions, which behave semiconservatively and are prone to evapoconcentration, increased in shrinking lakes and, along with TN and TP, were positively related to isotopically derived E/I estimates. Moreover, the most conservative ion, chloride, increased >500% in shrinking lakes. Conversely, only TP concentration was related to probability of permafrost presence, being highest at intermediate probabilities. Overall, the substantial increases of nutrients (TN >200%, TP >100%) and ions (>100%) may shift shrinking lakes towards overly eutrophic or saline states, with potentially severe consequences for ecosystems of northern lakes.

Multi-trophic resilience of boreal lake ecosystems to forest fires.

Fires are the major natural disturbance in the boreal forest, and their frequency and intensity will likely increase as the climate warms. Terrestrial nutrients released by fires may be transported to boreal lakes, stimulating increased primary productivity, which may radiate through multiple trophic levels. Using a before-after-control-impact (BACI) design, with pre- and postfire data from burned and unburned areas, we examined effects of a natural fire across several trophic levels of boreal lakes, from nutrient and chlorophyll levels, to macroinvertebrates, to waterbirds. Concentrations of total nitrogen and phosphorus were not affected by the fire. Chlorophyll a levels were also unaffected, likely reflecting the stable nutrient concentrations. For aquatic invertebrates, we found that densities of three functional feeding groups did not respond to the fire (filterers, gatherers, scrapers), while two groups increased (shredders, predators). Amphipods accounted for 98% of shredder numbers, and we hypothesize that fire-mediated habitat changes may have favored their generalist feeding and habitat ecology. This increase in amphipods may, in turn, have driven increased predator densities, as amphipods were the most numerous invertebrate in our lakes and are commonly taken as prey. Finally, abundance of waterbird young, which feed primarily on aquatic invertebrates, was not affected by the fire. Overall, ecosystems of our study lakes were largely resilient to forest fires, likely due to their high initial nutrient concentrations and small catchment sizes. Moreover, this resilience spanned multiple trophic levels, a significant result for ecologically similar boreal regions, especially given the high potential for increased fires with future climate change.

Interspecific exchange of avian influenza virus genes in Alaska: the influence of trans-hemispheric migratory tendency and breeding ground sympatry.

The movement and transmission of avian influenza viral strains via wild migratory birds may vary by host species as a result of migratory tendency and sympatry with other infected individuals. To examine the roles of host migratory tendency and species sympatry on the movement of Eurasian low-pathogenic avian influenza (LPAI) genes into North America, we characterized migratory patterns and LPAI viral genomic variation in mallards (Anas platyrhynchos) of Alaska in comparison with LPAI diversity of northern pintails (Anas acuta). A 50-year band-recovery data set suggests that unlike northern pintails, mallards rarely make trans-hemispheric migrations between Alaska and Eurasia. Concordantly, fewer (14.5%) of 62 LPAI isolates from mallards contained Eurasian gene segments compared to those from 97 northern pintails (35%), a species with greater inter-continental migratory tendency. Aerial survey and banding data suggest that mallards and northern pintails are largely sympatric throughout Alaska during the breeding season, promoting opportunities for interspecific transmission. Comparisons of full-genome isolates confirmed near-complete genetic homology (>99.5%) of seven viruses between mallards and northern pintails. This study found viral segments of Eurasian lineage at a higher frequency in mallards than previous studies, suggesting transmission from other avian species migrating inter-hemispherically or the common occurrence of endemic Alaskan viruses containing segments of Eurasian origin. We conclude that mallards are unlikely to transfer Asian-origin viruses directly to North America via Alaska but that they are likely infected with Asian-origin viruses via interspecific transfer from species with regular migrations to the Eastern Hemisphere.