长江口及其邻近水域网采浮游植物群落

根据2006年2月～11月在长江口及其邻近水域的采样调查,对调查水域网采浮游植物群落结构特征进行了研究.共鉴定出浮游植物5门72属177种(包括未定名种),浮游植物以硅藻为主,但甲藻在群落中的比重也很明显,此外还有少量的绿藻、蓝藻和金藻.浮游植物优势物种以可形成链状群体的物种为主,中肋骨条藻(Skeletonema costatum)在长江口水域全年都具有较高的优势度,另外还有季节性的优势种,春季的夜光藻(Noctiluca scientillans)和具齿原甲藻(Prorocentrum dentatum),夏季的细长翼鼻状藻(Proboscia alata f. gracillima),秋、冬季的琼氏圆筛藻(Coscinodiscus jonesianus)和星脐圆筛藻(Coscinodiscus asteromphalus).浮游植物物种多为温带近岸种,少数为暖水种或大洋高盐种.长江口水域网采浮游植物的细胞平均丰度在夏季最高,为2027.41×104 cells m-3,其次为春季,秋季最低,为22.15×104 cells m-3.冬季的细胞丰度在各站之间变化幅度是最小的.浮游植物物种组成、细胞丰度及多样性指数在区域上和时间上都表现出明显的差异.调查所获4季度月网采浮游植物的丰度资料与历史资料基本吻合,季节变化也基本一致,但也有个别季度差别较大,长江径流量的年际变动可能是造成这种差别主要原因之一.     

Coast of change: habitat loss and transformations in the Wadden Sea

In the southern North Sea, coastal people commenced with habitat conversions 1,000 years ago. Partly interrupted in late medieval times by large-scale inundations of marshland, progressive embankments transformed the landward half of the amphibic transition zone between a limno-terrestric and a brackish-marine ecosystem into arable land and freshwater lakes. Sea walls rigidly separated the land from the sea. Dynamic transitional habitats have vanished. Areal loss has diminished the capacity of the Wadden Sea to dissipate wave and tidal energy. A coastal ecosystem once rich in marsh plants, seagrass and diatoms on mud flats became transformed into one with less autochthonous phototroph production, dominated by sandy tidal flats, and dependent primarily on allochthonous plankton supply. The large estuaries have been dredged to serve as shipping canals, and have lost most of their former retention and filter capacity. Riverine loads are now flushed right into the North Sea. Symptoms of a syndromatic coastal habitat degradation are diagnosed, leading to a decline in natural habitat diversity. The conventional on-line coastal protection may not achieve a sustainable coastal habitat configuration. At sedimentary coasts immobilised by dikes and petrified shores, a more flexible response to sea level rise is recommended.     

Characterization, dynamics, and ecological impacts of harmful Cochlodinium polykrikoides blooms on eastern Long Island, NY, USA

We report on the emergence of Cochlodinium polykrikoides blooms in the Peconic Estuary and Shinnecock Bay, NY, USA, during 2002–2006. Blooms occurred during late summer when temperatures and salinities ranged from 20 to 25 °C and 22 to 30 ppt, respectively. Bloom patches achieved cell densities exceeding 10⁵ ml⁻¹ and chlorophyll a levels exceeding 100 μg l⁻¹, while background bloom densities were typically 10³–10⁴ cells ml⁻¹. Light, scanning electron and ultrathin-section transmission electron microscopy suggested that cells isolated from blooms displayed characteristics of C. polykrikoides and provide the first clear documentation of the fine structure for this species. Sequencing of a hypervariable region of the large subunit rDNA confirmed this finding, displaying 100% similarity to other North American C. polykrikoides strains, but a lower similarity to strains from Southeast Asia (88–90%). Bioassay experiments demonstrated that 24 h exposure to bloom waters (>5 × 10⁴ cells ml⁻¹) killed 100% of multiple fish species (1-week-old Cyprinodon variegates, adult Fundulus majalis, adult Menidia menidia) and 80% of adult Fundulus heteroclitus. Microscopic evaluation of the gills of moribund fish revealed epithelial proliferation with focal areas of fusion of gill lamellae, suggesting impairment of gill function (e.g. respiration, nitrogen excretion, ion balance). Lower fish mortality was observed at intermediate C. polykrikoides densities (10³–10⁴ cells ml⁻¹), while fish survived for 48 h at cell densities below 1 × 10³ cells ml⁻¹. The inability of frozen and thawed-, or filtered (0.2 μm)-bloom water to cause fish mortality suggested that the thick polysaccharide layer associated with cell membranes and/or a toxin principle within this layer may be responsible for fish mortality. Juvenile bay scallops (Argopecten irradians) and American oysters (Crassostrea virginica) experienced elevated mortality compared to control treatments during a 9-day exposure to bloom water (5 × 10⁴ cells ml⁻¹). Surviving scallops exposed to bloom water also experienced significantly reduced growth rates. Moribund shellfish displayed hyperplasia, hemorrhaging, squamation, and apoptosis in gill and digestive tissues with gill inflammation specifically associated with areas containing C. polykrikoides cells. In summary, our results indicate C. polykrikoides blooms have become annual events on eastern Long Island and that bloom waters are capable of causing rapid mortality in multiple species of finfish and shellfish.     

Litter pool sizes,decomposition, and nitrogen dynamics in <Emphasis Type="Italic">Spartina alterniflora</Emphasis>-invaded and native coastal marshlands of the Yangtze Estuary

Past studies have focused primarily on the effects of invasive plants on litter decomposition at soil surfaces. In natural ecosystems, however, considerable amounts of litter may be at aerial and belowground positions. This study was designed to examine the effects of Spartina alterniflora invasion on the pool sizes and decomposition of aerial, surficial, and belowground litter in coastal marshlands, the Yangtze Estuary, which were originally occupied by two native species, Scirpus mariqueter and Phragmites australis. We collected aerial and surficial litter of the three species once a month and belowground litter once every 2 months. We used the litterbag method to quantify litter decomposition at the aerial, surficial and belowground positions for the three species. Yearly averaged litter mass in the Spartina stands was 1.99 kg m⁻²; this was 250 and 22.8% higher than that in the Scirpus (0.57 kg m⁻²) and Phragmites (1.62 kg m⁻²) stands, respectively. The litter in the Spartina stands was primarily distributed in the air (45%) and belowground (48%), while Scirpus and Phragmites litter was mainly allocated to belowground positions (85 and 59%, respectively). The averaged decomposition rates of aerial, surficial, and belowground litter were 0.82, 1.83, and 1.27 year⁻¹ for Spartina, respectively; these were 52, 62 and 69% of those for Scirpus litter at corresponding positions and 158, 144 and 78% of those for Phragmites litter, respectively. The differences in decomposition rates between Spartina and the two native species were largely due to differences in litter quality among the three species, particularly for the belowground litter. The absolute amount of nitrogen increased during the decomposition of Spartina stem, sheath and root litter, while the amount of nitrogen in Scirpus and Phragmites litter declined during decomposition for all tissue types. Our results suggest that Spartina invasion altered the carbon and nitrogen cycling in the coastal marshlands of China.     

不同发育时间的互花米草盐沼对大型底栖动物群落的影响

2004-2006年对长江口崇明东滩湿地芦苇(Phragmites australis)盐沼和不同发育时间的互花米草(Spartina alterniflora)盐沼的大型底栖动物群落特征进行分析研究.结果表明:互花米草盐沼发育初期,大型底栖动物群落以腹足类为主,物种丰富度(D=2.18)和多样性(H′=2.19)均低于芦苇盐沼(D=2.61, H′=2.29);随着时间的推移,互花米草与本地生物逐渐形成互动和稳定的格局,大型底栖动物群落组成中多毛类的种类逐渐上升(由3种变为6种),物种数和物种丰富度也上升,从而逐步形成新的大型底栖动物群落,物种丰富度(D=2.70)和多样性(H′=2.48)逐渐上升并高于芦苇盐沼(D=2.19, H′=2.09);从大型底栖动物群落的重新形成到稳定阶段,需要若干年的时间.     

围垦对长江口南岸底栖动物群落结构及多样性的影响

通过对长江口南岸围垦潮滩和自然潮滩大型底栖无脊椎动物进行取样调查,研究了围垦潮滩的底栖动物群落结构及其多样性特性,分析了围垦对潮滩底栖动物群落结构及多样性的影响,研究发现,（1）围垦氏栖动物群落种类减少,种类组成发生变化;总趋势是,围垦以后,甲壳动物种类明显减少,由7种减少到1种;随着围垦时间延长,多毛类种类减少,由4种减少到3种,直到最后消失,而软体动物和昆虫幼虫种类所占比例则明显增加,分别从占总种数的29．41％,5．89％增加到50．00％和25．00％;（2）围垦1a且仍受潮水影响的潮滩,底栖动物种类丰度虽有降低,但其密度和生物量却明显增加,分别从132．10个/m^2,35.31g/m^2（湿重）增加到218．32个／m/ 2和79．66g/m^2（湿重）,围垦2a且潮水不能进入的潮滩,底栖动物生物量大大降低,降到3．02g/m^2（湿重）;（3）围垦时间短且仍受潮水影响的潮滩与未围垦的自然潮滩相比,其底栖动物多样性降低不明显,围垦时间长且潮水不能进入的潮滩,底栖动物多样性明显降低,反映了围垦导致潮滩湿地生境退化;（4）围垦对底栖动物群落结构及多样性的影响,是通过改变潮滩湿地生境中的多种环境因子造成的,如潮滩高保,水,动力,沉积物特性,植被演替等,是各种因子综合作用的结果。     

长江口附近海域大型底栖动物群落特征

利用2002年9月在长江口附近海域进行的大型底栖动物定量采集样品,采用物种优势度计算方法和大型多元统计分析软件PRIMER,研究了该海域大型底栖动物群落的优势种组成和物种多样性、生物量和丰度、群落等级聚类分析(CLUSTER)和非度量MDS标序以及群落受污染扰动情况。本次调查共获得长江口附近海域大型底栖动物154种,其中多毛类环节动物60种,甲壳动物30种,软体动物28种,棘皮动物25种,其它类群动物11种。群落中优势种的地位都不明显,只有虫(Listriolobussp.)、豆形短眼蟹(Xenophthalmus pinnotheroidesWhite)、拟单指虫(Cossurella dimorphaHartman)为相对重要的种类。栖息种数、平均生物量和丰度以及3个多样性指数H′、D和J的空间分布无明显的规律,在122°E以东海域呈不连续的斑块或镶嵌状分布。群落结构聚类分析和MDS标序表明,20个取样站的群落结构相似性程度都非常低,为10%-30%,仅有A12和E4两个站Bray-Curtis相似性系数达到50%。ABC曲线表明,近长江口的A4站和A14站的底栖动物群落已有受到一定程度的轻微污染扰动的趋势;而距长江口较远的P9和P5两站ABC曲线状况正常,表明该处的大型底栖动物群落尚未受到干扰。     

长江仪征—崇明段的肉足虫和纤毛虫

１９８８年５月至１９９０年７月用２５号筛娟网对长江仪征－崇明段的肉足类和纤毛类原生动物进行采集，共采集到７９种，其中肉足类５２种，纤毛类２７种。数量在０－１２００个／升之间，平均为１１７个／升。由于受到泥沙含量及海水的影响，调查水域的肉足虫和纤毛在种类组成，数量分布等方面存在着较大的地区差异。     

Ecohydrology as a new tool for sustainable management of estuaries and coastal waters

Throughout the world, estuaries and coastal waters have experienced degradation. Present proposed remedial measures based on engineering and technological fix are not likely to restore the ecological processes of a healthy, robust estuary and, as such, will not reinstate the full beneficial functions of the estuary ecosystem. The successful management of estuaries and coastal waters requires an ecohydrologybased, basin-wide approach. This necessitates changing present practices by official institutions based on municipalities or counties as an administrative unit, or the narrowly focused approaches of managers of specific activities (e.g., farming and fisheries, water resources, urban and economic developments, wetlands management and nature conservationists). Without this change in thinking and management concept, estuaries and coastal waters will continue to degrade, whatever integrated coastal management plans are implemented. To help in this process of change there is a need to (1) develop a profound understanding of the effects of biota and biotic processes on mediating estuary response to changing hydrology, sediment and nutrient flux and of the biota on hydrology at the river basin scale, and (2) to develop science-based remediation measures at the river basin scale, with elements of ecohydrology and phytotechnology at their core, to strengthen the ability of the biota to sustain and adapt to human-induced stresses.This revised version wa published online in March 2005 with corrections to the issue cover date.     

Purification and characterization of vitellin from the estuarine mysid Neomysis integer (Crustacea; Mysidacea)

Invertebrates account for roughly 95% of all animals, yet surprisingly, little effort has been invested to understand their value in signaling potential environmental endocrine disruption. There has been, however, much recent attention on vitellogenin induction in egg-laying invertebrates and vertebrates as indicators of exposure to estrogenic xenobiotics. Mysid shrimp (Crustacea: Mysidacea) have been put forward by several researchers and regulatory bodies (e.g., US-EPA) as suitable test organisms for the evaluation of environmental endocrine disruption. In view of developing sensitive assays to study endocrine disruption in the estuarine mysid Neomysis integer, we isolated and characterized vitellin, the major yolk protein in eggs. Vitellin was purified using gel filtration and characterized by electrophoresis using different staining procedures. Specific (as shown by Western blotting) polyclonal antibodies were produced in rabbit against the purified vitellin of N. integer. These antisera will be used to develop immunoassays to study vitellogenesis in mysids and to detect potential stimulatory or inhibitory effects of endocrine disruptors on the production of vitellin.