Filters: Tags: M1-Invertebrates (X)198 results (51ms)
Taenia arctos n. sp.(Cestoda: Cyclophyllidea: Taeniidae) from its definitive (brown bear Ursus arctos Linnaeus) and intermediate (moose/elk Alces spp.) hosts
Landscape level analysis of mountain pine beetle in British Columbia, Canada: spatiotemporal development and spatial synchrony within the present outbreak
Effect of ecosystem disturbance on diversity of bark and wood-boring beetles (Coleoptera : Scolytidae, Buprestidae, Cerambycidae) in white spruce (Picea glauca (Moench) voss) ecosystems of Alaska
Modern distribution of freshwater ostracodes in the southwest Yukon Territory and northern British Columbia, Canada
This biogeographical study documents the modern distribution of ostracodes in the southwest Yukon Territory and northern British Columbia, Canada. The study tested the hypothesis that dissolved ion composition and concentrations of the lake water are the primary determinants of the distribution of modern ostracodes in this region. A total of 28 freshwater species representing 8 genera were identified in the 33 study lakes. Species common in the southwest Yukon are widely distributed throughout North America, and include Cyclocypris ampla , Candona candida , Cypria turneri , Cypria ophtalmica , and Candona protzi . Concentrations of ostracode valves were highest in four lakes with moderate conductivity values ranging...
Ecology of testate amoebae (Protista) in south-central Alaska peatlands: building transfer-function models for palaeoenvironmental studies
Testate amoebae are valuable indicators of peatland hydrology and have been used in many palaeoclimatic studies in peatlands. Because the species' ecological optima may vary around the globe, the development of transfer function models is an essential prerequisite for regional palaeoclimatic studies using testate amoebae. We investigated testate amoebae ecology in nine peatlands covering a 250-km north–south transect in south-central Alaska. Redundancy analysis and Mantel tests were used to establish the relationship between the measured environmental variables (water-table depth and pH) and testate amoebae communities. Transfer-function models were developed using weighted averaging, weighted average partial least...
The distribution patterns of Orthoptera are described for the boreal zone. The boreal fauna of Eurasia includes more than 81 species. Many of them are widely distributed. The monotypic genus Paracyphoderris Storozhenko and at least 13 species are endemics or subendemics. About 50 species are known from boreal North America. Four endemic species are distributed very locally. Relationships between the faunas of the Eurasian and North American parts of the boreal zone are relatively weak. The boreal assemblages are usually characterized by the low levels of species diversity and abundance. Grasshoppers and their relatives occupy almost exclusively open habitats, such as different types of meadows, mountain steppes...
Working paper, monitoring tree-level insect population dynamics with multi-scale and multi-source remote sensing
Long-term monitoring of the rate of change of mountain pine beetle (Dendroctonus ponderosae Hopkins) populations requires detailed tree-level information over large areas. This information is used to assess the status of an infestation (e.g., increasing, stable, or decreasing), and to select and evaluate mitigation approaches. In this research project, the authors develop and demonstrate a prototype monitoring system, which enables the extrapolation of tree-level estimates of beetle damage from field data to a larger study area using a double sampling approach, and multi-scale, multi-source, high spatial resolution remotely sensed data. The project study area encompasses over 6 million ha and is located at the leading...
The role of interference competition in a sustained population outbreak of the aspen leaf miner in Alaska
Direct density-dependence through intraspecific competition may be an important mechanism permitting sustained herbivore outbreaks. In theory, interference competition could allow a relatively stable number of herbivore individuals to survive while moderating host plant damage. This research examined the potential role of intraspecific competition in permitting a decade-long outbreak of the aspen leaf miner, Phyllocnistis populiella, on Populus tremuloides in interior Alaska. A combination of observational and experimental studies examined larval food requirements, food resources, and the impacts of P. populiella larval density on survival, mass, and leaf mining damage. These results were then compared to those...
Comparison of Benthic Macroinvertebrates Colonizing Sand, Wood, and Artificial Substrates in a Low-Gradient Stream
ABSTRACT We compared macroinvertebrate assemblages sampled from artificial and natural substrates within a small, sandy-bottomed coastal plain stream, Alabama, USA. Separate samples were collected from natural coarse woody debris (CWD) accumulations, benthic sand substrate, and Hester-Dendy multiplate samplers (HDs, 54-d incubations). Shannon's H? was lowest and % dominant taxon was highest in sand samples. Proportion of the total assemblage as EPT taxa (Ephemeroptera, Plecoptera, and Trichcptera) was significantly higher on HDs than from sand, and proportion of the assemblage as Chironomidae was higher from sand than on CWD. Invertebrate biomass on HDs was almost two times higher than from sand, whereas biomass...
Experimental increases and reductions of light to streams: effects on periphyton and macroinvertebrate assemblages in a coniferous forest landscape
Increased light reaching streams as a result of riparian vegetation management is often thought to be responsible for enhanced algal productivity. However, concomitant changes in nutrients and other physical processes confound that interpretation. We manipulated light in two separate experiments to test the role of light as a controlling factor for periphyton productivity and biomass, and to observe invertebrate responses in small streams in central British Columbia, Canada. We did this by adding artificial light to reaches of three forested streams, and in a second experiment we used shadecloth to cover reaches of two streams flowing through clearcuts. Periphyton growth, productivity and composition, and macroinvertebrate...
Stable isotope ecology of land snails from a high-latitude site near Fairbanks, interior Alaska, USA
Land snails have been investigated isotopically in tropical islands and mid-latitude continental settings, while high-latitude locales, where snails grow only during the summer, have been overlooked. This study presents the first isotopic baseline of live snails from Fairbanks, Alaska (64°51′N), a proxy calibration necessary prior to paleoenvironmental inferences using fossils. δ13C values of the shell (− 10.4 ± 0.4‰) and the body (− 25.5 ± 1.0‰) indicate that snails consumed fresh and decayed C3-plants and fungi. A flux-balance mixing model suggests that specimens differed in metabolic rates, which may complicate paleovegetation inferences. Shell δ18O values (− 10.8 ± 0.4‰) were ~ 4‰ higher than local summer rain...
Climate variability and spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska
New aquatic insect (Ephemeroptera, Trichoptera, and Plecoptera) records for Alaska, U.S.A.: range extensions and a comment on under-sampled habitats
Significant westward range extension for the Limnephilid cassisfly Phanocelia Canadensis (Trichoptera): first record from Alaska.
A New Subspecies of Cicindela limbata (Coleoptera: Cicindelidae) from Alaska, and Further Review of the maritima group by Using Mitochondrial DNA Analysis
Regional outbreak dynamics of Dothistroma needle blight linked to weather patterns in British Columbia, Canada
Molecular profiling of soil animal diversity in natural ecosystems: Incongruence of molecular and morphological results