盐度对菊黄东方鲀受精卵孵化和仔鱼生长的影响

比较在0、5、10、15、20、25、30(自然海水)、35、40、45、50等11个盐度梯度下,菊黄东方鲀(Takiugu flavidus)的受精卵发育和仔鱼生长情况,测定仔鱼的不投饵存活系数(SAI).结果表明:1)菊黄东方鲀受精卵在盐度0~50范围内均可孵化,最适盐度20~25.盐度(x)与孵化时间(y)呈正相关关系,表达式为:y=0.345 x+141.1,R2=0.956.2)实验盐度范围内,菊黄东方鲀仔鱼SAI值为1.55~30.10.3)在盐度5~45条件下,仔鱼皆可存活,存活率为3%~27%.其中,在10~30盐度下存活率较高,为20%~27%.经15 d的培育,仔鱼平均全长为6.28~7.34 mm.低盐度对菊黄东方鲀仔鱼生长更有利,在15~20盐度条件下,仔鱼生长较好,最终平均全长为7.30~7.34 mm.4)根据SAI值和生长状况,仔鱼生长和存活的适宜生长盐度为10~30,最适盐度范围为15~20.     

中国恐龙蛋研究的历史与现状

本文对我国恐龙蛋研究历史作了简略回顾,大致分为三个研究阶段:形态分类、半自然分类和自然分类阶段.本文根据中国江西赣州晚白垩世南雄组产出的两枚含胚胎恐龙蛋的研究,认为这两枚恐龙蛋处于不同的发育阶段,蛋体形态和蛋壳显微结构表明它们同属于以往在广东发现的瑶屯巨型蛋(Macroolithus yaotunensis),骨骼学研究表明它们可能是黄氏河源龙(Heyuannia huangi)或与其亲缘关系相近的窃蛋龙所产.江西赣州晚白垩世含胚胎恐龙蛋的首次发现标志着我国恐龙蛋研究已进入自然分类阶段.     

兽脚类恐龙研究进展

兽脚类恐龙是恐龙动物中的主要代表类群之一。本文综述了兽脚类恐龙的组成及鉴别特征,并论述了其主要演化趋势,介绍了近年来在辽西地区发现的“带羽毛”兽脚类恐龙及其研究意义。     

热应力对恐龙化石风化损坏的影响研究

由热应力引起的热破裂作用是造成恐龙化石破坏的一个重要因素。在太阳照射条件下,由于受热不均匀及日照的长久往复循环作用,使得化石表面发生热破裂作用,导致化石表面产生裂缝,加速了恐龙化石风化。采用模拟实验的方式,主要针对恐龙化石试件的物理力学受力变形特性进行研究。通过有限差分软件FLAC3D进行数值模拟,揭示日光辐射造成的恐龙化石温度差异分布对化石风化的影响。试验结果表明:恐龙化石不同部位的温度差异,是造成化石内部热应力分布不均匀的重要原因,热应力的不均匀性导致化石发生热破裂,加速了化石风化受损,因此化石保存要尽量放在恒温环境下,避免化石温度往复变化。     

南郑梁山奥陶系与志留系界线附近的沉积特征及沉积环境

陕西南郑梁山地区上奥陶统内海相窄盐度生物化石丰富，以游泳生物为主，底栖生物较少，含笔石化石Ｄｉｐｌｏｇｒａｐｔｕｓｂｏｈｅｍｉｃｕｓ，小型薄壳腕足类和善于游泳的Ｄａｌｍａｎｉｔｉｎａ；粉细砂岩中可见丘状交错层理；沉积环境为深水陆棚。下志留统含大量单调的浮游笔石化石，产笔石Ｇｌｙｐ－ｔｏｇｒａｐｔｕｓｌｕｎｇｍａｅｎｓｉｓ；未见底栖生物化石，底部夹放射虫硅质岩；岩层横向上稳定；沉积环境为深水陆棚与大陆坡过渡带。     

热应力对内含裂隙恐龙化石的影响研究

为深入研究热应力对内含裂隙的恐龙化石的影响,该文模拟10℃,20℃,30℃,40℃,50℃及60℃六种不同温差情形,通过ABAQUS数值模拟软件,揭示地表温度与日照照射在化石表面的温度形成的温差对恐龙化石的影响机制。试验结果表明:在不同温差作用下,热应力的分布主要集中在恐龙化石裂隙的右上角位置,而右下角则没有出现明显的热应力,热应力分布出现不均匀现象,容易诱发恐龙化石开裂,加快风化速度。热应力值随着温差的增大而呈近似线性关系增大。在同一温差、不同轴压条件下,热应力值的增长率呈下降趋势,最大增长率为93.54%,形成于温差为10℃、轴压由0.04MPa变为0.12MPa阶段;热应力值最小增长率为17.46%,形成于温差为60℃、轴压由0.12MPa变为0.20MPa阶段。开裂角随着温差变大而增大,在温差为40℃时,开裂角达51.5°最大值;当温差继续增大时,开裂角呈减小趋势。恐龙化石的极限载荷随着温差的增大而呈下降趋势。其中,温差为10℃时,其极限载荷为最大值2.5MPa,而当温差为60℃时,其极限载荷为最小值1.5MPa。     

A Preliminary Study on the Red Beds in the Northern Heyuan Basin, Guangdong Province, China

The red beds of the northern Heyuan Basin （Guangdong Province, China） are more than 4,000 m thick. Based on the lithological characters, in ascending order these beds are divided into the Dafeng Formation, Zhutian Formation, and Zhenshui Formation of the Nanxiong Group, Shanghu Formation and Danxia Formation. The Nanxiong Group with relatively mature coarse clastic rocks attains about 2940 m in thickness. The Dafeng Formation is 837 m thick, consisting of conglomerates and sandy conglomerates; the Zhutian Formation, which is 1.200 m thick, consists of purplish red sandstone with gravels, poorly sorted sandstone, feldspathic quartzose sandstone banded granular conglomerate, siltstone, and sandy mudstone. The Zhutian Formation is rich in calcareous concretions. Heyuannia （Oviraptoridae） and turtle fossils were found in this formation. The Zhenshui Formation deposited to a thickness of 900 m consists of coarse sediments, including granular conglomerate, and gravelly sandstone with well developed cross-beddings; the Shanghu Formation, which is 820 m thick, consists of purplish red granular conglomerate coarse sandstone intercalated with fine si~tstone; the Danxia Formation characterized by the Danxia ~andform is composed of coarse c~astic gravels and sandy gravels. The lower part of the Nanxiong Group whence dinosaur eggs and derived oviraptorosaurs come, belongs to the Late Cretaceous. No fossils are found in the Shanghu Formation or the Danxia Formation, but their stratigraphic order of superposition on the Nanxiong Group clearly shows their younger age.     

兰州-民和盆地恐龙足印化石形成的地质特征

兰州—民和盆地恐龙足印化石赋存和保存的特征表明:该区早白垩世中期的构造稳定,盆地扩张时期出现的湖沼环境是恐龙足印化石形成的最佳时期和场所,形成之后的湖进序列是良好的覆盖层。     

A potential source of recruitment of Acartia pacifica nauplii: viable benthic resting eggs

Many estuarine and coastal planktonic copepods depend on the hatching of benthic resting eggs for recruitment of nauplii to the water column population. The distribution and abundance of viable resting eggs of Acartia pacifica in the Xiamen Bay were determined by the presence of nauplii in the laboratory. The number of viable eggs varied temporally and spatially. The maximum number (9.2×10⁴m^-2) of viable eggs was in summer. In spring the average abundance of viable eggs was 5.6×10⁴ m^-2. The abundances of viable eggs in fall and winter were similar, respectively 2.7×10⁴ and 3.3×10⁴ m^-2, which were the lowest in the year. The numbers of viable eggs inside the stations of the Xiamen Bay were higher than those outside the stations. The viable eggs were found at all depths (0～10 cm),although not in every station. The maximin number did not necessarily occur in the uppermost centimeter of the sediments but often occurred several centimeters below the water-sediment interface. The accumulation of viable eggs in the seabed of a subtropical bay constitutes a potential source of recruitment of nauplii into the pelagic population.     

Estimation of spawning habitats of market squid (Doryteuthis opalescens) from field surveys of eggs off Central and Southern California

Like many other loliginid squid, Doryteuthis (Loligo) opalescens deposits egg cases on the ocean floor. Depending upon temperature, egg cases may persist for 5–12 weeks before the paralarvae hatch. Because of this relatively long duration and squid’s pelagic life history, egg cases provide a practical life stage to survey. During 2001–2002, squid egg beds in Monterey Bay, Carmel Bay, and around the California Channel Islands were surveyed using a remotely operated vehicle with the goal of delineating the habitat of egg beds that are spawned during active commercial fishing. Egg cases were highly aggregated and densities reached 1338 capsules m⁻². Squid eggs were significantly shallower in Central California. Egg cases occurred between 20 and 93 m around the Channel Islands, and in Central California they were between 13 and 61 m. The temperatures in both regions were similar (10–12 °C), with some eggs in Southern California found up to 14.4 °C. Ninety-five percent of eggs were found on sand, suggesting that temperature and substrate are stronger behavioral cues than depth to stimulate spawning. Suitable spawning habitat was defined by three criteria: sandy benthic substrate, temperatures between 10 and 14.4 °C, and depths between 20 and 70 m when the first two criteria hold. Additionally, within this defined area, oxygen concentration is quantified. The greatest commercial landings of market squid occur in both Central and Southern California during a time of year when water temperatures of 10–12 °C are prevalent in the 20–70 m depth range.