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961.
We investigated the fledging probability of oystercatcher, Haematopus ostralegus, chicks as a function of hatching order, brood size, territory quality and food availability. Sibling dominance was related
to the hatching order in both low- (’leapfrogs’) and high-quality (’residents’) territories. Differences in hatchling mass
might have aided the establishment of a dominance hierarchy, since breeders produced small late eggs and hatchlings. These
mass differences were most pronounced in leapfrogs, and in large broods in years with lower food availability (’poor’ years).
Late hatchlings fledged less often and with lower body masses compared to early hatchlings in all situations. Leapfrogs produced
smaller broods and hatched their broods more asynchronously in poor years than leapfrogs breeding in years with more available
food (’good’ years) and residents breeding in both poor and good years. Large brood sizes resulted in lower survival of hatchlings
in poor years. These results favour the ’brood reduction’ hypothesis. However, contrary to the expectations of this hypothesis,
hatching order also affected fledging success in residents. Moreover, large brood size resulted in higher survival of hatchlings
in good years, particularly in residents. Thus, although large broods experienced losses due to sibling competition in some
years, they nevertheless consistently produced more fledglings per brood in all years, both as leapfrogs and residents. We
believe this effect is due to parental quality correlating with initial brood size. Most leapfrogs, at best, fledged one chick
successfully each year, losing chicks due to starvation. Nevertheless, leapfrog broods were reduced in size after hatching
significantly less quickly than resident broods. These results suggest that breeders lay and hatch insurance eggs to compensate
for unpredictable losses due to the high predation rates on both nests (ca 50%) and chicks (ca 90%), in accordance with the
’nest failure’ hypothesis.
Received: 14 February 2000 / Revised: 27 September 2000 / Accepted: 10 June 2000 相似文献
962.
J.M.N. van Kasteren M.J.P. Slapak 《Journal of Material Cycles and Waste Management》2001,3(2):114-117
This study is concerned with the influence of additives on the steam gasification of polyvinyl chloride (PVC) waste. Three
types of PVC waste, namely pipe waste, cable waste, and flooring, were tested. The presence of additives proved to have a
profound effect on the carbon-to-gas conversion. Plasticizers and other organic additives caused an increase in carbon-to-gas
conversion. Inorganic additives, especially calcium, caused a decrease in carbon-to-gas conversion, resulting in an overall
decrease in the yield of syngas for all three types of waste. This decrease is probably caused by the deposition of Ca on
the surface of the alumina bed material. In addition, calcium reacts with the HCl formed to give CaCl2. This results in a decrease in the recovery of hydrochloric acid.
Received: July 19, 2000 / Accepted: October 9, 2000 相似文献
963.
964.
Theresa M. Marteau Irma Nippert Sue Hall Caroline Limbert Margaret Reid Martin Bobrow Alan Cameron Martina Cornel Mariet van Diem Bernd Eiben Sixto García-Miñaur Janine Goujard Donna Kirwan Karen McIntosh Peter Soothill Corien Verschuuren-Bemelmans Catherine de Vigan Stephen Walkinshaw Lenore Abramsky Frank Louwen Peter Miny Jürgen Horst 《黑龙江环境通报》2002,22(7):562-566
965.
Management of Wetlands 总被引:1,自引:1,他引:0
966.
Female (SD) rats were fed diets containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) in various concentrations for three months. PCB 153 had no significant effect on the body weight gain when given alone or in combination with TCDD. The increases in relative liver weights were additive. For thymic atrophy no interactive effects became apparent. PCB 153 had no effect on the EROD induction by TCDD. PROD induction by PCB 153 was diminished in the presence of TCDD. The level of TCDD in the liver was decreased by PCB 153. Increasing TCDD dosage led to an increase in PCB 153 levels. 相似文献
967.
Identifying key issues in environmental wetland research using scaling and uncertainty analysis 总被引:1,自引:0,他引:1
Peter van Bodegom Chris Bakker Hugo Denier van der Gon 《Regional Environmental Change》2004,4(2-3):100-106
Quantification of the response of wetlands to environmental change and of climate change to wetland processes, is a pressing, but complex, issue. Findings of widely diverse investigations have to be generalised to identify the key issues and the gaps in knowledge. Two tools for generalisation, scaling and uncertainty analysis, were applied here to two case studies and act as stepping stones for analysis of key issues. The first case study is on methane emissions from wetland rice fields and the second is on the restoration of wet dune slacks. The type of problems encountered depends on the scale at which a process is studied. At the biogeochemical processes scale, knowledge on some key parameters, but especially on interactions between key parameters is limiting. At the vegetation scale, feedbacks between processes become especially important, whereas at even larger scales increasingly stringent approximations of interactions have to be made. Accumulating uncertainties at the landscape scale need careful evaluation. Apart from uncertainties in the approximations and their interactions, those introduced by spatial and temporal variability as well as by different data sources highly influence the accuracy of response estimates, while these last sources of uncertainty are neglected in many studies. Only by explicitly accounting for scaling effects and their resulting uncertainties, the interactions between wetlands and environment can be understood. 相似文献
968.
969.
Beike Leegte Birgit Sikkema-Raddatz Roel Hordijk Inge Davelaar Anneke van der Veen JanMaarten Cobben 《黑龙江环境通报》2001,21(7):550-552
We report a prenatal case of a maternally inherited abnormal chromosome 16, originally interpreted as a pericentric inversion only, but after family studies re-interpreted as a pericentric inversion (16) accompanied by an unbalanced (7;16) translocation. Because of the inversion 16 and an elder son with developmental delay and craniofacial dysmorphic features, in the past karyotyped as 46,XY, the chromosomes 16 of the mother and son were carefully re-examined. Using a whole chromosome 16 paint and sub-telomere probes of 16p and 16q, the karyotype of the mother was shown to be 46,XX,inv(16)(p11.2q23.2).ish t(7;16)(q36;p13.3)inv(16). Subsequently one chromosome 16 of the elder son appeared to be a der(16)t(7;16)(q36;p13.3). This is probably the result of a meiotic crossover between the chromosomes 16 in the mother. The prenatal karyotype was finally interpreted as 46,XY,inv(16)(p11.2q23.2).ish der(16)t(7;16)(q36;p13.3)inv(16). This is the same cytogenetic imbalance as his elder brother: a partial trisomy of chromosome 7 (q36→qter) and a partial monosomy of chromosome 16 (p13.3→pter). Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
970.
Jochem K. H. Spoor Lis van Gastel Fatima Tahib Amanda van Grieken Willem van Weteringen Frank Sterke Ahmet A. Baschat Jena L. Miller Tjeerd H. R. de Jong René M. H. Wijnen Alex E. Eggink Philip L. J. DeKoninck 《黑龙江环境通报》2023,43(3):355-358