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271.
Long-Term Variability in Bioassessments: A Twenty-Year Study from Two Northern California Streams 总被引:2,自引:2,他引:0
Long-term variability of bioassessments has not been well evaluated. We analyzed a 20-year data set (1984–2003) from four
sites in two northern California streams to examine the variability of bioassessment indices (two multivariate RIVPACS-type
O/E scores and one multimetric index of biotic integrity, IBI), as well as eight metrics. All sites were sampled in spring;
one site was also sampled in summer. Variability among years was high for most metrics (coefficients of variation, CVs ranging
from 16% to 246% in spring) but lower for indices (CVs of 22–26% for the IBI and 21–32% for O/E scores in spring), which resulted
in inconsistent assessments of biological condition. Variance components analysis showed that the time component explained
variability in all metrics and indices, ranging from 5% to 35% of total variance explained. The site component was large (i.e.,
>40%) for some metrics (e.g., EPT richness), but nearly absent from others (e.g., Diptera richness). Seasonal analysis at
one site showed that variability among seasons was small for some metrics or indices (e.g., Coleoptera richness), but large
for others (e.g., EPT richness, O/E scores). Climatic variables did not show consistent trends across all metrics, although
several were related to the El Ni?o Southern Oscillation Index at some sites. Bioassessments should incorporate temporal variability
during index calibration or include climatic variability as predictive variables to improve accuracy and precision. In addition,
these approaches may help managers anticipate alterations in reference streams caused by global climate change and high climatic
variability. 相似文献
272.
Vincent Y. Seaman Deborah H. Bennett Thomas M. Cahill 《Atmospheric environment (Oxford, England : 1994)》2009,43(39):6199-6204
Acrolein (2-propenal) is a common constituent of both indoor and outdoor air, can exacerbate asthma in children, and may contribute to other chronic lung diseases. Recent studies have found high indoor levels of acrolein and other carbonyls compared to outdoor ambient concentrations. Heated cooking oils produce considerable amounts of acrolein, thus cooking is likely an important source of indoor acrolein. A series of cooking experiments were conducted to determine the emission rates of acrolein and other volatile carbonyls for different types of cooking oils (canola, soybean, corn and olive oils) and deep-frying different food items. Similar concentrations and emission rates of carbonyls were found when different vegetable oils were used to deep-fry the same food product. The food item being deep-fried was generally not a significant source of carbonyls compared to the cooking oil. The oil cooking events resulted in high concentrations of acrolein that were in the range of 26.4–64.5 μg m?3. These concentrations exceed all the chronic regulatory exposure limits and many of the acute exposure limits. The air exchange rate and the decay rate of the carbonyls were monitored to estimate the half-life of the carbonyls. The half-life for acrolein was 14.4 ± 2.6 h, which indicates that indoor acrolein concentrations can persist for considerable time after cooking in poorly-ventilated homes. 相似文献
273.
Roussiez V Ludwig W Probst JL Monaco A 《Environmental pollution (Barking, Essex : 1987)》2005,138(1):167-177
This paper presents an attempt to reach natural background levels of heavy metals in surficial sediments of the Gulf of Lions (NW Mediterranean). To correct for the grain-size effect, normalization procedures based on a clay mineral indicator element are commonly used, after a first grain size separation by sieving. In our study, we tested the applicability of this method with respect to commonly used normalizer elements, and found that stable Cs shows the best ability to reflect the fine sediment fraction. Background levels were successfully reached for Co, Cr, Cu, Ni and Pb, compared to various literature references. Nevertheless, in the case of lead, the normalized data depicted a general enrichment in all samples, and the natural levels could only be reached when concentrations were corrected for the atmospheric contribution by analysing lead isotope ratios. Also for Zn, a general enrichment was found in our samples, although less important. 相似文献
274.
A novel application of cultural consensus models to evaluate conservation education programs 下载免费PDF全文
K.A.I. Nekaris Sharon McCabe Denise Spaan Muhammad Imron Ali Vincent Nijman 《Conservation biology》2018,32(2):466-476
Conservation professionals recognize the need to evaluate education initiatives with a flexible approach that is culturally appropriate. Cultural‐consensus theory (CCT) provides a framework for measuring the extent to which beliefs are communally held and has long been applied by social scientists. In a conservation‐education context, we applied CCT and used free lists (i.e., a list of items on a topic stated in order of cultural importance) and domain analysis (analysis of how free lists go together within a cultural group) to evaluate a conservation education program in which we used a children's picture book to increase knowledge about and empathy for a critically endangered mammal, the Javan slow loris (Nycticebus javanicus). We extracted free lists of keywords generated by students (n = 580 in 18 schools) from essays they wrote before and after the education program. In 2 classroom sessions conducted approximately 18 weeks apart, we asked students to write an essay about their knowledge of the target species and then presented a book and several activities about slow loris ecology. Prior to the second session, we asked students to write a second essay. We generated free lists from both essays, quantified salience of terms used, and conducted minimal residuals factor analysis to determine presence of cultural domains surrounding slow lorises in each session. Students increased their use of words accurately associated with slow loris ecology and conservation from 43% in initial essays to 76% in final essays. Domain coherence increased from 22% to 47% across schools. Fifteen factors contributed to the domain slow loris. Between the first and second essays, factors that showed the greatest change were feeding ecology and slow loris as a forest protector, which increased 7‐fold, and the humancentric factor, which decreased 5‐fold. As demonstrated by knowledge retention and creation of unique stories and conservation opinions, children achieved all six levels of Bloom's taxonomy of learning domains. Free from the constraints of questionnaires and surveys, CCT methods provide a promising avenue to evaluate conservation education programs. 相似文献
275.
276.
Understanding threats acting on marine organisms and their conservation status is vital but challenging given a paucity of data. We studied the cumulative human impact (CHI) on and conservation status of seahorses (Hippocampus spp.)—a genus of rare and data-poor marine fishes. With expert knowledge and relevant spatial data sets, we built linear-additive models to assess and map the CHI of 12 anthropogenic stressors on 42 seahorse species. We examined the utility of indices of estimated impact (impact of each stressor and CHI) in predicting conservation status for species with random forest (RF) models. The CHI values for threatened species were significantly higher than those for nonthreatened species (category based on International Union for Conservation of Nature Red List). We derived high-accuracy RF models (87% and 96%) that predicted that 5 of the 17 data-deficient species were threatened. Demersal fishing practices with high bycatch and pollution were the best predictors of threat category. Major threat epicenters were in China, Southeast Asia, and Europe. Our results and maps of CHI may help guide global seahorse conservation and indicate that modeling and mapping human impacts can reveal threat patterns and conservation status for data-poor species. We found that for exploring threat patterns of focal species, species-level CHI models are better than existing ecosystem-level CHI models. 相似文献
277.
Nalzala Thomas Mary Rosana Kanniyambatti Lourdusamy Vincent Joseph Dhandayuthapani Aparna Annamalai Jayakumar Vijayalakshmi 《Environmental science and pollution research international》2021,28(23):28911-28925
Environmental Science and Pollution Research - The advent of novel technologies has led to the need for environmental and economic integration. Energy consumption plays a vital role in human... 相似文献
278.
The present paper investigated the short-term colonization by plants of a highly degraded soil in field conditions. The objectives were to identify, through phytosociological analysis, the plant species able to grow on such polluted areas and to characterize pollutant effects at different biological levels through analyses of plant oxidative status, plant growth or community indexes of richness and biodiversity. Our results showed that among the plants present in the uncontaminated surrounding area, only few species were able to colonize the polluted soil. These species were typical of the first years of grassland successions. Ecological indexes proved that the polluted soil vegetation presented a lower degree of species richness and biodiversity than the control area. These discrepancies were partly explained by pollutant phytotoxicity. Indeed, for several species including Erigeron canadensis and Oenothera biennis, we observed toxic effects of the polluted soil on plant height and biomass. Moreover, at the cellular level, changes in antioxidant enzyme activities (SOD, CAT, APX, GPX and GRD) and lipid peroxidation level (MDA) were observed. Such biochemical changes seemed to play an important role on plant sensitivity/tolerance to pollutants and thus to render them more or less competitive for colonization of such disturbed areas. 相似文献
279.
280.
Donatus Bapentire Angnuureng Rafael Almar Nadia Senechal Bruno Castelle Kwasi Appeaning Addo Vincent Marieu Roshanka Ranasinghe 《Journal of Coastal Conservation》2017,21(3):381-392
The present work investigates cross-shore shoreline migration as well as its alongshore variability (with deformation) on timescales of days to years using 6 years of time-averaged video images. The variability of the shoreline is estimated through empirical statistical methods with comprehensive reference to three scales of variability. At the meso-to macro-tidal barred Biscarrosse beach, shoreline responds in decreasing order at seasonal (winter/summer cycles, 52%), event (storms, 28%) and inter-annual scales. Whereas seasonal evolution is dominated by wave climate modulation, short-term evolution is influenced by tidal range and surf-zone sandbar characteristics. The influence of tide range and sandbars increases when timescale decreases. This is even more the case for the alongshore deformation of the shoreline which is dominated by short-term evolution. An EOF analysis reveals that the first mode of shoreline change time series is associated with cross-shore migration and explains 58% of the shoreline variability. The rest of the modes are associated to deformation which explain 42% of shoreline variability. 相似文献