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241.
Ruth M. Casper Simon N. Jarman Nicholas J. Gales Mark A. Hindell 《Marine Biology》2007,152(4):815-825
The diet of pinnipeds is most commonly inferred from morphologically diagnostic remains of prey in their scats. Although this
method can generate quantitative estimates of diet simply, important prey types may not always be detected. DNA-based methods
improve detection of prey in scats, but they are not quantitative. While some studies have combined morphological and DNA-based
methods, these have only assessed prey that are represented by their hard remains in scats. To overcome this bias, we apply
molecular and morphological analyses to the soft and hard portions of faecal samples respectively, to estimate the diet of
lactating Antarctic fur seals (Arctocephalus gazella) on Heard Island. The diet of this population is of particular interest because it is expanding rapidly and may rely to some
extent on mackerel icefish (Champsocephalus gunnari), which are subject to commercial fisheries. Based on results from morphological analysis and likely important prey types,
we tested for DNA remains of C. gunnari, myctophids and squid in faecal samples. The proportion of samples (n = 54) yielding no dietary information was reduced from around 25.9% using either method alone, to 9.3% when combined. Detection
of all prey types tested for was notably improved by integrating molecular and morphological data. Data from either method
alone would have underestimated the number of animals consuming C. gunnari by around 25.7%. Detection of multiple prey types in samples increased from 9.3% when using morphological analysis only,
to 33.3% when using DNA only, to 46.3% when using both methods. Taken in isolation, morphological data inferred that individual
seals consume either C. gunnari or myctophids, probably foraging in separate locations characteristic of those prey. Including molecular data demonstrated
that while this may be true of some individuals, many other seals consume a mixed diet of at least C. gunnari, myctophids and squid. This new approach of combining DNA-based and morphological analyses of diet samples markedly increased
the number of samples yielding dietary information, as well as increasing the amount of information attained from those samples.
Our findings illustrate the broad potential of this technique to improve insight into trophic interactions in marine ecosystems.
相似文献
Ruth M. CasperEmail: |
242.
Concentrations of phthalate esters and identification of other additives in PVC children’s toys 总被引:1,自引:0,他引:1
Ruth Stringer Iryna Labunska David Santillo Paul Johnston John Siddorn Angela Stephenson 《Environmental science and pollution research international》2000,7(1):27-36
This study was intended to provide data on the composition of soft PVC toys, addressing the widest practicable range of chemical
additives and including non-phthalate additives. The study also included toys from as many countries as possible, since for
many, no data were available. A total of 72 toys were purchased in 17 countries. The majority (64) were PVC or had PVC sections.
In almost all the soft PVC toys analysed, phthalates comprised a sizeable proportion (most frequently 10–40%) of the total
weight of the toy.
The predominant phthalates detected were diisononyl phthalate (DINP) and di(2-ethylhexyl) phthalate (DEHP). Other phthalates
identified in high concentrations in some toys include isomeric mixes of diisooctyl phthalate (DIOP) and diisodecyl phthalate
(DIDP). The estrogenic chemical nonylphenol was isolated from 13 toys, while 2 toys were found to contain the fungicide Fungitrol
11 (Folpet). 78% of PVC toys contained one or more extractable organic compounds in addition to those reported above.
Some of these data have been released previously by Greenpeace and made available on the internet.This report, however, which
is intended for a technically expert audience, has been peer reviewed and contains further analytical data that have not been
published before. 相似文献
243.
Reducing nitrogen loading of inland and marine waters--evaluation of Danish policy measures to reduce nitrogen loss from farmland 总被引:1,自引:0,他引:1
An evaluation in December 2003 of the Danish National Action Plan for the Aquatic Environment II showed that nitrogen leaching from farmland had declined to almost half the amount of that in 1989. This can be ascribed to successful implementation of several measures, the most efficient of which were related to the use of fertilizers: lowered nitrogen standards for crops, increased nitrogen utilization in manure and catch crops. Although the objectives of the plan were almost met and measurements have shown a similar, but not percentually as high a decrease in nitrogen concentrations in both inland and coastal waters, the ecological impact in estuaries and coastal areas is not yet satisfactorily significant. As a consequence, a new National Action Plan for the Aquatic Environment III, including both nitrogen and phosphorus reduction from farming, was agreed to in April 2004. To ensure that good ecological status can be achieved in water bodies according to the requirements of the European Union Water Framework Directive, the national measures will be combined with additional measures for individual river basins. 相似文献
244.
Application of stable isotope analysis (SIA) in jellyfish allows definition of trophic patterns not detectable using gut content analysis alone, but analytical protocols require standardization to avoid bias in interpreting isotopic data. We determined δ13C and δ15N in Aurelia sp. from the northern Gulf of Mexico (30°00′N, 89°00′W–30°24′N, 88°00′W) to define differences in stable isotope composition between body parts and whole body, the effect of lipid extraction on δ13C in tissues, and fractionation values from medusa to prey. The isotopic composition of bell and whole Aurelia sp. was not different. The increase in δ13C values after lipid removal suggested a correction is needed. To aid future analyses, we derived a correction equation from empirical data for jellyfish samples. Laboratory feeding experiments indicated medusae increased +4 ‰ in δ13C and +0.1 ‰ in δ15N compared to their diet. These results suggest protocols commonly applied for other species may be inaccurate to define Aurelia sp. trophic ecology. Because Aurelia spp. are commonly found in marine ecosystems, accurately defining their trophic role by use of SIA has implications for understanding marine food webs worldwide. 相似文献
245.
Baccarelli A Pfeiffer R Consonni D Pesatori AC Bonzini M Patterson DG Bertazzi PA Landi MT 《Chemosphere》2005,60(7):898-906
Exposure measurements of concentrations that are non-detectable or near the detection limit (DL) are common in environmental research. Proper statistical treatment of non-detects is critical to avoid bias and unnecessary loss of information. In the present work, we present an overview of possible statistical strategies for handling non-detectable values, including deletion, simple substitution, distributional methods, and distribution-based imputation. Simple substitution methods (e.g., substituting 0, DL/2, DL/ radical2, or DL for the non-detects) are the most commonly applied, even though the EPA Guidance for Data Quality Assessment discouraged their use when the percentage of non-detects is >15%. Distribution-based multiple imputation methods, also known as robust or "fill-in" procedures, may produce dependable results even when 50-70% of the observations are non-detects and can be performed using commonly available statistical software. Any statistical analysis can be conducted on the imputed datasets. Results properly reflect the presence of non-detectable values and produce valid statistical inference. We describe the use of distribution-based multiple imputation in a recent investigation conducted on subjects from the Seveso population exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), in which 55.6% of plasma TCDD measurements were non-detects. We suggest that distribution-based multiple imputation be the preferred method to analyze environmental data when substantial proportions of observations are non-detects. 相似文献
246.
Data from the National Institute of Education's Safe School Study Report suggested that teachers in American urban public schools are emotionally and physically victimized and that the result is heightened level of stress associated with teaching. This study, which is part of larger, longitudinal project, explores the linkages between reported experiences of victimization by 291 urban public school teachers and task-specific stressors in the performance of the teaching role. The level of reported stress and nature and degree of victimization differ by the grade level taught and the race of the teacher. Generally, minority teachers (black and brown) are less likely to report being stressed or victimized than are white teachers, while elementary school teachers report their work to be most stressful. There is no evidence of a specific causal ordering between fear of victimization and teacher stress. Rather, each may feed upon and facilitate the other. 相似文献
247.
We seek to bridge the macro concept of corporate social responsibility (CSR) with micro research in organizational justice. A theoretical model is presented whereby employees' perceptions of CSR impact their subsequent emotions, attitudes, and behaviors, mediated by instrumental, relational, and deontic motives/needs, as well as moderated by organizations' social accounts. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
248.
Managing Protected Woodlands: Fuelwood Collection and Law Enforcement in Lake Malawi National Park 总被引:3,自引:0,他引:3
Abstract: We examined the decisions women make in their collection of fuelwood within a protected area in Malawi. We used law enforcement data and behavioral observations of fuelwood harvesting practices to examine the risk of detection and penalties posed by law enforcement activities. Our results indicate that, at their current levels, law enforcement patrols have little effect on wood collection practices. The low risk of detection and light penalties appear to favor illegal wood collection, which is practiced by the majority of women. Alternative strategies should be pursued to enhance the conservation of the woodland and its management as a fuelwood resource for local communities. 相似文献