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δ13C was used to identify seasonal variations in the importance of autochthonous and allochthonous sources of productivity for
fish communities in intermittently connected estuarine areas of Australia’s dry tropics. A total of 224 fish from 38 species
were collected from six intermittently connected estuarine pools, three in central Queensland (two dominated by C3 forest and one by C4 pasture) and three in north Queensland (one dominated by C3 and two by C4 vegetation). Samples were collected before and after the wet season. Fish collected in the two forested areas in central
Queensland had the lowest δ13C, suggesting a greater incorporation of C3 terrestrial material. A seasonal variation in δ13C was also detected for these areas, with mean δ13C varying from −20 to −23‰ from the pre- to the post-wet season, indicating a greater incorporation of terrestrial carbon
after the wet season. Negative seasonal shifts in fish δ13C were also present at the pasture site, suggesting a greater dependence on carbon of riparian vegetation (C3
Juncus sp.) in the post-wet season. In north Queensland, terrestrial carbon seemed to be incorporated by fish in the two C4 areas, as δ13C of most species shifted towards slightly heavier values in the post-wet season. A two-source, one-isotope mixing model also
indicated a greater incorporation of carbon of terrestrial origin in the post-wet season. However, no seasonal differences
in δ13C were detected for fish from the forested area of north Queensland. Overall, hydrologic connectivity seemed to be a key factor
in regulating the ultimate sources of carbon in these areas. It is therefore important to preserve the surrounding habitats
and to maintain the hydrologic regimes as close to natural conditions as possible, for the conservation of the ecological
functioning of these areas. 相似文献
114.
Response patterns in adult forest trees to chronic ozone stress: identification of variations and consistencies 总被引:1,自引:0,他引:1
Nunn AJ Reiter IM Häberle KH Langebartels C Bahnweg G Pretzsch H Sandermann H Matyssek R 《Environmental pollution (Barking, Essex : 1987)》2005,136(3):365-369
The responsiveness of adult beech and spruce trees to chronic O(3) stress was studied at a free-air O(3) exposure experiment in Freising/Germany. Over three growing seasons, gas exchange characteristics, biochemical parameters, macroscopic O(3) injury and the phenology of leaf organs were investigated, along with assessments of branch and stem growth as indications of tree performance. To assess response pattern to chronic O(3) stress in adult forest trees, we introduce a new evaluation approach, which provides a comprehensive, readily accomplishable overview across several tree-internal scaling levels, different canopy regions and growing seasons. This new approach, based on a three-grade colour coding, combines statistical analysis and the proficient ability of the "human eye" in pattern recognition. 相似文献
115.
Hilda Granda Suzana Gispert Gisela Martinez Manuel Gomez Raul Ferreira Teresa Collazo Carlos Magariño Luis Heredero 《黑龙江环境通报》1994,14(8):659-662
A nationwide programme for the prevention of sickle cell (SS and SC) disorders was initiated in Cuba in 1983. Couples at risk were identified by screening pregnant women and the partners of those who carry an abnormal haemoglobin, followed by genetic counselling and the offer of prenatal diagnosis. Prenatal diagnosis was performed in one laboratory, which had carried out 1068 prenatal tests for Hb SS and SC disorders by the end of 1992. The centralization of the service has permitted rapid identification and resolution of problems. 相似文献
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