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Abstract A review of the chondrichthyan and osteichthyan fish fossils found in Japan is provided in the form of a series of tabular compilations covering the Late Mesozoic and Cenozoic Era. On the basis of this compilation, considerable changes are recognized in the fish faunas over a period of time. At the end of the Cretaceous Period a number of cartilaginous fishes disappeared. From the Oligocene to the Miocene, modern sharks including the family Carcharhinidae increased, whereas the Hexanchidae and Lamnidae declined. Most Miocene teleostean fishes differ from the Recent congeners at the species level. 相似文献
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井下“落鱼”打捞工期的不确定性导致施工成本不可控,制定合理的打捞经济决策点至关重要。本文以渤海油田某“落鱼”井为例,不打捞“落鱼”则需在“落鱼”上部进行套管开窗侧钻,为两开井身结构,打捞“落鱼”则在套管鞋下裸眼侧钻,为一开井身结构,放弃打捞或者盲目打捞都并非最经济的方案。通过对冲砂打捞工期进行量化,提出了经济工期和决策工期,通过现场尝试冲砂打捞作业,在决策工期内分析其作业难度,并判断是否能够在经济工期内完成作业,最大程度降低总体实施成本,提高油田开发经济效益。渤海油田A井应用该决策方法,共节约费用近420万元。提出的“落鱼”井打捞经济工期和决策工期计算方法具有一定的推广价值。 相似文献
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《Marine pollution bulletin》2014,78(1-2):43-50
Many cultured pearl farms are located in areas of the Pacific that have thriving, highly diverse fish communities but the impacts of farming on these communities are poorly understood. We studied the effects of pearl oyster farming on shore fish abundance and diversity in the lagoon of Ahe, French Polynesia by adapting roving diver census methods to the coral reef bommies of the lagoon and compared 16 sites with high pearl farming impact to others with no direct impact. Pearl farming has a slightly positive effect on reef fish abundance (N) and no significant impact on fish diversity (H) or community composition. This is important when considering the ecological sustainability of pearl farming in French Polynesia and suggests that a potential synergy between pearl farms and marine conservation should be further explored. 相似文献
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《Limnologica》2014
One of the potential impacts of invasive gobies on native fish fauna is predation on eggs and fry. Therefore, the diet composition of two invading gobiid species, the tubenose goby Proterorhinus semilunaris and round goby Neogobius melanostomus, was examined in the Dyje river system (Danube basin, Central Europe) during the 2011 reproductive season to ascertain the extent of gobiid predation on heterospecific and conspecific eggs and juveniles. Consumption of fish eggs and juveniles by invading gobies was very low. The diets of both species consisted largely of benthic macroinvertebrates, and particularly insect larvae. These results indicate that invading gobies in the Dyje river system are likely to impact native fish fauna more through competitive effects than through direct predation on eggs and juveniles. 相似文献
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