53 research outputs found
The importance of sedimenting organic matter, relative to oxygen and temperature, in structuring lake profundal macroinvertebrate assemblages
We quantified the role of a main food
resource, sedimenting organic matter (SOM), relative
to oxygen (DO) and temperature (TEMP) in structuring
profundal macroinvertebrate assemblages in
boreal lakes. SOM from 26 basins of 11 Finnish lakes
was analysed for quantity (sedimentation rates),
quality (C:N:P stoichiometry) and origin (carbon
stable isotopes, d13C). Hypolimnetic oxygen and
temperature were measured from each site during
summer stratification. Partial canonical correspondence
analysis (CCA) and partial regression analyses
were used to quantify contributions of SOM, DO and
TEMP to community composition and three macroinvertebrate
metrics. The results suggested a major
contribution of SOM in regulating the community
composition and total biomass. Oxygen best explained
the Shannon diversity, whereas TEMP had largest
contribution to the variation of Benthic Quality Index.
Community composition was most strongly related to d13C of SOM. Based on additional d13C and stoichiometric
analyses of chironomid taxa, marked differences
were apparent in their utilization of SOM and
body stoichiometry; taxa characteristic of oligotrophic
conditions exhibited higher C:N ratios and lower C:P
and N:P ratios compared to the species typical of
eutrophic lakes. The results highlight the role of SOM
in regulating benthic communities and the distributions
of individual species, particularly in oligotrophic
systems
Passive Diffusion Technique for Concentration of Short-Chain Volatile Fatty Acids from Seawater
A diffusion chamber is described which concentrates short-chain, volatile fatty acids from seawater while simultaneously separating them from interfering salts. The procedure relies on the passive diffusion of volatile compounds from acidified seawater samples and their subsequent absorption onto a base-impregnated filter. The method is simple, efficient, and adaptable to most commonly used methods of volatile acid analysis
Data from: Genetic structure, admixture, and invasion success in a Holarctic defoliator, the gypsy moth (Lymantria dispar, Lepidoptera: Erebidae)
Characterizing the current population structure of potentially invasive species provides a critical context for identifying source populations and for understanding why invasions are successful. Non-native populations inevitably lose genetic diversity during initial colonization events, but subsequent admixture among independently introduced lineages may increase both genetic variation and adaptive potential. Here we characterize the population structure of the gypsy moth (Lymantria dispar Linnaeus), one of the world's most destructive forest pests. Native to Eurasia and recently introduced to North America, the current distribution of gypsy moth includes forests throughout the temperate region of the northern hemisphere. Analyses of microsatellite loci and mitochondrial DNA sequences for 1738 individuals identified four genetic clusters within L. dispar. Three of these clusters correspond to the three named subspecies; North American populations represent a distinct fourth cluster, presumably a consequence of the population bottleneck and allele frequency change that accompanied introduction. We find no evidence that admixture has been an important catalyst of the successful invasion and range expansion in North America. However, we do find evidence of ongoing hybridization between subspecies and increased genetic variation in gypsy moth populations from Eastern Asia, populations that now pose a threat of further human-mediated introductions. Finally, we show that current patterns of variation can be explained in terms of climate and habitat changes during the Pleistocene, a time when temperate forests expanded and contracted. Deeply diverged matrilines in Europe imply that gypsy moths have been there for a long time and are not recent arrivals from Asia
Application of a DNA barcode using the 16S rRNA gene to diagnose pest Arion species in the USA
Methanogenesis from Methanol and Methylamines and Acetogenesis from Hydrogen and Carbon Dioxide in the Sediments of a Eutrophic Lake
Anaerobic metabolism of particulate organic matter in the sediments of a hypereutrophic lake*
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