Late Holocene paleofish populations in Effingham Inlet, British Columbia, Canada

Paleontological studies of fish remains in laminated sediments provide a proxy relationship between fish populations and ocean climate. This study examines climate variability from approximately 500 y B.P. to 4000 y B.P. as recorded in fish remain abundances (primarily scales) collected from laminated sediments within Effingham Inlet on the west coast of Vancouver Island, British Columbia. The study also discusses technical issues involving fish remains from laminated sediments, including sampling resolution, sediment volume, identification of remains and appropriate abundance considerations.The dominant species in the assemblage include Northern anchovy and Pacific herring, with lesser percentage-abundances from rockfish, hake, elasmobranches and surfperch. The data indicate that Northern anchovy experienced a shift in scale deposition abundance at approximately 2800 y B.P. with not only a greater total abundance but also a greater consistency of deposition with time. Pacific herring underwent cyclical deposition that changed little through time. Statistical analysis reveals that none of these species is directly responding to climatic signals as indicated in the lithological and palynological record, but that this could have been partially due to the sampling resolution of the piston core. Analysis indicates a lack of correlation between the two dominant species, as might be expected on the basis of their opposing lifestyle strategies with respect to sea surface temperatures.With appropriate sampling strategies, paleohistorical fish remains from laminated sediments reflect changes in population structure and behaviour for some species, illustrate basic secondary trophic information, and provide potential clues to basin-scale oceanographic/climatological variability.     

Surface nitrogen and plankton in Skaha Lake, British Columbia (Canada)

This study (1970–71) of an oligotrophic lake subject to cultural enrichment indicates the presence of complex interrelations between plankton and nitrogen levels in surface waters. Generally inorganic nitrogen was high in the winter (0.4–0.5 ppm) and Iow in summer (less than 0-1 ppm). However, in late July and August a large increase in nitrogen (1.5 ppm) was recorded. This correlated with the Gloeotrichia echinulata J. E. Smith ex P. Richt. bloom (Cyanophyceae) and the increase in nitrogen fixation, or nitrogenase activity (measured as acetylene reduction). It was calculated that the cyanophyte bloom could have contributed a minimum of 2350 kg nitrogen to the lake in August 1970 which is c. 62% of the nitrate-nitrogen occurring at any time.     

Macrolichen diversity as an indicator of stand age and ecosystem resilience along a precipitation gradient in humid forests of inland British Columbia,Canada

The distributional ecology of 87 macrolichens is reported from 14 unmanaged mid-seral and old forest stands along a precipitation gradient in south-central British Columbia. We used a combination of univariate and multivariate statistics to investigate the role of forest structure and stand age in the distribution of epiphytic macrolichens in interior cedar-hemlock forests. Old forests support a higher number of species; although mean species richness is not significantly different between the two age classes. Terricolous and epixylic community structure is correlated with stand age and log characteristics, but the epiphtytic community is not. Epiphytic community structure is strongly associated with precipitation in the old stands, but not in the mid-seral stands. Old forests at the wetter end of the precipitation gradient contained several old-growth associated species, all of which are hygrophytic. Most epiphytic macrolichens associated with old forests are not dependent on specific structural attributes. However, western red cedar (Thuja plicata Donn ex D. Don) harbors the greatest number of arboreal macrolichen species by far in these unmanaged stands and should, therefore, be considered a key indicator in managed forests. Our study suggests that most macrolichen species found in old forests can also occur in 70- to 165-year-old forests dating from stand-replacing fires. Old forests, however, clearly provide important habitat for oceanic epiphytes at the edge of their ecological range in the interior of British Columbia. Our findings illustrate that the macrolichen flora in wet toe-slope stands in humid inland British Columbia has a high level of resilience following disturbance under natural succession conditions. It also underlines the point that some species, like Lobaria pulmonaria, are good indicators of old-growth forests in certain regions but not in others, suggesting a careful use of the term old-growth dependence.     

A tale of two populations: vital rates of fishers in British Columbia,Canada

Fishers (Pekania pennanti) are a forest-dependent carnivore of conservation concern in British Columbia, Canada. Ecological, spatial, and genetic evidence suggests that there are 2 distinct populations (Boreal and Columbian) that occur in forests at low to moderate elevations in the boreal and central interior regions of the province. In British Columbia, fishers occur at low densities relative to other parts of their range in North America, are trapped for their fur, and are sensitive to habitat change. Despite these factors, little demographic information exists to assist with management decisions for these populations. We collated and analyzed survival and reproductive data from 100 radio-tagged fishers from 5 independent studies conducted between 1990 and 2012 in British Columbia: 2 in the Boreal population, and 3 in the Columbian population. We also collated litter size data from 1 den box study and a translocation project of fishers from the Columbian population. Annual survival rates were not significantly different between the populations or between males and females; however, adult survival rates were higher than subadults (0.79 and 0.63, respectively). Subadult females had significantly lower survival rates than other sex or age classes. Reproductive rates were significantly different between the 2 populations (denning rate = 0.54 [Columbian], 0.82 [Boreal]; $\overline{x}$ litter size = 1.7 [Columbian], 2.6 [Boreal]). These differences resulted in net reproductive rates in the Columbian population that were less than half of those in the Boreal population (0.92 kits/reproductive season compared to 2.13, respectively). Population growth rates suggest that the Columbian population may have been declining during the studies, whereas the Boreal population may have been increasing (0.96 compared to 1.20). Consequently, we suggest that focused and intensive habitat and population management for fishers are needed in British Columbia to ensure population sustainability, particularly for the Columbian population.     

Low connectivity and declining genetic variability along a depth gradient in Corallium rubrum populations

This study examines the possible effect of depth on the connectivity and genetic variability in red coral (Corallium rubrum; Octocorallia: Alcyonacea) populations. Patterns of genetic structuring along a depth gradient (from 20 to 70 m) were investigated in two locations of the western Mediterranean coast (northern Catalan and eastern Ligurian Seas) using 10 microsatellite loci. Strong patterns of genetic structuring among the samples were found both within and between the two study sites. In both locations, consistent patterns of reduction in genetic variability along the depth gradient were also observed, suggesting that depth has an important role in determining the patterns of genetic structure in Corallium rubrum. Moreover, a threshold in connectivity was observed among the samples collected across 40–50 m depth, supporting the hypothesis that discrete shallow- and deep-water red coral populations occur. This finding has major implications for management strategies and the conservation of commercially exploited deep red coral populations.     

Autumnal mixing in Mahoney Lake,British Columbia

Salinity, water temperature and meteorlogical measurements were made over a 5 month period (June–Oct.) at Mahoney Lake, British Columbia to study autumnal mixing. The measurements were made during a time when the lake had been well stratified by a much larger than average runoff the previous spring. The potential energy of stratification decreased from 50 to 24 MJ, in the top 8 m of the water column, from mid August to mid October. Analysis of the energy available from wind shear on the water surface and from penetrative convection during the autumn cooling period was made. Winds were found to be weak (av. 2.17 m s ^–1) at Mahoney Lake, and their average contribution to mixing energy during the study period was less than 30%. Penetrative convection from thermals descending from the cool surface contributed an average of 2.21 J m^–2 d^–1 to mixing which represented 72 % of the energy available. An efficiency factor of 0.20 for the penetrative convection energy, larger than values previously reported in the literature, was found to fit the measured loss of potential energy of stratification during the period.     

Ectoparasitic insects of bats in British Columbia, Canada

One species of parasitic bug (Hemiptera : Cimicidae), 3 species of fleas (Siphonaptera: Ischnopsyllidae), and 2 species of parasitic flies (Diptera : Nycteribiidae) were collected from 9 species of bats (Chiroptera : Vespertilionidae) in southern interior and northeastern British Columbia, Canada. Female bats that return daily to maternity roosts were more frequently infested with both cimicids and ischnopsyllids than were male bats. Some differences in ectoparasite infestation can be attributed to differences in roosting behavior of the host. New national records for 2 parasite species, and 8 new host records are established for Canada.     

Midge-inferred Holocene summer temperatures in Southeastern British Columbia,Canada

Using fossil midge stratigraphies, we inferred Holocene summer temperatures at three subalpine lakes in eastern British Columbia. The late-glacial sediment indicated cool conditions, with an abundance of Microspectra atrofasciata/radialis type fossils at Thunder Lake and Redmountain Lake, and Sergentia at Windy Lake. Sergentia and Tanytarsus lugens/Corynocera oliveri type were dominant in the early Holocene, together with Chironomus at Redmountain Lake. At Thunder and Windy lakes, the early Holocene was dominated by warm-adapted taxa such as Microtendipes. Quantitative midge-temperature inference models reconstruct a 4 to 8 °C rise in mean July air temperature for Windy and Thunder lakes at the Pleistocene/Holocene transition. Early-Holocene temperatures averaged 3 to 4 °C warmer than those extant today. In contrast, no long-term temperature trend was evident at Redmountain Lake. This site may not reflect actual trends in air temperature due to runoff from a persistent snow pack in the watershed. Comparison of midge and pollen data suggests an inverse relationship between summer temperature and precipitation through the middle to late Holocene.     

Multiscale Habitat Use by Wolverines in British Columbia,Canada

ABSTRACT Wolverine (Gulo gulo) distribution in British Columbia, Canada, includes multiple-use lands where human use and resource extraction may influence habitat selection. We evaluated seasonal habitat use by resident adult wolverines using radiotelemetry locations from 2 multiple-use landscapes in British Columbia. Food, predation risk, and human disturbance hypotheses were considered in logistic regression analyses of used and random landscapes. Male wolverine habitat associations were most supported by the food hypothesis in both summer and winter. Moose (Alces alces) winter ranges, valley bottom forests, and avalanche terrain were positively associated with winter male wolverine use. Habitat use by male wolverines in winter was also negatively associated with helicopter skiing areas in the Columbia Mountains. Habitat associations of females were more complex; combinations of variables supporting food, predation risk, or human disturbance hypotheses were included in most supported models from both summer and winter in both study areas. Females were associated with alpine and avalanche environments where hoary marmot (Marmota caligata) and Columbia ground squirrel (Spermophilus columbianus) prey are found in summer. Roaded and recently logged areas were negatively associated with female wolverines in summer. In the Columbia Mountains, where winter recreation was widespread, females were negatively associated with helicopter and backcountry skiing. Moose winter ranges within rugged landscapes were positively associated with females during winter. Our analysis suggests wolverines were negatively responding to human disturbance within occupied habitat. The population consequences of these functional habitat relationships will require additional focused research. Our spatially explicit models can be used to support conservation planning for resource extraction and tourism industries operating in landscapes occupied by wolverines.     

Autotrophic picoplankton community dynamics in a pre-alpine lake in British Columbia,Canada

Autotrophic picoplankton (APP) were studied in Chilko Lake, a large, deep ultra-oligotrophic pre-alpine lake (elevation: 1172 m) in the south central coast mountains of British Columbia. Data from 1985 (untreated) and 1990 (treated) were used to compare and contrast APP community response to a whole-lake fertilization experiment. The APP communities of Chilko Lake were dominated by the coccoid cyanobacteria Synechococcus and its colonial morph which comprised about 99% of the APP community of Chilko Lake. Chlorella-like eukaryotic picoplankters and small cyanobacteria were rare, comprising < 1 % of the APP community. In 1990 autotrophic picoplankters contributed an average of 73% to total chlorophyll, and 54% to total photosynthesis. Average APP abundance ranged from lows of 4,000–5,000 cells ml^-1 in winter and spring to highs of 50000–150000 cells ml^-1 in early August with no apparent autumnal increase. APP populations were uniformly distributed in the epilimnion, but during calm periods in August often formed a peak near the metalimnion/hypolimnion boundary. Seasonal and vertical distribution patterns of APP showed little relation to temperature or to light. When nutrients were added to the lake in 1990, APP populations doubled within 3 wk of addition and average abundance (6.16 × 10⁴ cells · ml^-1) was twice 1985 APP numbers. Bottom-up control by scarce nutrient supplies is considered the primary factor regulating community composition and abundance during the initial population growth phase (June, July) with top-down control by grazing during nutrient colimitation periods when the epilimnion is deplete of both nitrogen and phosphorus (August, September).     

Speciation along a depth gradient in a marine adaptive radiation

Oceans are home to much of the world''s biodiversity, but we know little about the processes driving speciation in marine ecosystems with few geographical barriers to gene flow. Ecological speciation resulting from divergent natural selection between ecological niches can occur in the face of gene flow. Sister species in the young and ecologically diverse rockfish genus Sebastes coexist in the northeast Pacific, implying that speciation may not require geographical isolation. Here, I use a novel phylogenetic comparative analysis to show that rockfish speciation is instead associated with divergence in habitat depth and depth-associated morphology, consistent with models of parapatric speciation. Using the same analysis, I find no support for alternative hypotheses that speciation involves divergence in diet or life history, or that speciation involves geographic isolation by latitude. These findings support the hypothesis that rockfishes undergo ecological speciation on an environmental gradient.     

Cryptococcus gattii in wildlife of Vancouver Island, British Columbia, Canada

Although Cryptococcus gattii has emerged as an important pathogen of humans and domestic animals on Vancouver Island, Canada since 1999; its distribution in regional wildlife species is largely unknown. Opportunistic sampling methods were employed to obtain nasal swabs for fungal culture from wild mammal species residing within the coastal Douglas fir biogeoclimatic zone on the southeast coast of the island. Samples were collected from 91 animals representing 14 species. Cryptococcus gattii was isolated from the nasal swabs of two eastern gray squirrels (Sciurus carolinensis) trapped in Duncan, British Columbia. The relative proportion of nasal colonization in wild mammal species is consistent with findings in domestic animals, suggesting that animals may be good indicators of environmental organisms.     

Body mass variation in Marbled Murrelets in British Columbia, Canada

Body mass was measured in Marbled Murrelets Brachyramphus marmoratus from May to August, 1994–1998 at Desolation Sound, and during June and July 1997 at Mussel Inlet, British Columbia, Canada, to assess seasonal, sexual, site and intra-annual variation. Birds were captured by mist-net, and by night-lighting, and were sexed using molecular techniques. The breeding status of females (gravid or not) in 1997 was determined from plasma levels of egg-yolk precursors. Adult males weighed 203.7 ± 14.8 g, n  = 495 (juveniles 166.6 ± 28.8 g, n  = 31) and females weighed 201.2 ± 20.5 g, n  = 344 (juveniles 148.3 ± 23.5 g, n  = 20). Murrelets caught in mist-nets were significantly lighter than those caught by night-lighting. Female mass was constant across years of the study, but males caught by night-lighting were heavier in 1998 than in 1997. Females declined in mass during the egg-laying period, but when gravid females were removed from the analysis, or when the post-laying data were analysed, no declines were found. Marbled Murrelets appear to maintain mass at a constant level all season, and are probably more income than capital breeders. Variation in body mass in this species may be constrained by the need to fly with speed and agility to avoid aerial predators.     

The Abundance and Distribution of Wolverines in British Columbia,Canada

ABSTRACT The abundance and distribution of carnivores and their habitat are key information needed for status assessment, conservation planning, population management, and assessment of the effects of human development on their habitat and populations. We developed a habitat quality rating system, using existing wolverine (Gulo gulo) distribution, wolverine food, ecosystem mapping, and human development data. We used this and empirically derived estimates of wolverine density to predict wolverine distribution and abundance at a provincial scale. Density estimates for wolverines in high-quality habitat averaged 6.2 wolverines/1,000 km² (95% CI = 4.2–9.5). We predicted mean densities ranging from 0.3/1,000 km² in rare-quality habitat to 4.1/1,000 km² in moderate-quality habitat. Our predicted population estimate for wolverines in British Columbia was 3,530 (95% CI = 2,700-4,760). We predicted highest densities of wolverines in interior mountainous regions, moderate densities in interior plateau and boreal forest regions, and low densities in mainland coastal regions and drier interior plateaus. We predicted that wolverines would be rare on Vancouver Island, along the outer mainland coast, and in the dry interior forests, and absent from the Queen Charlotte Islands, interior grassland environments, and areas of intensive urban development.     

Microsatellite variability and heterozygote excess in Elymus trachycaulus populations from British Columbia in Canada

Microsatellite markers were used to assess the genetic diversity and population structure in four populations of Elymus trachycaulus from British Columbia and one population of Elymus alaskanus from Northwest Territories. Fourteen microsatellite loci were used in this study. Our results indicated that E. trachycaulus is highly polymorphic, with an average percentage of polymorphic loci of 96.5% over the four populations. Average expected heterozygosity values (H_E or gene diversity) varied from 0.418 to 0.585 with a mean of 0.497. Most of the genetic variation was found within populations (85%) and the differentiation among populations was found to be 15% (F_st = 0.15). Interpopulation genetic distances corresponded well with the geographic distance between the population sites of origin, as well as morphological characteristics. Tests for Hardy–Weinberg equilibrium (HWE) for all loci and all populations revealed that all loci significantly differ from HWE. Subsequent analysis indicated that departure from HWE at some loci was due to an excess of heterozygotes. Possible explanations for heterozygote excess are discussed. The most likely reason for observed heterozygote excess could be due to the polyploidy nature of the species.     

Climatic change and fire potential in South-Central British Columbia, Canada

The incidence and severity of forest fires are linked to the interaction between climate, fuel and topography. Increased warming and drying in the future is expected to have a significant impact on the risk of forest fire occurrence. An increase in fire risk is linked to the synchronous relationship between climate and fuel moisture conditions. A warmer, drier climate will lead to drier forest fuels that will in turn increase the chance of successful fire ignition and propagation. This interaction will increase the severity of fire weather, which, in turn, will increase the risk of extreme fire behaviour. A warmer climate will also extend fire season length, which will increase the likelihood of fires occurring over a greater proportion of the year. In this study of the North Okanagan area of British Columbia, Canada, the impacts of climate change of fire potential were evaluated using the Canadian Forest Fire Danger Rating System and multiple climate scenario analysis. Utilizing this approach, a 30% increase in fire season length was modelled to occur by 2070. In addition, statistically significant increases in fire severity and fire behaviour were also modelled. Fire weather severity was predicted to increase by 95% during the summer months by 2070 while fire behaviour was predicted to shift from surface fire‐intermittent crown fire regimes to a predominantly intermittent‐full crown fire regime by 2070 onwards. An increase in fire season length, fire weather severity and fire behaviour will increase the costs of fire suppression and the risk of property and resource loss while limiting human‐use within vulnerable forest landscapes. An increase in fire weather severity and fire behaviour over a greater proportion of the season will increase the risks faced by ecosystems and biodiversity to climatic change and increase the costs and difficulty of achieving sustainable forest management.