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William H. Clements Jeffrey L. Arnold Todd M. Koel Rob Daley Cathie Jean 《Aquatic Ecology》2011,45(1):137-149
We examined responses of benthic macroinvertebrate communities to natural geothermal discharges in 32 streams in Yellowstone
National Park (YNP), USA. Geothermal discharges played a major role in structuring benthic communities in YNP, as downstream
communities were characterized by low species richness, reduced abundance of EPT taxa and increased abundance of tolerant
caddisflies (Trichoptera), chironomids and non-insects. While some taxa were a subset of tolerant organisms that were also
common at references sites, others (the damselfly Argia sp., the caddisfly Oxyethira sp. and the exotic New Zealand mudsnail Potamopyrgus antipodarum Gray 1843) were found almost exclusively in geothermal streams. Because geothermal waters are a common feature of YNP, monitoring
programs designed to assess long-term status and trends of Yellowstone’s aquatic ecosystems must account for the influence
of these discharges. To separate geothermal effects from other potential anthropogenic disturbances in YNP (e.g., atmospheric
deposition, road construction, wastewater, global change), we developed a multimetric index based on responses of benthic
communities to geothermal discharges. Streams were placed into one of four geothermal categories based on conductivity (reference = < 150 μS/cm; low, moderate and high = 151–300, 301–600 and >600 μS/cm, respectively). The index clearly distinguished among
these categories and showed a well-defined threshold response to geothermal effects at very low levels of conductivity. Although
the index was specific to geothermal effects, the approach used to develop the index has broad applicability for other systems
where impacts of stressors must be assessed within the context of natural environmental gradients. Our findings may provide
important insights into how benthic macroinvertebrate communities respond to global change. Reduced discharge and warmer temperatures
predicted for Rocky Mountain streams may favor the establishment and expansion of exotic species such as New Zealand mudsnails
(P. antipodarum), which are highly tolerant of geothermal influences. 相似文献
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SERRATE: a new player on the plant microRNA scene 总被引:7,自引:0,他引:7
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Ruiz-Moreno D Willis BL Page AC Weil E Cróquer A Vargas-Angel B Jordan-Garza AG Jordán-Dahlgren E Raymundo L Harvell CD 《Diseases of aquatic organisms》2012,100(3):249-261
Coral diseases are taking an increasing toll on coral reef structure and biodiversity and are important indicators of declining health in the oceans. We implemented standardized coral disease surveys to pinpoint hotspots of coral disease, reveal vulnerable coral families and test hypotheses about climate drivers from 39 locations worldwide. We analyzed a 3 yr study of coral disease prevalence to identify links between disease and a range of covariates, including thermal anomalies (from satellite data), location and coral cover, using a Generalized Linear Mixed Model. Prevalence of unhealthy corals, i.e. those with signs of known diseases or with other signs of compromised health, exceeded 10% on many reefs and ranged to over 50% on some. Disease prevalence exceeded 10% on 20% of Caribbean reefs and 2.7% of Pacific reefs surveyed. Within the same coral families across oceans, prevalence of unhealthy colonies was higher and some diseases were more common at sites in the Caribbean than those in the Pacific. The effects of high disease prevalence are potentially extensive given that the most affected coral families, the acroporids, faviids and siderastreids, are among the major reef-builders at these sites. The poritids and agaricids stood out in the Caribbean as being the most resistant to disease, even though these families were abundant in our surveys. Regional warm temperature anomalies were strongly correlated with high disease prevalence. The levels of disease reported here will provide a much-needed local reference point against which to compare future change. 相似文献
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James F. Lawrence Cathie Ménard 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1997,696(2):3355
Clenbuterol, a beta-agonist, was determined in samples of beef liver and muscle. The method employed an acidic aqueous extraction followed by protein precipitation. The supernatant liquid was passed through a weak cation-exchange cartridge and then through a commercially available immunoaffinity cartridge. Clenbuterol was eluted from the immunoaffinity cartridge with 80% ethanol in water. The eluate was concentrated and analysed directly by reversed-phase liquid chromatography using gradient elution and UV detection at 245 nm. Detection limits were estimated to be 0.3 ng g−1 clenbuterol. A single immunoaffinity cartridge was used for ten sample extracts with no significant loss in capacity. No organic solvents other than ethanol and methanol were employed in the procedure. Recoveries of clenbuterol from samples of beef liver and muscle spiked at 2 and 5 ng g−1 carried through the entire procedure were 63±11% (range, 53–74%) compared to pure standards. Absolute recoveries of pure standards (30 ng clenbuterol) carried through the same analytical steps were 70±5% (n = 6), the losses being primarily due to the ion-exchange step. 相似文献
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Ectopic expression of snapdragon transcription factors facilitates the identification of genes encoding enzymes of anthocyanin decoration in tomato 下载免费PDF全文