共查询到20条相似文献，搜索用时 78 毫秒
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During their spring migration, Atlantic herring (Clupea harengus) populations in the Baltic Sea rely on shallow transitional waters, such as estuaries, bays, and lagoons for spawning. Such inshore spawning grounds are ecologically important by providing suitable substrates for demersal egg deposition. These habitats are often highly impacted by multiple anthropogenic threats. Decades of eutrophication have caused a decline in depth distribution of submerged aquatic vegetation, the main herring spawning substrate in the Baltic Sea. Nowadays, spawning beds are limited to the shallow littoral zone (≤3 m depth). Accordingly, macrophytes are increasingly exposed to mechanic forcing due to storm-induced wave action. Generally, reproductive success and year class strength of the Western Baltic herring population is strongly determined by the survival of early life stages such as eggs and larvae in local nursery areas. However, explicit mechanisms by which local stressors might affect overall recruitment are currently not well understood. Hypothesizing that aquatic vegetation limited by water depth causes high herring egg mortality due to increased exposure to storm-induced hydrodynamics, we performed a combination of field studies investigating the impact of storm events on herring egg loss. Results of an egg loss experiment revealed a total egg loss of 29% in one single spawning bed during a storm event within the spawning season and the quantification of eggs attached to macrophyte litter on the shoreline emphasize the potential for regional weather extremes such as storm events to act as influential stressors for herring reproduction. 相似文献
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Mark J. Brush 《Estuaries and Coasts》2014,37(1):1-23
The availability of suspended sediments will be a dominant factor influencing the stability of tidal wetlands as sea levels rise. Watershed-derived sediments are a critical source of material supporting accretion in many tidal wetlands, and recent declines in wetland extent in several large river delta systems have been attributed in part to declines in sediment delivery. Little attention has been given, however, to changes in sediment supply outside of large river deltas. In this study, significant declines in suspended sediment concentrations (SSCs) over time were observed for 25 of 61 rivers examined that drain to the East and Gulf Coasts of the USA. Declines in fluvial SSC were significantly correlated with increasing water retention behind dams, indicating that human activities play a role in declining sediment delivery. There was a regional pattern to changes in fluvial sediment, and declines in SSCs were also significantly related to rates of relative sea level rise (RSLR) along the coast, such that wetlands experiencing greater RSLR also tend to be receiving less fluvial sediment. Tidal wetlands in the Mid-Atlantic, Mississippi River Delta, and Texas Gulf especially may become increasingly vulnerable due to rapid RSLR and reductions in sediment. These results also indicate that past rates of marsh accretion may not be indicative of potential future accretion due to changes in sediment availability. Declining watershed sediment delivery to the coastal zone will limit the ability of tidal marshes to keep pace with rising sea levels in some coastal systems. 相似文献
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联合国教科文组织地面沉降工作组（UNESCO Working Group on Land Subsidence）前主席Dr.Arnold Ivan Johnson于2011年8月31日在美国丹佛去世。 相似文献
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Jef Caers 《Mathematical Geosciences》2011,43(4):503-504
Association Announcement
Dr. Lawrence Drew—International Association for Mathematical Geosciences Krumbein Medalist 2010 相似文献10.
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C.I.P.W.标准矿物计算法,是岩浆岩化学成份计算方法中应用较广的一种。该方法计算的内容比较庞杂,在对大量岩石样品进行计算时,工作量很大,且容易出错。采用便于地质工作者随身携带的袖珍计算机处理,不仅迅速准确,而且方便可靠。 相似文献
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R.J.E.布朗博士是加拿大著名的冻土学家,在国际冻土学界享有盛名,是我国冻土科学工作者的好朋友。两年前的1980年11月,癌症夺去了他的生命,结识他的中国朋友无不感到悲痛,他的逝世对冻土科学的发展是莫大的损失。 相似文献
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Г.Е.РЯБУХИН 《地质学报》1958,37(3)
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根据模型试验资料,提出由静力触探比贯入阻力Ps划分砂土密实度的界限值,为利用静力触探判定砂土密实度提供依据。 相似文献
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