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排序方式: 共有235条查询结果,搜索用时 31 毫秒
191.
Hillary Smith Sergio Marrocoli Alejandro Garcia Lozano Xavier Basurto 《Conservation biology》2019,33(1):9-21
Wildlife hunting is essential to livelihoods and food security in many parts of the world, yet present rates of extraction may threaten ecosystems and human communities. Thus, governing sustainable wildlife use is a major social dilemma and conservation challenge. Commons scholarship is well positioned to contribute theoretical insights and analytic tools to better understand the interface of social and ecological dimensions of wildlife governance, yet the intersection of wildlife studies and commons scholarship is not well studied. We reviewed existing wildlife-hunting scholarship, drawing on a database of 1,410 references, to examine the current overlap with commons scholarship through multiple methods, including social network analysis and deductive coding. We found that a very small proportion of wildlife scholarship incorporated commons theories and frameworks. The social network of wildlife scholarship was densely interconnected with several major publication clusters, whereas the wildlife commons scholarship was sparse and isolated. Despite the overarching gap between wildlife and commons scholarship, a few scholars are studying wildlife commons. The small body of scholarship that bridges these disconnected literatures provides valuable insights into the understudied relational dimensions of wildlife and other overlapping common-pool resources. We suggest increased engagement among wildlife and commons scholars and practitioners to improve the state of knowledge and practice of wildlife governance across regions, particularly for bushmeat hunting in the tropics, which is presently understudied through a common-pool resource lens. Our case study of the Republic of Congo showed how the historical context and interrelationships between hunting and forest rights are essential to understanding the current state of wildlife governance and potential for future interventions. A better understanding of the interconnections between wildlife and overlapping common-pool resource systems may be key to understanding present wildlife governance challenges and advancing the common-pool resource research agenda. 相似文献
192.
Boevé Jean-Luc Sonet Gontran Jacobson Herbert R. Angeli Sergio 《Die Naturwissenschaften》2023,110(2):1-1
The Science of Nature - 相似文献
193.
Xiuhua Wang Carol Seaman Myunghee Paik Timothy Chen Arthur Bank Sergio Piomelli M.D. 《黑龙江环境通报》1994,14(9):851-857
Prenatal diagnosis of sickle cell diseases is obtained rapidly and precisely by polymerase chain reaction (PCR) with Ddel restriction analysis and dot-blotting with alllele-specific oligonucleotides (ASO). Prenatal diagnosis of HgbSS and HgbSC was performed in 500 pregnancies, 196 by Southern blot and 304 by PCR. PCR drastically shortened the interval from sampling to reporting, allowing acceptance even of samples with unknown paternal phenotype, and resulted in an overall four-fold increase in diagnoses. In 108 pregnancies, the diagnosis was an affected fetus; 25 were HgbSC: 3 (12 per cent) were terminated; 83 were HgbSS: four ended in miscarriage; 40/79 (51 per cent) were terminated. The gestational age at the time of report to the mother appeared to be a major outcome determinant when the fetal diagnosis was HgbSS. The change-point in the maternal decision was found at 20 weeks of gestation. Before the 20th week, most mothers (64 per cent) chose termination; thereafter, the majority (72 per cent) chose continuation. The odds ratio of termination in earlier relative to later reporting was 4·7. In order to offer a choice to the mothers at risk of delivering a fetus affected by sickle cell disease, the diagnosis should be reported before the 20th week of gestation. 相似文献
194.
Valeria Mezzanotte Nadia Prato Sergio Sgorbati Sandra Citterio 《Water environment research》2004,76(5):463-467
Microbial populations were studied by plate counts and flow cytometry along the polishing sequence of a wastewater plant. The comparison between plate count and flow cytometry showed comparable trends, but plate counts detected less than 10% of the total intact bacteria counted by flow cytometry. Six months monitoring showed that, in spite of the high ozone doses, the disinfection effect of ozonation was insignificant. This is in agreement with the variability of ozone demand, not only related to chemical oxygen demand or total suspended solids. Membrane-intact bacterial population decreased after ozonation, slightly regrew between ozone and biological activated carbon (BAC), and sharply increased after BAC, probably for damaged bacteria regrowth and saprophytes release; BAC effluent had the highest bacterial counts. Preliminary investigations on the effluent microbial composition showed that the beta Proteobacteria subclass is the most represented in the BAC effluent, whereas the alpha subclass is the most sensitive to ozone effect. 相似文献
195.
Summary. Orb-web-spiders present a series of different strategies for prey capture, involving the use of different types of silk for
web building, the use of adhesive traps in the webs, the secretion of toxic compounds to the spider’s preys in the adhesive
coating of the capture web and the biosynthesis of a wide range of structurally related acylpolyamine toxins in their venoms.
The polyamine toxins usually block neuromuscular junctions and/or the central nervous system (CNS) of Arthropods, targeting
specially the ionotropic glutamate receptors; this way these toxins are used are as chemical weapons to kill / paralyze the
spider’s prey. Polyamine toxins contain many azamethylene groups involved with the chelation of metal ions, which in turn
can interact with the glutamate receptors, affecting the toxicity of these toxins. It was demonstrated that the chelation
of Ni+2, Fe+2, Pb+2, Ca+2 and Mg+2 ions by the desalted crude venom of Nephilengys cruentata and by the synthetic toxin JSTX-3, did not cause any significant change in the toxicity of the acylpolyamine toxins to the
model-prey insect (honeybees). However, it was also reported that the chelation of Zn+2 ions by the acylpolyamines potentiated the lethal / paralytic action of these toxins to the honeybees, while the chelation
of Cu+2 ions caused the inverse effect. Atomic absorption spectrometry and Plasma-ICP analysis both of N. cruentata venom and honeybee’s hemolymph revealed that the spider’s venom concentrates Zn+2 ions, while the honeybee’s hemolymph concentrates Cu+2 ions. These results are suggesting that the natural accumulation of Zn+2 ions in N. cruentata venom favors the prey catching and/or its maintenance in the web, while the natural accumulation of Cu+2 ions in prey’s hemolymph minimizes the efficiency of the acylpolyamine toxins as killing/paralyzing tool. 相似文献
196.
Andrea Gori Cristina Linares Sergio Rossi Rafel Coma Josep-Maria Gili 《Marine Biology》2007,151(4):1571-1584
Paramuricea clavata (Risso, 1826) and Eunicella singularis (Esper, 1794) are the most representative gorgonian species in hard bottoms sublittoral communities in the Western Mediterranean
Sea. Reproductive cycles of two populations of both species were studied in two distinct locations approximately 600 km apart
(Medes Islands and Cape of Palos), in order to assess interpopulation variability on a relevant geographic scale. Seasonal
variation of lipid concentration levels in the gorgonian tissue was used as a tool to quantify energy storage by each studied
population in order to explain possible interpopulation differences in gonadal output. Sex ratio in Medes Islands populations
of both species was 1:1, while in Cape of Palos sex ratio was significantly male biased (1:7) in P. clavata, and female biased (1.7:1) in E. singularis populations. Spawning timing occurred in all cases coinciding with a marked increase in sea-water temperature in spring,
and after the most successful feeding season, but comparing localities there was a clear temporal shift in the time of gametes
release, appearing well linked to the shift in sea-water temperature rising in spring in both sites at the depth where populations
are placed. Therefore, in this study the temperature appears as the main synchronizing factor of gonadal development within
these populations. Significant differences in gonadal volume per polyp were found in both species owing mainly to differences
in the number of gonads per polyp between populations, with Cape of Palos populations displaying higher values in both studied
species, suggesting that the exposition to different local conditions may be reverted in a different gonadal output. But the
observed patterns in lipid concentrations levels in gorgonians disable us to conclude that lipid concentration levels explain
the observed differences in gonadal output found in this study. 相似文献
197.
Georgios Tsounis Sergio Rossi Maria Aranguren Josep-Maria Gili Wolf Arntz 《Marine Biology》2006,148(3):513-527
Red coral (Corallium rubrum, L. 1758) is an over-exploited Mediterranean gorgonian. The gonadal development cycle of this gorgonian is examined at the
Costa Brava (NW Mediterranean) taking into account for the first time colony size, depth and spatial horizontal variability.
This study compares the gonad development and fertility in two colony size classes (colonies <6-cm height, and >10-cm height,
both at 40–45-m depth), and two populations at different depths (16–18-m depth, and 40–45-m depth, both consisting of <6-cm
high colonies) in a 15-month period. The fertility of seven size classes (<2 cm to >12 cm high colonies, in 2 cm intervals)
was examined in the deep population, where large colonies were present. Furthermore, reproductive output was compared in 6
populations (distributed along more than 70-km coastline) one month before spawning (June). Red coral was found to be dioecious
and gonochoric with a sex ratio of 1:1, which differs from other NW Mediterranean populations. On the other hand, fertility
of different size classes indicates that small colonies of 2-cm height already produce gonads, which is in line with previous
studies. Female and male polyp fertility and sperm sac size increase significantly with colony size [sperm sac diameter: 476±144 μm
(mean±SD) and 305±150 μm in the >10-cm and <6-cm height colonies, respectively), whereas no significant effect on oocyte diameter
was found (oocyte diameter: 373.7±18.7 μm). Depth staggered spawning, that is, an earlier release of gonads in the shallow
populations, was observed in summer 2003, coinciding with the highest temperature gradient between shallow and deep water
during the study period. Colonies of <6-cm height were significantly less fertile than colonies >12 cm, thus the recommendation
of this study is that a minimum height should be incorporated into fishing regulations. The six studied populations at the
Costa Brava showed a comparable reproductive potential, which demonstrates little variability within the homogenous population
structure and range of size classes (due to overharvesting) found at the Costa Brava. The study of reproductive output is
an important tool for ecosystem management, and this work recommends basing specific exploitation laws for distinctive populations
on colony size, which is found to have a larger effect on reproductive potential than mesoscale variability.
An erratum to this article can be found at 相似文献
198.
199.
Octocorals are an important part of many ecosystems as they add three-dimensional complexity to the benthos and thereby increase biodiversity. The Mediterranean red coral (Corallium rubrum, L. 1758) is a longevous octocoral that is harvested commercially, yet natural and anthropogenic influences on its population size structure are little understood. This study found that some harvested red coral populations had a significantly different size structure when compared to populations at the nearby Marine Protected Area (MPA) of Medas Islands at the Spanish Costa Brava (NW Mediterranean). Eighty-nine percent of the red corals in the harvested Costa Brava area are less than 10 years old and 96% of all colonies have not yet grown more than second-order branches. The size/age distribution of the harvested population is notably skewed towards younger and smaller colonies. Thus, although red coral is still abundant, its population structure is strongly distorted by harvesting. The results confirm that MPAs are useful to distinguish between anthropogenic and natural influences on population structure. However, 14 years of protection appears to be an insufficient recovery time for a longevous octocoral population such as red coral. 相似文献
200.
Amanda C. Lima Sergio N. Monteiro Kestur G. Satyanarayana 《Journal of Polymers and the Environment》2012,20(1):245-253
In recent times, environmental safety has been on priority in the development of new materials leading to a recycling and
reuse approach to conserve the materials resources. This has resulted in more focus on the application of natural materials
such as lignocellulosic fibers. This paper presents the characterization of continuous and aligned jute fabrics obtained from
new and used sacks as well as the preparation and characterization of their composites incorporated into recycled polyethylene
or as isolated pieces up to 40 wt%. These environmentally friendly composites were subjected to bend test and the fracture
surface analyzed by SEM. The fabric from new sacks showed greater damage tolerance than that from the used sacks. The flexural
stress increased steadily with increasing used fabric content up to 30 wt%, which is explained using fractographic studies
on ruptured specimens. Used jute fabric composites are found to be viable alternative materials for low strength conventional
materials based on cost–performance comparison with conventional materials. 相似文献