Sediments of lakes Rotoroa and Rotoiti,South Island,New Zealand     

E. T. Chittenden  C. W. Childs  R. E. Smidt 《新西兰海洋与淡水研究杂志》2013,47(1):61-76

The chemistry and mineralogy of the sediments of Lakes Rotoroa and Rotoiti, South Island, New Zealand (41° 51 S, 172° 38 E and 41° 50 S, 172° 50 E respectively) , were studied. In general, the cation exchange properties, element concentrations, and mineral compositions of the sediments show little variation between samples from each lake. However, some nutrient concentrations, notably exchangeable calcium, magnesium, and potassium, and total nitrogen and sulphur, are higher in sediments from weed beds than in sediments underlying deeper water; iron and manganese concentrations tend to show the opposite trend. Concentrations of exchangeable calcium and total nitrogen, sulphur, manganese, and iron generally decrease down the sediment profiles from the sediment/water interface. Differences between lakes, notably higher concentrations of illite and of the elements potassium, aluminium, titanium, and zirconium, and lower concentrations of calcium in the sediments of Lake Rotoiti than in those from Lake Rotoroa, are probably due mainly to the different geological settings rather than to differences in the diagenetic processes operating within the lakes. Mineralogical analyses indicate that the lake sediments are derived mainly from the valleys of the major inflow rivers rather than from the slopes at the sides of each lake.  相似文献   

Possible functions of surface structure and size in some planktonic eggs of marine fishes     

D. A. Robertson 《新西兰海洋与淡水研究杂志》2013,47(2):147-153

Chorionic surface sculpturing on the eggs of 7 marine fish species was examined under a scanning electron microscope. The effect of sculpturing on descent rates of 3 of these eggs was experimentally compared with 10 non‐sculptured egg types of different sizes. It is suggested that although in some species sculpturing represents vestigial tendrils, in others sculpturing and increased egg size may relate to ascent rates between the spawning site and the sea surface.  相似文献   

泉州市三个海湾浮性鱼卵和仔稚鱼的种类组成与数量分布特点     

张跃平  洪一川 《台湾海峡》2009,28(3):379-385

本文根据2007年3月至2008年2月期间在泉州地区3个海湾的调查资料，对其浮性鱼卵和仔稚鱼的种类组成与数量分布特点进行初步研究和探讨．结果表明，本调查海域共出现鱼卵和仔稚鱼51种（含未定种），隶属于21科，主要是近岸底层鱼类、近海中上层鱼类和港湾河口型鱼类三个生态类型．各站鱼卵总平均丰度是81．2彬网，仔稚鱼总平均丰度31．0个／网．数量平面分布呈现优势种明显，占总量比例大，不同季节不同海湾差别较大，规律性不强等特点．整体数量上与往年比有下降趋势．  相似文献   

几种理化因子对梅氏新本尼登虫卵发育的影响          下载免费PDF全文

林克冰  何丽斌  周宸 《海洋科学》2008,32(2):1-4

观察在不同的水温、盐度、酸碱度条件下梅氏新本尼登虫(Neobenedenia melleni)卵发育以及毛蚴孵出的变化,以研究理化条件对卵发育的影响。结果表明,18~29℃之间,梅氏新本尼登虫虫卵的发育和孵化速度随温度的升高而加快,水温<18℃或>33℃发育停滞;盐度<13.7虫卵不发育,盐度<22.9或>44.3卵发育停滞在眼点期,盐度居22.9~44.3之间,其改变对虫卵发育没有显著影响;酸碱度变化对虫卵发育没有明显的影响,pH为5.5或9.5时,卵均可正常发育并孵化,但孵化出的纤毛幼虫在pH<6.0或>9.0时,存活时间和活力明显降低。  相似文献   

神奇的球状冰(冰球、冰蛋)     

解飞  卢鹏  程斌  杨倩  李志军 《湖泊科学》2022,34(2):695-698

大量球状冰集聚排列是自然界中较为罕见的现象,一般发生在浅滩、湖岸和河岸处.因球状冰形态特征的特殊性,常被称之为冰球、冰蛋.球状冰的形成与发展受气象、水动力和水滨地形条件等多因素共同控制,且具有一定的时空限制,必须在短时间内多因素协同干预才可能引发冰球集聚.正是凭借"制造"条件的苛刻性导致了冰球集聚现象的罕见,也造成了全球各地冰球出现的位置、形态和数量之间存在差异.已有来自于德国、俄罗斯、芬兰和加拿大等多个国家关于冰球现象的报道,但发生频率极少,约20～ 30年一次.近年来在吉林省的查干湖和四海湖发现了冰蛋现象,但关于球状冰从形成到大量集聚之间的定量研究依然缺少实测数据分析支撑.毫无疑问,来自大自然的神奇现象为科学探索研究提供了更多的动力和乐趣.  相似文献   

胶州湾内纺锤水蚤休眠卵的研究   总被引：5，自引：0，他引：5  

仲学锋  肖贻昌 《海洋科学》1992,16(5):55-59

描述了胶州湾内双刺纺锤水蚤(Acrlia bifilasa)和太平洋纺锤水蚤(A.pacifica)卵的形态,揭示了底泥中休眠卵数量季节变动与种群数量变动的关系,并探讨了温度、盐度、泥覆盖等环境因子对休眠卵孵化率的影响。  相似文献   

Vertical distribution of fish eggs and larvae in the Irish Sea and southern North Sea   总被引：4，自引：1，他引：4  

Conway  D. V. P.; Coombs  S. H.; Smith  C. 《ICES Journal of Marine Science》1997,54(1):136-147

  相似文献   

A potential source of recruitment of Acartia pacifica nauplii: viable benthic resting eggs   总被引：4，自引：0，他引：4  

WANG Guizhong  JIANG Xiaodong  LI Shaojing  WU Lisheng  WU Dingxun 《海洋学报(英文版)》2005,24(2)

1 Introduction M any estuarine and coastal copepods that havepreviously been classified as holoplankton m ightbestbe described as adultm eroplankton since they actuallyspend a portion oftheir life cycle in the seabed as rest-ing eggs [review ed by G rice and M arcus (1981) andM arcus (1996)]. R esting eggs can be extrem ely abun-dant (106 m ) in bays and estuaries especially w here -2w aterdepths are less than 20 m (M arcus,1989).Theyare likely to profoundly influence the dynam ics ofpel…  相似文献   

贵州瓮安陡山沱期矿化生物群的研究进展和意义   总被引：6，自引：2，他引：6  

尹崇玉  高林志  邢裕盛 《地球学报》2002,23(1):47-54

贵州瓮安陡山沱期矿化（磷酸盐化和硅化）生物群的研究近年来倍受关注，它为研究包括后生动物在内的多细胞生物早期演化提供了十分难得的机遇。最近，由于其中部分磷酸盐化球状化石保存了与某些后生动物胚胎早期发育阶段类似的卵裂特征，被认为是后生动物的休眠卵和胚胎化石。但是，由于至今未发现可靠的囊胚期到原肠胚期和幼体孵化的化石证据，此类化石的动、植物之争一直没有停止。作者近期对该套含磷地层进行了系统的分析研究，除已报道的大量休眠卵和胚胎化石外，还发现保存原肠发育特征的磷酸盐化实体化石、蓝藻细胞集合体、可疑海绵动物化石及类似瓶形的不明化石等。研究表明，陡山沱期矿化生物群具有多样性特征，包含了多种门类的不同类型，是迄今为止全球保存最完好的未元古纪磷质化石库。  相似文献   

广东河源盆地红层研究现状   总被引：1，自引：0，他引：1  

张显球凌秋贤  林建南 《地层学杂志》2005,29(11):602-607

近年来河源盆地的恐龙及蛋化石研究有突破性进展，在东源发现窃蛋龙类oviraptosaurs黄氏河源龙（Heyuannia huangi Lu）等恐龙化石，并收集到至少4属4种蛋化石一万余枚；含蛋层可以划分为上、下二层，下层以圆形蛋类及树枝蛋类大量富集为特征，上层以长形蛋为主。在盆地北部新发现了火山岩——弱熔结火山角砾岩，并新建立了适合本区的岩石地层单位系统——仙塘组、东源组、高埔岗组和莘庄村组，它们可与南雄、丹霞等盆地进行对比。  相似文献