Sustainable seafood consumption in China

Changing forms of seafood consumption in China hold immense significance for the marine ecosystems that supply this market, and are a fundamentally important challenge to address for global environmental sustainability. Drawing on recent findings from extensive ethnographic and survey research with seafood traders and consumers in China, this paper analyses policies for improving sustainable seafood consumption in China. The paper evaluates how existing policy initiatives undertaken by civil society and the government are affected by the distinctive social, economic and political context in China, and discusses how future efforts can better build on this context. To improve sustainable seafood consumption will require an effective strategy for working in a market environment characterised by a much greater public interest in food safety than food sustainability, and by a governance environment characterised by the strong role of the state.     

Seasonality in nutrient concentrations in Galveston Bay

In order to investigate factors controlling nutrient cycling in the shallow and turbid coastal ecosystem of Galveston Bay, data from: (1) the Texas Water Commission (TWC) database 1980–1989, and (2) salinity transects in 1989 and 1993 are presented and analyzed. Statistical regression and time-series analysis were carried out on data acquired by TWC between 1980 and 1989, in an attempt to establish seasonally of nutrient and chlorophyll-a (chl.-a.) concentrations in the bay and to determine factors which regulate these concentrations.A strong seasonality was found for phosphorus and chl.-a. in the upper and mid-bay stations. A recurring maximum for phosphate occurred in September and a chl.-a. maximum occurred regularly in March–April. It is hypothesized that benthic regeneration of phosphorus at the end of summer is responsible for the phosphate maximum. The inverse correlation of the partition coefficient (K_d) for phosphate with the concentration of suspended particulate matter (SPM), coupled to a strong enrichment of phosphate in suspended particles at low SPM concentrations, indicates additional control by geochemical and physical processes such as particle sorting and/or particle-colloid interactions. Nitrate is inversely correlated with salinity at the upper and mid-bay stations, indicating the Trinity River is a major source.Nutrient concentrations in the lower bay (East and West Bay stations) are considerably lower and less predictable, as they are not correlated with salinity or temperature. Data from the 1989 and 1993 transects confirm the yearly maximum in phosphate concentration in late summer months, with peak concentrations in the upper Trinity Bay. It is concluded that despite possible phosphate buffering by physical and geochemical mechanisms, relatively large concentration maxima recur regularly every year during the summer, possibly caused by a benthic source of phosphate.     

Uncertainty in predictions of oil spill trajectories in open sea

A method is introduced to calculate and to account for the uncertainties in the predictions of oil spill trajectories using a classic oil spill model. The method considers the output of the oil spill model as a function of random variables, which are the input parameters, and calculates the standard deviation of the output results which gives a measure of the uncertainty of the model given the uncertainties of the input parameters.Instead of a single trajectory that is calculated by the oil spill model using the mean values of the parameters, a band of trajectories can be defined when various simulations are done taking into account the uncertainties of the input parameters. This band of trajectories defines envelopes of the trajectories that are likely to be followed by the spill given the uncertainties of the input.The method is applied to an oil spill that occurred in open sea near Madeira Islands, in the Atlantic Ocean, in December 1989. The simulations allow the understanding of how a change in the wind direction drove the spill towards the Islands.The envelope of likely trajectories that is obtained with the uncertainty modelling shows a band of trajectories that is in better agreement with the observations than the single trajectory simulated by the oil spill model, based on mean parameters.     

Analysis of Triphenyltin in Fish

A procedure to analyse triphenyltin and other organotins in fish tissues is described. The method consists of the following steps: homogenization of the fish, extraction by heating under reflux in a water/hexane mixture, centrifugation, separation of the hexane layer followed by reduction of the volume by evaporation, methylation of the organotin with a Grignard reaction, clean-up of the fish extract by column chromatography, and detection by gas chromatography with flame photometric detection. The extraction was carried out without adding acid or base to the aqueous phase, as the extraction efficiency was independent of pH. The methylation was successfully carried out in the fish extract. For clean-up of the fish extract a florisil column was used, from which the triphenylmethyltin was eluted with hexane. Using this method, triphenyltin has a recovery of 77 ± 10%, with a limit of detection of 0·8 ng/g for 0·1 g fish samples.     

Variation in the occurrence of marine birds at fronts in the Bering Sea

Topographically-induced flow gradients can concentrate seabird prey in several different ways, and are potentially important to marine birds in shelf ecosystems such as the south-eastern Bering Sea. We tested the hypothesis that attendance by seabirds was greater at fronts maintained by strong surface flow gradients than at fronts maintained by weak or intermittent surface flow gradients. An analysis of 62 crossings of flow gradients identified from temperature and salinity gradients showed that local increase in attendance was greater in areas of strong surface flow gradient than in an area of weak surface flow gradients. Attendance by marine birds depended on the strength of a flow gradient rather than on the presence or absence of a front.     

Application of Two Turbulence Closure Schemes in the Modelling of Tidal Currents and Salinity in the Hooghly Estuary

This paper has two purposes. The first is to study the circulation and salinity in Hooghly Estuary, along the east coast of India and the second is to compare the performance of two turbulence closure schemes by modelling it. A breadth averaged numerical model using a sigma co-ordinate system in the vertical is briefly described. Vertical diffusion of momentum and salt are parameterized by a simple first-order turbulent closure or by a one equation model for turbulent kinetic energy (TKE) which uses a specified mixing length. The results are compared with the available neap and spring tide observations along the estuary for both low and high discharge periods.The computed elevations and currents are in reasonable agreement with the observations showing no major differences in vertical current profiles by both the turbulent schemes. However, there is a slight under-prediction of bottom currents. The salinity profiles predicted by TKE model show better matching with observations. Statistical tests are also conducted to study the comparative performance of the turbulent closure schemes. The maintenance of two layer structure in residual currents and salt variability are also studied by using the model.     

Non-linear effects in the packets of internal waves in the ocean

The mechanisms for the generation of mean density and current velocity fields in a medium with a vertical shear, conditioned by the non-linearity of packets of internal waves are analysed. Modulation instability of internal waves is studied allowing for the earth's rotation. A non-linear Schrödinger's equation for the evolution of the envelope has been derived. Also corrections to the mean density and current velocity in the approximation, quadratic by the wave's amplitude, non-oscillating on the wave's time scale have been obtained. The longitudinal modulation conditions have been analysed.Translated by V. Puchkin. UDK 551.466.8.     

南海北部流切变环境中台风引起的近惯性振荡的比较研究

通过2008年和2009年布放在南海北部的声学多普勒流速剖面仪(ADCP)锚系潜标,本文观测到了三次由台风引起的近惯性振荡(NIO)事件,分别编号为2008a,2009a,2009b,并对其进行了比较研究.其中2008a在三次事件中强度最大,持续时间最长(15 d),而2009a和2009b仅分别持续了4 d和8 d.三次事件的垂直能量分布和位相传播有明显的区别.在频率偏移方面,2008a的峰值频率略低于局地科氏频率(红移),而2009a和2009b则体现出蓝移.不同的NIO事件的特征表现主要由台风扰动和背景流场环境共同决定,特别是背景流场通过平流和调制作用在其中起了重要的作用.本文的研究为不同背景流场中NIO的不同响应提供了观测的证据.通过分析数模提供的背景流场的涡度和有效科氏频率,2008a事件中较强的振幅和较长的持续时间是由于背景的剪切流场的波导效应造成,其改变了台风过后NIO的能量分布,将入射波能量集中于负涡度区域.而2009a和2009b事件中由于涡度不明显,因此没有类似效应.     

Coanda effect in coastal flows

In the present paper some numerical simulations and experiments were carried out to study jet-wall interaction in shallow waters. Namely, modifications of the hydrodynamic field concerning the interaction of river run-off with a shallow coastal water body, due to the presence of marine structures, were investigated. Stratification effects due to salinity and temperature were neglected, and the interest was focused on barotropic features (Coanda effect). The numerical analysis was carried out by means of shallow water equations, numerically solved by finite difference, and the present method was validated by means of a typical simple-shaped test case. The experiments were carried out in a shallow water tank, flow visualizations were performed, and the velocity field was obtained by PIV. The main features of jet-wall interaction flow were investigated in simple-shaped geometries, and applications were shown for two practical cases: Pescara channel harbour (Adriatic Sea, Italy) and the proposed design of Latina harbour (Tyrrhenian Sea, Italy).     

Reproduction of higher harmonics in irregular waves

The basic features of higher harmonic waves were originally presented by Stokes in 1847 who showed that a 2nd-order regular wave would attain a higher, sharper crest and a flatter trough than the basic linear one. In this paper, these characteristics are investigated for an irregular wave train. This was done to make it possible to reproduce in a laboratory flume a wave train which has the correct profile and rms according to 2nd-order theory. The 2nd-order wave heights and the overall horizontal asymmetries of the wave train were calculated for a 1st-order PM and a Jonswap spectrum. The theoretical predictions show that the traditional wave generation in a laboratory flume which is based on linear theory produces free 2nd-order waves in addition to the bound 2nd-order waves described by Stokes. These free, parasitic waves incorrectly distort the shape of the waves and produce a varying rms as a function of distance from the wave paddle. In the 2nd-order theory presented in this paper, these free (parasitic) waves are calculated for the entire spectrum. Knowing these, they can be eliminated by compensating for them by using a 2nd-order control signal on the wave paddle. This is verified by a series of model tests which show that realistic wave profiles can be generated only by means of 2nd-order control signals. The theory and corresponding paddle control are presented for any type of translating, rotating or combined wave generator.     

南海北部滨珊瑚骨骼微生物侵蚀

微生物对珊瑚骨骼的侵蚀作用相对肉眼可见的大型生物侵蚀更加隐蔽, 研究也相对稀少, 国内更是空白。本文对采自涠洲岛、大亚湾以及西沙琛航岛的滨珊瑚骨骼切片在扫描电镜下开展微生物侵蚀研究。在涠洲岛和大亚湾的滨珊瑚骨骼切片中存在微生物侵蚀形成的“橘色条带”, 可能与当地水体富营养化有关, 而琛航岛的样品中则没有类似的条带。扫描电镜观察发现, 这些“橘色条带”为内生藻Ostreobium quekettii, 是一种热带珊瑚礁区常见的侵蚀微生物。O. quekettii侵蚀的珊瑚骨骼结构被破坏, 其厚度减小, 孔隙率提高了1.54%至6.76%、抗压强度下降了27.1%至51.2%, 使得珊瑚骨骼变得更加“疏松”, 且在整个骨骼次表面形成了一层“骨质疏松层”。该种侵蚀微生物扮演了“先行者”的角色, 使珊瑚更容易被大型生物侵蚀, 而大型生物侵蚀又会进一步促进微生物侵蚀, 该“正反馈效应”正好解释了在富营养化的南海北部发现的珊瑚骨骼内侵蚀加剧的现象。     

Ecological knowledge interactions in marine governance in Kenya

Proponents of integrated, collaborative, and adaptive governance advocate the inclusion of a diversity of stakeholders and their knowledge and values in governance processes. This paper examines knowledge interactions at different scales of decision-making within two marine social-ecological systems in southern Kenya. Ecological knowledge systems are shown to be diverse and fluid even within broad conceptual classifications. Knowledge interactions at the local level are mediated by socio-cultural, institutional, and historical factors, whilst knowledge integration within district to national levels is primarily structured by institutional factors linked to centralised decision-making. In policy arenas, knowledge bounded to the marine environment is subjugated by knowledge dealing with terrestrial parks, inland fisheries, and wildlife tourism.     

台湾海峡西南部海域春季悬浮体及沉积物来源与输运机制

台湾海峡作为连接东海和南海的重要通道,其悬浮体和沉积物的来源和输运格局非常复杂。2005年4~5月利用带有浊度传感器和荧光传感器的SD204型CTD对台湾海峡西南部海域627个站位的悬浮体特性进行了综合调查,并采集了底层沉积物。在室内分别利用英国Marlvern公司生产的Mastersizer 2000型激光粒度仪和德国ELEMENTOR公司生产的ELEMENTOR varioELIII型元素分析仪对表层沉积物进行了粒度分析和沉积物碳、氮含量测定,结果表明,台湾海峡西南部海域春季受粤东沿岸流、韩江冲淡水、九龙江冲淡水及台湾海峡混合水影响,其中粤东沿岸流在向北输运过程中影响强度逐渐减弱,韩江冲淡水影响范围较大,并且在西南季风的控制下向东北方向输运;长时间尺度的沉积物输运格局表明,近岸沉积物由岸向海输运,远海地区沉积物由海向岸输运,并且在汕尾南部海域、南澳岛东南部海域形成了沉积物的汇聚区,沉积物以陆源为主;表层沉积物的输运过程受控于区域内水团、悬浮体分布及运动格局;在春季上升流形成早期尽管叶绿素荧光值相对较低,但其对表层沉积物的输运过程起着非常重要的控制作用。     

A shipborne magnetic survey in Hudson Bay

A marine magnetic total-field survey of Hudson Bay was conducted from 1975 to 1978. Approximately 62 000 line-km of data, or 35 000 five-minute averages, were acquired. The data were corrected for secular variation by means of a polynomial in latitude, longitude, and time, first fitted to annual mean differences from nine observatories and then integrated over time. The data were corrected for diurnal and transient variations by means of a linear interpolation, over geomagnetic latitude, of running hourly mean values from two neighbouring magnetic stations (numbering seven in all). Crossover differences are analysed in terms of a mixture of normal distributions resulting from the intermittent transient variations, and indicate the effectiveness of the corrections. The variance of the data is reduced, as a result of the corrections, by 87% during quiet periods and by 53% during disturbed periods, the weighted variance being reduced by 66%. Navigational accuracy is estimated, from a novel method utilizing crossover differences and field gradients, to be approximately 300 m. Anomalies are presented in profile form, and discussed briefly.Contribution from the Earth Physics Branch No. 973.     

Development of a thin diatom layer observed in a stratified embayment in Japan

The temporal evolution of a thin phytoplankton layer was observed by field measurements using a research vessel and mooring instruments in the Yatsushiro Sea, a semi-enclosed narrow embayment in Japan, in early August 2013. The subsurface chlorophyll maximum developed into a thin layer within 2 days just below the pycnocline at around 10-m depth, where turbulent mixing (the dissipation rate of turbulent kinetic energy) was weak (low). The layer persisted for 1.5 to 2 days and declined after irradiance drastically decreased at the sea surface. At the peak period, the layer thickness, which is defined as the full-width at half-maximum of the peak in chlorophyll a concentration, ranged from 0.6 to 1.4 m, and the maximum concentration reached 42.3 mg m^?3. The horizontal extent of the layer was approximately 10 km along the longitudinal axis of the bay. The phytoplankton population characterized by the layer was dominated by a chain-forming centric diatom, Chaetoceros spp. The formation mechanisms of the thin diatom layer were investigated using the observed data and a vertical one-dimensional model that includes physical and biological processes. The results suggest that the development of the thin layer was caused by in situ growth and aggregation due to nutrient-dependent sinking of the species under weak turbulence. The study highlights that continuous multidisciplinary observations and understanding species-specific physiological responses to environmental variations are necessary to elucidate drastically fluctuating phytoplankton dynamics in a coastal water.     

Catch share programs in the Western Pacific—A solution in search of a problem?

The movement toward catch shares by NOAA Fisheries and fisheries managers worldwide responds to dysfunctional fisheries plagued by a host of interrelated problems including radically shortened seasons, a race to fish, supply gluts, lowered product quality, increased bycatch, safety issues, excess capacity, and lack of profitability. However, the NOAA Catch Shares Policy recognizes that catch shares are not appropriate for every fishery, and others have agreed that the success of catch shares programs depends on their fit with ecological, economic, and social characteristics. This article describes the characteristics of the Hawaii-based deep-set longline fleet, identified by NOAA Fisheries as a possible candidate for catch shares because it operates under a bigeye tuna quota instituted by the Western and Central Pacific Fisheries Commission. One of the main concerns in the fishery is the potential for closing during the holiday season, a culturally important time for fish consumption in Hawaii. An evaluation of the fishery suggests that many of the problems leading to development of catch shares programs in other fisheries are not present, but that some warning signs exist which could be addressed by catch share programs or other management alternatives.     

Mass flux and undertow in a surf zone

The mass of water carried shoreward by the breaking waves in a surf zone will, in a two-dimensional situation, be compensated by a seaward return flow, the undertow. It is shown that the undertow is driven by the local difference between radiation stress and the set-up pressure gradient which only balance each other in average over the depth. Turbulent shear stresses are required to maintain a steady situation. Comparison with measurements confirms the theoretical results.     

Short-term temperature and salinity variations in the Tsushima Strait in 2004: Behavior of the surface low-salinity water in the strait

Temporal variations in temperature and salinity observed in 2004 were investigated on a short time scale in the Tsushima Strait. The data were obtained by long-term in situ measurements at Mitsushima and Futaoi Island using an instrument equipped with a piston-type wiper to avoid biofouling. In addition, the temperature and salinity values of the surface layer obtained by a commercial ferryboat between Hakata and Busan were used to investigate their spatiotemporal variations. Temperature and salinity variations with a time scale of several days had a negative correlation in the summer. This evidence suggests that a warm and less saline water mass, which is considered to be mainly the Changjiang Diluted Water (CDW), flowed intermittently through the Tsushima Strait in summer. In late July 2004, a large low-salinity water mass was detected in the Tsushima Strait. At that time, the freshwater transport through the Tsushima Strait transiently reached about 12 × 10⁴ m³s⁻¹, which is estimated from observed acoustic Doppler current profiler (ADCP) data along a ferryboat line and inferred salinity profiles. This estimated value is more than double the maximum of the climatological monthly mean of the Changjiang discharge. Furthermore, salinity and surface current data obtained by high frequency ocean radar (HF radar) indicate that water properties at Mitsushima may occasionally represent part of the water flowing through the western channel via a countercurrent, although Mitsushima is geographically located in the eastern channel.     

Basic Laws in Mechanics of Turbulent Flows

- Turbulent flow is a basic form of fluid motion widely observed in nature. In hydraulic engineering, especially in the study of sediment movement, turbulence is a key problem. In this paper, based on the stochastic theory of wall turbulence developed by the author and the results by other investigators, fluc-tuation and mean structures and drag coefficient for Newtonian and drag reduction flows in all states (laminar, transitional, turbulent) and in all regions (smooth, transitional, rough) are theoretically discussed in detail. General laws for laminar and turbulent flows obtained by the author are verified by the experimental results obtained by others, and there is good agreement between them.     

珠江河口地形致动力结构研究——以崖门为例

局部地形对于河口动量和能量平衡有重要作用,影响了潮波性质和物质输运特性。选取珠江河口崖门这一典型的地貌单元,通过水尺和座底式支架的观测,对其特殊地形边界影响下的动力结构进行了探讨。结果表明:(1)过水面积的缩窄导致崖门口处形成局部高水位区,来流方向水位壅高,去流方向水位梯度增大;(2)忽略斜压作用的情况下,由水位梯度所产生的正压项是主要的动力项。沿河道方向的二维垂向平均动量平衡中,急流时刻主要是正压项和对流加速度项平衡,憩流时刻主要是正压项和局地加速度项平衡;(3)地形变化所产生的形态阻力比床面粗糙所产生的肤面阻力要大数倍到一个数量级。