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51.
Michael D. Arendt Albert L. Segars Julia I. Byrd Jessica Boynton J. David Whitaker Lindsey Parker David W. Owens Gaëlle Blanvillain Joseph M. Quattro Mark A. Roberts 《Marine Biology》2012,159(1):101-112
Satellite transmitters were attached to 25 reproductively active and four inactive adult male loggerhead sea turtles (86.6–107.0 cm
SCLmin) captured from the Port Canaveral, FL, USA shipping channel to assess horizontal and vertical distributions. During
the breeding period, male loggerheads aggregated (44% of 755 turtle days) in a 117.6 km2 core area that encompassed the shipping channel. Median dive duration during the breeding period was 27 min (IQR = 15–42
min) and males spent 4% (IQR = 3–5%) of the time at the surface, with significantly shorter dives associated with reproductively
active males. Migrant and resident males dispersed concurrently, with residents shifting > 30 km east across the continental
shelf over a more protracted departure schedule than migrants. Dive duration and time spent at the surface increased through
the fall. Cluster analysis revealed the strongest association for dive duration with sea state during and after the breeding
period, with significantly longer dives during more turbulent conditions. In contrast, univariate associations with surface
interval duration were not elucidated. 相似文献
52.
Phytophagous insects commonly interact through shared host plants. These interactions, however, do not occur in accordance with traditional paradigms of competition, and competition in phytophagous insects is still being defined. It remains unclear, for example, if particular guilds of insects are superior competitors or important players in structuring insect communities. Gall-forming insects are likely candidates for such superior competitors because of their ability to manipulate host plants, but their role as competitors is understudied. We investigate the effect of invasive populations of an oak gall wasp, Neuroterus saltatorius, on a native specialist butterfly, Erynnis propertius, as mediated by their shared host plant, Quercus garryana. This gall wasp occurs at high densities in its introduced range, where we stocked enclosures with caterpillars on trees that varied in gall wasp density. Biomass production of butterflies was lower in enclosures on high-density than on low-density trees because overwintering caterpillars were smaller, and fewer of them eclosed into adults the following spring. To see if the gall wasp induced changes in foliar quality, we measured host plant quality before and after gall induction on 30 trees each at two sites. We found a positive relationship between gall wasp density and the percentage change in foliar C:N, a negative relationship between gall wasp density and the percentage change in foliar water at one site, and no relationship between the percentage change in protein-binding capacity (i.e., phenolics) and gall-wasp density. Additionally, there was a negative relationship between foliar quality and butterfly performance. Our results provide evidence for a plant-mediated impact of an invasive oak gall wasp on a native butterfly and suggest that gall wasps could act as superior competitors, especially when they occur at high densities. 相似文献
53.
54.
With energy crises looming, conflicts over resource extraction and production are on the rise. For communities lacking voice to participate in these conflicts, community-based organisations and local non-governmental organisations help to unite, communicate, and negotiate with other stakeholders. In this paper we compare two cases that demonstrate the roles of organisations in providing voice to citizenry impacted by environmental justice issues. We use Senecah's concept of Trinity of Voice for the purposes of evaluation. These cases provide contrasting examples of how local/regional organisations chose to either expand their organisation's mission to intervene or stick to a strict reading of their mission thus excluding involvement. In both examples we found that organisational involvement, or lack thereof, influenced how citizens were involved in decision-making with one case leading to legislation protecting property owners from industrial activities, and the other leading to a lack of effective involvement and negatively impacted citizens. 相似文献
55.
Gerald J. Kauffman Andrew R. Homsey Andrew C. Belden Jessica Rittler Sanchez 《Environmental monitoring and assessment》2011,177(1-4):193-225
In 1940, the tidal Delaware River was ??one of the most grossly polluted areas in the United States.?? During the 1950s, water quality was so poor along the river at Philadelphia that zero oxygen levels prevented migration of American shad leading to near extirpation of the species. Since then, water quality in the Delaware Basin has improved with implementation of the 1961 Delaware River Basin Compact and 1970s Federal Clean Water Act Amendments. At 15 gages along the Delaware River and major tributaries between 1980 and 2005, water quality for dissolved oxygen, phosphorus, nitrogen, and sediment improved at 39%, remained constant at 51%, and degraded at 10% of the stations. Since 1980, improved water-quality stations outnumbered degraded stations by a 4 to 1 margin. Water quality remains good in the nontidal river above Trenton and, while improved, remains fair to poor for phosphorus and nitrogen in the tidal estuary near Philadelphia and in the Lehigh and Schuylkill tributaries. Water quality is good in heavily forested watersheds (>50%) and poor in highly cultivated watersheds. Water quality recovery in the Delaware Basin is coincident with implementation of environmental laws enacted in the 1960s and 1970s and is congruent with return of striped bass, shad, blue crab, and bald eagle populations. 相似文献
56.
Sex chromosome aneuploidy (SCA) can be detected on prenatal diagnostic testing and cell free DNA screening (cfDNA). High risk cfDNA results should be confirmed with diagnostic testing. This summary article serves as an update for prenatal providers and assimilates data from neurodevelopmental, epidemiologic, and registry studies on the most common SCA. This information can be helpful for counseling after prenatal diagnosis of sex chromosome aneuploidy. Incidence estimates may be influenced by ascertainment bias and this article is not a substitute for interdisciplinary consultation and counseling. 相似文献
57.
Christopher James Lemieux Jessica Thompson D. Scott Slocombe Rudy Schuster 《Journal of Environmental Planning and Management》2015,58(4):654-677
It has been argued that regional collaboration can facilitate adaptation to climate change impacts through integrated planning and management. In an attempt to understand the underlying institutional factors that either support or contest this assumption, this paper explores the institutional factors influencing adaptation to climate change at the regional scale, where multiple public land and natural resource management jurisdictions are involved. Insights from two mid-western US case studies reveal that several challenges to collaboration persist and prevent fully integrative multi-jurisdictional adaptation planning at a regional scale. We propose that some of these challenges, such as lack of adequate time, funding and communication channels, be reframed as opportunities to build interdependence, identify issue-linkages and collaboratively explore the nature and extent of organisational trade-offs with respect to regional climate change adaptation efforts. Such a reframing can better facilitate multi-jurisdictional adaptation planning and management of shared biophysical resources generally while simultaneously enhancing organisational capacity to mitigate negative effects and take advantage of potentially favourable future conditions in an era characterised by rapid climate change. 相似文献
58.
On estimating the exponent of power-law frequency distributions 总被引:5,自引:0,他引:5
Power-law frequency distributions characterize a wide array of natural phenomena. In ecology, biology, and many physical and social sciences, the exponents of these power laws are estimated to draw inference about the processes underlying the phenomenon, to test theoretical models, and to scale up from local observations to global patterns. Therefore, it is essential that these exponents be estimated accurately. Unfortunately, the binning-based methods traditionally used in ecology and other disciplines perform quite poorly. Here we discuss more sophisticated methods for fitting these exponents based on cumulative distribution functions and maximum likelihood estimation. We illustrate their superior performance at estimating known exponents and provide details on how and when ecologists should use them. Our results confirm that maximum likelihood estimation outperforms other methods in both accuracy and precision. Because of the use of biased statistical methods for estimating the exponent, the conclusions of several recently published papers should be revisited. 相似文献
59.
ABSTRACTMiami, FL, is one of the most climate-vulnerable cities in the United States. At an average elevation of only 6 feet above sea level, parts of the city could be made uninhabitable by rising oceans within the next 40 years. The effects of climate change are already beginning to be seen, but the subject of climate change is nevertheless modelled, imagined and contested in the future tense. Today's young people are similarly future oriented, but unlike older generations they will live to feel climate change's full future effects. This study investigates knowledge of and experiences with climate change among young adults in Miami, and their visions of the future in light of predicted changes. Semi-structured interviews were conducted with 19 long-term residents of the city between the ages of 18 and 30 who were students at Miami-Dade College or Florida International University. I discuss participants’ sense of personal responsibility to inform themselves and the individualised understandings of climate science that emerge, their disillusionment with politics and resulting perception of individual responsibility for climate mitigation, and their negotiation of personal future plans in light of fatalistic visions of the future. These young adults’ perspectives on rising seas in their home city are revealed to be socially structured by ideals of individual agency and self-reliance, which become paradoxically disempowering because of the impossibility of addressing the transformational impacts of climate change through individualised means. 相似文献
60.