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11.
While there are numerous reports of predator-induced morphological defenses for freshwater zooplankton, freshwater larvae, and benthic marine animals, a literature search revealed no reports of predator-induced morphological defenses for marine zooplankton. Rarity of predator-induced morphological defenses in marine zooplankton would imply a difference in predation risks compared to those experienced by freshwater organisms and benthic marine adults, whereas the presence of such plasticity in defenses would imply that risks are modified by developmental responses. This study reports a predator-induced change in defenses and vulnerability of a marine planktonic larva. Specifically, when reared in the presence of zoea larvae of Cancer spp., veliger larvae of the intertidal snail Littorina scutulata developed significantly smaller shell apertures and rounder shells than did cohort veligers reared in the absence of predator cues. Pairwise predation trials demonstrated that veligers reared with caged zoeas throughout development had greater survival than predator-naive veligers during short-term exposure to zoeas. The development of predator-induced morphological defenses by some marine larvae introduces a range of testable hypotheses on developmental plasticity that reduces vulnerability of planktonic larvae and other marine zooplankton to predators. 相似文献
12.
Hedman CJ Krick WR Karner Perkins DA Harrahy EA Sonzogni WC 《Journal of environmental quality》2008,37(5):1817-1824
The presence and levels of the cyanobacterial toxins microcystin-LR, anatoxin-a, and cylindrospermopsin were measured in various Wisconsin waters where algal nuisance or bloom conditions were noted. Out of 74 samples analyzed, 36 had detectable levels of microcystin-LR (49%), and four had detectable levels of anatoxin-a (5%). Cylindrospermopsin, the toxin produced by Cylindrospermopsis (a warm water species that has been moving its range northward, including to Wisconsin), was not detected in the field samples tested. Concentrations of microcystin-LR ranged from 1.2 to 7600 microg L(-1). Anatoxin-a ranged from 0.68 to 1750 microg L(-1), which is the highest concentration reported from around the world. Cyanobacterial toxins, because of their high potency, deserve continued scrutiny by resource managers and public health officials responsible for recreational waters. 相似文献
13.
Previous experimental studies of participation have typically examined its motivational (especially commitment) benefits. These studies showed that these benefits are neither large nor consistent. The present study focused on the cognitive benefits of participation in decision making (pdm) and on the role of a different motivational mediator, self-efficacy. Unlike previous research which claimed to study the cognitive (informational) effects of participation, the present experiment: (a) allowed the information concerning task strategies to emerge from group discussion rather than being manipulated by the experimenter; (b) measured the actual strategies that were developed and used by subjects in the pdm condition; and (c) measured self-efficacy which was associated with the discovery and use of these strategies. It was found that the strategies developed by the subjects and their self-efficacy completely mediated the effect of participation on performance. Further, participation in setting goals, consistent with previous studies, did not affect performance but did affect self-efficacy. 相似文献
14.
We present a family who sought prenatal diagnosis in order to bear a healthy child to serve as an HLA–identical bone marrow donor for their son affected with Wiskott–Aldrich syndrome. They intended to abort HLA-incompatible fetuses who would have been unsuitable bone marrow donors. This case led us to conclude that prenatal diagnosis should not be used to benefit a third party or facilitate the conception or abortion of a fetus for the purpose of generating an organ for transplantation. The limits of parental autonomy and physician responsibility are discussed. 相似文献
15.
Recent attention has focused on resource management initiatives at the watershed scale with emphasis on collaborative, locally driven, and decentralized institutional arrangements. Existing literature on limited selections of well-established watershed-based organizations has provided valuable insights. The current research extends this focus by including a broad survey of watershed organizations from across the United States as a means to estimate a national portrait. Organizational characteristics include year of formation, membership size and composition, budget, guiding principles, and mechanisms of decision-making. These characteristics and the issue concerns of organizations are expected to vary with respect to location. Because this research focuses on organizations that are place based and stakeholder driven, the forces driving them are expected to differ across regions of the country. On this basis of location, we suggest basic elements for a regional assessment of watershed organizations to channel future research and to better approximate the organizational dynamics, issue concerns, and information needs unique to organizations across the country. At the broadest level, the identification of regional patterns or organizational similarities may facilitate the linkage among organizations to coordinate their actions at the much broader river basin or ecosystem scale. 相似文献
16.
The authors explored the process of evaluating contextual performance in the context of a politically charged atmosphere. They hypothesized that the negative relationship between perceptions of organizational politics and contextual performance is weaker among workers high in three of the Big Five model of personality dimensions—agreeableness, extraversion, and conscientiousness. Data were collected from a matched sample of 540 supervisors and subordinates employed in the private sector. Results indicated that the interaction of politics and the personality dimension of agreeableness explained a significant incremental amount of variance in the interpersonal facilitation facet of contextual performance. These findings demonstrate the need to consider both the situation and the person as antecedents of contextual performance. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
17.
Andrew P. Rees Hermann W. Bange Damian L. Arvalo-Martínez Yuri Artioli Dawn M. Ashby Ian Brown Hanna I. Campen Darren R. Clark Vassilis Kitidis Gennadi Lessin Glen A. Tarran Carol Turley 《Ambio》2022,51(2):398
Human activities are changing the Arctic environment at an unprecedented rate resulting in rapid warming, freshening, sea ice retreat and ocean acidification of the Arctic Ocean. Trace gases such as nitrous oxide (N2O) and methane (CH4) play important roles in both the atmospheric reactivity and radiative budget of the Arctic and thus have a high potential to influence the region’s climate. However, little is known about how these rapid physical and chemical changes will impact the emissions of major climate-relevant trace gases from the Arctic Ocean. The combined consequences of these stressors present a complex combination of environmental changes which might impact on trace gas production and their subsequent release to the Arctic atmosphere. Here we present our current understanding of nitrous oxide and methane cycling in the Arctic Ocean and its relevance for regional and global atmosphere and climate and offer our thoughts on how this might change over coming decades.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01633-8. 相似文献
18.
Clarifying the role of fire in the deciduous forests of eastern North America: reply to Matlack 下载免费PDF全文
19.
The Mediterranean deep-water kelp Laminaria rodriguezii is an endangered species in the Adriatic Sea
20.
Yard EE Gilchrist J Haileyesus T Murphy M Collins C McIlvain N Comstock RD 《Journal of Safety Research》2010,41(6):471-474