The wind-forced response on a buoyant coastal current: Observations of the western Gulf of Maine plume

The freshwater plume in the western Gulf of Maine is being studied as part of an interdisciplinary investigation of the physical transport of a toxic alga. A field program was conducted in the springs of 1993 and 1994 to map the spatial and temporal patterns of salinity, currents and algal toxicity. The observations suggest that the plume's cross-shore structure varies markedly as a function of fluctuations in alongshore wind forcing. Consistent with Ekman drift dynamics, upwelling favorable winds spread the plume offshore, at times widening it to over 50 km in offshore extent, while downwelling favorable winds narrow the plume width to as little as 10 km.Using a simple slab model, we find qualitative agreement between the observed variations of plume width and those predicted by Ekman theory for short time scales of integration. Near surface current meters show significant correlations between cross-shore currents and alongshore wind stress, consistent with Ekman theory. Estimates of the terms in the alongshore momentum equation calculated from moored current meter arrays also indicate a dominant Ekman balance within the plume. A significant correlation between alongshore currents and winds suggests that interfacial drag may be important, although inclusion of a Raleigh drag term does not significantly improve the alongshore momentum balance.     

The Prince Edward Islands pelagic ecosystem, south Indian Ocean: a review of achievements, 1976–1990

This review summarizes the main research findings of the multi-year oceanographic and biological studies conducted in the vicinity of the Prince Edward Archipelago during the period 1976 to 1990. The Prince Edward Islands represent a flow-through system on the mainstream of the Antarctic Circumpolar Current. Although there are no taxonomic differences between the pelagic communities of the upstream, inter-island and downstream regions, these mesoscale subsystems may operate differently. The mesoscale oceanographic and biological processes appear to be affected by the position of the Subantarctic Front (SAF) in the vicinity of the islands. Both the rich benthic community, which is supported by the local enhancement of primary production, and the strong advection of zooplankton/micronekton from the upstream region provide the food resources necessary for the survival of the huge community of land-based predators present on the islands. Collectively this is termed the ‘life-support system'. Future studies should concentrate on the meridional shifts in the position of the SAF and its influence on background productivity upstream and downstream of the Prince Edward Archipelago.     

Weaving marine food webs from end to end under global change

Marine food web dynamics are determined by interactions within and between species and between species and their environment. Global change directly affects abiotic conditions and living organisms, impinging on all trophic levels in food webs. Different groups of marine researchers traditionally study different aspects of these changes. However, over medium to long time scales perturbations affecting food webs need to be considered across the full range from nutrients to top predators. Studies of end-to-end marine food webs not only span organism sizes and trophic levels, but should also help align multidisciplinary research to common goals and perspectives. Topics are described that bridge disciplinary gaps and are needed to develop new understanding of the reciprocal impacts of global change on marine food webs and ocean biogeochemistry. These include (1) the effects of nutrients on biomass and production, (2) the effects of varying element ratios on food web structure and food quality, (3) bulk flows of energy and material in food webs and their efficiencies of transfer, (4) the ecological effects of species richness and the roles of microbial organisms, (5) the role of feeding behaviour in food web dynamics and trophic controls, (6) the spatial dynamics of communities and links between different food webs, (7) the combined effects of body size and behaviour in determining dynamics of food webs, and (8) the extent to which the ability of marine organisms (and communities) to adapt will influence food web dynamics. An overriding issue that influences all topics concerns the time and space scales of ecosystem variability. Threads link different nodes of information among various topics, emphasizing the importance of tackling food web studies with a variety of modelling approaches and through a combination of field and experimental studies with a strong comparative approach.     

基于"当前"统计模型的机动目标运动要素解算

在避碰过程中,舰船一般处于机动状态.因而,对机动目标运动要素解算的精度直接影响到避碰的效果.通过对多种模型的比较,选用了"当前"统计模型,"当前"统计模型相对于其他模型能够更为真实地反映目标的机动变化.仿真结果表明,此算法收敛迅速并有较高精度,其解算所得的目标运动要素能够满足舰船避碰等实用要求.     

Fluxes of biogenic carbon in the Southern Ocean: roles of large microphagous zooplankton

The Southern Ocean is an extreme environment, where waters are permanently cold, a seasonal ice cover extends over large areas, and the solar energy available for photosynthesis is severely restricted, either by vertical mixing to considerable depths or, especially south of the Antarctic Circle, by prolonged seasonal periods of low or no irradiance. Such conditions would normally lead to low productivity and a water column dominated by recycling processes involving microbial components of pelagic communities but this does not seem to be the case in the Southern Ocean, where there is efficient export to large apex predators and deep waters. This paper investigates the role of large microphagous zooplankton (salps, krill, and some large copepods) in the partitioning of biogenic carbon among the pools of short- and long-lived organic carbon and sequestered biogenic carbon. Large microphagous zooplankton are able to ingest microbial-sized particles and thus repackage small, non-sinking particles into both metazoan biomass and large, rapidly sinking faeces. Given the wide spatio-temporal extent of microbial trophic pathways in the Southern Ocean, large zooplankton that are omnivorous or able to ingest small food particles have a competitive advantage over herbivorous zooplankton. Krill efficiently transfer carbon to a wide array of apex predators and their faecal pellets are exported to depth during occasional brief sedimentation episodes in spring time. Salps may be a significant link towards some fish (directly) and other apex predators (indirectly) and, at some locations (especially in offshore waters) and time, they may account for most of the downward flux of biogenic carbon. Large copepods are a trophic link towards fish and at least one whale species, and their grazing activity generally impedes the export of organic particles to depth. As a result, biogenic carbon is channelled mainly towards apex predators and episodically into the deep ocean. Without these original interactions, Antarctic waters might well be dominated by microbial components and recycling processes instead of active export from the generally small primary producers towards large apex predators.     

Eradication of algae in ships'' ballast water by electrolyzing

In order to verify the effectiveness of electrolytic treatment on ships' ballast water,experiments are carried out by a pilot system in laboratory. The raw seawater and seawater with different concentrations of different algae are simulated as ships' ballast water. The algae in the raw seawater can be killed if it is treated by electrolysis with an initial residual chlorine concentration of 5 mg/L. If the seawater with one kind of algae (Nitzschia closterum, Dicrateria spp., or Pyramidomonnas sp.105cells/mL) is treated by electrolysis with an initial residual chlorine concentration of 5 mg/L, the alga can be sterilized. If the seawater with one kind of algae (Dunaliella sp., Platymonas or Chlorella spp.)is directly treated by electrolyzing with an initial residual chlorine concentration of 4 mg/L, the instant mortality changes with the concentration of different algae. However, after 72 hours, in all treated samples, there are no live algal cells found.     

多船避碰决策理论与模型分析

考虑到多船避碰的影响因素众多,除考虑周围船舶的态势外,还需考虑风流等自然因素的影响,以及避碰规则的种种制约,为此,分析多船的会遇局面以及避碰的机理,充分考虑影响避碰的各个因素,运用静态非完全信息的博弈论建立多船避碰决策的数学模型.     

Small scale retentive structures and Dinophysis

Despite its rarity, Dinophysis acuminata is in terms of economic impact, the first toxic algal species along the coasts of Western Europe. It is observed at low levels (< 20 cell l^− 1) all the year round but toxic events occur mainly in late spring and summer. D. acuminata ecophysiology is largely unknown due to the inability to culture it. Therefore, standard biomass models based on inorganic nutrition are largely inadequate. Presently, any progress in describing the conditions of population growth of this species will be a step forward to prediction of harmful events at the coast. This species has been observed at increased, albeit low cell densities in retentive eddies located in pycnocline layers. A concentration build-up of one species results from the balance between growth and loss processes, one of the latter being dispersal. The scales of interest for a D. acuminata population are of the order of 10 nautical miles on the horizontal and duration of 10 days, for a reported achievable growth rate of 0.6 day^− 1. A three dimensional (3D) hydrodynamical model of the Bay of Biscay has been elaborated to reproduce hydrological structures over the last decade. We attempt here to relate the existence of retentive structures revealed from simulations under realistic forcing conditions and the toxic coastal events recorded in the 10-year time series of the French plankton monitoring network database. The eddies in the coastal area appear to be directly related with the Dinophysis coastal events and they may be a potential effective tool to predict those.     

On the relation of structure, perception and activity in marine planktonic copepods

The goal of this paper is to illustrate how in juvenile and adult subtropical marine planktonic copepods various structures or morphological features function in concert to detect prey and predators. Without motion by either food (e.g. flagellate, ciliate) or feeder (e.g. feeding current) or both (e.g. Acartia spp. and ciliate) few feeding activities will occur. Through motion a food particle is either perceived mechanically or chemically to be followed by appendage activities. A combination of mechano- and chemosensors on their cephalic appendages (and probably on other extremities) serve juvenile and adult copepods to perceive signals. Perception is followed by alternation of motion and sensing by these appendages, or by no motion at all (e.g. behavior by Eucalanus pileatus when perceiving a weak hydrodynamic signal). Non-moving and extended sensors (setae) are best suited for mechanical/hydrodynamic perceptions in those copepods which lack a feeding current and hardly move. Numerous mechanosensors arranged in three dimensions on the first antennae (A1) are required to perceive the precise location of moving prey at a distance (e.g. Oithona feeding on ciliates but also sinking particles). Those copepods which create a weak or intermittent feeding current can supplement nutrition with carnivory, which requires perception by the A1 (e.g. Centropages velificatus adults). These two groups require, in addition to perception of prey motion/location, rapid motion by their appendages (A1, second maxillae M2, etc.) to capture the prey. Nauplii, which satiate at far lower food levels than adults, have one of several means of food acquisition: encounter through forward motion, perception through feeding current, or perception of a moving food particle. The nearly continuous motion of most calanoid nauplii makes them vulnerable to predation because all three pairs of appendages are usually moving. Opposite are nauplii of cyclopoid and a few calanoid species which move only occasionally. Copepodid stages and adults use non-moving and often extended setae on the tips of their A1 to perceive predators at a distance. This structure and their pronounced escape motion may reduce their vulnerability to predation as compared to nauplii.     

A generalized model of pelagic biogeochemistry for the global ocean ecosystem. Part II: Numerical simulations

This paper presents a global ocean implementation of a multi-component model of marine pelagic biogeochemistry coupled on-line with an ocean general circulation model forced with climatological surface fields (PELAgic biogeochemistry for Global Ocean Simulations, PELAGOS). The final objective is the inclusion of this model as a component in an Earth System model for climate studies. The pelagic model is based on a functional stoichiometric representation of marine biogeochemical cycles and allows simulating the dynamics of C, N, P, Si, O and Fe taking into account the variation of their elemental ratios in the functional groups. The model also includes a parameterization of variable chlorophyll/carbon ratio in phytoplankton, carrying chl as a prognostic variable. The first part of the paper analyzes the contribution of non-local advective–diffusive terms and local vertical processes to the simulated chl distributions. The comparison of the three experiments shows that the mean chl distribution at higher latitudes is largely determined by mixing processes, while vertical advection controls the distribution in the equatorial upwelling regions. Horizontal advective and diffusive processes are necessary mechanisms for the shape of chl distribution in the sub-tropical Pacific. In the second part, the results have been compared with existing datasets of satellite-derived chlorophyll, surface nutrients, estimates of phytoplankton community composition and primary production data. The agreement is reasonable both in terms of the spatial distribution of annual means and of the seasonal variability in different dynamical oceanographic regions. Results indicate that some of the model biases in chl and surface nutrients distributions can be related to deficiencies in the simulation of physical processes such as advection and mixing. Other discrepancies are attributed to inadequate parameterizations of phytoplankton functional groups. The model has skill in reproducing the overall distribution of large and small phytoplankton but tends to underestimate diatoms in the northern higher latitudes and overestimate nanophytoplankton with respect to picoautotrophs in oligotrophic regions. The performance of the model is discussed in the context of its use in climate studies and an approach for improving the parameterization of functional groups in deterministic models is outlined.     

Influence of horizontal model grid resolution on the simulated primary production in an embedded primary production model in the Norwegian Sea

The purpose of this paper is to investigate the influence of horizontal grid resolution in a physical model on an embedded primary production model. The area for the experiment was along the west coast of Norway, from 60° N to 70° N, an area of high mesoscale activity. The HYbrid Coordinate Ocean Model was coupled with the NORWegian ECOlogical Model system, and run in a nested system, consisting of three model grids with horizontal resolution of 50 km, 16 km and 4.5 km (hereafter: COARSE, MEDIUM and FINE) in the focus area. Two main results were obtained, first, the composition of the phytoplankton functional groups changed with increasing model grid resolution. In FINE, the diatoms produced a larger part (60%) of the total annual primary production than the flagellates, whereas in COARSE and MEDIUM, the primary production from the two phytoplankton groups was the same. This was explained by a higher transport of silicate into the euphotic layer in FINE compared to the other two. Second, the differences in the primary production first became large when the resolution of the model grid reached the Rossby radius of deformation. Whereas the total net primary production in MEDIUM only was 5% larger than in COARSE, the total net primary production in FINE was 20% higher than in COARSE. This was explained by the models ability to resolve mesoscale activity.     

基于排队论的湛江港湾内锚地总体布局分析

针对湛江港湾内船舶密度大、种类多、大小各异以及锚位供不应求的情况,为科学规划锚地,通过实地调研湛江港锚泊需求和锚地运行状况,在锚位等级划分的基础上,利用排队论方法建立湛江港湾内最佳锚位数的计算模型,并基于测算出的锚位需求提出近期和远期锚地规划方案。相比于不做锚位等级划分而单一计算锚位数的做法,得出的湛江港湾内锚泊需求更符合实际,锚地位置布局更合理、功能划分更完善、锚泊安全更有保障,可以减少锚地过度建设造成的资金浪费,具有显著的社会经济效益。     

Effects of job demands and social interactions on fatigue in short sea cargo shipping

Although fatigue is considered an important problem in shipping, little is known about potential mitigating factors or resources for coping. Adopting a Job Demands–Resources framework, this article examines the effects of both job demands (stressors) and resources on fatigue, focusing on social interactions on board as a potential source of social support. Using an incomplete repeated-measures design, the study combined information from documents with surveys on seven cargo ships. Findings indicated that fatigue levels were highest for those working on deck and for individuals at higher hierarchical levels. Higher numbers of port calls (and to some extent lower numbers of days at sea) also increased fatigue levels. By contrast, night watches and the number of days in port had no effect on fatigue. Supportive social interactions reduced fatigue (main effect), but their effect was weaker when the number of port calls increased (interaction effect). All main effects were mediated by individuals’ perceptions of work pressure. Taken together, findings highlight the importance of considering social interactions on board to advance our understanding of stressors and strain in seafaring.     

协调版共同结构规范对港口工况下散货船的影响分析

协调版共同结构规范（CSR-H）对港口工况下船体梁强度和船体构件局部强度的要求与先前的油船共同结构规范（CSR-OT）基本一致,而相比散货船共同结构规范（CSR-BC）有明显变化。通过对比分析CSR-H和CSR-BC对于港口工况具体要求的差异,并结合实船数据分析,阐述基于CSR-H要求的港口工况对散货船结构设计的影响;并探讨针对符合CSR-H的散货船,如何合理选取船体梁许用静水弯矩值和许用静水剪力值。     

纤维增强塑料（FRP）筋混凝土结构在港口工程中的应用

为解决海港工程中钢筋混凝土结构钢筋锈蚀问题,采用纤维增强塑料（FRP）筋代替传统钢筋,结合国内外相关规范,提出了港口工程中适用的FRP筋增强混凝土构件的设计计算方法,并对不同的设计控制指标进行了足尺寸构件力学性能试验验证,同时在某出运码头部分节段全部采用纤维增强塑料（FRP）替代钢筋工程试验,为解决港口工程耐久性问题提供了良好的工程实例。     

The influence of upwelling and entrainment on the algal bloom in the Baltic Sea

Hydrodynamic processes control many geochemical and ecological processes in the sea. In this paper, the influence of up- and downwelling and entrainment on the ecosystem components are studied. The ecohydrodynamic model was initially used to simulate the whole Baltic Sea to get the boundary conditions for the Gulf of Riga. Then, to study the influence of different hydrodynamic conditions on the algal bloom, three simulations were made for the Gulf of Riga using different boundary and entrainment conditions. It appears that upwelling in the gulf was strongly dependent on open boundary conditions between the Baltic Proper and the gulf. The vertical transport in the Gulf of Riga was many times more intensive in the calculation system Baltic Proper and Gulf of Riga, than in the case where only the Gulf of Riga was simulated. The blue–green algal bloom was influenced by the vertical transport due to different nutrients' limitation mechanism.     

Winter–spring dynamics in sea-ice carbon cycling in the coastal Arctic Ocean

An understanding of microbial interactions in first-year sea ice on Arctic shelves is essential for identifying potential responses of the Arctic Ocean carbon cycle to changing sea-ice conditions. This study assessed dissolved and particulate organic carbon (DOC, POC), exopolymeric substances (EPS), chlorophyll a, bacteria and protists, in a seasonal (24 February to 20 June 2004) investigation of first-year sea ice and associated surface waters on the Mackenzie Shelf. The dynamics of and relationships between different sea-ice carbon pools were investigated for the periods prior to, during and following the sea-ice-algal bloom, under high and low snow cover. A predominantly heterotrophic sea-ice community was observed prior to the ice-algal bloom under high snow cover only. However, the heterotrophic community persisted throughout the study with bacteria accounting for, on average, 44% of the non-diatom particulate carbon biomass overall the study period. There was an extensive accumulation of sea-ice organic carbon following the onset of the ice-algal bloom, with diatoms driving seasonal and spatial trends in particulate sea-ice biomass. DOC and EPS were also significant sea-ice carbon contributors such that sea-ice DOC concentrations were higher than, or equivalent to, sea-ice-algal carbon concentrations prior to and following the algal bloom, respectively. Sea-ice-algal carbon, DOC and EPS-carbon concentrations were significantly interrelated under high and low snow cover during the algal bloom (r values ≥ 0.74, p < 0.01). These relationships suggest that algae are primarily responsible for the large pools of DOC and EPS-carbon and that similar stressors and/or processes could be involved in regulating their release. This study demonstrates that DOC can play a major role in organic carbon cycling on Arctic shelves.     

Hinterland strategies of port authorities: A case study of the port of Barcelona

Port authorities generally focus on the development of the local port area and play a minor role in the development of port hinterlands, whereas shippers, forwarders, barge and rail operators have always been involved in the port-hinterland connection. The increasing importance of intermodal hinterland networks for the competitive position of ports has urged port authorities to become active in the hinterland. This new role has already been suggested by different academics. However, limited empirical evidence exists of port authorities taking stakes in inland terminals or developing transport services. Barcelona, as one of the leading port authorities in this respect, is used as a case study in this paper. The case study provides insight in the components and execution of the hinterland strategy of Barcelona. It shows that the strategy of the port authority of Barcelona and the consequent active involvement in the hinterland has had a significant impact on attracting container volumes from distant hinterlands and improving the accessibility of the port.     

Are the innovation processes in seaport terminal operations successful?

The maritime and port sector is widely considered conservative concerning the ability to introduce innovation in respect to other industries. This may be due to the lack of cooperative interactions among the several players involved. It does not mean that innovation does not occur in this industry. Along with some technical innovations, managerial, organizational, and cultural innovations also take place in the sector. The literature has considered the assessment and effects of the adoption of particular innovation, but still few studies underline the innovation path in a broad sense with a specific focus on terminal operators. The present article aims at filling this gap through a field analysis grouping together case studies developed in different world regions and examining the adoption path of innovation through a mix of three different techniques (i.e. the H- and I-indexes, a Systems of Innovation Analysis, and a Qualitative Comparative Analysis). Research outcomes underline how, even if no unique recipe for success can be found, specific factors (e.g. a ranking of innovation objectives, coordination among actors, and institutions) can influence the achievement of success. The analyses allow suggesting strategic and policy advice that may help link in a better way the innovation drivers with their actual effects.     

舰船自动智能避碰数学模型及其仿真研究

为了提高舰船航行的安全和效率,达到最佳操船效果,需要建立舰船自动智能避碰数字模型.当前模型在分析舰船避碰风险度的基础上,通过人工智能、进化计算和软计算等方法实现舰船自动智能避碰,存在避碰识别准确率较低的问题.本文提出一种新的舰船自动智能避碰数学模型,首先对舰船会遇态势进行判断;然后建立预测舰船碰撞风险判断模型,预测本舰船实施自动智能避碰方案后的复航时机是否已到,以及本舰船立即复航是否能够让清目标舰船或其他所有目标舰船;最后依据舰船碰撞风险判断结果,以当前舰船潜在碰撞风险为例,建立舰船自动智能避碰数学模型.仿真结果证明,所提模型能够实现舰船自动智能避碰.