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云南罗平中三叠世安尼期生物群的发现及其意义 总被引：15，自引：0，他引：15
本文介绍了云南罗平地区新发现的罗平生物群的产出层位、生物面貌、保存特征、古地理位置及其研究意义。该生物群产于关岭组二段薄层泥晶灰岩中,地层对比和化石鉴定表明其时代为中三叠世安尼期,以鱼类为主,伴生有爬行类、两栖类（？）、棘皮动物、节肢动物（甲壳类、昆虫等）、双壳类、腹足类以及植物化石;化石保存完好,分布广泛,埋藏方式独特。罗平生物群无论在丰度、分异度及化石保存上都极为罕见和独特,对研究埋藏学、古生态学、古地理以及三叠纪海洋生物尤其是海生爬行类都具有极为重要的意义。 相似文献
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朱龙 《广东海洋大学学报》1999,(1)
１９９３年７月至１９９８年８月对蓬莱沿海定置网渔获的鱼类进行初步调查,结果表明,蓬莱沿海鱼类共有１３７种,分别隶属于５９科１０８属。根据其适温类型可分为暖水性鱼类３４种,占总数的２４．８２％;暖温性鱼类８３种,占总数的６０．５８％;冷温性鱼类２０种,占总数的１４．６０％。根据食性类型,可分为３类,其中游泳动物食性的鱼类３６种,占总数的２６．２８％;浮游动物食性有２２种,占总数的１６．０６％;底栖动物食性７９种,占总数的５７．６６％．从栖息生境的多样性来看,可分为中上层鱼类３８种,占总数的２７．７４％;近底层鱼类２５种,占总数的１８．２５％;底层鱼类６４种,占总数的４６．７１％;岩礁性鱼类１０种,占总数的７．３０％。并就渔业开发与保护提出了建议。 相似文献
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采用底层拖网法,用渔获率作为鱼类资源数量分布的指标,进行了杭州湾调查海域2012年5月(春季)、10月(秋季)2个季节的鱼类种类组成、区系特点、数量分布等研究。结果表明:(1)杭州湾海域春、秋两季共获得并鉴定出的鱼类有31种,隶属于9目15科,其中以石首鱼科和■虎鱼科的种类为最多,各有5种,分别占总种数的16.7%;鳀科鱼类次之,有4种,占总种数的13.3%,优势种有睛尾蝌蚪■虎鱼、龙头鱼、刀鲚、棘头梅童鱼;(2)根据鱼类适温性可将该海域的鱼类分为暖水性、暖温性和冷温性3种适温类型,以暖温性种类为主,暖水性种类次之,而冷温性种类极少,仅有1种;(3)根据其生态习性,可分为河口性、沿岸性和近海性3种生态类群;(4)渔获数量分布规律是春季在调查海域的内侧或者说中西部较高,而湾口较低,秋季则正好相反。 相似文献
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A new Upper Cretaceous vertebrate tracksite has been discovered at Tamajón (Iberian Ranges, Guadalajara, Spain). The track level is a relatively smooth and slightly undulating sandy ferruginous crust, corresponding to an erosive surface at the base of a small meandering channel. It is incised into the underlying planar cross-bedded sandstones of coastal bars located at the middle-upper part of the Utrillas Formation (middle-upper Cenomanian). The site shows an extraordinary concentration of vertebrate tracks, among which numerous sets of two to five isolated digit impressions (“swim tracks”) and, at least, two trackways referred to crocodyliforms, and a single tridactyl footprint probably produced by a theropod dinosaur can be recognized. There are also several long traces (epichnial grooves) revealing sharp direction changes (up to 90°) which seem to be fish fin traces (Undichna unisulca), although crocodyliforms (tail marks) and/or fish invertebrates cannot be rejected as possible tracemakers. Some crocodyliform tracks reveal a thin raised rim, due to the displacement of the sediment by the pressure produced by the feet. Several impressions are moderately deformed by small sediment slides, only preserving their deepest part (claw marks). This is clearly indicative of a soft substrate with a high degree of plasticity and water content at the time of the track registration. Nevertheless, the sediment was hard enough to preserve manus and pes print morphologies and also possible crocodyliform tail and/or fish fin traces. Small rhizoliths can also be recognized and may belong to herbaceous wetland vegetation. The morphology of the palaeochannel, the sedimentary context and the track preservation seem to indicate that the tracks were impressed in a shallow channel located near the coast, under wet conditions and in different moments of time. This discovery represents the first occurrence of vertebrate ichnites in the Utrillas Formation, a stratigraphic unit where osteological and ichnological remains are relatively scarce, and it confirms that some crocodyliforms lived in near coast channels during the deposition of this unit. 相似文献
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Abstract. The fish assemblages of a strictly protected area and of a neighbouring fished area, located off a Mediterranean urbanized coast (Carry-le-Rouet, France), were compared in order to select the most evident, constant, and easily recorded indices of the 'reserve effect'. Visual censusing was repeated simultaneously at both sites eight time a year during 3 years along four permanent transects layed on shallow rocky bottoms (9–14 m). Overall species richness was 16% higher in the reserve, but differences in average instantaneous richness were only marginally significant. The most contrasting results were shown by the occurrence frequency, abundance, and demographic structure of two types of target species. The type A target species group comprises 16 large meso- and macrocarnivores particularly threatened by spearfishing, including the common nectobenthic sparids Diplodus spp. Type B target species are represented by two small territorial fishes particularly impacted by angling: the serranid Serranus cabrilla and the terminal phase males of the labrid Coris julis . The size structure of Diplodus spp., S. cabrilla , and C.julis subpopulations strongly argues for the role of protected areas as a reservoir of large spawners. Fishing pressure is assumed to modify the social conditions of the C. julis local populations and to induce earlier sex change. 相似文献
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Organotins, especially tributyltins (TBT) are highly toxic to many marine organisms. These compounds are introduced in marine waters by ship trafficking, ship scrapping activities, as antifouling compounds and sewage disposal. Marine fishes, crustaceans and molluscans are easily prone to organotins contamination. In view of this, a baseline monitoring study was conducted in order to establish the levels of organotins in edible marine fishes, bivalves, shrimps, squids and crabs collected from Mumbai, Goa and Karwar on the west coast of India. At these locations average organotin concentration found in fishes, clams, shrimps, squids and crabs was 108, 852, 179, 70 and 89 ng Sn g−1 dw, respectively. In all the samples butyltins dominated over phenyltins. The levels of organotins suggest that all the organisms were contaminated with organotins and their consumption may pose health problems to humans. 相似文献
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黄海鱼类食物网的研究 总被引：80，自引：1，他引：80
于1985年3月—1986年10月和1988年5月间,对黄海海域40科69属80种鱼的食性及其相互关系进行了较系统地调查、分析。结果表明:1.黄海鱼类饵料分为4个生态类型;2.黄海鱼类摄食有明显的季节变化;3.黄海鱼类基本属于第二—第四营养级;4.日本鳀、脊尾褐虾、太平洋磷虾等优势饵料生物在黄海鱼类食物网中起着举足轻重的作用;5.黄海多数鱼类间的食物竞争关系基本是协调的。 相似文献
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在1979年7月—1981年11月间,在长江口采集到24尾体长为32—214mm的东方鲀属鱼类标本,经形态特征和解剖比较研究后,认为是一新种,定名为晕环东方纯Takifugu coronoidus Ni et Li nov. sp.。正副模式标本存放于中国水产科学研究院东海水产研究所和中科院海洋研究所。 相似文献
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东山湾鱼类食物网研究 总被引：17，自引：1，他引：17
本文分析了东山湾８５种经济鱼类的食物关系，结果表明，东山湾鱼类的食性类型可分为：浮游生物食性；底栖生物食性；游泳动物食性；浮游生物和底栖生物食性；底栖生物和游泳动物食性及浮游生物，底栖生物和游泳动物食性等６种，这些鱼类可分为４个营养级：（１）杂食性鱼类；（２）低级肉食性鱼类；（３）中级肉食性鱼类；（４）高级肉食性鱼类，其中低级肉食性鱼类占优势。东山湾 鱼类食物网的能量流动可简要归纳为６种途径，小公 相似文献