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111.
Peter H. Gleick Elizabeth L. Chalecki 《Journal of the American Water Resources Association》1999,35(6):1429-1441
ABSTRACT: A wide variety of regional assessments of the water-related impacts of climatic change have been done over the past two decades, using different methods, approaches, climate models, and assumptions. As part of the Water Sector research for the National Assessment of the Implications of Climatic Variability and Change for the United States, several major summaries have been prepared, looking at the differences and similarities in results among regional research projects. Two such summaries are presented here, for the Colorado River Basin and the Sacramento River Basin. Both of these watersheds are vitally important to the social, economic, and ecological character of their regions; both are large snowmelt-driven basins; both have extensive and complex water management systems in place; and both have had numerous, independent studies done on them. This review analyzes the models, methods, climate assumptions, and conclusions from these studies, and places them in the context of the new climate scenarios developed for the National Assessment. Some significant and consistent impacts have been identified for these basins, across a wide range of potential climate changes. Among the most important is the shift in the timing of runoff that results from changes in snowfall and snowmelt dynamics. This shift has been seen in every regional result across these two basins despite differences in models and climate change assumptions. The implications of these impacts for water management, planning, and policy are discussed. 相似文献
112.
Morton-Bermea Ofelia Beramendi-Orosco Laura Martínez-Reyes Ángeles Hernández-Álvarez Elizabeth González-Hernández Galia 《Environmental geochemistry and health》2016,38(1):195-202
Environmental Geochemistry and Health - Tree rings may be used as indicators of contamination events providing information on the chronology and the elemental composition of the contamination. In... 相似文献
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115.
Ofelia Morton-Bermea Omar Amador-Muñoz Lida Martínez-Trejo Elizabeth Hernández-Álvarez Laura Beramendi-Orosco María Elena García-Arreola 《Environmental geochemistry and health》2014,36(5):987-994
The increase in platinum (Pt) in the airborne particulate matter with size ≤2.5 µm (PM2.5) in urban environments may be interpreted as result of the abrasion and deterioration of automobile catalyst. Nowadays, about four million vehicles in Mexico City use catalytic converters, which means that their impact should be considered. In order to evaluate the contribution of Pt to environmental pollution of the metropolitan area of Mexico City (MAMC), airborne PM2.5 was collected at five different sites in the urban area (NW, NE, C, SW, SE) in 2011 during April (dry-warm season), August (rainy season) and December (dry-cold season). Analytical determinations were carried out using a ICP-MS with a collision cell and kinetic energy discrimination. The analytical and instrument performance was evaluated with standard road dust reference material (BCR-723). Median Pt concentration in the analyzed particulate was is 38.4 pg m?3 (minimal value 1 pg m?3 maximal value 79 pg m?3). Obtained Pt concentrations are higher than those reported for other urban areas. Spatial variation shows that SW had Pt concentration significantly higher than NW and C only. Seasonal variation shows that Pt median was higher in rainy season than in both dry seasons. A comparison of these results with previously reported data of PM10 from 1991 and 2003 in the same studied area shows a worrying increase in the concentration of Pt in the air environment of MAMC. 相似文献
116.
Christopher N. Templeton ?a?lar Ak?ay S. Elizabeth Campbell Michael D. Beecher 《Behavioral ecology and sociobiology》2012,66(11):1503-1509
Animals frequently use signals to modulate aggressive interactions. Establishing that a signal is aggressive or threatening requires demonstrating that it is more commonly used in agonistic contexts, that it predicts subsequent aggressive behaviors by the sender, and that receivers respond differently to this signal. Like many birds, song sparrows (Melospiza melodia) produce a low-amplitude “soft song” vocalization that has been hypothesized to be an aggressive signal. Soft song meets the first two criteria, but previous research has failed to demonstrate that soft song provokes aggression or that receivers even perceive soft song differently from normal loud song. We used a playback experiment with taxidermic mount presentation to test whether territorial male song sparrows respond differently to loud and soft song playbacks. Subjects reacted more strongly to the soft song playback by approaching the mount more closely, increasing wing wave displays, and increasing the proportion of their own songs that were soft songs, with further trends toward increasing the number of flights and attacks. These results confirm that soft song is a conventional signal of aggression in song sparrows and that increased receiver retaliation maintains its reliability. 相似文献
117.
Cleland EE Allen JM Crimmins TM Dunne JA Pau S Travers SE Zavaleta ES Wolkovich EM 《Ecology》2012,93(8):1765-1771
Earlier spring phenology observed in many plant species in recent decades provides compelling evidence that species are already responding to the rising global temperatures associated with anthropogenic climate change. There is great variability among species, however, in their phenological sensitivity to temperature. Species that do not phenologically "track" climate change may be at a disadvantage if their growth becomes limited by missed interactions with mutualists, or a shorter growing season relative to earlier-active competitors. Here, we set out to test the hypothesis that phenological sensitivity could be used to predict species performance in a warming climate, by synthesizing results across terrestrial warming experiments. We assembled data for 57 species across 24 studies where flowering or vegetative phenology was matched with a measure of species performance. Performance metrics included biomass, percent cover, number of flowers, or individual growth. We found that species that advanced their phenology with warming also increased their performance, whereas those that did not advance tended to decline in performance with warming. This indicates that species that cannot phenologically "track" climate may be at increased risk with future climate change, and it suggests that phenological monitoring may provide an important tool for setting future conservation priorities. 相似文献
118.
Quantitative polymerase chain reaction (qPCR) for the identification and quantification of microbes has become a common tool
for the study of harmful algal blooms (HABs). We developed a qPCR method for the diatom genus Pseudo-nitzschia. Several species of this genus form toxic blooms through the production of the neurotoxin domoic acid (DA). Outbreaks of
toxicity attributed to DA along the US west coast have caused sickness and death of marine mammals and seabirds through food
web contamination. The method developed here quantifies Pseudo-nitzschia spp. at low abundances in natural samples, thereby, providing a method to improve our understanding of the environmental
conditions leading to blooms of these species. This has been accomplished previously by techniques for identification and
quantification that are slow and laborious compared to qPCR. The approach was successfully tested and validated using eight
species of Pseudo-nitzschia and 33 non-target organisms and employed to follow local bloom dynamics. 相似文献
119.
The indirect, ecosystem-level consequences of ocean fishing, and particularly the mechanisms driving them, are poorly understood. Most studies focus on density-mediated trophic cascades, where removal of predators alternately causes increases and decreases in abundances of lower trophic levels. However, cascades could also be driven by where and when prey forage rather than solely by prey abundance. Over a large gradient of fishing intensity in the central Pacific's remote northern Line Islands, including a nearly pristine, baseline coral reef system, we found that changes in predation risk elicit strong behavioral responses in foraging patterns across multiple prey fish species. These responses were observed as a function of both short-term ("acute") risk and longer-term ("chronic") risk, as well as when prey were exposed to model predators to isolate the effect of perceived predation risk from other potentially confounding factors. Compared to numerical prey responses, antipredator behavioral responses such as these can potentially have far greater net impacts (by occurring over entire assemblages) and operate over shorter temporal scales (with potentially instantaneous response times) in transmitting top-down effects. A rich body of literature exists on both the direct effects of human removal of predators from ecosystems and predators' effects on prey behavior. Our results draw together these lines of research and provide the first empirical evidence that large-scale human removal of predators from a natural ecosystem indirectly alters prey behavior. These behavioral changes may, in turn, drive previously unsuspected alterations in reef food webs. 相似文献
120.
Many species of marine fish are typified by large population sizes, strong migratory behavior, high fecundity, and pelagic
eggs and larvae that are passively transported by ocean currents, all features that tend to increase gene flow, and hence
reduce genetic partitioning, among localized populations. The plaice, Pleuronectes platessa, is a commercially important demersal species that exhibits all of these characteristics. We analyzed genetic variation at
eight microsatellite loci in samples of spawning adults (N = 348) from the coasts of Ireland, Iceland, and, for the first time, from the Baltic Sea. Significant differentiation was
observed between Iceland and Irish and Baltic Sea samples. However, there were no genetic differences between Irish and Baltic
Sea samples, which contrast with the significant differentiation reported between Baltic Sea and North Sea/Atlantic populations
of other flatfish species. To increase the data set, we carried out a cross-calibration exercise, allowing us to perform a
joint analysis of data with an earlier study on adult and juvenile plaice (N = 480) collected over a broad geographic range, using six microsatellite loci in common to the two studies. Significant differentiation
was observed between fish collected at the northern (Iceland, Faeroes, Norway) and southern (Bay of Biscay) parts of the species
range. In contrast, the results showed little evidence of genetic structuring over much of the continental shelf of Europe.
We believe that bathymetric and hydrographic barriers are the major factors shaping genetic structure, while lack of structure
over much of the European continental shelf may be explained by a combination of past historical events, population structure,
and dynamics of the species. 相似文献