Nutrient Fluxes from Land to Sea: Consequences of Future Scenarios on the Oder River Basin – Lagoon – Coastal Sea System

Eutrophication management is still one of the major challenges in the Baltic Sea region. Intense transformation processes in several Baltic Sea states have led to drastic changes in e.g., landuse and thereby nutrient emissions and water quality. Several future development directions are possible. The Oder catchment – lagoon – coastal water system serves as a pilot study area, since it has a major influence on the nutrient loads into the Baltic Sea and about 90% of the catchment is located in Poland, a state with transitional economy. Different scenarios for landuse changes in the Oder catchment are developed and their consequences on nutrient emissions simulated. Next to politically induced changes of agricultural landuse in general, specific aspects such as cultivation of energy maize and increased animal stocks are considered. Nitrogen emissions are likely to increase due to agricultural landuse changes whereas phosphorus emissions will not change or even decrease according to the application of the EC‐Urban Waste Water Treatment Directive. Resulting nitrogen loads to the Oder Lagoon could increase up to 23%, phosphorus loads could decrease by 11% compared to 2005. These trends may lead to higher nitrogen availability compared to phosphorus at least in the Oder lagoon. Interannual differences in discharge also have profound effects on nutrient emissions. A good status of the Oder river basin – lagoon – coastal sea system according to EC‐Directives is not very likely to be achieved under the investigated circumstances. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

中国主要入海河流河口集水区划分与分类

采用GIS技术开展中国主要入海河流的流域边界及其汇水单元、河口集水区的划分及其分类。基于ArcGIS水文分析模块划分出15条入海河流的汇水单元,并通过5种不同汇水单元面积等级的划分来表达各入海河流汇水单元的详细程度;划分的流域面积与相关文献资料对比偏差在10%以内;在流域与汇水单元划分的基础上,基于感潮河段的数据收集,确定出88个中国主要入海河流的河口集水区。通过建立分类指标体系,采用聚类分析方法,划分出5类河口:第一类EDA主要分布在环渤海地区、山东半岛和广东沿海;第二类EDA主要分布在长江口和杭州湾周围;第三类EDA主要分布在江苏北部沿海和辽东半岛;第四类包括山东江苏交界处沿海、江苏南部沿海;第五类主要分布在福建浙江沿海、珠江口、长江口、海河口附近、辽河河口附近,并利用快速生物评价法验证河口分类的合理性。研究成果可为进一步开展我国近海河口和海域营养盐基准制订与生态分区提供基础空间数据与方法借鉴。     

黄河三角洲横向水文结构连结空间尺度变异性分析

水文连通是影响滨海湿地生态和水文过程的基础要素之一。引入无标度网络模型改进已有横向静态水文连通参数化方法,将其应用于较大尺度（100 hm²）量化黄河三角洲滨海湿地的水文连通,并结合已有研究结果分析3个尺度（1 m²,100 m²和100 hm²）水文连通的空间变异性。研究结果显示,潮间区和生态补水区的水文连通较强,3个尺度的空间变异性主要来自于水文连通指数较高的样点;盐沼区和河滨区相对较弱,空间变异性主要来自于水文连通指数较小的样点,且大尺度水文连通空间变异性相对中尺度和小尺度更高。小尺度和中尺度方法描述了一个样地与周边较小范围的空间区域土壤水分连通状况,在大的潮汐或补水条件下不同区域各个样地倾向于保持一致;而大尺度方法则侧重于描述区域内的水文过程,这是导致尺度差异的根本原因。     

Water quality modelling of the western Scheldt estuary

In 1987 the National Institute for Coastal and Marine Management (theNetherlands) initiated the SAWES project (Systems Analysis WEstern Scheldt).The main goals of the project were to acquire knowledge with respect to thepollution problems in the Scheldt estuary and to apply this knowledge tomanagement issues of the Scheldt on an operational level. The main interestwas to understand quantitatively the relation between inputs of pollutingsubstances and effects on the ecosystem. In the framework of the project, awater quality model for the Scheldt estuary was made. In 1995, the modelarea was expanded to include the Belgian coastal region at the mouth of theestuary. The model calculates the fate of discharged substances andestablishes the relation between pollution inputs and the resulting waterquality, including general water quality (oxygen, pH, alkalinity, major ionchemistry and nutrients) as well as pollutant concentrations. The modelincorporates all chemical processes which affect these concentrations,including the precipitation/dissolution of metal sulphides which to a largeextent controls the fate of trace metals. Based on calibration andverification exercises, it has been shown that the model provides a goodrepresentation of the physical and chemical processes taking place withinthe estuary and can therefore be used to support policy development for theestuary. For example, the model can compute how the water and sedimentquality in the estuary will respond to reduced inputs of waste or to suchhuman activities as dredging. This revised version was published online in July 2006 with corrections to the Cover Date.     

Seasonal variations of community structures phytoplankton in groundwater discharge areas along the Northern Yucatán Peninsula coast

The highly touristic Yucatán Peninsula is principally constituted with coastal marine environments. Like other coastal areas, this has been affected by the increase of waste water discharge, hydrological modifications and land use changes in the area. The phytoplankton community structure is one of the main components of coastal ecosystems and the most affected in hydrological processes. In order to follow the seasonal variations, the phytoplankton was characterized to follow the hydrological variability in two sites (Dzilam and Progreso) of the Northern Yucatán Peninsula. For this, cruises were carried out monthly during one year, from April 2004 to March 2005, with two samplings per season (dry, rainy and "nortes"). Hydrological variability was associated with seasonality and directly linked to groundwater discharges in the Dzilam area, and waste water discharges in the Progreso area. The highest nutrient concentrations occurred mainly during the rainy season. The phytoplankton community changes observed throughout the year suggested that the hydrological and chemical variability associated with seasonality and anthropogenic impacts have a strong influence. The substitution of diatoms by dinoflagellates as the dominant group in Progreso was the result of seasonal variability itself, but also could have been caused by eutrophic processes; while in Dzilam, the major presence of diatoms could have been favored by groundwater discharges. The results of this study can be used to understand the linkages between stressors from the anthropogenic activities and coastal water quality and changes.     

Origin here,impact there—The need of integrated management for river basins and coastal areas

This study highlights the effect that estuarine polluted waters may have on adjacent coastal waters and the need of an integrated management of the coastal area. Pollution of land-to-sea water plumes varies spatially and temporally, being difficult, costly and time consuming to determine. However, the reduction in water quality of both estuarine and coastal environments and the consequent degradation of its biological communities is at issue. Chlorophyll-a analysis from water and stable nitrogen isotopic analysis (δ¹⁵N) from opportunistic macroalgae Ulva species were respectively used as proxies to detect phytoplankton proliferation and nitrogen related nutrient fluxes in the water. These analytical techniques were combined with the use of three-dimensional hydrodynamic models, and revealed to constitute reliable early warning instruments, able to identify coastal areas at risk, and supporting an integrated management of coastal and river basin areas. The approach detected synchronized δ¹⁵N signal variations along time between estuarine sites (Mondego estuary, Portugal) and nearby adjacent coastal shore sites (NE Atlantic coast). The higher values recorded by macroalgal tissues’ δ¹⁵N signals, which occurred simultaneously to higher chlorophyll-a values, were linked to the anthropogenic contamination of the water, probably related with the Mondego valley land use patterns throughout the year (reflecting the opening of sluices that drain agriculture fields). Modeling scenarios point to a Mondego’s influence that is able to reach its adjacent coastal shores in about 7 km from its river mouth. The methodology used here is replicable elsewhere and allowed to track nutrients from the source, inside the estuary, until the final area of impact, where primary producers may use those for growth, and to define vulnerable areas on adjacent coastal zones.     

Harmful algal bloom forecast system for SW Ireland. Part II: Are operational oceanographic models useful in a HAB warning system

This study investigated the application of a three-dimensional physical hydrodynamic model in a harmful algal bloom forecast system for Bantry Bay, southwest Ireland. Modelled oceanographic conditions were studied and used to help understand observed changes in the chemical and biological patterns from the national biotoxins and phytoplankton monitoring program. The study focused on two toxic events in 2013. An upwelling event was predicted by the model prior to the appearance and population increase of potentially toxic diatoms, Pseudo-nitzschia, and associated domoic acid in shellfish. A downwelling episode was provided as a forecast in the model prior to the arrival of a Dinophysis bloom and detection of its associated biotoxins in Bay shellfish. The modelled forecast products developed included expected surface, mid-depth and bottom current pathways at the mouth of the Bay and on the adjacent shelf. The rate and direction of water volume flow at the mouth and mid-bay sections were produced by the model to examine predicted upwelling and downwelling pulses. The model also calculated the evolution of water properties (temperature, salinity and density) with depth along the Bay axis and on the adjacent continental shelf. Direct measurements of water properties at a fixed point, mid-bay, were comparable to model calculations. The operational model for southwest Ireland produces a reliable 3-day physical hydrodynamic forecast of the dominant regional physical processes that result in water exchange events between Bantry Bay and its adjacent shelf. While simulated physical hydrodynamics were provided as a 3-day forecast, the upwelling and downwelling signals from the model, closely linked to toxic HAB episodes, were evident up to 10 days prior to the contamination of shellfish in the Bay.     

Use of the coastal areas adjacent to the Douro estuary as a nursery area for pouting, Trisopterus luscus Linnaeus, 1758

In the present study, the nursery role of the coastal areas adjacent to the Douro estuary for pouting, Trisopterus luscus Linnaeus, 1758, was analysed. The distribution and abundance patterns, diet and growth of T. luscus were studied based on samples collected on seven occasions from November 2000 to March 2002 using a 12 m otter‐trawl with 18 mm mesh size at 12 sites within the estuary and six sites in the adjacent coastal areas. This species occurred only in the coastal areas adjacent to the estuary and a marked seasonal pattern was reported, which reflected the peak abundance of juveniles that use this area as a nursery ground. No marked relationships were obtained between T. luscus abundance and the environmental variables considered. Nonetheless, the highest densities of pouting were recorded at sites where water temperature was high compared with the other sampling areas. Diet of T. luscus juveniles was mainly composed of crustaceans Decapoda, Mysidacea and Amphipoda. The growth rate determined for T. luscus juveniles off the Portuguese coast was higher than those reported for North European areas, and was similar to those obtained in the eastern Mediterranean.     

黄河口湿地有机碳来源及其对碳埋藏提升策略的启示

滨海湿地是地球上具有多种独特功能的生态系统,是地球上重要的碳库之一,其在全球碳循环中的作用在近年来越来越受到人们的重视。总结了用C/N、稳定碳同位素和生物标志物等方法追踪黄河口湿地有机碳来源的研究成果,并据此探讨了黄河口湿地的固碳提升策略。黄河口湿地是我国典型的滨海湿地,碳来源复杂,但各种示踪方法均表明有机碳的来源中陆源输入较海源输入优势明显,而且陆源输入以地表径流和植被为主,但海源输入从内陆向近海逐渐增强,碳的来源有明显的时空变化并且受到人类活动的强烈干扰。从有机质来源看,提升黄河口湿地的碳埋藏能力应该从合理调配河流淡水资源、保护植被、加快植物群落演替等方面入手。目前有机碳来源的研究还存在覆盖区域有限、碳源区分粗略、影响因子研究较少等问题,缺乏系统性,多限于观测,对机制的理解十分薄弱,因此难以对碳埋藏能力的提升提供定量化的指导。今后的研究要从以下几个方面加强:1)不同区域和不同环境条件之间的比较研究;2)探寻更具特异性的生物指标、优化数据模型,使来源区分更细致;3)不同来源有机质在沉积物中埋藏效率的对比研究;4)构建湿地碳埋藏能力评估体系,综合考虑各方面因素研发和集成能够最大限度提高滨海湿地碳埋藏能力的技术。     

Bacterial diversity of water and sediment in the Changjiang estuary and coastal area of the East China Sea

The Changjiang estuary and the coastal area of the East China Sea (ECS) represent important interfaces of terrestrial and marine environments. This study included analyses of water and sediments collected during different seasons in these regions to determine the composition of microbial assemblages by means of 16S rRNA gene clone libraries. We retrieved 1946 sequences and 779 distinct operational taxonomic units from 36 clone libraries. Shannon–Weaver diversity index values and rarefaction analysis indicated that bacterial diversity in the sediment samples was much higher than in the water samples. Proteobacteria (72.9%) was the most abundant phylum, followed by Firmicutes (6.4%), Bacteroidetes (4.6%) and Actinobacteria (4.1%). In the water, clone sequences related to Alphaproteobacteria were the most abundant, whereas in the sediment samples, sequences affiliated with Gammaproteobacteria were predominant. Principal coordinate analysis showed that water samples collected from the Changjiang estuary and the ECS clustered separately. However, this spatial pattern could not be observed in sediment samples, which were mainly distinguished from one another by the season. Bacterial diversity in the Changjiang estuary was higher than that in the ECS, which may be the result of the mixing of bacterial communities from the Changjiang River, the estuary and the coastal ocean.     

Individual-based modelling of the development and transport of a Karenia mikimotoi bloom on the North-west European continental shelf

In 2006, a large and prolonged bloom of the dinoflagellate Karenia mikimotoi occurred in Scottish coastal waters, causing extensive mortalities of benthic organisms including annelids and molluscs and some species of fish (Davidson et al., 2009). A coupled hydrodynamic-algal transport model was developed to track the progression of the bloom around the Scottish coast during June–September 2006 and hence investigate the processes controlling the bloom dynamics. Within this individual-based model, cells were capable of growth, mortality and phototaxis and were transported by physical processes of advection and turbulent diffusion, using current velocities extracted from operational simulations of the MRCS ocean circulation model of the North-west European continental shelf. Vertical and horizontal turbulent diffusion of cells are treated using a random walk approach. Comparison of model output with remotely sensed chlorophyll concentrations and cell counts from coastal monitoring stations indicated that it was necessary to include multiple spatially distinct seed populations of K. mikimotoi at separate locations on the shelf edge to capture the qualitative pattern of bloom transport and development. We interpret this as indicating that the source population was being transported northwards by the Hebridean slope current from where colonies of K. mikimotoi were injected onto the continental shelf by eddies or other transient exchange processes. The model was used to investigate the effects on simulated K. mikimotoi transport and dispersal of: (1) the distribution of the initial seed population; (2) algal growth and mortality; (3) water temperature; (4) the vertical movement of particles by diurnal migration and eddy diffusion; (5) the relative role of the shelf edge and coastal currents; (6) the role of wind forcing. The numerical experiments emphasized the requirement for a physiologically based biological model and indicated that improved modelling of future blooms will potentially benefit from better parameterisation of temperature dependence of both growth and mortality and finer spatial and temporal hydrodynamic resolution.     

基于水体盐度和水文结构的滨海湿地海陆水文连通性

以水体盐度作为核心指标,综合水文结构连通指标(沟渠水面率、进出水渠密度、海陆距离以及沟塘距离)构建海陆水文连通性指数。在多尺度空间分析的基础上,选择150 m×150 m网格作为评价单元,对研究区内海陆水文连通性进行空间定量分析和等级划分。结果表明: 研究区海陆水文连通性由海向陆逐渐递减,但递减速率存在差异,这是由于研究区内水体盐度空间分异明显,对水文连通性变化速率造成一定影响。将海陆水文连通性划分为优、良、中、差4个等级,优与良所在区域主要分布在近海地区,土地利用类型以咸水养殖塘和农田为主;中与差所在区域主要分布在内陆地区,土地利用类型以淡水养殖塘和农田为主。滨海湿地的水文过程十分复杂,定量化滨海湿地海陆水文连通性能够为滨海湿地现状评估以及湿地修复提供参考资料。     

Spatial and temporal analyses of water quality and phytoplankton biomass in an urbanized versus a relatively pristine salt marsh estuary

The robust growth of coastal communities in the southeastern United States is putting unique pressures on estuarine resources. Urbanization of estuarine systems may alter ecosystem function and thus affect the spatial scale and magnitude of nutrient concentrations and primary production temporally and spatially. We examined the spatial and temporal patterns of nutrient and chlorophyll a (Chl a) concentrations in two shallow well-mixed estuaries, (1) a developed estuary, Murrells Inlet (MI), South Carolina, and (2) a relatively pristine estuary, North Inlet (NI), South Carolina. The summer chlorophyll a maximum in MI was characteristically higher than in NI, which may be indicative of eutrophication. Correlations between salinity and inorganic nutrients (N and P) suggest that nutrient import from upland sources may be more pronounced in MI during stochastic precipitation events. Although inorganic nutrient concentrations between the estuaries were similar overall, during a wet period, inorganic N concentration in MI was increased to a greater extent than in NI, while only minimal increases in inorganic P were observed in both estuaries. Chlorophyll a concentrations decreased from the dry to wet period. Geographic Information System (GIS) plots of intensive spatial sampling in MI indicated spatial gradients of nutrient concentrations within this estuary that appeared to be consistent over time. These observations were investigated in more detail using regression analyses to examine the influences of coastal dilution and nutrient sources on relationships between water quality constituents. Results indicate the importance of stochastic rain events in affecting the linkages of estuarine processes to upland runoff in the urbanized estuary, MI.     

基于自然地理特征的长江口水域分区

河口分区是营养盐基准制定的前提,也是进行河口资源管理的得力工具。基于长江口2005-2006年的调查数据,参考国内外相关研究成果,结合长江口本身的特征,提出以自然地理特征为基础,利用层级分区方法,对长江口水域进行分区。经一、二级分区后,长江口水域可划分为长江口过渡区、长江口外近海区、杭州湾和舟山海区等4个海区。4个海区的自然地理特征各具特色,且各海区间的分界线具有明确的地理学意义。采用单因素方差分析法对各分区的水体特征和沉积物特征进行一致性检验,不同分区间的差异性较为显著,说明分区结果较为合理。     

Residency and movement patterns of bonnethead sharks, Sphyrna tiburo, in a large Florida estuary

The use of a coastal estuary by bonnethead sharks, Sphyrna tiburo, was examined by acoustic monitoring, gillnet sampling and tag- recapture studies. Acoustic monitoring data were used to define the residency and movement patterns of sharks within Pine Island Sound, Charlotte Harbor, Florida. Sharks were monitored for periods of 1–173 days with individuals regularly moving in and out of the detection range of the acoustic system. Patterns of movement could not be correlated with tidal level or time of day. Home range sizes within the Pine Island Sound population were typically small with individuals using core areas on a daily basis. However, core areas shifted within the study site over time resulting in eventual usage of most of the available habitat. Gillnet sampling revealed that S. tiburo were abundant in shallow water near seagrass beds, but that presence of individuals at specific sites was variable. Tag-recapture data showed that most individuals remained within the Pine Island Sound region over time and did not appear to undergo long coastal migrations. The movement and residence patterns of S. tiburo suggest that individuals are resident within the estuary, but do not show site fidelity to specific areas within the estuary.     

A dynamic mass balance model for phosphorus fluxes and concentrations in coastal areas

This paper presents a general, process-based mass balance model (CoastMab) for total phosphorus (TP) in defined coastal areas (at the ecosystem scale). The model is based on ordinary differential equations and calculates inflow, outflow and internal fluxes on a monthly basis. It consists of four compartments: surface water, deep water, erosion/transportation areas for fine sediments and accumulation areas for fine sediments. The separation between surface water and deep water is not done based on water temperature, but on sedimentological criteria instead (from the theoretical wave base). There are algorithms for all major internal TP fluxes (sedimentation, resuspension, diffusion, mixing and burial). Validations were performed using data from 21 different Baltic coastal areas. The results show that the model predicts monthly TP in water and chlorophyll a very well (generally within the uncertainty bands of the empirical data). The model has also been put through sensitivity tests, which show that the most important factor regulating the predictions of the model is generally the TP concentration in the sea beyond the coast. The model is simple to apply, since all driving variables may be accessed from maps or monitoring programs. The driving variables include coastal area, section area (between the defined coastal area and the adjacent sea), mean and maximum depths, latitude (used to predict water temperatures, stratification and mixing), salinity and TP concentration in the sea. Many of the model structures are general and could be used for areas other than those included in this study, e.g., for open coasts, estuaries or tidal coasts, as well as for other substances than phosphorus.     

First results with a new estuarine fish tracking system

A 'sonar buoy' tracking system has been developed at the MAFF Fisheries Laboratory based upon acoustic transmitting tags and relay units which retransmit the pulsed acoustic signal as a radio signal. The output from several such 'sonar buoys' is monitored by a single automatic recording station on the shore. The system has been used on salmon in the estuary of the River Fowey in Cornwall, providing useful data on the behaviour of returning adults before they enter the river. The tags also transmit a radio frequency signal to allow tracking in the river itself. Of fourteen fish tagged in 1985, six were recorded entering the river between 12 h and 41 days after being released. Another fish was recaptured in a coastal net 160 km to the east. These few preliminary results indicated two distinct patterns of behaviour: one fish remained in deep water in the lower estuary for several days, often lying near moored ships or jetties; at other times fish made extensive excursions up the estuary with the tide, usually returning with the ebb.     

The palaeoenvironments of coastal lagoons in the southern Baltic Sea,II. δ13C and δ15N ratios of organic matter — sources and sediments

Organic carbon and nitrogen isotope values (δ¹³C, δ¹⁵N) and C/N ratios of six sediment cores from six coastal lagoons (including the Oder Estuary) were measured to chart the coastal development and to reconstruct the local palaeoenvironments of the southern Baltic Sea region during the Holocene. In addition, δ¹³C, δ¹⁵N and C/N values of major organic matter sources in the coastal lagoons and their drainage areas are investigated to determine the origin of organic matter (i.e. terrigenous or marine) in the sediments: plankton, aquatic macrophytes, typical C3 shore plants and peat. The δ¹³C, δ¹⁵N and C/N values of the samples collected show the clearly identifiable stages in the development of the water bodies: post-glacial lake stages with sandy sedimentation, lacustrine phases with high autochthonous productivity, terrestrial stages with peat formation, sedimentation as a result of marine transgression, and brackish sedimentation after the formation of sand spits and barrier islands. These stages are the results of sea level changes in the region. The values allow derivation of differences in the palaeoenvironments of the lagoons in the study area. A distinct terrestrial input is evident in the sediments of the lagoonal Oder Estuary, which can be attributed to the direct inflow of the Oder River into the lagoon. The isotope and C/N values also suggest a contribution of C4 plant detritus for the water bodies in the northeastern part of the study area (Barther Bodden, Grabow). The burial of autochthonous organic matter (i.e. plankton, aquatic macrophytes) in the sediment could be derived for all lagoons in this investigation.     

Comparison of inshore and offshore fish larval assemblages within the wider Yangtze River estuary (China)

It is hypothesized that fish larvae undertake vertical movements in estuarine waters. To test this hypothesis, a sampling period was selected during times when many spring‐spawning fish reach maximum abundance in coastal waters so that spring and summer variations in larval fish assemblages could be determined in the Yangtze River estuary. Six oceanographic surveys were conducted across the salinity gradient of an inshore (freshwater) and offshore area (brackish intersection) during spring (May) and summer (August) between 2010 and 2012. The fish larval community was dominated by species of Engraulidae, Gobiidae, Champsodontidae and Mugilidae. The pre‐flexion and flexion larval stages of euryhaline marine species, which are dependent on estuaries as nursery areas, were common. The brackish and marine larval assemblage was the most abundant with taxa such as Coilia mystus and Engraulis japonicus accounting for more than 57.3% of the total catch. Spatial differences in the taxonomic composition of larval fish assemblages were evident between the inshore and offshore areas. Additionally, the Yangtze River runoff regulatory functions as affected by the Three Gorges Reservoir operational mode (hydrological alternating operations) showed weak influences on fish and habitat environments. Low salinities from high freshwater inflow limited bay anchovy production in the inshore area.