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21.
About 50 species of small, demersal fish live together on a shallow mud bottom in Moreton Bay, Queensland, Australia. The patterns of coexistence of these fish in this topographically uniform, but hydrologically unpredictable, habitat were studied using partitioned information statistics. The patterns were considered simultaneously over several environmental scales and biological levels. It was found that the community patterns were insensitive to the scale of the environment, but seemed to be coupled over supraspecific biological levels. It is suggested that supraspecific coupling allowed this complex community to exist in a simple environment. A theory of community organization, which involves the concept of connectedness, is proposed. This theory explains the above phenomena and also reconciles, in a general context, the predictability and unpredictability theories of community organization.  相似文献   
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23.
1.  Five species of emballonurid bats (Rhynchonycteris naso, Saccopteryx leptura, Balantiopteryx plicata, Saccopteryx bilineata, and Peropteryx kappleri), were studied in Costa Rica and Trinidad. Stomach contents suggest that prey size generally increases for bat body size, but within these species there is considerable overlap. R. naso, S. leptura, and P. kappleri each appear to be specialized for foraging in a particular habitat type; B. plicata and S. bilineata are more opportunistic and feed over a variety of habitats during the year. While the other species feed in the proximity of surfaces, B. plicata is further separated from the other species by wing specializations favoring high altitude flight.
2.  Foraging dispersion is more closely related to body size than it is to social structure at the roost: small bats group-forage while larger bats feed in solitary beats. In all of the species, food is spatially and temporally variable, and the location of foraging sites changes seasonally in accordance with these locally varying patterns of aerial insect abundance. In the case of S. bilineata, the locations of foraging sites were positively correlated with levels of phenological activity in the underlying plant communities.
3.  Colony sizes ranged from small groups of 2–10 bats (S. leptura, P. kappleri), to intermediate colonies of 5–50 bats (R. naso, S. bilineata), to very large colonies with hundreds of bats (B. plicata).
4.  R. naso, S. leptura, and S. bilineata colonies have colony-specific annual foraging ranges which are actively defended against conspecifics from other colonies. In most cases, all members of a given colony of one of these species will be found foraging in a common site at any time. In R. naso and S. bilineata, currently used foraging sites are partitioned socially. In the former species, adult breeding females occupy a central area and groupforage while younger non-breeding females and males occupy peripheral foraging areas in the colony territory. In S. bilineata, the colony foraging site is partitioned into individual harem territories defended by harem males and containing the individual beats of all current harem females. For this latter species, details of roost site subdivision are mapped directly onto foraging dispersions. In general, there is a close correlation between dayroost group membership and location of nocturnal foraging sites in all of the study species.
  相似文献   
24.
ABSTRACT: To provide a basis for regional hydroclimatic forecasting, New England (NE) precipitation and streamflow are compared with indices for the El Niño/Southern Oscillation, the Pacific North American (PNA) pattern, and the North Atlantic Oscillation (NAO). Significant positive correlations are found between the NAO index and monthly streamflow at western inland locations, with the strongest seasonal correlations occurring in winter. Smoothed records for the winter NAO and winter streamflow are highly correlated at some sites, suggesting that interrelationships are most significant in the low frequency spectrum. However, correlations between the NAO and precipitation are not significant, so further examination of other factors is needed to explain the relationship between the NAO and streamflow. NAO related regional air temperature, sea surface temperature (SST), storm tracking, and snowfall variability are possible mechanisms for the observed teleconnection. Exceptionally cool regional air temperatures, and SSTs, and unique regional storm track patterns characterized NE's climate during the famous 1960s drought, suggesting that concurrent (persistent) negative NAO conditions may have contributed to the severity of that event. Monthly and winter averaged regional streamflow variability are also significantly correlated with the PNA index. This, along with results from previous studies, suggests that tropospheric wave character and associated North Pacific SST anomalies are also related to NE regional drought conditions.  相似文献   
25.
Diffusion coefficients (T=23 +/- 2 degrees C) and accessible porosities for HTO, 36Cl(-) and 125I(-) were measured on Opalinus Clay (OPA) samples from the Mont Terri Underground Rock Laboratory (URL) using the through-diffusion technique. The direction of transport (diffusion) was perpendicular to bedding. Special cells that allowed the application of confining pressure were designed and constructed. The pressures ranged from 1 to 5 MPa, the latter value simulating the overburden at the Mont Terri URL (about 200 m). The test solution used in the experiments was a synthetic version of the Opalinus Clay pore water, which has Na(+) and Cl(-) as the main components (I=0.42 M). The measured values of the effective diffusion coefficients (D(e)) and rock capacity factors (alpha) are: D(e)=1.2-1.5 x 10(-11) m(2) s(-1) and alpha=0.09-0.11 for HTO, D(e)=4.0-5.5 x 10(-12) m(2) s(-1) and alpha=0.05 for 36Cl(-) and D(e)=3.2-4.6 x 10(-12) m(2) s(-1) and alpha=0.07-0.10 for 125I(-). For non-sorbing tracers (HTO, 36Cl) the rock capacity factor alpha is equal to the diffusion-accessible porosity epsilon. The experimental results showed that pressure only had a small effect on the value of the diffusion coefficients. Increasing the pressure from 1 to 5 MPa resulted in a decrease of the diffusion coefficient of approximately 17% for HTO, approximately 28% for 36Cl(-) and approximately 30% for 125I(-). Moreover, the diffusion coefficients for 36Cl(-) and 125I(-) are smaller than for HTO, which is consistent with an effect arising from anion exclusion. The diffusion coefficients of HTO and 125I(-) measured in this study are in good agreement with recent measurements at three other laboratories performed within the framework of a laboratory comparison exercise. The values of the diffusion-accessible porosities show a larger degree of scatter.  相似文献   
26.
Stakeholder involvement (SI) can include many activities, from providing information on a website to one-on-one conversations with people confronting an issue in their community. For carbon dioxide capture and storage (CCS), there are now quite a few surveys of public attitudes towards CCS that are being used to inform the design of SI efforts. These surveys, focused on the nascent commercial deployment of CCS technologies, have demonstrated that the general public has little knowledge about CCS—yet the surveys go on to collect what are known as “pseudo opinions” or “non-attitudes” of respondents who know little or nothing about CCS. Beyond establishing the lack of knowledge about CCS, the results of these surveys should not be relied upon by the larger CCS community and public and private decision makers to inform the critical task of implementing and executing SI activities. The paper discusses the issues involved in providing information as part of the survey, maintaining that such information is never unbiased and thus tends to produce pseudo opinions that reflect the pollster's or researcher's bias. Other content and methodological issues are discussed, leading to the conclusion that most of the survey results should be used neither as a gauge of public attitudes nor as an indication of public acceptance. Then the framing of SI in CCS is examined, including the assumptions that clear stakeholder acceptance is a realistic goal and that the public has a decisive say in choosing the energy technologies of the present and the future. Finally, a broader suite of SI activities is recommended as more suited to realistic and contextual goals.  相似文献   
27.
The COVID-19 pandemic has had an enormous impact on almost all aspects of human society and endeavor; the natural world and its conservation have not been spared. Through a process of expert consultation, we identified and categorized, into 19 themes and 70 subthemes, the ways in which biodiversity and its conservation have been or could be affected by the pandemic globally. Nearly 60% of the effects have been broadly negative. Subsequently, we created a compendium of all themes and subthemes, each with explanatory text, and in August 2020 a diverse group of experienced conservationists with expertise from across sectors and geographies assessed each subtheme for its likely impact on biodiversity conservation globally. The 9 subthemes ranked highest all have a negative impact. These were, in rank order, governments sidelining the environment during their economic recovery, reduced wildlife-based tourism income, increased habitat destruction, reduced government funding, increased plastic and other solid waste pollution, weakening of nature-friendly regulations and their enforcement, increased illegal harvest of wild animals, reduced philanthropy, and threats to survival of conservation organizations. In combination, these impacts present a worrying future of increased threats to biodiversity conservation but reduced capacity to counter them. The highest ranking positive impact, at 10, was the beneficial impact of wildlife-trade restrictions. More optimistically, among impacts ranked 11-20, 6 were positive and 4 were negative. We hope our assessment will draw attention to the impacts of the pandemic and, thus, improve the conservation community's ability to respond to such threats in the future.  相似文献   
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