Episodic Mass Invasions of Juvenile Gadoids into the Wadden Sea and their Consequences for the Population Dynamics of Brown Shrimp (Crangon crangon)

Abstract. The brown shrimp Crangon crungon is considered to be a key species in the coastal waters of the North Sea and in particular in the Wadden Sea, since it occurs in masses and acts as both a highly efficient predator and important prey. The Wadden Sea is the nursery ground for brown shrimp. In 1990, a mass invasion of O-group whiting ( Merlangius merlangus ) reduced Crangon numbers to almost zero. Similar events, which had previously been reported in the 19th century, were observed in 1959 (whiting), 1970 (cod, Gadus morhua ), and 1983 (cod and whiting).
The 1990 invasion and the decline of the shrimp stock are documented on the basis of surveys that are compared with the years preceding and following. Consequences for the food web in the Wadden Sea and the reasons for the complete recovery of the shrimp stock in each case within one year after its collapse are discussed with regard to the Crangon crungon behaviour and reproductive potential. Sampling error and the impact of fisheries are also considered.     

Recruitment of shrimp (Pandalus borealis) in the Barents Sea related to spawning stock and environment

The shrimp spawn in autumn, and the females carry their eggs as out roe until spring when the larvae hatch. Within a period of 2 months the shrimp larvae settle to the bottom. It has been claimed that the year-class strength probably is determined during the larval phase. Today's assessment and forecast of the shrimp stock productivity and potential fishing yields are weak. This is partly due to poor knowledge on population dynamics from hatching until the shrimp are caught in the fishery at the age of 3 or 4 years. We, therefore, here identify the most important abiotic and biotic factors that affect recruitment in addition to spawning stock biomass. Since 1995, a net attached to the underbelly of the survey trawl used at the annual cruise in the Barents Sea has caught juvenile shrimp. The abundance of settled shrimp larvae varies in time and space. The recruitment to the fishery has been quite stable with the exception of the 1996 year-class, which was observed as 1-year-olds but has not been registered since. The temporal pattern of the three youngest year-classes is studied in relation to abiotic factors such as sea temperature, ice index and North Atlantic Oscillation, as well as biotic factors such as spawning stock biomass and presence of copepods, euphausiids and predating cod. Recruitment indices and factors identified by the Spearmann correlation to be significantly correlated with recruitment were used as input in a principal component analysis (PCA) and a generalized additive model (GAM) was applied. Abundance of 1-year-old shrimp is positively correlated to spawning stock biomass the previous year and to temperature of the previous winter, and negatively correlated with the number of 1-year-old cod. Two-year-old shrimp show significant correlation with temperature, whereas there is a strong negative correlation with euphausiids. Three-year-old shrimp are significantly correlated with the number of 2-year-old shrimp the previous year but negatively correlated to temperature at sampling time. This is probably due to less overlap with the main predator cod when cold. Ricker functions indicate an increased density-dependent mortality with age. When predicting the recruitment of shrimp to the fishery, the spawning stock biomass, the abundance of cod and euphausiids, as well as the temperature should be included.     

Sources and fate of manganese in a tidal basin of the German Wadden Sea

Dissolved and particulate Mn concentrations were investigated on a seasonal scale in surface waters of the NW German Wadden Sea (Spiekeroog Island) in 2002 and 2003. As the Wadden Sea forms the transition zone between the terrestrial and marine realms, Mn was analysed in coastal freshwater tributaries and in the adjoining German Bight as well. Additionally, sediments and porewaters of the tidal flat sediments were analysed for Mn partitioning and microbial activity.Dissolved Mn concentrations show strong tidal and seasonal variation with elevated concentrations during summer at low tide. Summer values in the Wadden Sea (av. 0.7 μM) are distinctly higher than in the central areas of the German Bight (av. 0.02 μM), suggesting a possible impact of the Wadden Sea environment on the Mn budget of the North Sea. Seasonality is also observed for particulate Mn in the Wadden Sea (winter av. 800 mg kg^− 1; summer av. 1360 mg kg^− 1). Although particles are relatively Mn-poor during winter, the high SPM load during this season causes elevated excess concentrations of particulate Mn, which in part exceed those of the dissolved phase. Therefore, winter values cannot be ignored in balance calculations for the Wadden Sea system.Porewater Mn concentrations differ depending on sediment type and season. Maximum concentrations are found in surface sediments at a mixed flat site (190 μM) during summer, while winter values are distinctly lower. This indicates that enhanced microbial activity owing to higher temperature during summer leads to increased reduction of Mn-oxides in surface sediments and enhances the corresponding diffusive and advective Mn flux across the sediment-water interface. Draining of Mn-rich porewaters from sediments is also documented by analyses of tidal creek waters, which are highly enriched in Mn during summer.Furthermore, an important Mn source is freshwater discharged into the Wadden Sea via a flood-gate. The concentration of dissolved Mn in freshwater was highly variable during the sampling campaigns in 2002 and 2003, averaging 4 μM. In contrast, particulate Mn displayed a seasonal behaviour with increasing contents during summer. On the basis of salinity variations in the Wadden Sea, the total amount of Mn contributed to the Wadden Sea via freshwater was estimated. This balance shows the importance of the freshwater environment for the Mn inventory of the Wadden Sea. During winter the total Mn inventory of the Wadden Sea water column may be explained almost completely by freshwater discharge, whereas in summer the porewater system forms the dominating source.     

闽江口及其附近海域棘头梅童鱼资源的研究

利用2006～2007年4个季节的底拖网捕捞渔获调查数据,对闽江口及附近海域底拖网鱼类中的棘头梅童鱼的资源状况进行了分析.结果表明：棘头梅童鱼在春季和冬季的渔获质量所占比例较高,分别为3.2%和4.8%;而夏季和秋季的渔获质量所占比例较低,分别为1.8%和1.5%.优势体长组为110～120mm;4个季节的资源密度波动于1.44～38.61kg/km2之间,其平均值为16.14kg/km2.4个季节的平均资源现存量约为58.09t,其中冬季资源量最大（138.99t）;资源密度在春、冬季明显高于夏、秋季;资源分布与水温、水深及盐度等环境因子关系密切.其喜栖息于低温、低盐和浅水海域,秋、冬季分布较广,部分出现离岸及南移现象.文中还应用ELEFAN技术分析了棘头梅童鱼的Von Bertalanffy生长参数（K）、极限体长（L∞）、总死亡系数（Z）、自然死亡系数（M）和开发率（E）,各指标值分别为0.60、183.75mm、2.42、0.69和0.71.这说明其生长较为迅速,但捕捞死亡率过高,已出现过度捕捞现象,应该加强保护以实现资源可持续再生与利用.     

Reproductive and growth strategies of Idotea balthica basteri (Pallas, 1772) population in the Bizerte lagoon (Tunisia,Southern Mediterranean)

We analysed several life history traits of the marine isopod Idotea balthica basteri (Pallas, 1772) from the Bizerte lagoon, Southern Mediterranean Sea. Growth was continuous throughout the life of the animal with a high growth rate in the first life phase, and the growth curve was described according to von Bertalanffy's model. The lowest growth rate (0.23 mm) was recorded in winter (December, January and February) and the maximum rate (2.31 mm) between April and June. The total number of hatched eggs or embryos was positively correlated with the body length of ovigerous females. This population of I. balthica basteri was iteroparous, showing distinct strategies of reproduction. Large ovigerous females with high fecundity were collected during the whole sampling period, while breeding in smaller females with low fecundity was restricted to the period from late spring to early autumn, Manca size increased significantly with increasing female body size and there was also a significant trade‐off between manca size and the number of eggs per brood. Reproductive allocation, ranging between 17.1 ± 1.2% in winter and 23.2 ± 1.8% in summer, was positively correlated with female weight. Accordingly, parental investment in producing a juvenile varied between 1.02% per manca in winter to 3.38% in spring. Evaluated traits show that late summer and autumn cohorts have a K‐strategy, whereas cohorts born in winter and spring, and which exhibit a shorter life time, exhibit faster development, earlier reproduction and a smaller parental investment tending towards an r‐selected strategy.     

Applying Dynamic Energy Budget (DEB) theory to simulate growth and bio-energetics of blue mussels under low seston conditions

A Dynamic Energy Budget (DEB) model for simulation of growth and bioenergetics of blue mussels (Mytilus edulis) has been tested in three low seston sites in southern Norway. The observations comprise four datasets from laboratory experiments (physiological and biometrical mussel data) and three datasets from in situ growth experiments (biometrical mussel data). Additional in situ data from commercial farms in southern Norway were used for estimation of biometrical relationships in the mussels. Three DEB parameters (shape coefficient, half saturation coefficient, and somatic maintenance rate coefficient) were estimated from experimental data, and the estimated parameters were complemented with parameter values from literature to establish a basic parameter set. Model simulations based on the basic parameter set and site specific environmental forcing matched fairly well with observations, but the model was not successful in simulating growth at the extreme low seston regimes in the laboratory experiments in which the long period of negative growth caused negative reproductive mass. Sensitivity analysis indicated that the model was moderately sensitive to changes in the parameter and initial conditions. The results show the robust properties of the DEB model as it manages to simulate mussel growth in several independent datasets from a common basic parameter set. However, the results also demonstrate limitations of Chl a as a food proxy for blue mussels and limitations of the DEB model to simulate long term starvation. Future work should aim at establishing better food proxies and improving the model formulations of the processes involved in food ingestion and assimilation. The current DEB model should also be elaborated to allow shrinking in the structural tissue in order to produce more realistic growth simulations during long periods of starvation.     

Crown foliage dynamics of mangrove <Emphasis Type="Italic">Kandelia obovata</Emphasis> in Manko Wetland,Okinawa Island,Japan

The crown foliage dynamics of Kandelia obovata (S., L.) Yong were investigated, including leaf recruitment, survival and leaf growth. Newly flushed leaves occurred successively throughout the year, with a maximum in July and a minimum in January. The highest leaf death was in August, whereas it was the lowest in January. The relative mortality rate of leaves seemed to depend on the season when new leaves flushed. The growth pattern of leaves varied among seasons. The maximum leaf area was significantly larger in winter than in autumn, but showed no significant difference between the winter and the other seasons. The half-expansion period and the intrinsic rate of increase were respectively longer and lower in winter than in the other seasons. Therefore, leaves flushed in summer grew faster in their initial stage and attained their maximum leaf area sooner than those flushed in winter. This most likely results from the difference in temperature between summer and winter. The crown leaf area was almost stable throughout the year, as if homeostatic control is likely to function. Stipule litterfall decreased significantly with increasing flower and propagule litterfalls, indicating that a high production of flowers and propagules results in low leaf recruitment. This may be because flower production and propagule growth impose a severe burden on K. obovata.     

南黄海冷水团海域溶解氧和叶绿素最大现象值及营养盐累积的季节演变

基于2006-2007年在南黄海冷水团海域开展的4个季度月的调查资料, 重点研究了该海域溶解氧(DO)、叶绿素a(Chl a)最大值现象和营养盐累积的季节演变规律。结果表明:春至秋季黄海冷水团海域DO和Chl a最大值层深度具有先加深后变浅的趋势, 出现最大值层的海域面积呈现出先增大后缩小的变化过程, DO和Chl a最大值层的深度及面积在夏季均达到最大, 至冬季DO和Chl a最大值现象消失;夏季冷水团海域深水区DO最大值处的氧含量整体高于春季, 而冷水团边界附近氧最大值处的氧含量整体低于春季;春至秋季冷水域深水区次表层Chl a最大值处的Chl a含量先降低后升高, 于夏季时最低, 入秋后开始升高, 而一年四季中冷水域边界附近Chl a最大值处的Chl a含量却在夏季时最高, 而且显著高于深水区。黄海冷水团海域的底层营养盐储库具有一定的空间异质性, 冷水域底层通常分别在深水区和西部边界处存在营养盐高值核心, 其中位于深水区的高值核心位置季节变化不明显, 而位于冷水域西部边界附近的高值核心位置则呈现出自春季至夏季向西移动、入秋后又向东部移动的季节变化特征。水文物理因素和生物化学过程对DO、Chl a最大值及营养盐储库的季节演变具有重要的调控作用。     

Variability of the water temperature in the western Wadden Sea on tidal to centennial time scales

Daily observations of the sea surface temperature in the Marsdiep tidal inlet, which connects the shallow Dutch western Wadden Sea with the deeper North Sea, already started in the summer of 1860, over 140 years ago. Since the year 2000 the sampling frequency has strongly increased because of the use of electronic sensors and data logging by computer. Analysis of these temperature data has revealed variations with time scales from tidal, daily, seasonal, inter-annual, to centennial. The tidal temperature variations are generated by advection of the seasonally varying temperature gradient between Wadden Sea and North Sea, while the daily variations are mainly caused by the daily variation of solar radiation. The seasonal variation in sea surface temperature only lags a few days behind the coastal surface air temperature, contrary to the sea surface temperature in the deeper nearby North Sea, which is delayed with about 1 month. The North Atlantic Oscillation index has been used as large-scale proxy for the atmospheric forcing of the Wadden Sea temperature. Only for the winter and spring a significant correlation is found between temperature and the winter index. However, this correlation is so strong that also the annual mean temperature is correlated significantly with the North Atlantic Oscillation. At longer time scales, from decadal to centennial, also large temperature variations are observed, of the order of 1.5 °C. However, these are not related to long-term changes of the North Atlantic oscillation. These long-term temperature changes involve a cooling of about 1.5 °C in the first 30 years of the record and a similar warming in the last 25 years. In between, these long-term changes were smaller and more irregular. Similar conclusions can also be applied to individual seasons as well as to the date of the onset of spring.     

Variability of the water temperature in the western Wadden Sea on tidal to centennial time scales

Daily observations of the sea surface temperature in the Marsdiep tidal inlet, which connects the shallow Dutch western Wadden Sea with the deeper North Sea, already started in the summer of 1860, over 140 years ago. Since the year 2000 the sampling frequency has strongly increased because of the use of electronic sensors and data logging by computer. Analysis of these temperature data has revealed variations with time scales from tidal, daily, seasonal, inter-annual, to centennial. The tidal temperature variations are generated by advection of the seasonally varying temperature gradient between Wadden Sea and North Sea, while the daily variations are mainly caused by the daily variation of solar radiation. The seasonal variation in sea surface temperature only lags a few days behind the coastal surface air temperature, contrary to the sea surface temperature in the deeper nearby North Sea, which is delayed with about 1 month. The North Atlantic Oscillation index has been used as large-scale proxy for the atmospheric forcing of the Wadden Sea temperature. Only for the winter and spring a significant correlation is found between temperature and the winter index. However, this correlation is so strong that also the annual mean temperature is correlated significantly with the North Atlantic Oscillation. At longer time scales, from decadal to centennial, also large temperature variations are observed, of the order of 1.5 °C. However, these are not related to long-term changes of the North Atlantic oscillation. These long-term temperature changes involve a cooling of about 1.5 °C in the first 30 years of the record and a similar warming in the last 25 years. In between, these long-term changes were smaller and more irregular. Similar conclusions can also be applied to individual seasons as well as to the date of the onset of spring.     

渤海西南部小型水母群落特征与环境因子相关性研究

根据2020年8月至2021年5月对渤海西南部浮游动物调查的4个航次数据,分析该海域水螅水母、栉水母群落结构和季节变化特征,讨论了环境因子对小型水母丰度的影响。研究发现,渤海西南部小型水母种类组成和丰度分布存在季节变化,全年调查共发现小型水母13种,11种水螅水母、2种栉水母;春、夏、秋、冬该海域水母种数分别为4种、9种、7种和2种,丰度均值分别为30.74 ind./m3、30.78 ind./m3、12.08 ind./m3、0.57 ind./m3;优势种为嵊山秀氏水母（Sugiura chengshanense）、八斑芮氏水母（Rathkea octopunctata）、锡兰和平水母（Eirene ceylonensis）、半球美螅水母（Clytia hemisphaerica）、球型侧腕水母（Pleurobrachia globosa）,优势种季节更替率平均为91.67%,呈现明显季节演替。水温和盐度是影响渤海西南部小型水母丰度季节变化的主要环境因子,春季水温回升及适宜营养盐含量促进小型水母生长繁殖,夏季桡足类为小型水母提供了丰富的饵料促进其生长,秋季群落主要受盐度的影响。根...     

黄、东海陆架海域温度垂直结构类型划分与温跃层分析

基于黄、东海陆架海域1997—1999年4个季节调查的CTD资料,采用拟阶梯函数逼近法对温度垂直剖面拟合逼近,然后按拟合均方差和跃层强度对黄、东海陆架区的温度垂直结构进行类型划分,共划分为6个类型:三层结构型(T型)、主跃层上位型(U型)、主跃层下位型(L型)、多阶梯状结构型(M型)、异常结构型(A型)和垂直均匀型(H型)。分析结果表明:温度垂直结构类型在黄海区域为:春季呈L型;夏季呈U型;秋季呈T型;冬季呈H型。东海北部春季基本呈T型;夏季西部呈T型,东部呈U型;秋、冬季演变为H型;东海南部春、夏季主要呈L型;秋、冬季除近岸出现逆温类型外,大部分区域呈H型。利用风和潮的混合卷挟模式阐述了各种温度垂直结构的形成机制,最后给出了黄、东海陆架海域的主温跃层特征值的区域分布和季节变化。     

长山列岛邻近海域鱼类群落功能多样性的季节和空间变化

为查明黄、渤海生态交错带长山列岛邻近海域鱼类功能多样性的时空变化,根据2016-2017年在长山列岛邻近海域开展的鱼类生物资源和环境因子的调查数据,结合食性、营养级、洄游类型、适温性、恢复力和鱼卵类型等13种功能性状,应用群落特征加权平均数指数、功能多样性指数和Spearman秩相关分析等方法,研究了该海域鱼类功能多样性的季节变化、空间格局及其与环境因子的关系。结果表明,春、冬季的优势类群为端位或上位口、生长系数较低、脆弱性较高、恢复力较低、定居或短距离洄游的平扁形、暖温性底层鱼类,夏、秋季表现出更多的功能性状,例如长距离洄游、栖息位置处于中上层、体型为侧扁形和纺锤形等;夏、秋季的功能丰富度指数显著高于春、冬季,功能均匀度指数在春季最高,功能离散度指数在秋季最低且显著低于其他季节;春季功能均匀度指数和春、秋季功能离散度指数均表现出西高东低的分布趋势,夏、冬季的功能丰富度指数和秋季的功能均匀度指数均表现出东高西低的分布趋势;功能多样性指数与环境因子具有一定的相关性。长山列岛邻近海域作为黄、渤海生态交错带,鱼类洄游引起优势功能性状和功能多样性呈现出一定的季节变化,环境因子的变化使得功能多样...     

渤、黄、东海海流和潮汐共同作用下的悬浮物输运、沉积及其季节变化

渤、黄、东海是一个水动力状况相当复杂的半封闭宽陆架海，本海区悬浮颗粒物含量高，季节变化明显，影响范围广，是世界上悬浮物含量最高的海域之一。对于该海域悬浮物的输运沉积过程、分布规律以及底质分布等中外学者均进行过比较深入的研究(秦蕴珊，1963； Honjo et al.，1974；Milliman et al.，1985，1986；秦蕴珊等，1987，1989；杨作升等，1992；Li et al.，1997；孙效功等，2000；雷坤等，2001)。然而，以往的研究大都基于实际海洋调查资料，由于受实测资料在时间和空间覆盖范围上的限制，很难从整体上把握渤、黄、东海陆架区悬浮物输运的时间和空间变化规律。数值模拟的方法能很好地克服上述局限，已有学者从不同角度对渤、黄、东海的某些海域的悬浮物进行了模拟研究。 董礼先等(1989)首先模拟了在二维潮流场作用下，黄、渤海推移质和悬移质的输运状况，得出潮流作用下海底的冲淤状况。Graber等(1989)利用有限水深的风浪模型、模拟了风浪对悬浮物输运、沉积的作用。Yanagi等(1995)用拉格朗日粒子追踪方法对整个东中国海冬季悬浮物的输运、沉积过程进行了计算。江文胜等(2000，2001)考虑了风等气象要素、外海传入的潮波的作用、悬浮物的沉降及再悬浮机制，对渤海中悬浮物的浓度进行了数值模拟。 海洋环流、潮汐、潮流和波浪均对悬浮物的输运与沉积产生影响，尤其在中陆架和外陆架地区，环流对悬浮物的长期输运起决定性作用，因此以往仅针对潮流、风浪作用的模拟很不完整，其结果与实际情况的差别也会较大。其次，海水的流动处在不断变化之中，小到日变化、月变化，大到季节变化、年际变化，因此定常风场、定常温盐场的环流模拟，即诊断流场并不符合实际情形。本文将首先对渤、黄、东海月平均风场、温盐场作用下的环流场进行模拟，进而探讨环流以及潮汐、潮流共同作用下的悬浮物输运过程及其季节变化规律。     

黄、东海环流的数值研究Ⅲ——正压环流的数值模拟

依据黄、东海环流的的动力学模型 ,运用“流速分解法”对黄、东海正压环流进行了数值模拟。计算结果表明冬季黄海正压环流主要受风应力影响 ,基本形态为黄海暖流由济州岛西南进入南黄海中部 ,其东西两侧分别为两支向南流动的沿岸流 ;夏季主要受到潮致体力的影响 ,为一逆时针涡旋。东海环流主要是边界力作用驱动的结果 ,东海黑潮、台湾暖流和对马暖流较稳定。冬季风应力对东海环流表层流场有消弱作用 ,在夏季则有一定增强作用。     

Seasonal distribution of Calanus sinicus (Copepoda, Crustacea) in the East China Sea

On the basis of the four-season investigation in 23°30′~33°N and 118°30′~128°E of the East China Sea from 1997 to 2000, the seasonal distribution of Calanus sinicus was studied with aggregation intensity, regression contribution and other statistical methods. It was inferred that C. sinicus’s predominance presented from winter to summer, especially in spring and summer, because its dominance amounted to 0.62 and 0.29 respectively. The percent of its abundance in copepod abundance was 76.71% in summer, greater than 66.60% in spring, greater than 19.02% in winter, greater than 4.02% in autumn. The occurrence frequency in winter and spring was 83.08% and 93.89%, higher than that in summer and autumn, 76.71% and 73.87%. Compared with other dominant species of copepods, C. sinicus’s contribution to the copepod abundance was obviously greater than that of the other species in winter, summer and spring, but smaller in autumn. C. sinicus tended to have an aggregated distribution. The clumping index peaked in summer (50.19), followed in spring (19.60), declined in autumn (13.18) and was the lowest in winter (3.04). The abundance changed in different seasons and areas, relating to temperature but not salinity in spring and autumn, to salinity but not temperature in summer; to neither temperature nor salinity in winter. In spring and summer, its high abundance area was often located in the mixed water mass formed by the Taiwan Warm Current, the Huanghai Sea Cold Water Mass, the coastal water masses and the Changjiang Dilute Water. In spring and autumn, its abundance was affected by the warm current, as well as the runoff from continental rivers affected it in summer. It can be inferred that C. sinicus was adapted to wide salinity and temperature, as a euryhalinous and eurythermous species in the East China Sea.     

Seasonal variation in the transport of suspended matter in the East China Sea

Seasonal variation in the transport of suspended matter across the East China Sea is investigated with the use of results of field observations and diagnostic numerical experiments. Suspended matter is transported from the shelf edge to the inner shelf in summer and from the inner shelf to the shelf edge in autumn and winter due to the vertical circulation mainly induced by the monsoon wind. The maximum transport of suspended matter from the inner shelf to the shelf edge occurs in autumn.     

南黄海悬浮体浓度的平面分布特征及其输运规律

重点分析和探讨了南黄海悬浮体浓度的平面分布及其水平输运,结果显示悬浮体浓度具有显著的空间区域化分布特征,其与该海域环流场的布局和季节转换存在良好的对应关系,南黄海环流是该海域悬浮体运移的主要动力和控制因素;江苏近岸海域在一年四季均为悬浮体浓度的最高值区,其悬浮体主要来源于潮流和海浪所引起的沉积物再悬浮以及苏北沿岸水的携带和输送,而且夏季悬浮体在该海域的累积还可为冬半年在黄海西部沿岸流作用下将其输运至东南海域提供很好的物源保证;长江口东北部海域在春、夏、秋三季出现东北向扩展的高值区,体现了长江冲淡水的影响;石岛外海在冬、春、秋三季也存在悬浮体浓度高值区,并具有向南黄海中部泥质区扩展的态势,这是鲁北沿岸流将现代黄河物质输运至此的结果。发现调查海域中部表底层在春秋季均存在云团状高值区,而且该海域悬浮体浓度自春季至秋季出现"双峰现象",这与春秋季水华期间浮游植物繁殖所产生的有机碎屑有关,并使作为悬浮体组成的海洋浮游生物有机质向沉积物转移,据此进一步指出这一物源可能对南黄海冷涡泥质区的形成、发育也具有一定的作用,该观点深化了对南黄海中部冷涡泥质区受上层生物活动影响以及泥质区物源的认识。     

渤海海域搜救困难度研究

为优化海上搜救资源部署、提高救助成功率,结合层次分析法与模糊综合评价法,从海上搜救的自然环境、辖区信息和行动评估3个方面选取11个指标构建海上搜救困难度评价模型,在验证模型可靠性的基础上,首次对渤海海域开展二维搜救困难度评价和研究。使用成功率来表征搜救困难度并进行时空分布特征分析,成功率越低则困难度越高。结果表明：渤海海上搜救成功率全年分布趋势为海岸线周边海域相对较低,渤海中部海域相对较高。整体来看,夏季成功率远高于其他季节,春、秋季次之,冬季最低。冬季辽东湾及秦皇岛沿岸海域成功率为全年和全海域最低。对渤海沿岸港口海域及中部海域各选1个长期观测的站点开展年变化特征分析,发现同一地点的搜救成功率年变化主要受水温影响,证实了冬季是搜救困难度最高的季节。综上所述,冬季渤海沿岸海域,尤其是辽东湾及秦皇岛沿岸海域为高困难度搜救区,需要加大日常巡逻管理,改善搜救系统部署。     

Numerical investigation of the South China Sea deep circulation

Based on a two-level nested model from the global ocean to the western Pacific and then to the South China Sea（SCS）, the high-resolution SCS deep circulation is numerically investigated. The SCS deep circulation shows a basin-scale cyclonic structure with a strong southward western boundary current in summer（July）, a northeastsouthwest through-flow pattern across the deep basin without a western boundary current in winter（January）,and a transitional pattern in spring and autumn. The sensitivity ...