Topographically generated fronts,very nearshore oceanography,and the distribution of chlorophyll,detritus, and selected diatom and dinoflagellate taxa

At four sites (Sunset Bay, Miller's Cove, and Shore Acres 43° 20.13 N; 124° 22.40 W, Nellies Cove 42° 44.75 N; 124° 29.75 W) along the Oregon coast, USA, relationships between fronts associated with shore-parallel foam lines and the distributions of chlorophyll, selected phytoplankters, and detritus were investigated. Sampling dates at the study sites were as follows: Sunset Bay, 1 August 1997, 25 June 1999 and 20 July 1999; Miller's Cove, 24 August 2000; Shore Acres, 19 July 1999 and 16 August 2000; Nellies Cove 17 August 2000 and 31 August 2000. Conductivity, temperature and depth data were used to describe the water masses on either side of the fronts, and vertical plankton tows with a 53-m mesh net were used to describe the distribution of selected phytoplankters and detritus. At the cove sites during upwelling, fronts marked the presence of warm water within the bay and cooler water offshore. Chlorophyll a (Chl a) and phytoplankton concentrations were generally lower within the coves than seaward while detritus concentrations were higher. From 3 July 2000 to 15 September 2000, a period when upwelling winds from the north prevail, a time series of samples was collected at Sunset Bay. The front was only present during periods of upwelling favorable winds. During these periods there were significantly higher concentrations of Chl a, Pseudo-nitzschia spp., and Protoperidinium spp. seaward of the front than landward. During downwelling winds the front was absent and there were no significant differences in the concentrations inside and outside the mouth of the bay. At Shore Acres, an exposed, relatively straight stretch of shoreline, the shore-parallel front appears to be formed by boundary mixing. Chl a and phytoplankton from the coastal ocean spread well shoreward of the boundary-mixing front. When present, the front at the mouth of the coves and bay indicated the presence of water masses with distinct physical and biological characteristics, but not at Shore Acres. Alongshore differences in the very nearshore oceanography, by altering the availability of continental shelf phytoplankton production, may affect both the growth rates of intertidal benthic suspension feeders and community structure.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Communicated by J.P. Grassle, New Brunswick     

A coupled numerical model to investigate the air–sea interaction at the coastal upwelling area of Cabo Frio,Brazil

This work investigates the capability of an oceanic numerical model dynamic and thermodynamically coupled to a three-dimensional mesoscale atmospheric numerical model to simulate the basic features of the air–sea interaction in the coastal upwelling area of Cabo Frio (RJ, Brazil). The upwelling/downwelling regime is an important feature in the oceanic circulation of Cabo Frio and determines the sustainability of local ecosystems. This regime is predominantly driven by the atmospheric circulation and is well documented, being suitable to be used as test reference for atmospheric and oceanic coupled and uncoupled models. The oceanic boundary conditions, coastline shape and coupling effect have been tested. The uncoupled oceanic model forced by a NE (SW) wind field generates a realistic upwelling (downwelling) phenomenon regardless of the proximity of the lateral boundary and how realistic is the shape of the coastline. The atmospheric-oceanic coupled model generates an upwelling location and intensity similar to the uncoupled simulation, but the upwelling is gradually enhanced by the sea-breeze circulation. It also generates vertical profiles of mixing ratio that compare better to the observations than the uncoupled simulation and air potential temperature and wind vertical profiles that represent particular features of the atmospheric circulation at Cabo Frio.     

Annual life cycle of the copepod<Emphasis Type="Italic"> Eucalanus inermis</Emphasis> at a coastal upwelling site off Mejillones (23°S), northern Chile

Eucalanus inermis is an abundant species in the eastern tropical and subtropical South Pacific, including the oceanic and coastal waters off Chile and Peru. Its annual life cycle was studied through a time-series sampling (weekly intervals) during 2002, at a fixed coastal station at an upwelling site (Mejillones Bay, 23°S) off northern Chile. The more-or-less continuous occurrence and abundance of naupliar and copepodid stages indicated that the species reproduces during most of the year, with two peaks: one during the austral spring and the other during the summer. Thereafter, an abrupt decline in the population was observed during winter. The abundances of E. inermis copepodids and nauplii were positively correlated with sea surface temperature, suggesting temperature-dependent development and growth during the spring–summer period. Three cohorts could be distinguished during one annual cycle, with generation times >30 days. The estimate of mean weight-specific daily growth (0.12 day^–1) is lower than that of other species in the area, but it is consistent with a slower development rate. The distribution of this copepod is associated with the equatorial subsurface waters characterized by low-oxygen content (<0.5 ml l^–1). The ascent of this water mass to the near-surface during coastal upwelling in the spring–summer period and the presence of E. inermis adults favor their reproduction and the development of cohorts in the food-rich upwelling environment. The wintertime disappearance of E. inermis from shallow waters is, thus, interpreted as a movement to deep waters (>200 m depth), probably in a lethargic mode, within the oxygen minimum zone in the adjacent oceanic area.Communicated by P.W. Sammarco, Chauvin     

Sustainable management of shellfish resources in Bandon Bay, Gulf of Thailand

Bandon Bay (Surat Thani Province) is one of the most productive coastal areas in southern Thailand. The Tapi River and 18 channels are the main sources of freshwater, nutrients, organic matter and sediment to the bay and the loading of freshwater and nutrients provide essential support for the production of phytoplankton in the estuarine ecosystem. Bandon Bay is important as natural spawning, nursery and feeding grounds for shellfish such as oysters, blood cockles, green mussels, short-necked clams, mud crabs and shrimps, and the estuary also serves as an excellent area for mariculturing of shellfish. In fact, oysters and blood cockles cultured in Bandon Bay are now being exported worldwide. However, Bandon Bay is also a textbook example of overexploitation of coastal resources in the tropics including all the derived changes in the estuarial ecosystem with severe socio-economic consequences. Hence, there is an urgent need for setting up an integrated management plant for a sustainable use of shellfish resources in Bandon Bay. The present study attempts to integrate water quality simulation results, socio-economic data and information on existing shellfish resource use in the process of proposing a set of sustainable management strategies for shellfish resources in Bandon Bay. These strategies involve: (1) using water quality modeling to monitor ecological and environmental changes in shellfish culture beds and their natural habitats in the process of setting up a master plan for management of waste water discharge into Bandon Bay; (2) zoning of shellfish mariculture in the coastal area in order to solve conflicts between resource users; (3) setting up a clear system for taxation of mariculture where the revenue may be used for (4) setting up and managing mangrove strips as filters of pollution and sediment around Bandon Bay; and finally (5) it is suggested to form a committee with members representing all relevant stakeholders plus the local government in order to work on resolving the existing and potential future conflicts over resource usage in Bandon Bay. This methodology may be seen as an important contribution towards a Bandon Bay sustainable management approach, based on the principles of integrated coastal zone management because it is science-based and takes into consideration the needs and perceptions of people involved in coastal resource extraction.     

Responses of marine fouling communities to sewage abatement in Kaneohe Bay,Oahu, Hawaii

The development of marine fouling communities was followed as part of a sewage abatement study in Kaneohe Bay (Oahu, Hawaii). Panels immersed near the outfall during sewage discharge were dominated by dense mats of blue-green algae and diatoms. This mat was significantly lighter at this station when sewage did not flow into the bay, and it never developed on panels within the same sector of the bay but away from the influence of the outfall. Taxonomic diversity, and the frequency of filamentous algae and the serpulidHydroides elegans were reduced near the outfall during discharge. It is suggested that this reduction in diversity and abundance of certain key foulers is due to competitive exclusion by the dense blue-green and diatom mats, and is not a direct effect of the sewage effluent.     

The effects of intensive aquaculture on nutrient residence time and transport in a coastal embayment

Aquaculture in many countries around the world has become the biggest source of seafood for human consumption. While it alleviates the pressure on wild capture fisheries, the long-term impacts of large-scale, intensive aquaculture on natural coastal systems need to be better understood. In particular, aquaculture may alter habitat and exceed the carrying capacity of coastal marine ecosystems. In this paper, we develop a high-resolution numerical model for Sanggou Bay, one of the largest kelp and shellfish aquaculture sites in Northern China, to investigate the effects of aquaculture on nutrient transport and residence time in the bay. Drag from aquaculture is parameterized for surface infrastructure, kelp canopies, and bivalve cages. A model for dissolved inorganic nitrogen (DIN) includes transport, vertical turbulent mixing, sediment and bivalve sources, and a sink due to kelp uptake. Test cases show that, due to drag from the dense aquaculture and thus a reduction of horizontal transport, kelp production is limited because DIN from the Yellow Sea is consumed before reaching the interior of the kelp farms. Aquaculture drag also causes an increase in the nutrient residence time from an average of 5 to 10 days in the middle of Sanggou Bay, and from 25 to 40 days in the shallow inner bay. Low exchange rates and a lack of DIN uptake by kelp make these regions more susceptible to phytoplankton blooms due to high nutrient retention. The risk is further increased when DIN concentrations rise due to river inflows.     

Sea level rise and eelgrass (Zostera marina) production: A spatially explicit relative elevation model for Padilla Bay, WA

The dynamics that govern the elevation of a coastal wetland relative to sea level are complex, involving non-linear feedbacks among opposing processes. Changes in the balance between these processes can result in significant alterations to vegetation communities that are adapted to a specific range of water levels. Given that current sedimentation rates in Padilla Bay, Washington are likely less than historical levels and that eustatic sea level rise is accelerating, the extensive Zostera marina (eelgrass) meadows in the bay may be at risk of eventual submergence. We developed a spatially explicit relative elevation model and used it to project changes in the productivity and distribution of eelgrass in Padilla Bay over the next century. The model is mechanistic and incorporates many of the processes and feedbacks that govern coastal wetland elevation change. Accretion estimates made using ²¹⁰Pb dating of sediment cores, sediment characteristics measured within cores, and eelgrass productivity and decomposition data were used to initialize and calibrate the model. Validation was performed using an elevation change rate measured with a network of surface elevation tables. Both the field data and model simulations revealed a net accretion deficit for the bay. Simulations using current rates of sea level rise indicated an overall expansion of eelgrass within Padilla Bay over the next century as it migrates from the center of the bay shoreward.     

Environmental assessment of Kuwait Bay: an integrated approach

Kuwait Bay is an imperative characteristic of the State of Kuwait. It has a number of major activities existing around it, including, business, industrial and recreational ones. The phase of construction and development of projects, and their resulting pollution have led to major change in the features of the area. The purpose of this research is to serve as a managing tool for decision-making through the environmental assessment of Kuwait Bay. Due to the multiplicities and diversities of the man-made activities and the natural environmental setting of the bay, the impacts are out looked on a holistic approach rather than on a single approach. The methodology of assessment including, sampling and analysis of water and sediment, statistical analysis, as well as application of the Rapid Impact Assessment Matrix (RAIM) in order to analysis the impacts in an integrated approach. The southern areas of the bay are the main sources of pollution that distributed northward to cover the central region of the bay. Sulaibikhat Bay (South-West sector of the bay) is the most vulnerable area due to its exposure to anthropogenic activities such as reclamations, sewage inflow and other activities. The area near Shuwaikh Port is suffering due to reclamation processes. The northern and north-west sectors suffer from coastal erosion as well as from pollutants arriving via Shatt Al Arab.     

Relationship between bottom characteristics and benthic organisms in the shallow water of Oppa Bay,Miyagi

An investigation was conducted to examine the species composition, abundance and biomass of benthic macrofaunal invertebrates in Oppa Bay, Miyagi Prefecture, Japan, in August 1984. Among 212 species identified, nearly half (105) were Polychaetes. Usually five species, Ampharete sp. 1, Neosabellides sp. 1, Nephtys polybranchia, Chaetozone sp. 1, and Lumbrineris longifolia were numerically dominant. The faunal features of dominant species were clearly divided into two areas using two indicator species, Amphalete sp. 1 and Neosabellides sp. 1. The former species decreased in numbers in the area from the river to the bay mouth, while the latter increased. Sediments consisted of sand at the river mouth and in the northern bay; and of silt-clay in the central bay, bay mouth and southern part of the bay. Gradients of species diversity (H) were expressed as a function of distance by linear regression. The relationship was positive (r=0.812) from the river to the bay mouth accompanied by increasing depth; and negative (r=-0.906) from northern to southern parts of the bay in proportion to the increase of silt-clay in sediments.     

Zooplankton community structure across an eddy-generated upwelling band close to a tropical bay-mangrove ecosystem

Mesoscale eddies in the world’s oceans are ubiquitous and bring about episodic pulses of nutrients into the photic zone. Transient in nature, the role of eddy pumping in coastal enrichment via plankton production, and subsequent organic flux is not yet fully realised. In the context of a cyclonic cold-core eddy that propagates annually under the influence of the East India Coastal Current and enriches coastal waters in the western Bay of Bengal north of 16°N, a detailed study on zooplankton community structure along with phytoplankton composition and associated water quality was undertaken during April–May 2002 coinciding with the spring intermonsoon. Zooplankton samples were collected at 32 hydrographically different (salinity 24.5–35.6 PSU) GPS fixed locations representing bay-mangrove areas and nearshore waters (30 m) close to the River Godavari, which is one of India’s largest estuarine systems. During the study, the bay-coastal waters were typified by elevated nutrient levels (nitrate 10.73–22.04 μM), high salinity (27.98–35.52 PSU), and relatively low temperatures (30.63–31.40°C). Altogether, 95 zooplankton taxa were encountered with copepods forming the predominant population. Agglomerative Hierarchical Cluster Analysis (AHCA) and Non-metric Multidimensional Scaling (NMDS) based on Bray–Curtis similarity (PRIMER) analysis revealed appreciable alterations in zooplankton structure across bay-mangrove locations and coastal waters (Stress 0.11; ANOSIM test Global R: 0.94, P = 0.1%). Similarity Percentage (SIMPER) analysis revealed zooplankton associations through “discriminating species” for each location (Kakinada Bay, Cluster I, 27.9 ± 3.0 PSU; upwelling band, cluster II, 35.5 ± 0.2 PSU; offshore waters, cluster III, 34.2 ± 0.4 PSU; mangrove outlets, cluster IV, 32.7 ± 1.3 PSU and mangrove creeks, cluster V, 33.5 ± 0.6 PSU). The index of multivariate dispersion (IMD) illustrated high variability in zooplankton standing stock for mangrove/sea locations relative to the bay. Concurrent observations on phytoplankton revealed the importance of diatoms (r: 0.640, P ≤ 0.05). Within the eddy-generated band of upwelled water, a significant top-down control of diatoms by herbivorous zooplankton resulted in a comparative increase in abundance of dinophyceans. Based on zooplankton abundance data and species association patterns, it was possible to distinguish different zooplankton/copepod communities in accordance with mesoscale variability in physical, chemical and biological processes under tropical conditions. This was confirmed through canonical correspondence analysis (CCA) that represented coastal-offshore waters and the Bay environment in this area.     

Seasonal and diurnal presence of finless porpoises at a corridor to the ocean from their habitat

A number of local populations of finless porpoises (Neophocaena phocaenoides) are widely distributed throughout the warm coastal waters of Asia. The Omura Bay population, consisting of approximately 300 individuals, is the smallest of five populations inhabiting Japanese waters. It is a relatively new population that established after the global warming that took place approximately 9000 years ago. To observe whether these porpoises appear in the major corridor to the ocean from Omura Bay, we used acoustic monitoring to record occurrences of finless porpoises from November 2007 to May 2009. A stereo acoustic event recorder recorded the intensity and the sound source direction of biosonar signals, providing independent traces of sound sources corresponding to each detected animal. A total of 226 individuals were detected over the 1.5-year monitoring period, of which 76% occurred at night and 73% occurred during March and April. We compared the presence of porpoises to the Japanese anchovy catch in Omura Bay and the Hario Strait over the same period. Results suggested that possible reductions in anchovy resources in the bay could attract porpoises to the outside of their normal habitat. In total, 70% of the porpoise recordings took place when the tidal current was moving out of Omura Bay. Porpoises might follow the prey that are transported out of the bay due to the strong outbound current. The finless porpoises confined to the bay might extend their swimming area if prey is available.     

Anthropogenic impacts on sedimentation in Jiaozhou Bay,China

In the last 150 years, China transformed its economy from a feudal system (pre-1911) to a modern market economy. During this time, policy-driven rapid development created a series of ecological and environmental problems, especially in the coastal economic regions. Although the synthetic effects are certainly identifiable, the specific effects of different policies in different developing periods have been difficult to disentangle. Here we show that the footprints of Chinese policies in the last 150 years, and their different influences on coastal environments, were archived in the temporal dynamics of sedimentation in Jiaozhou Bay. Before 1935, natural processes predominantly controlled the sedimentation in Jiaozhou Bay. After the introduction of modern economic policies in 1935, the sediment mass accumulation rate (MAR) was overwhelmingly driven by the sea areas of the bay as a result of policy-driven anthropogenic activities (i.e. saltern development, mariculture, and land reclamation). An increasing MAR at the early stage of each policy, followed by a decrease at the late stage was observed. Land reclamation in the 1990s led to a much quicker increase of MAR than the earlier saltern development. Our results demonstrated that marine exploitation, instead of natural processes, are currently regulating the ecological environments of Chinese bays.     

Océanographie biologique estivale et phytoplancton dans le sud-est de la baie d'Hudson

A biological oceanographic study of phytoplankton in the southeastern section of Hudson Bay was conducted in August and September 1976 in an effort to determine the relationships between phytoplankton and the summer hydrographic conditions in an Arctic coastal environment. Consistently low levels of nitrates were found in the deep waters of the Bay. Some physical oceanographers hypothesize that the deeper waters of Hudson Bay are uncoupled from the Atlantic Ocean, as intensive mixing of incoming oceanic waters occurs in the Hudson Strait. Such a circulation pattern, together with possibly low nutrient regeneration in Hudson Bay, could account for the low levels of nitrate observed in the deep waters. Average chlorophyll: adenosine triphosphate ratios of about 5:1 were observed in the surface coastal waters during this study, suggesting a possible nitrogen-limitation of phytoplankton at the end of the summer. The geographic distribution pattern of the phytoplankton taxa was related to the freshwater inflow from rivers and to the overall production of the phytoplankton. These results are discussed in relation to the previously reported low biological production of Hudson Bay.

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Contribution au programme du Groupe interuniversitaire de recherches océanographiques du Québec (GIROQ).     

Seasonal and interannual variability of hydrology and nutrients in the Northeastern Black Sea

The main objective of this work was to investigate the temporal variability of hydrochemical parameters in two coastal regions of the Northeastern Black Sea: the Gelendzhik bay, influenced by anthropogenic activities and the Golubaya bay an open coastal region. Dissolved oxygen, biochemical oxygen demand, pH, alkalinity, phosphate, organic phosphorus, silicates, nitrates, nitrites, ammonia, organic nitrogen, oil products and heavy metals were measured. Si/P and Si/N ratios showed that the Gelendzhik bay waters were significantly enriched in nitrogen and phosphorus compounds. Unlike the Golubaya bay, phosphates were always present in the Gelendzhik bay, and development of photo-synthesis was not limited by these. Features of seasonal variability of nutrients in the Gelendzhik bay (increased concentrations and pronounced summer-autumn maximum) appeared to be a result of human impact—outflow of nutrients with shore input and recreational activities during the summer holiday season. The data obtained indicate that pollution from local spots from the coast of the Black Sea, related primarily to eutrophication, could play a large role in the nutrient balance of the sea and could affect its ecological state.     

Dye tracing of a subsurface chlorophyll maximum of a red-tide dinoflagellate to surface frontal regions

Rhodamine dye (3701) was injected into a 22-m subsurface chlorophyll maximum of the red-tide forming dinoflagellate Prorocentrum mariae-lebouriae var. minimum in the northern Chesapeake Bay (USA) and traced for a sixday period as it spread over a 600 km² area. The precise physical mechanisms, which resulted in the transfer of dye and organisms to the surface, are documented. The major component of the dye and organisms was transported from the central bay into major tributary estuaries via net nontidal flow of bottom waters and surfaced upstream in frontal regions. Once in surface waters, the dye and organisms flowed downriver toward the bay. Due to the three-layer flow of the rivers at this time, the dinoflagellate and the rhodamine re-entered the bay proper at middepth below the fresher Susquehanna plume, thus forming a near-surface chlorophyll maximum (4–6 m) flowing in an opposite direction to the deep subsurface chlorophyll maximum (18–26 m). Current meter arrays verified the opposite flows of these two lenses. The near-surface, southward-flowing lens was followed downstream to an area where the influence of the Susquehanna begins to subside as indicated by isopycnals inclined to the surface. Here the near-surface lens is mixed upward to the surface forming massive red tides (25 000 cells ml^–1) delineated by a frontal region. In addition to the predominant along channel flow, major cross stream Ekman transport and upwelling of dye and organisms was detected in response to wind forcing resulting in localized surface patch formation along the western shore shoaling regions of the bay proper. Thus, annual variations in the locations of surface red tides can be correlated to streamflow and windinduced variations in the locations of frontal regions.     

Identifying human-induced influence on microbial community: A comparative study in the effluent-receiving areas in Hangzhou Bay

Microbial compositions showed high differences in two study areas. COD was the key anthropogenic indicator in the coastal wastewater disposal area. Distinctive microbes capable of degrading toxic pollutants were screened. Microbial communities in effluent-receiving areas followed “niche theory”. Microbial community structure is affected by both natural processes and human activities. In coastal area, anthropegenetic activity can usually lead to the discharge of the effluent from wastewater treatment plant (WWTP) to sea, and thus the water quality chronically turns worse and marine ecosystem becomes unhealthy. Microorganisms play key roles in pollutants degradation and ecological restoration; however, there are few studies about how the WWTP effluent disposal influences coastal microbial communities. In this study, sediment samples were collected from two WWTP effluent-receiving areas (abbreviated as JX and SY) in Hangzhou Bay. First, based on the high-throughput sequencing of 16S rRNA gene, microbial community structure was analyzed. Secondly, several statistical analyses were conducted to reveal the microbial community characteristics in response to the effluent disposal. Using PCoA, the significant difference of in microbial community structure was determined between JX and SY; using RDA, water COD and temperature, and sediment available phosphate and ammonia nitrogen were identified as the key environmental factors for the community difference; using LDA effect size analysis, the most distinctive microbes were found and their correlations with environmental factors were investigated; and according to detrended beta-nearest-taxon-index, the sediment microbial communities were found to follow “niche theory”. An interesting and important finding was that in SY that received more and toxic COD, many distinctive microbes were related to the groups that were capable of degrading toxic organic pollutants. This study provides a clear illustration of eco-environmental deterioration under the long-term human pressure from the view of microbial ecology.     

Long-term movements of tiger sharks satellite-tagged in Shark Bay,Western Australia

Tiger sharks are important predators in the seagrass ecosystem of Shark Bay, Australia. Although sharks appear to return to a long-term study site within the Eastern Gulf periodically, the extent of their long-term movements is not known. Five sharks fitted with satellite transmitters showed variable movement patterns. Three sharks remained within the Shark Bay region and another made a 500 km round-trip excursion to oceanic waters northwest of the bay. These four sharks showed relatively low displacement rates relative to sharks tracked over shorter time periods, suggesting that sharks move through large home ranges that include Shark Bay. Although no reliable position fixes were obtained for the fifth shark, we were able to use the timing of satellite uplinks and the position of the satellite to determine that it had moved at least 8,000 km to the coastal waters of southeast Africa in 99 days—the longest recorded movement by a tiger shark. This movement and previously documented trans-Atlantic movements suggest that tiger shark populations may mix across ocean basins and that tiger sharks are subject to anthropogenic effects at great distances from protected waters. Finally, our method for using single satellite uplinks may be useful in estimating movements for wide-ranging species that rarely provide high quality location estimates.     

福建北部海域浙闽沿岸流消亡期浮游植物的种类组成与分布特征

根据2009年4月在福建北部海域(24°47’17.0"~26°48’02.9"N,119°29’36.0"~120°57’13.8"E)所获浮游植物网采样品和同步观测的理化参数,并结合2007年"908专项"春季航次相应范围的调查资料,分析该海域浮游植物种类组成、分布特点、年际变化及其与环境因子的关系.本航次共记录浮游植物3个门类85种,其中硅藻75种、甲藻9种、蓝藻1种.物种组成以广温种为主(占47.06%),其次为暖水种(占36.47%),温带种仅占7.06%.调查区浮游植物丰度平均为137.89×104cells m-3,其平面分布呈现从近岸往外海、从北往南递增的态势.聚类分析显示本海区浮游植物可划分为2个群落,群落Ⅰ主要由近岸低盐种组成,仅分布于受浙闽沿岸流影响较直接的闽江口以北的近岸测站;群落Ⅱ主要为外海高盐种和广温广盐种,广泛分布于受台湾暖流影响较大的闽江口以南及三沙湾外侧水域.主成分分析(PCA)表明,对本海区浮游植物的分布起主导作用的是温度和盐度,而与营养盐的关系不密切,反映调查期间浙闽沿岸流已基本退出本海区,浮游植物的分布主要受制于台湾暖流.浮游植物丰度的平面分布格局与以往的调查结果基本一致,但其群落结构存在年际变化,"908专项"春季航次的优势种为近岸低盐种和广温广盐种,优势种突出,多样性指数低;而本次调查外海性广温种成为优势种之一,多样性指数(H’)和均匀度(J’)均较高,这可能与考察期间受东北季风强度所左右的浙闽沿岸流强弱有关.     

Effect and its time lags of water level fluctuations in Three Gorges Reservoir on the macroinvertebrates in a tributary bay北大核心CSCD

In order to study how water level fluctuations (WLF) of reservoir influence the macroinvertebrate in tributary bay, we studied the effect of WLF of the Three Gorges Reservior on macroinvertebrate communities in Xiangxi Bay, and the time lags of such effect, based on the surveys in spring and summer from 2005 to 2010. In this research, WLF was represented by water level drawdown (WLD) and the sum of absolute values of rate of water level fluctuations (RWlf). Pearson correlation analysis was used to analyze the relationship between WLF and macroinvertebrates. No significant correlation was found between macroinvertebrates and sum of absolute values of RWLF, while WLD showed significant influence on some biotic parameters. In spring, WLD did not cause significant effect to macroinvertebrates (P > 0.05). In summer, however, the influence was significant, especially in the area of the downstream (XX01 - XX02) of the Xiangxi Bay (P < 0.05). The middle reach of the bay (XX05), located in the conjunction area between Xiangxi Bay and a secondary tributary of the TGR, was also affected significantly (P < 0.05). The relative abundance of Tubificidae declined with the increase of the WLF, while abundance of Chironomidae increased. The time lags of the influence to macroinvertebrates were about 15 days. This analysis indicated that WLF in the mainstream of the reservoir mainly influences the downstream of the tributary bay, and also affects the conjunction area of the secondary tributary. Chironomidae are more tolerant than Tubificidae in water-body with dramatic disturbance, therefore can be considered as the indicator of the effect of summer WLF on macroinvertebrates.     

Genetic structure and gene flow of eelgrass <Emphasis Type="Italic">Zostera marina</Emphasis> populations in Tokyo Bay,Japan: implications for their restoration

Massive losses of eelgrass Zostera marina beds in Japan have occurred over the past 100 years. Toward their restoration, transplantation of eelgrass has been attempted in some areas, including Tokyo Bay. This study examined population genetic structures and gene flow in eelgrass in Tokyo Bay to establish guidelines for conducting restoration. Genotypes of a total of 360 individuals from 12 beds were determined using five microsatellite markers. The eelgrass beds in inner bay had above-average genetic diversity. A neighbor-joining tree based on F _ST values among beds revealed that a strong gene flow had occurred among six beds in the inner bay. Genetic assignment testing of drifting shoots indicated that those with seeds migrate in both directions between the inner and outer bay. We suggested that the restoration of eelgrass in the innermost part of Tokyo Bay, where natural habitats have been lost, should be conducted using the inner bay beds.