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651.
The planning step of an ecological risk assessment includes the largest role for public participation in the entire assessment, for it is here that the risk manager must ensure that the assessment will yield the information he needs to make a decision. This essay discusses some general characteristics of public participation in ecological risk assessments, including the ways in which different lifestyles may lead to the establishment of community specific management goals and hence of different endpoints; the type and nature of the input provided by the public to the risk assessment and the ways in which input from the public differs from input from the scientific community; and a discussion of definitions of stakeholders and participatory processes which emphasizes their contextual nature. The essay concludes with a review of some of the challenges facing a risk manager as he designs a participatory process. Six major areas are discussed, each incorporating suggestions that should reduce difficulties in implementation of such a process and increase the likelihood of acceptance of its outcome, and hence the overall quality of the risk assessment. 相似文献
652.
Amniotic band syndrome is a rare cause of fetal head deformity. We report a case in which antenatal ultrasound in the first half of pregnancy indicated the presence of a fetal cranial deformity, reported as either anencephaly or encephalocele. At assessment autopsy, disruption of the fetal skull was associated with amniotic band formation. Appropriate genetic counselling can be offered to such patients only when detailed pathological examination of the aborted fetus is made. The recurrence rate of amniotic band syndrome does not warrant amniocentesis in a subsequent pregnancy. 相似文献
653.
Population frequencies of alternative male phenotypes in tree lizards: geographic variation and common-garden rearing studies 总被引:2,自引:0,他引:2
Diana K. Hews Christopher W. Thompson Ignacio T. Moore Michael C. Moore 《Behavioral ecology and sociobiology》1997,41(6):371-380
Tree lizards (Urosaurus ornatus) vary in throat fan (dewlap) color. Earlier, we described five dewlap types (Orange, Orange-Blue, Yellow, Yellow-Blue, and
Blue), and reported that only males had blue in the dewlap and that presence or absence of a discrete blue patch was correlated
with male alternative reproductive phenotypes in a central Arizona population. Here, with a modified scheme characterizing
two dewlap elements, background color (orange, yellow, blue) and blue patch occurrence, we assessed: (1) sexual, annual, and
geographic variation in the frequencies of dewlap elements; (2) simple habitat correlates; and (3) the effects of laboratory
rearing regime on dewlap type. Within a population, frequencies of males and females expressing orange or yellow backgrounds
did not differ, suggesting that control of background is similar in the sexes. Within several populations, frequencies of
the dewlap elements did not differ across years (and probably generations), indicating that phenotype frequencies are relatively
stable. Among five populations frequencies of background colors varied, as did frequencies of male types (blue patch present
or absent). Dewlap frequencies did not correlate with habitat (boulders or mesquite trees), although few populations were
sampled. In male and female offspring reared from eggs to sexual maturity in a common-garden laboratory study, background
color frequencies in both sexes and blue patch frequencies in males differed among offspring from different populations. Offspring
frequencies matched respective parental population frequencies. Results suggest that among-population variation in frequencies
of the two dewlap elements are mediated by differences in genetics, in maternal effects, or both. Thus, differences in male
behavior functionally linked to the blue patch also may be controlled by genetic or maternal effects.
Received: 17 January 1997 / Accepted after revision: 30 August 1997 相似文献
654.
655.
Nest Predators and Fragmentation: a Review and Meta-Analysis 总被引:14,自引:0,他引:14
Anna D. Chalfoun ‡ Frank R. Thompson III † Mary J. Ratnaswamy§ 《Conservation biology》2002,16(2):306-318
656.
Japanese scallop (Patinopectin yessoensis Jay) larvae grew faster and were larger after 18 d when fed a diet of high-light(HL)-grown Chaetoceros simplex or HL Pavlova lutheri relative to diets of the same phytoplankton species grown at low light (LL). When provided as saturating rations to larval scallop, these diets could be ranked: HL C. simplex>LL C. simplex>HL P. lutheri>LL P. lutheri. In both phytoplankton species, HL-grown cells contained more of the short-chain saturated fatty acid (FA), 16:0 than LL-grown cells. Scallop growth rates were a significant function of the amounts (mg g-1 dry wt) and the proportions (as percentage of total FAs) of the FAs 14:0 and 14:0+16:0 (total saturated FAs) in their diet. The proximate biochemical composition of HL- versus LL-grown phytoplankton showed no significant differences in protein, total lipid, carbon, carbohydrate or nitrogen per cell which were consistently associated with the greater nutritional value of HL cells. In spite of this high variability in proximate composition, the larval growth rate was a significant function of the average carbon content, nitrogen content and cell volume of the phytoplankton cells. Increased amounts of the essential polyunsaturated FAs 20:5 3 and 22:6 3 in the phytoplankton were negatively correlated with larval scallop growth rates. Thus HL-grown phytoplankton cells were nutritionally superior to LL-grown cells. This nutritional superiority seems to be determined by the fatty acid composition of the cells which, in turn, is controlled by variation in irradiance. The general tendency of predator FA profiles to resemble that of their prey was not observed in larvae fed P. lutheri. The much greater amounts of 18:4 3, 20:5 3, and 22:6 3 FA in P. lutheri relative to C. simplex were not evident in the scallop larvae fed these cells. 相似文献
657.
Development of rapid ammonium uptake during starvation of batch and chemostat cultures of the marine diatom Thalassiosira pseudonana 总被引:1,自引:0,他引:1
Cell nitrogen quotas and uptake rates following ammonium additions were measured during ammonium-limited growth transients obtained by starving batch and chemostat cultures of Thalassiosira pseudonana (Clone 3 H). During starvation, cell quotas decreased by more than 50% in batch cultures. In chemostat cultures, the drop in cell quota during starvation decreased with dilution rate, from more than 50% at 1.45 d-1, to less than 10% at 0.22 d-1. Minimal levels of 3 to 4×10-2 pg-at. N cell-1 were reached after 24 h starvation in both batch and chemostat cultures. Uptake rates over the first minute of perturbation experiments were 3 times the long-term (10 to 30 min) rates. In batch cultures, specific uptake rates increased from 4 d-1 to 20 d-1 after 24 h starvation. Uptake rates per cell were independent of starvation time and dilution rate in chemostat cultures, but lower in non-starved batch cultures. The implications of these data for models of phytoplankton growth are discussed: the data support models which predict a depression in average growth rates when diatoms encounter microscale patches in oligotrophic environments. 相似文献
658.
Mary Lou Thompson Lawrence H. Cox Paul D. Sampson David C. Caccia 《Environmental and Ecological Statistics》2002,9(4):321-339
Environmental regulatory standards are intended to protect human health and environmental welfare. Current standards are based on scientific and policy considerations but appear to lack rigorous statistical foundations and may have unintended regulatory consequences. We examine current and proposed U.S. environmental regulatory standards for ozone from the standpoint of their formulation and performance within a statistical hypothesis testing framework. We illustrate that the standards can be regarded as representing constraints on a percentile of the ozone distribution, where the percentile involved depends on the defined length of ozone season and the constraint is stricter in regions with greater variability. A hypothesis testing framework allows consideration of error rates (probability of false declaration of violation and compliance) and we show that the existing statistics on which the standards are based can be improved upon in terms of bias and variance. Our analyses also raise issues relating to network design and the possibilities of defining a regionally based standard that acknowledges and accounts for spatial and temporal variability in the ozone distribution. 相似文献
659.
The ecological constraints model predicts that daily travel distance and home range size of social animals will increase as group size increases in order to meet the dietary needs of additional group members. This theory has been supported more predominantly by studies of frugivorous primate species than by studies of folivorous species. We examined the ranging patterns of mountain gorillas in Bwindi Impenetrable National Park, Uganda, who include both herbaceous vegetation and fruit in their diet, to determine how ecological, behavioral, and social parameters influence movement patterns. Data were collected from three groups of gorillas with overlapping home ranges at a low-altitude location (1,450–1,800 m) and one group at a high-altitude location (2,100–2,500 m) in Bwindi from September 2001 to August 2002. We analyzed daily travel distance and home range size in relation to group size, while also considering patterns of frugivory, rainfall, and location (proxy for food availability) within the park. Both daily travel distance and home range size were positively related to group size. In addition, the degree of frugivory positively influenced daily travel distance and home range size, while rainfall negatively influenced daily travel distance only. Finally, groups at the low-altitude location, with higher fruit availability, traveled less than the group at the high-altitude location. These results demonstrate that mountain gorillas in Bwindi provide support for the ecological constraints model, but further studies are needed to determine how fine-scale spatial and temporal availability of food resources influence movement patterns. Ranging patterns of Bwindi gorillas are compared to those observed in other gorilla populations in the context of the ecological constraints model.Communicated by D. Watts 相似文献
660.
Theoretical considerations implicate food availability and intrusion pressure as important determinants of territory size, but empirical studies have led to contradictory conclusions about cause-and-effect relationships among these three variables. To investigate this problem, we provided patches of electronically controlled artificial flowers, which were defended by male Calypte anna. Food availability was experimentally manipulated, and intrusion rate and territory size were calculated from behavioral observations of the territory owner. Changes in both food availability and intrusion rate were found to be significantly correlated with changes in territory size under certain conditions. Intrusion rate, which was influenced by food availability, was negatively associated with territory size so long as food availability was high. This association persisted even after possible effects of food availability were controlled statistically. Food availability was negatively correlated with territory size only when intrusion rates were high and after owners had been defending territories for 3 days. As food availability and intrusion rate increased, owners increasingly restricted their defense to the patch itself; partial regressions revealed a significant association for intrusion rate but not food availability. When intrusion rate was low and food availability varied from low to high levels, no relationship was observed between food availability and territory size, apparently because of opposing influences of food abundance on territory size.
Correspondence to: P.W. Ewald 相似文献