Copepod diversity in the water masses of the southern East China Sea north of Taiwan

The warm oceanic current Kuroshio and the continental shelf water of the East China Sea meet in the western North Pacific, north of Taiwan and form an upwelling when they converge. The intrusion of the Kuroshio westward over the East China Sea shelf thus results in complicated exchanges of waters between these two water masses. We studied the copepods in the plankton collection taken from an east–west transect crossing these waters in April 1995 when the intrusion of the Kuroshio over the East China Sea shelf was beginning to retreat. The taxonomy of copepods was carefully treated and erroneous species records reported in the literature were guarded against. We evaluated the copepod diversity, the association of copepod species, and the association of stations in these water masses.     

Large-scale physical controls on phytoplankton growth in the Irminger Sea, Part II: Model study of the physical and meteorological preconditioning

The upper water column in the Irminger Sea is characterized by cold fresh arctic and subarctic waters and warm saline North Atlantic waters. In this study the local physical and meteorological preconditioning of the phytoplankton development over an annual cycle in the upper water column in four physical zones of the Irminger Sea is investigated. Data from four cruises of the UK's Marine Productivity programme are combined with results from a coupled biological–physical nitrogen–phytoplankton–zooplankton–detritus model run using realistic forcing. The observations and model predictions are compared and analyzed to identify the key parameters and processes which determine the observed heterogeneity in biological production in the Irminger Sea. The simulations show differences in the onset of the bloom, in the time of the occurrence of the maximum phytoplankton biomass and in the length of the bloom between the zones. The longest phytoplankton bloom of 90 days duration was predicted for the East Greenland Current of Atlantic origin zone. In contrast, for the Central Irminger Sea zone a phytoplankton bloom with a start at the beginning of May and the shortest duration of only 70 days was simulated. The latest onset of the phytoplankton bloom in mid May and the latest occurrence of the maximum biomass (end of July) were predicted for the Northern Irminger Current zone. Here the bloom lasted for 80 days. In contrast the phytoplankton bloom in the Southern Irminger Current zone started at the same time as in Central Irminger Sea, but peaked end of June and lasted for 80 days. For all four zones relatively low daily (0.3–0.5 g C m^− 2d^− 1) and annual primary production was simulated, ranging between 35.6 g C m^− 2y^− 1 in the East Greenland Current of Atlantic origin zone and 45.6 g C m^− 2y^− 1 in the Northern Irminger Current zone. The model successfully simulated the observed regional and spatial differences in terms of the maximum depth of winter mixing, the onset of stratification and the development of the seasonal thermocline, and the differences in biological characteristics between the zones. The initial properties of the water column and the seasonal cycle of physical and meteorological forcing in each of the zones are responsible for the observed differences during the Marine Productivity cruises. The timing of the transition from mixing to stratification regime, and the different prevailing light levels in each zone are identified as the crucial processes/parameters for the understanding of the dynamics of the pelagic ecosystem in the Irminger Sea.     

The distribution of artificial radionuclides in the English Channel, southern North Sea, Skagerrak and Kattegat, 1990–1993

This paper presents the initial results concerning the distribution of artificial radionuclides from research cruises conducted in collaboration by three European institutes as part of an EEC MAST research project. Ten cruises were undertaken covering the English Channel, southern and eastern North Sea, Skagerrak and Kattegat over a period of 2.5 yr. A large number of analyses of four artificial radionuclides (¹³⁷Cs, ⁹⁹Tc, ¹²⁵Sb, ⁹⁰Sr), which behave conservatively in seawater, provided information about the general distribution of water masses and circulation patterns as well as about single transport events in the study area. Controlled liquid releases from the La Hague nuclear fuel reprocessing plant are transported eastwards, forming a characteristic distribution pattern in the Channel and the southern North Sea. This includes a near-coastal “plume” and a distinct boundary between waters contaminated predominantly by La Hague and by Sellafield. Spatial and temporal distributions of radionuclide ratios were used, for the first time, to calculate transit times from the English Channel to the coast of Jutland. The data published herein provide an essential input to the calibration of numerical models simulating water transport processes. The results demonstrate the continuing usefulness of artificial radionuclides as oceanographic tracers, even at the very low concentrations observed at present in north-west European Shelf waters.     

Autumn net copepod abundance and assemblages in relation to water masses on the continental shelf of the Yellow Sea and East China Sea

Copepod species diversity, abundance and assemblages in relation to water masses over the continental shelf of the Yellow Sea (YS) and East China Sea (ECS) were studied extensively based on the net plankton samples in autumn 2000. Multivariate analysis based on copepod assemblage resulted in recognition of five groups (Groups 1−5) corresponding to the water masses. Groups 1 and 2 delineated from inshore stations with low salinity YS Surface Water, and offshore stations with YS Cold Water in the YS. Group 3 located in the joint area of YS and ECS mainly with Mixed Water. Groups 4 and 5 in the ECS delineated two assemblages mainly from inshore and shallow stations with ECS Mixed Water in the southeastern ECS, and offshore stations along the ECS shelf edge controlled by saline Kuroshio Water. Salinity and temperature were more important in characterizing copepod assemblage of the continental shelf than chlorophyll a.     

Why is the southwest the most productive region of the East Sea/Sea of Japan?

The East Sea/Sea of Japan is a moderately productive sea that supports a wealth of living marine resources. Of the East Sea subregions, the southwest has the highest productivity. Various authors have proposed coastal upwelling, the Tsushima Current, the Changjiang Dilute Water, eddies, or discharge from the Nagdong River as potential sources of additional nutrients. In this paper, we propose, using satellite data from 1998 to 2006, that the biological productivity of the southwestern region is enhanced mainly by wind-driven upwelling along the Korean coast. Firstly, the climatology of seasonal patterns suggests that the enhanced chlorophyll a along the Korean coast is of local origin. Secondly, coastal upwelling is frequent in all seasons except winter. For example, along the coast of the Ulgi region, enhanced chlorophyll a due to coastal upwelling was observed for 25–92% of the time between Jun and Sep in the period 1998–2006. Thirdly, the advection of upwelled water through various pathways to the deeper basin was observed. Fourthly, there appeared to be a strong correlation between the interannual chlorophyll a variations of the coastal upwelling regions and the Ulleung Basin. The chlorophyll a patterns of both regions were closely related to the wind pattern in the upwelling regions, but not to that in the Ulleung Basin. Finally, changes in advection pathways also appeared to affect the productivity of the Ulleung Basin. Since 2004, there has been a shift in the pathways of upwelled water, and consequent increases in chlorophyll a in the Ulleung Basin were observed. This last observation requires further investigation.     

Modelling the effects of physical–biological interactions and spatial variability in spawning and nursery areas on transport and retention of sardine Sardinops sagax eggs and larvae in the southern Benguela ecosystem

A particle-tracking individual-based model (IBM) coupled with a 3-D hydrodynamic model was used to investigate how spatial variability in spawning and nursery grounds may influence transport and retention of sardine (Sardinops sagax) eggs and larvae in the southern Benguela ecosystem. A temperature-dependent Bělehrádek development model based on laboratory growth data was used to determine the duration of one egg and two larval stages. Successful transport/retention depended on each particle's stage of development rather than its age. Results show that recruitment could occur in two distinct nursery areas on the west and south coasts of South Africa. Three viable recruitment ‘systems’ were identified: two are retention-based (spawned and retained on the west coast (WC–WC) or the south coast (SC–SC)) and one is transport-based (spawned on the south coast and transported to the west coast (SC–WC)). In the WC–WC system, the vertical distribution of eggs influenced retention; at intermediate depths of spawning (25–50 m) eggs avoided both offshore Ekman drift and deep cold water. In the SC–SC system, the area of spawning was important; > 50% of eggs from the eastern Agulhas Bank (EAB) were retained in the south coast nursery grounds, whereas very few eggs were transported there from west of Cape Agulhas. In the SC–WC system, area of spawning was also important; 40% of the eggs spawned on the western Agulhas Bank (WAB) were transported to the west coast nursery ground. Sardine life history strategy could be divided between two main systems: the west coast system (spawning on the WAB and WC, and recruiting to the WC) and the Agulhas Bank system (spawning on the central and eastern Agulhas Bank, and recruiting to the SC).     

中国沿海台风的统计特征及台风浪的数值模拟

文章统计了自1945年以来北太平洋地区相关预报中心的数据,采用NOAA(National Oceanic and Atmospheric Administration)的卫星数据,对影响中国沿海的台风的路径、气压等特征做了统计分析,得到了登陆台风的9种典型路径以及最低气压的空间分布。其次采用第三代海浪数学模型SWAN(Simulating Wave Nearshore)模拟了东海特征路径上的台风。     

Pigments, size and distribution of Synechococcus spp. in the Black Sea

Pigments, size and distribution of Phycoerythrin-containing unicellular cyanobacteria Synechococcus spp. within the euphotic zone were studied for the first time in April–May 1994 in the western and southwestern Black Sea by epifluorescence microscopy and flow-cytometry. Synechococcus was present in varying quantities at every station and depth studied. Surface spatial distribution of Synechococcus revealed that cells were much more abundant in offshore waters than near coastal regions under the direct influence of the Danube river. Minimum and maximum cell concentrations ranged between 9×10² and 1.45×10⁵ cells/ml at the surface, between 2×10³ and 1.23×10⁵ cells/ml at the chlorophyll sub-maximum layer, and between 1.3×10² and 3.5×10² at the nitrite maximum layer. Cells at the chlorophyll sub-maximum layer (based on in-situ fluorometer readings) fluoresce brighter and longer than the ones at the surface and lower depths. Spectral properties of chromophore pigment types of total 64 clonal isolates from different depths down to the lower layer of the euphotic zone (60 m) in the southern Black Sea coast revealed that all have type 2 phycoerythrobilin in common, lacking in phycourobilin. In vivo fluorescence emission maxima for the phycoerythrobilin were about the same (578 nm) for all isolates. All isolates examined showed in vivo absorption maxima at between 435 and 442 nm and at about 681 nm due to chlorophyll-a. Based on the flow cytometer mean forward light scatter data for size distribution, it could be concluded that cells at the surface mixed layer (0–10 m) were larger in cell size than the cells at lower depths (20–60 m).     

Large-scale physical controls on phytoplankton growth in the Irminger Sea Part I: Hydrographic zones, mixing and stratification

Hydrographic surveys in three consecutive seasons in the Irminger Sea in 2001/2002 have revealed six physical regimes (zones) in which different surface mixing and spring re-stratification processes dominate. They are the South Irminger Current, the North Irminger Current, the Central Irminger Sea, the Polar-origin East Greenland Current, the Atlantic-origin East Greenland Current and the Reykjanes Ridge. The variations in restratification processes in particular have significant implications for the timing of shallow spring mixed layer development and therefore the timing and strength of the spring bloom. The relative roles of heat and freshwater in controlling re-stratification are examined for each hydrographic zone, and it is shown that the simplest concept of solar warming generating spring stratification is appropriate for the Irminger Current and the central Irminger Sea. However in the East Greenland Current and the Reykjanes Ridge zones, the springtime arrival of fresh or saline water at the surface dominates re-stratification and generates the earliest and strongest spring blooms of the region. In the cool fresh centre of the Irminger Sea the relatively low chlorophyll-a throughout the year cannot be wholly explained by stratification or nutrient concentrations. Details of the annual cycle in temperature, salinity, chlorophyll-a and nutrients are presented for each hydrographic zone.     

Biological effects of dilution of Dead Sea brine with seawater: implications for the planning of the Red Sea–Dead Sea “Peace Conduit”

The Dead Sea is a severely disturbed ecosystem. Its water level has been decreasing at a rate of nearly 1 m per year during the last decade due to anthropogenic intervention in its water balance. Since the peace treaty between Israel and Jordan was established in 1994, a proposal for the construction of a water carrier, the “Peace Conduit,” between the Gulf of Aqaba (Red Sea) and the Dead Sea is being investigated. This water carrier is intended to mitigate damaging processes that currently occur in the Dead Sea and its surrounding area. The difference in elevation of about 416 m could be exploited for seawater desalination by reverse osmosis. To examine the possible effects of the mixing of Dead Sea brines with seawater and seawater concentrates on the Dead Sea as an ecosystem, we have set up simulation experiments under field conditions in experimental ponds at Sedom, in which Dead Sea water was diluted with Red Sea water. The main components of the Dead Sea biota are the unicellular green alga Dunaliella and several types of red halophilic Archaea. Phosphate is the limiting inorganic nutrient. Massive Dunaliella blooms developed, accompanied by dense communities of red halophilic Archaea, in some of the experimental ponds, imparting a brown-red coloration to the brines. The extent of biological development depended on the extent of dilution and on phosphate availability. The results of the simulation experiments show that biological phenomena and their impact on the Dead Sea ecosystem should be taken into consideration during the planning of the “Peace Conduit.”     

Distributions of oxygen and carbon stable isotopes and CFC-12 in the water masses of the Southern Ocean at 30°E from South Africa to Antarctica: results of the CIVA1 cruise

This study presents oceanic distributions of stable isotopes (δ¹⁸O of water and δ¹³C of ΣCO₂) and CFC-12 from samples collected during the CIVA1 cruise (February/March 1993), across the Southern Ocean, along a meridian section at 30°E, from South Africa (44°S) to Antarctica (70°S). The isotopic measurements show important variations between the subantarctic surface waters with low δ¹⁸O–high δ¹³C values and the antarctic surface waters with very low δ¹⁸O–low δ¹³C values. The surface distributions of δ¹³C values follow the major frontal oceanic structures; the vertical distribution shows the progressive upwelling from the subantarctic zone to the antarctic divergence of ¹³C-depleted CO₂ derived from remineralization of organic matter. Along the Antarctic continental shelf, between 2500 and 4000 m, a core of water with δ¹⁸O values close to −0.1‰ is associated with a relative maximum in CFC-12 concentration, although this core is not detected by its temperature and salinity parameters. This water mass, which corresponds to recently formed deep water, may originate from the eastward extension of the Weddell gyre or from bottom waters coming from the East and formed near Prydz Bay.     

Eddies around Madagascar — The retroflection re-considered

The Agulhas Current with its retroflection and attendant eddy-shedding is the cause of some of the greatest mesoscale variability in the ocean. This paper considers the area to the south and east of Madagascar, which provides some of the source waters of the Agulhas Current, and examines the propagating sea surface height signals in altimetry and output from a numerical model, OCCAM. Both show bands of variability along the axis of the East Madagascar Current (EMC) and along a zonal band near 25°S. Sequences of images plus associated temperature data suggest that a number of westward-propagating eddies are present in this zonal band. The paper then focuses on the region to the south of the island, where ocean colour and infra-red imagery are evocative of an East Madagascar Retroflection. The synthesis of data analysed in this paper, however, shows that remotely observed features in this area can be explained by anticyclonic eddies moving westward through the region, and this explanation is consistent with numerical model output and the trajectories of drifting buoys.     

Th-derived particulate organic carbon fluxes in the northern Barents Sea with comparison to drifting sediment trap fluxes

Large-volume sampling of ²³⁴Th was conducted to estimate particulate organic carbon (POC) export in conjunction with drifting sediment trap deployments in the northern Barents Sea in July 2003 and May 2005. ²³⁴Th-derived POC fluxes averaged 42.3 ± 39.7 mmol C m^− 2 d^− 1 in 2003 and 47.1 ± 30.6 mmol C m^− 2 d^− 1 in 2005. Sediment trap POC fluxes averaged 13.1 ± 8.2 mmol C m^− 2 d^− 1 in 2003 and 17.3 ± 11.4 mmol C m^− 2 d^− 1 in 2005, but better reflected the transient bloom conditions that were observed at each station within a season. Although ²³⁴Th fluxes agreed within a factor 2 at most stations and depths sampled, sediment trap POC fluxes were lower than large-volume POC flux estimates at almost every station. This may represent an under-collection of POC by the drifting sediment traps or, conversely, an over-collection of POC by the large-volume sampling of ²³⁴Th. It is hypothesized that the offset between the two methods is partly due to the presence of the prymnesiophyte Phaeocystis pouchetii, which potentially causes a large variation in > 53-μm POC/²³⁴Th ratios. Due to the large proportion of dissolved carbon or mucilage released by P. pouchetii, and because it is thought that P. pouchetii does not contribute significantly to the vertical export of biogenic matter in the Barents Sea, the application of large-volume sampling of ²³⁴Th may yield relatively high, and possibly inaccurate POC/²³⁴Th ratios. Hence, POC fluxes derived from ²³⁴Th sampling may be inappropriate and drifting sediment traps might be a more reliable method to measure the vertical export of biogenic matter in regions that have recurrent P. pouchetii blooms, such as the Barents Sea.     

Surface patterns of zooplankton spatial variability detected by high frequency sampling in the NW Mediterranean. Role of density fronts

High frequency sampling was performed in daylight hours along a 35 km transect in the Ligurian Sea to investigate the upper layer zooplankton distribution during the spring phytoplankton bloom. The results show detailed spatial structure and biomass of key zooplankton functional groups, copepods, salps and krill larvae, within the different water masses characterizing this region. Although observed values of total copepod biomass distribution were rather constant along the transect, species-specific patterns were observed in the copepod spatial distribution. The larger species Calanus helgolandicus, as well as Centropages typicus, Oithona spp., and Oncaea spp., were associated with the frontal zone. However, Acartia spp. had a scattered distribution, and Clausocalanus/Paracalanus did not have a clear pattern. In addition, krill larvae were concentrated in the frontal area and salps had a scattered pattern. The cross-shore zooplankton distribution appeared strongly influenced by both the Northern Ligurian current governing inshore waters, which acts as a major flushing forcing, and the Ligurian front, which governs offshore waters and may act as retention area for zooplankton.     

Chemical and physical fronts in the Bohai, Yellow and East China seas

Associated with strong mixing and stirring, as well as enhanced bioproductivity and ecotones, oceanic fronts have garnered worldwide attention in recent years. Research into oceanic fronts, especially thermal fronts, has gained momentum since the advent of satellites and their increased accessibility. Yet, studies of salinity and nutrient fronts —particularly those that are subsurface are few and far between. This study reviews the most widely accepted facts about surface and subsurface temperature and salinity fronts in the Bohai, Yellow and East China seas and their seasonal variations. The distribution of nutrients in the surface and bottom waters are mapped and nutrient fronts, for the first time, are identified systematically.These fronts are generally strongest in winter when southward flowing coastal currents are influenced most by winter monsoons, and the contrasts between these cold, fresh, nutrient-rich currents and the northward flowing warm, saline but nutrient-poor Kuroshio are strongest. Surface fronts are generally weakest in summer when coastal currents may be weaker and temperature, salinity and nutrient contrasts are diminished. The existence of fronts and why some are disconnected are mainly related to oceanic features such as topography, boundaries between water masses and current flow patterns. Three latitudinal temperature and nutrient fronts in the southern East China Sea in winter may suggest eastward flowing currents. These currents have not been described previously.     

Mussel and Seaweed Cultivation in Offshore Wind Farms: An Opinion Survey

German coastal regions and adjacent offshore waters are claimed for a variety of different, and often overlapping, uses. Conflicts of interest are expected to increase due to the planned construction of offshore wind farms. The development of an integrated approach combining different commercial activities, such as open ocean aquaculture and wind farming, could be a possible solution to overcome these conflicts. To illuminate existing perception and opinions on this multiple-use idea, this study examines the attitudes of representatives of eight different actor groups toward potential offshore wind farm–mariculture integration in the German North Sea. Results from our questionnaire survey show that the respondents’ attitudes toward the suggested multiple-use setting seem to be largely influenced by their general opinion toward offshore wind farms. The Fisheries actor group differs from the other questioned groups in that negative attitudes are overall predominant. This case study points to the need for a credible mechanism that more successfully integrates key actor groups, such as fisheries, into future planning and research issues.     

Dynamics of inorganic nutrient species in the Bohai seawaters

Within the frame of a Sino-German Joint Research Program, two cruises of “R/V Dong Fang Hong 2” were carried out in September–October 1998 and April–May 1999, respectively, to understand the dynamics of nutrients in the Bohai. Nutrient species (NO₃⁻, NO₂⁻, NH₄⁺, PO₄³⁻ and SiO₃²⁻) are determined colorimetrically on board for five anchor and 30 grid stations. In situ incubation experiments are performed to determine planktonic nutrient uptake and benthic exchange flux. Nutrient concentrations display short-term variability and seasonal change in the Bohai, with higher levels in shallow coastal waters than in the Central Bohai. The influence of riverine discharge on nutrient levels can be seen from salinity isopleths, nutrient distribution and species ratios. Near-bottom (nb) waters have similar nutrient concentrations as to the surface waters in the Central Bohai, whereas stratification takes place in the Bohai Strait and North Yellow Sea. In situ incubation experiments provide evidence that the uptake ratio (i.e. N, P) by phytoplankton is proportional to the ratios among nutrient species in ambient waters. Based on the data of this study and previously publications, a preliminary estimate of nutrient budgets via riverine input and atmospheric deposition is established. The results indicate that atmospheric deposition gains importance over rivers in delivering nutrients into the Bohai and sustain the new production, following recent decrease in riverine inflow caused by drought periods in North China and damming practices. A historical review of nutrient data indicates that concentrations of nitrogen increase and phosphorus and silica decrease in the Central Bohai over last 40 years. This potentially has an important influence on the health of ecosystem in Bohai (e.g. food web and community structure), though further study is needed to examine the scenario in more detail.     

Inshore Stocks of Atlantic Cod Are Important for Rebuilding the East Coast Fishery

Cod (Gadus morhua) inhabit not only the famous fishing banks of the Northwest Atlantic continental shelf, but also inshore waters from Labrador to New England. Relatively little is known about the life history of inshore cod, their historic levels of abundance, and their relationship to offshore stocks. Inshore cod stocks along the East Coast should be managed under a new paradigm that recognizes the importance of these fish to the stock complex. Recently documented fishers' ecological knowledge (FEK) suggests inshore stocks of cod may exist along the Newfoundland and Labrador coastline that have yet to be scientifically documented. Coastal communities adjacent to the local population of cod in Gilbert Bay, Labrador have initiated efforts to protect and manage this stock locally through a co-management approach. The Gilbert Bay experience, FEK, and related science and education could provide insight into ways to protect and enhance the health of local stocks remaining along the northeast coast of North America.     

东海海上风电场通航安全对策研究

作为国家级示范项目、上海市重点工程——东海海上风电场，其施工及运行安全问题倍受瞩目。现根据该项目规划，结合水域特点，对其施工和运行期间的通航安全问题进行研究，并提出对策，为今后其他海上风电项目的建设积累宝贵经验。     

An Overview of Spatial Management and Marine Protected Areas in the East China Sea

Marine ecosystems of the East China Sea are rich in biodiversity, with 12,933 species of which approximately 47.7% are endemic. As anthropogenic impacts are intensifying, fishery resources and biodiversity in the East China Sea are under threat from overfishing, habitat loss, pollution, and biological invasions. Marine protected areas (MPAs) and other spatial management measures are believed useful tools to protect and restore biological resources. Seventeen nature reserves, seven special marine reserves, and three fishery resource conservation zones covering a combined area of 102,156 km² have so far been established in the Chinese East China Sea in order to protect fishery resources, biodiversity, and marine landscapes. This article provides a review and inventory of MPAs in the Chinese East China Sea as implemented by the People's Republic of China.