南海中北部表层沉积物的矿物沉积

本文研究了南海中北部500多个样品的矿物学。认为,本区表层沉积物中矿物种类繁多,分布较为普遍,碎屑矿物(含火山物质)、粘土矿物、自生矿物常有出现。以前者为最显著(共60多种,其中重矿物50多种,轻矿物近10种),主要分布于陆架区及深海盆;粘土矿物次之,多分布于陆坡～深海盆;自生矿物较少,陆架～深海盆均有分布。文中根据矿物沉积特征和环境差异,把它划分为6个矿物区。     

Annual Cycle of Zooplankton Biomass, Abundance and Species Composition in the Neritic Area of the Balearic Sea, Western Mediterranean

Abstract. Seasonal changes in zooplankton biomass, abundance and species composition were studied at a neritic station in the Balearic Sea between April 1993 and May 1994. Sampling was carried out every 10 days in a zone influenced by the main current circulating through the Mallorca channel. Three main peaks of zooplankton biomass and abundance were observed: (1) at the beginning of summer when the thermocline developed, (2) in autumn when the thermocline broke down, and (3) in early spring. The smaller zooplankton fraction (100–250 μm) comprised on average 32 % of the total biomass and 73 % of total abundance. Copepods were the predominant group (64 % of the total abundance) with Clausocalanus, Oithona and Paracalanus being the most abundant genera. Paracalanus parvus, Clausocalanus furcatus, Acartia clausi, Oithona plumifera, Temora stylifera, Centropages typicus and Oncaea mediterranea were found to be the most important species in the area. Other abundant groups were cladocerans (15 %) and meroplankton larvae (12 %), both of which were particularly numerous during the stratified period. The copepod community was characterized by the above‐cited perennial species, which were abundant during the cycle studied. However, the influence of the hydrological conditions of the Balearic Sea, such as the Atlantic water influx and the physical structure of the water column (stratification and mixing), promoted the observed variability in zooplankton as well as the appearance of characteristic species during the annual cycle.     

The Reproductive Cycle of Ophioderma brevispinum (Echinodermata: Ophiuroidea)

Abstract. .The reproductive cycle of the brittlestar Ophioderma brevispinum is described using histological and organ index data for a population in Massachusetts, U.S.A. The cycle consists of a one month mid-summer spawning phase followed by gametogenesis and gradual gonadal growth during the winter, and greatly accelerated gonadal growth from May to June. At the end of the spawning season, oogonia proliferate near the base of the ovary, and a continuous layer of spermatogonia lines the testis. As oocytes grow to a maximum diameter of 350 um, yolk granules accumulate and the cytoplasm becomes less basophilic. Prior to spawning, the testis becomes branched and sulcate, and a whorl of spermatozoa produced by columns of spermatids accumulates in the lumen. Comparisons between the reproductive cycles of different populations of O. brevispinum and its congeners support the hypothesis that temperature may be a critical exogenous factor, but definitely not the only factor, in the initiation and duration of the growth and spawning phases of the ophiuroid reproductive cycle.     

南海西部表层沉积物钙质浮游生物分布与碳酸盐溶解

对南海西部300多个表层沉积样品中的浮游有孔虫和钙质超微化石定量分析表明，几乎所有样品均含浮游有孔虫、钙质超微化石，但丰度相差十分悬殊，浮游有孔虫丰度介于0．5～36673个／g之间，钙质超微化石丰度为0～1725个／10个视域，两者的分布规律相似。在陆坡区钙质浮游生物最富集，尤其在西沙群岛西南、南沙西部礁滩附近海区丰度最高；向深海盆区和陆架浅水区，钙质浮游生物丰度均下降。但从两者的丰度分布来看，其溶解程度不同，浮游有孔虫更容易溶解，在200～2000m水深区，丰度最高，2000m以下丰度锐减；而钙质超微化石的最富集区在500～3000m，且3000m以下仍较丰富。从碳酸盐的分布来看，本区碳酸盐的临界补偿深度(CCrD)为3500m，而CCD大于4300m，碳酸盐的溶解主要由有孔虫和钙质超微化石构成。     

Impact of urban stormwater runoff on estuarine environmental quality

Urban stormwater runoff could contribute to the deterioration of water quality of a receiving water body. In this research, field studies and laboratory experiments were conducted to assess the microbial contamination resulting from urban stormwater runoff into the Lake Pontchartrain estuary. Fecal coliform, Escherichia coli and enterococci were used as indicator organisms. The specific objectives of the research were to examine the distribution of the indicator organisms in different environmental elements (water column, suspended particles and sediment) and to further investigate the mechanisms related to their fate. Results of the research indicated satisfactory water quality at the study sites during dry weather periods. However, a significant increase was observed in the concentrations of the indicator organisms in the water columns and sediment at specific study sites following a given stormwater event. Three to seven days were needed for the elevated indicator organisms to return back to their background levels in the water column and sediment, respectively. The mechanism of sedimentation contributed to a reduction in the microbial concentration in the water column, as the indicator organisms were found to attach to the suspended particles in the stormwater. The percentage of fecal coliform, E. coli and enterococci attached to the suspended particles was found to be within the range of 9.8–27.5%, 21.8–30.4%, and 8.4–11.5% of the total indicator organisms in the stormwater loaded into the estuary, respectively. About 75–80% of the total indicator organisms remained free-floating for some distance in the water column before dying off.     

末次盛冰期以来渤、黄、东海陆架底质分布演变过程模拟研究

渤、黄、东海陆架底质的形成分布与末次盛冰期之后的海侵密切相关。末次盛冰期结束、海侵开始以来 ,潮流是渤、黄、东海陆架上的永久性主导作用应力。为从长期沉积动力演变过程的角度 ,探讨渤、黄、东海陆架底质形成分布的有关成因问题 ,利用数值模拟手段 ,再现了末次盛冰期以来 6个时期渤、黄、东海陆架潮流作用下海底的冲淤格局及底质分布。结果表明 ,扬子浅滩南侧东海外陆架的砂质沉积基本上是自 - 80 m海面以来形成的。扬子浅滩形成于 -5 2 m海面之后 ,至 - 3 0 m海面时已有一定规模 ,全新世最大海侵之后 ,逐渐形成现在规模的扬子浅滩。南黄海中部泥自 - 5 2 m海面时就已开始形成 ,- 3 0 m海面时范围很大 ,侵入北黄海 ,全新世最大海侵以来 ,逐渐调整到现在的范围。渤海中央泥、北黄海西部泥、浙闽岸外泥、辽东半岛西侧与北侧的砂质沉积、西朝鲜湾与江华湾中的砂质沉积以及苏北浅滩是自全新世最大海侵以来逐渐形成的。海州湾中砂质沉积形成的盛期在公元 8世纪之后。济洲岛西南泥、南黄海东部泥很可能分别形成于 - 3 0 m海面、- 5 2 m海面以来。全新世渤、黄、东海陆架底质分布的演变过程大致分为 2个阶段 :全新世最大海侵之前为渤、黄、东海陆架底质分布宏观格局的形成阶段 ;全新世最大海侵至今为渤     

Locomotor activity rhythm in the Japanese eel Anguilla japonica elvers

Under artificial LD cycles(6,12,18 L),the elvers of Japanese eel,Anguilla japonica,showed a 24 h cycle of locomotor activity rhythm being most active at light transitions:the eels' activity rose to a primary peak after lights-off,followed by a quiescent period during which they buried into the shelters or lying motionlessly on sand for most of the time,and then reached a secondary peak before lights-on.Elvers could resynchronize their activity rhythm with a new photo cycle within 4 d.Moreover,their activity level at dark phase significantly increased as the light period was prolonged:higher activity levels during shorter dark period.However,the elvers did not display clearly the existence of a circadian rhythm under constant light or dark conditions.The timing of daily activity rhythm evidenced in the Japanese eels may occur through the action of the LD cycles with a weak participation of an endogenous circadian system.In all the LD cycles,over 99% of the activity occurred in the dark phase,indicating that the eels were always nocturnally active no matter what time of day it might be.Under 12 L conditions,the eels' activity level and the time outside sand were significantly elevated both at light and dark phases as temperature increased from 10~15 to 20~25 ℃.The activity rhythm pattern(i.e.,two peaks occurring around light transitions) did not apparently change among temperatures.However,in contrast with the primary activity peaks immediately after lights-off at 20 and 25 ℃,the timing of the primary peaks at 10 and 15 ℃ showed a latency of a few hours following lights-off,indicating the inhibiting effect of low temperature on the eels' activity.     

Reproductive Cycle of the Caribbean Feather Star Nemaster rubiginosa (Echinodermata: Crinoidea)

Abstract. The reproductive cycle of the comatulid crinoid Nemaster rubiginosa from Discovery Bay, Jamaica is described histologically. The cycle is annual and may be divided into (1) a "resting" phase (summer) in which most adults possess immature, unsexable gonads, (2) a recovery phase (early fall) marked by the re-initiation of gametogenesis and rapid gonadal growth, (3) a breeding phase (late fall and winter) during which the gonads are mature and repeated spawning likely takes place, and (4) a post-spawning phase (spring) during which relict gametes are removed from the shrinking gonads. Although unsexable individuals predominate during the "resting" phase, a small proportion of the adult population is unsexable at all times of the year. The reproductive condition of animals in the same month in two successive years was very similar, suggesting that the timing of reproduction is quite predictable from year to year. The re-initiation of gametogenesis in the early fall is correlated with both rising sea temperature and shortening daylength, and the October to March breeding season corresponds to the period of short daylengths at the study site. The well-defined and synchronized annual reproductive cycle of Nemaster rubiginosa contrasts with the more prolonged and variable reproductive cycles reported for other tropical crinoids and points to a diversity of breeding patterns among tropical crinoids.     

欧氏六线鱼Hexagrammos otakii Jordan & Starks性腺发育的周年变化研究

根据对青岛附近水域欧氏六线鱼（已达性成熟年龄）性腺周年宏观和组织学观察，性腺发育可分为：①重复发育Ⅱ期；②开始成熟期；③接近成熟期；④临产期或产卵期；⑤产后期。按性腺指数变化并结合性腺组织切片确定，欧氏六线鱼性腺发育在青岛海区一年一个周期，繁殖期在１０月下旬至１２月，繁殖盛期是１１月下旬至１２月中旬。     

Deep ocean fluxes and their link to surface ocean processes and the biological pump

Intense studies of upper and deep ocean processes were carried out in the Northwestern Indian Ocean (Arabian Sea) within the framework of JGOFS and related projects in order to improve our understanding of the marine carbon cycle and the ocean’s role as a reservoir for atmospheric CO₂. The results show a pronounced monsoon-driven seasonality with enhanced organic carbon fluxes into the deep-sea during the SW Monsoon and during the early and late NE Monsoon north of 10°N. The productivity is mainly regulated by inputs of nutrients from subsurface waters into the euphotic zone via upwelling and mixed layer-deepening. Deep mixing introduces light limitation by carrying photoautotrophic organisms below the euphotic zone during the peak of the NE Monsoon. Nevertheless, deep mixing and strong upwelling during the SW Monsoon provide an ecological advantage for diatoms over other photoautotrophic organisms by increasing the silica concentrations in the euphotic zone. When silica concentrations fall below 2 μmol l⁻¹, diatoms lose their dominance in the plankton community. During diatom-dominated blooms, the biological pathway of uptake of CO₂ (the biological pump) appears to be more efficient than during blooms of other organisms, as indicated by organic carbon to carbonate carbon (rain) ratios. Due to the seasonal alternation of diatom and non-diatom dominated exports, spatial variations of the annual mean rain ratios are hardly discernible along the main JGOFS transect.Data-based estimates of the annual mean impact of the biological pump on the fCO₂ in the surface water suggest that the biological pump reduces the increase of fCO₂ in the surface water caused by intrusion of CO₂-enriched subsurface water by 50–70%. The remaining 30 to 50% are attributed to CO₂ emissions into the atmosphere. Rain ratios up to 60% higher in river-influenced areas off Pakistan and in the Bay of Bengal than in the open Arabian Sea imply that riverine silica inputs can further enhance the impact of the biological pump on the fCO₂ in the surface water by supporting diatom blooms. Consequently, it is assumed that reduced river discharges caused by the damming of major rivers increase CO₂ emission by lowering silica inputs to the Arabian Sea; this mechanism probably operates in other regions of the world ocean also.