Mechanisms of the southward translation of meddies

Meddies are warm and saline anticyclonic eddies found at the mid-depth of the Mediterranean Outflow in the Eastern North Atlantic. They are observed to move almost southward at average speeds as high as 1.3±0.2 cm s⁻¹. This paper examines a mechanism which accelerates this curious translation to a reasonable speed when combined with nonlinearity and a suitable vertical eddy structure. This mechanism is thepseudo-topographic β effect due to the westward decrease in the thickness of the mid-layer induced by the surface southward mean current. The linear dispersion relation including this effect is shown to account for a quarter of the surface southward mean current or a fifth of the observed southward translation of meddies. Three-layer quasi-geostrophic experiments reveal that the surface southward mean current certainly enhances the southward translation velocity of meddies to a speed in agreement with observation, if the meddy has a current structure of plausible intensity and vertical coherence. In the light of the current-induced pseudo-topographic β effect, previous hypotheses are also re-examined through dynamic arguments together with numerical experiments; they are suggested to have some difficulty either in dynamics or in correspondence with observation. Thus the nonlinear effect due to secondary eddies combined with thecurrent-induced pseudo-topographic β effect is the most likely mechanism responsible for the rapid southward translation of meddies among those examined in the paper.     

Length‐mass models for some common New Zealand littoral‐benthic macroinvertebrates,with a note on within‐taxon variability in parameter values among published models

Regression models are developed and presented to predict dry mass (mg) from two linear dimensions (mm) for 17 benthic macroinvertebrate taxa common to littoral zones of New Zealand lakes. We also provide regression models to predict body length from head capsule width for the major insect taxa. Dry mass was best explained as a power function of all linear dimensions: M = aL _b .Parameters are presented in the log₁₀‐transformed linear form of this power function. Body length was a simple linear function of head capsule width for all insect taxa, hence parameters for these models are presented as untransformed values. We also provide family level models for the Chironomidae, and compare our chironomid body length‐mass model with other published Chrionomidae length‐mass models. There was a very high degree of variability in parameter values among published length‐mass models for the family Chironomidae (mean coefficient of variation for mass at length = 148%). We discuss the potential causes and implications of this variability.     

A pleistocene mummified ostracod from the Wairarapa district

A mummified specimen of Scottia insularis Chapman is recorded from beds of Upper Nukumaruan age (Pleistocene) at Gladstone in the Wairarapa Valley. This is the first record of a mummified species from New Zealand.     

南海礁栖海藻共附生真菌Pestalotiopsis neglecta SCSIO41 403次级代谢产物研究

研究南海礁栖腔节藻Coelarthrum sp.共附生真菌Pestalotiopsis neglecta SCSIO41403的次级代谢产物。采用中压正相柱层析色谱法和半制备高效液相色谱法, 对真菌发酵产物进行分离纯化, 制备获得6个次级代谢产物单体化合物, 使用核磁共振、质谱等波谱学方法, 结合其理化性质以及文献数据对比, 分别鉴定为: gamahorin (1)、microsporaline C (2)、7-hydroxy-5-methoxy-4,6-dimethylphthalidc (3)、demethyl nectriapyrone A (4)、4-hydroxybenzaldehyde (5)和4-hydroxyphenethyl acetate (6)。这6个化合物均为首次从该菌株发现, 其中化合物1、2、5和6是首次从海洋动植物共附生真菌中发现。抗菌活性筛选显示其中化合物3对白色念珠菌有明显抑制活性。     

Correspondence between the distribution of hydrodynamic time parameters and the distribution of biological and chemical variables in a semi-enclosed coral reef lagoon

Hydrodynamic modeling can be used to spatially characterize water renewal rates in coastal ecosystems. Using a hydrodynamic model implemented over the semi-enclosed Southwest coral lagoon of New Caledonia, a recent study computed the flushing lag as the minimum time required for a particle coming from outside the lagoon (open ocean) to reach a specific station [Jouon, A., Douillet, P., Ouillon, S., Fraunié, P., 2006. Calculations of hydrodynamic time parameters in a semi-opened coastal zone using a 3D hydrodynamic model. Continental Shelf Research 26, 1395–1415]. Local e-flushing time was calculated as the time requested to reach a local grid mesh concentration of 1/e from the precedent step. Here we present an attempt to connect physical forcing to biogeochemical functioning of this coastal ecosystem. An array of stations, located in the lagoonal channel as well as in several bays under anthropogenic influence, was sampled during three cruises. We then tested the statistical relationships between the distribution of flushing indices and those of biological and chemical variables. Among the variables tested, silicate, chlorophyll a and bacterial biomass production present the highest correlations with flushing indices. Correlations are higher with local e-flushing times than with flushing lags or the sum of these two indices. In the bays, these variables often deviate from the relationships determined in the main lagoon channel. In the three bays receiving significant riverine inputs, silicate is well above the regression line, whereas data from the bay receiving almost insignificant freshwater inputs generally fit the lagoon channel regressions. Moreover, in the three bays receiving important urban and industrial effluents, chlorophyll a and bacterial production of biomass generally display values exceeding the lagoon channel regression trends whereas in the bay under moderate anthropogenic influence values follow the regressions obtained in the lagoon channel. The South West lagoon of New Caledonia can hence be viewed as a coastal mesotrophic ecosystem that is flushed by oligotrophic oceanic waters which subsequently replace the lagoonal waters with water considerably impoverished in resources for microbial growth. This flushing was high enough during the periods of study to influence the distribution of phytoplankton biomass, bacterial production of biomass and silicate concentrations in the lagoon channel as well as in some of the bay areas.     

杂色龙虾线粒体基因组全序列的测定与分析

为了解杂色龙虾(Panulirus versicolor)线粒体基因组多态位点及遗传变异,对龙虾类的分类研究奠定基础,作者通过常规PCR步移扩增法获得杂色龙虾线的线粒体基因组全序列,分析了其线粒体基因组的基本特征以及基因排列情况,并结合中国龙虾(Panulirus stimposni)、波纹龙虾(Panulirus homarus)线粒体基因组全序列,综合分析了龙虾属线粒体编码基因多态位点及基因变异状况。结果表明:杂色龙虾线粒体基因组全序列为15 700 bp,由13个蛋白质编码基因、22个t RNA基因、2个r RNA基因和D-loop区组成,保持了泛甲壳动物线粒体基因组的原始排列。杂色龙虾线粒体DNA的碱基组成具有AT偏好性,A+T含量为67%,4种碱基的含量分别为(A=34.6%,T=32.1%,C=20.5%,G=12.8%)。预测了杂色龙虾18个t RNA以及2个r RNA的二级结构。龙虾属线粒体基因组中的nad 2、nad 5基因以及D-loop区的多态位点比例较高,适合作为分子标记用于龙虾类系统进化关系、种内多态性以及遗传分化等方面的研究。     

厦门海沧经济开发区环境地质条件及其变化趋势预测Ⅱ.环境地质条件变化趋势预测

通过野外调查和室内分析,研究并预测了海沧经济开发区的环境地质条件变化趋势。结果表明,该区原生地质环境在一个相当长的时期内不会发生重大变化,而次生地质环境随着总体规划的逐步实施将变得更加美好。只要依据科学规律办事,经济建设与地质环境协调发展是完全可能的。     

A pair of Langmuir cells in two laboratory tanks (II) on generation mechanism

Vertical and cross-wind profiles of mean currents were measured systematically in vertical cross-sections of two wind-wave tanks with aspect ratios of order one to study the secondary flow in the tanks. A pair of Langmuir cells turned out to be driven by a close combination of the pressure gradient along the tank and the side-wall effects. That is, part of the adverse pressure gradient produced a parabolic cross-wind profile with the smallest downwind current at the centerline and the largest current along the two sidewalls. As a result, upwelling occurred in the center zone where the return flow was strongest, probably because of the entrainment action of the wind-driven current. In order to compensate for this upwelling, downwelling occurred along the two side-walls from the flow continuity. The resulting vertical circulation formed a pair of Langmuir circulations across the span and served to maintain the parabolic profile formed by the pressure gradient. A positive feedback mechanism is thus found between the primary and secondary circulations through upwelling of the return flow in the center zone. Vertical shears of the span-averaged downwind current measured in two tanks were found to be systematically different from each other. This difference seems to depend on the magnitude of the advective Reynolds stresses in the two tanks.     

红树植物次生木质部的结构与进化

研究了红树科Rhizophoraceae的木榄Bruguiera gymnorrhiza、海莲Bruguiera sexangula、角果木Ceriops tagal和秋茄Kandelia candel;马鞭草科Verbenaceae的白骨壤Avicennia marina;紫金牛科Mysinaceae的桐花树Aegiceras corniculatum和海桑和Sonneratiaceae的海桑Sonneratia caeseolaria次生木质部的结构与进化关系,红树科植物的次生木质部结构比马鞭草科、紫金牛科和海桑科的植物原始;红树科中的竹节树属Carallia和山红树属Pellacalyx为陆生的非红树植物,它们次生木质部结构比海生的红树料红树植物木榄属、秋茄属、角果木属更为进化,即导管为单穿孔、管间纹孔式为互利式纹孔.单穿孔的导管存在,是长期的进化过程中,遇到干旱环境而产生的特化现象,而海生红树科植物进入海滩沼译后,木质部仍具有原始性状.