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611.
Large-scale biodiversity patterns in freshwater phytoplankton 总被引:4,自引:0,他引:4
Our planet shows striking gradients in the species richness of plants and animals, from high biodiversity in the tropics to low biodiversity in polar and high-mountain regions. Recently, similar patterns have been described for some groups of microorganisms, but the large-scale biogeographical distribution of freshwater phytoplankton diversity is still largely unknown. We examined the species diversity of freshwater phytoplankton sampled from 540 lakes and reservoirs distributed across the continental United States and found strong latitudinal, longitudinal, and altitudinal gradients in phytoplankton biodiversity, demonstrating that microorganisms can show substantial geographic variation in biodiversity. Detailed analysis using structural equation models indicated that these large-scale biodiversity gradients in freshwater phytoplankton diversity were mainly driven by local environmental factors, although there were residual direct effects of latitude, longitude, and altitude as well. Specifically, we found that phytoplankton species richness was an increasing saturating function of lake chlorophyll a concentration, increased with lake surface area and possibly increased with water temperature, resembling effects of productivity, habitat area, and temperature on diversity patterns commonly observed for macroorganisms. In turn, these local environmental factors varied along latitudinal, longitudinal, and altitudinal gradients. These results imply that changes in land use or climate that affect these local environmental factors are likely to have major impacts on large-scale biodiversity patterns of freshwater phytoplankton. 相似文献
612.
The effects of preen oils and soiling on the UV–visible reflectance of carotenoid-pigmented feathers
Lorenzo Pérez-Rodríguez Francois Mougeot Gary R. Bortolotti 《Behavioral ecology and sociobiology》2011,65(7):1425-1435
Plumage coloration, particularly when carotenoid-based, is important in social signaling in birds. Although feather color
is a relatively stable trait, individuals may modify it with “cosmetic” substances such as preen oils. In addition, dirt accumulation
may influence plumage coloration and further affect signal perception by receivers. Here, we analyze the separate potential
effects of preen oils and soil accumulation on the reflectance properties of carotenoid-pigmented feathers across the visual
range of most bird species, which includes the ultraviolet (UV). Using the yellow portion of tail feathers of Bohemian waxwings
(Bombycilla garrulus), we performed two separate experiments where: (a) preen oils and/or soil were removed, or (b) preen oils (from black-billed
magpies Pica pica or eagle owls Bubo bubo) were added. Preen oil addition reduced brightness but increased UV hue and yellow chroma. UV chroma was reduced by the addition
of magpie (but not owl) preen oil. Soil accumulation had little effect on plumage reflectance in the UV range but significantly
reduced yellow chroma. According to models of avian vision, both of these effects are detectable by birds and biologically
meaningful when compared with natural variation between the sexes and age classes. We conclude that preen oil and soil accumulation
can significantly affect the UV–visible reflectance of carotenoid-based plumages. As such traits typically advertise individual
quality, preening and soiling have the potential to modify the information content of carotenoid-based plumage traits and
how these signals are perceived by receivers. 相似文献
613.
This study used structural equation modelling to examine the effects of socio-demographic variables and outdoor recreation participation on pro-environmental behaviour (PEB) among an ethnically diverse population of adult state-park visitors near Atlanta, Georgia, USA (N?=?319). Data collected through intercept surveys at three state parks were used to examine interactions among potential predictors of PEB, including socio-demographics (ethnicity, gender, education, and income), outdoor recreation participation (during childhood and adulthood), and environmental value orientations (biocentric and anthropocentric). The best fitting model accounted for 40% of the variance in self-reported PEB and indicated the strongest positive relationship between adult outdoor recreation participation and PEB (β?=?0.54, t?=?5.70). Biocentric and anthropocentric value orientation scores were also significant antecedents of PEB (β?=?0.17, t?=?1.99, and β?=?0.19, t?=?2.56, respectively), and both were influenced by socio-demographic variables. Overall, results suggest that a diverse public's environmental ethos and propensity to engage in PEBs could be influenced by outdoor recreation opportunities. 相似文献
614.
Harikishan Santha Julián Sandino Gary F Shimp Shihwu Sung 《Water environment research》2006,78(3):221-226
Laboratory studies were conducted to evaluate the performance and operational stability of a Temperature-Phased Anaerobic Digestion (TPAD) system modified to operate in the sequential-batch mode. The system fed with a 40:60 mixture (dry weight) of primary sludge (PS) and waste activated sludge (WAS) at 5.5% solids showed stable performance with minimum variation in operational parameters such as biogas production, VFA to alkalinity ratio, pH, and foam accumulation at system retention times as short as 12 days. The maximum volatile solids removal (VSR) of 52.5% was achieved at a system retention time of 16 days. The system did not show any effects of "shock loading" at the retention times studied and outperformed a "conventional" mesophilic system operated at a longer retention time. The system was effective in reducing the densities of pathogenic indicator organisms in the biosolids to levels lower than those specified by U.S. EPA for Class A designation. 相似文献
615.
The Southeastern United States is a global center of freshwater biotic diversity, but much of the regions aquatic biodiversity is at risk from stream degradation. Nonpoint pollution sources are responsible for 70% of that degradation, and controlling nonpoint pollution from agriculture, urbanization, and silviculture is considered critical to maintaining water quality and aquatic biodiversity in the Southeast. We used an ecological risk assessment framework to develop vulnerability models that can help policymakers and natural resource managers understand the impact of land cover changes on water quality in North Carolina. Additionally, we determined which landscape characteristics are most closely associated with macroinvertebrate community tolerance of stream degradation, and therefore with lower-quality water. The results will allow managers and policymakers to weigh the risks of management and policy decisions to a given watershed or set of watersheds, including whether streamside buffer protection zones are ecologically effective in achieving water quality standards. Regression analyses revealed that landscape variables explained up to 56.3% of the variability in benthic macroinvertebrate index scores. The resulting vulnerability models indicate that North Carolina watersheds with less forest cover are at most risk for degraded water quality and steam habitat conditions. The importance of forest cover, at both the watershed and riparian zone scale, in predicting macrobenthic invertebrate community assemblage varies by geographic region of the state. 相似文献
616.
A bacterium classified as Achromobacter xylosoxidans strain IR08 by phenotypic typing coupled with 16S rRNA gene analysis wasisolated from a soil contaminated with electrical transformer fluid for over sixty years using Aroclor 1221 as an enrichment substrate.The substrate utilization profiles revealed that IR08 could grow on all three monochlorobiphenyls (CBs), 2,4'- and 4,4'-dichlorobiphenylas well as 2-chlorobenzoate (2-CBA), 3-CBA, 4-CBA, and 2,3-dichlorobenzoate. Unusually, growth was poorly sustained on biphenyland benzoate. In growth experiments, IR08 degraded all CBs (0.27 mmol/L) in less than 96 h with concomitant stoichiometric release ofinorganic chloride and growth yields were 2-3 times higher than those observed on biphenyl. In contrast to most of the chlorobiphenyl-degrading strains described in the literature, which are reported to form CBA, no metabolite was identified in the culture broth byHPLC analysis. When co-incubated with respective CBs and biphenyl, strain IR08 preferentially utilized the chlorinated analoguesin less than 96 h while it took another 264 h before 90% of the initially supplied biphenyl could be degraded. The promotion of co-metabolic transformation of halogenated substrates by the inclusion of their non-halogenated derivatives may not therefore, result inuniversal benefits. 相似文献
617.