The effect of seasonal and inter-annual variability of river run-off on the salinity of coastal waters in the north-western Black Sea

The paper considers the correlation between the variability of river discharges in the northwestern Black Sea and water salinity (from 1962 to 1994). As the most complete series, we have chosen salinity data collected at the port of Odessa. The dominant oscillations in the intra-annual variability of river discharges (Danube, Dniester, Dnieper, Yuzhny Bug) and salinity attain about 2–3 months and one year, respectively. In the inter-annual variability of river discharges and water salinity, cyclicities equal to about 4–6 months and 9–12 years, respectively, have been identified. Through analysing the inter-annual variations, an inversely proportional dependence has been found between the overall river discharges and salinity (between discharges in April and salinities in May, the correlation coefficient has amounted to −0.61). For each river, we have obtained the following dependences: for Odessa-Dniester, −0.72; and for Odessa-Danube, −0.65. Translated by Vladimir A. Puchkin.     

Tapes philippinarum seed exposure to metals in polluted areas of the Venice lagoon

The concentration changes of 12 metals (As, Hg, Cd, Cr, Co, Cu, Pb, Mn, Ni, V, Zn, Fe, and Hg) in the soft tissues of Tapes philippinarum during growth were investigated. Clams were seeded in two contaminated areas of the Venice lagoon (San Giuliano and Fusina) and in an area of the Marano lagoon (Lignano Sabbiadoro) close to the clam-farm where the seed was produced. Metal trends were very different according to the considered element, the study site and the growth period.Arsenic was always higher in clam tissues than in surface sediments and suspended particles in all the three stations. Mercury, Cd and Cu were higher in the clams from Marano and Fusina but not in those from San Giuliano. Zinc and Co in clams exceeded the concentrations in the sediment and suspended particles only at Marano. The other elements (Cr, Pb, Mn, Ni, and Fe) were always higher in SPM and sediments. In general metal concentrations in clams were more highly correlated to concentrations in the suspended particles rather than in the surface sediments and in suspended clams rather than in bottom clams, nevertheless significant differences between stations and contaminants were found. Metal concentrations in clams were always lower than the European regulatory limits.     

Irish estuaries: Water quality status and monitoring implications under the water framework directive

The status of water quality of Irish estuaries is reviewed; this sheds light on the rationale behind the design of the national monitoring programme. Relative to other EU Member States, Ireland's coastal monitoring programme is relatively young and not as advanced. The monitoring programmes in Ireland pre Water Framework Directive (WFD) were structured on a salinity-based typology, with an emphasis on quantifying the variability of the component elements. Although monitoring is a significant obligation under the WFD, there is little guidance on developing monitoring protocols; Member States are developing ad hoc monitoring programme. The Irish Environmental Protection Agency (EPA), responsible authority, undertook research programmes to assist design and implementation of the WFD. A substantial new national monitoring programme was developed. However, the Irish programme is not optimised; the programme is being refined to include elements not yet covered, notably the biota. New research, by the authors, aims to develop a robust approach towards monitoring integrating data and model results. This paper presents changes in Irish marine water quality monitoring policy and some of the associated research necessary to change policy.     

Governance strengths and weaknesses to implement the marine strategy framework directive in European waters

The ambitious Marine Strategy Framework Directive (MSFD) has been the focus of much marine research across Europe in the pursuit of achieving Good Environmental Status in the four European Union marine regions; Baltic Sea, Black Sea, Mediterranean Sea and North-east Atlantic. This research addresses the Strengths, Weakness, Opportunities and Threats (SWOT) of the current European marine governance structures and its relationship to implement the MSFD. Results of the SWOT analysis were acquired through a combination of approaches with MSFD experts and stakeholders including: 30 face-to-face interviews, an online survey with 264 stakeholder respondents and focus groups within each European marine region. The SWOT analysis concurrently identifies common strengths and weakness and key governance issues for implementing the MSFD for European marine regions. This paper forms one assessment within the governance component of the Options for Delivering Ecosystem Based Marine Management (ODEMM) project and presents timely issues that can be of benefit to national and European Union policy makers.     

The measurement of sand transport in two inlets of Venice lagoon,Italy

Sand transport in Lido and Chioggia inlets was measured using modified Helley–Smith sand traps equipped with 60-micron nets. The traps had an efficiency of about 4% only but provided enough material for analysis. Very fine sand (0.07 < d < 0.11 mm) only was collected in the traps. Transport of sand was greatest in the bottom 10% of the water column and followed a Rouse profile. Sand extended to a height of about 4 m above the bed during peak flows corresponding to the estimated thickness of the boundary layer; and observed in synoptic ADCP profiles. The sand in the benthic boundary layer was largely inorganic (>95%); above this layer, organic content varied widely and was greatest near the surface. The movability number Ws/U_∗$W_s/U_{\ast }$ showed a linear relationship to dimensionless grain diameter (D_*): (Ws/U_∗)=(D_∗/10)$\left(W_s/U_{\ast }\right)=\left(D_{\ast }/10\right)$; D_* < 10. Sand concentration in suspension was simulated by a mean Rouse parameter of −2.01 ± 0.66 (Lido inlet) and −0.82 ± 0.27 (Chioggia inlet). The β parameter ( Hill et al., 1988) was correlated with D_* and movability number in the form: β=2.07−2.03D_∗+59(Ws/U_∗)²$\beta =2.07-2.03D_{\ast }+59{\left(W_s/U_{\ast }\right)}^2$ (r² = 0.42). Von Karman's constant was back-calculated from a Law of the Wall relationship as a test on the accuracy of U_* estimates; a mean value of 0.37 ± 0.1 (compared to the accepted value of 0.41) suggest U_* was accurate to within 10%. The constant of proportionality (γ = 3.54 × 10⁻⁴) between reference concentration (C_a) and normalized excess bed shear stress was in line with the published literature.     

Analysis, synthesis and modelling of high-resolution observations of salt-marsh eco-geomorphological patterns in the Venice lagoon

The present paper describes observations, analyses and models of salt-marsh channel network and vegetation patterns with the aim of contributing to the development of predictive models of ecological and morphological co-evolution. Existing and new observations are described, with particular emphasis on remote sensing and ancillary field surveys, which are shown to allow reliable, accurate and repeatable quantitative characterizations of landform and vegetation properties over the spatial scales of interest. The observed channel network morphological characters are then used as the basis and validation of models describing the emergence of channel network and vegetation spatial patterns. In particular, with reference to observations performed in the Venice Lagoon, the note describes: (i) new, 2-cm resolution, characterizations of channel network geometry obtained from “proximal sensing” photographic observations; (ii) the reliable quantitative maps of salt-marsh vegetation which may be retrieved from hyperspectral remote sensing data and field ancillary observations; (iii) a synthesis of recent and new analyses of the statistical properties of vegetation and landform spatial organization, that may be inferred from the maps so derived; (iv) recent and new conceptual and quantitative ecological and geomorphic models developed and validated by remote-sensing and field observations. A coherent observational and theoretical eco-morphodynamic framework is then proposed.     

Benthic macrofauna changes in areas of Venice lagoon populated by seagrasses or seaweeds.

Two areas of the Venice lagoon populated by seagrasses (three stations covered by Cymodocea nodosa (Ucria) Asherson, Zostera marina Linnaeus, Zostera noltii Hornemann) or seaweeds (two stations: one covered by Ulva rigida C. Agardh and another at present without seaweed biomass) were monitored by means of six surveys over a year in order to study macrofaunal composition and seasonal changes. The seagrass stations showed a mean species richness (28-30 S m(-2)), individual abundance (1854-4018 N m(-2)) and biomass (22.3-37.7 g m(-2) ash-free-dry-weight, AFDW) ca. 3-8 times higher than those populated by seaweeds (10-15 S m(-2), 494-1395 N m(-2) and 5.6-13.7 g m(-2) AFDW). Differences among seagrass or seaweed stations were much lower. The Ulva-dominated station showed a macrofauna completely different both from the other stations and the communities recorded ca. 30 years ago, before the prolific growth of Ulva. In this station, frequent biomass decompositions and anoxic crises created critical conditions for life favouring organisms with reduced life cycles, younger individuals and the epifaunal species instead of the infaunal ones. In particular, Ulva grazers and scrapers such as Gammarus aequicauda Stock and Gibbula adriatica Philippi were found to be by far the most abundant species, whereas the taxa characteristic of the associations found in the past, in the presence of seagrasses or seaweeds and typical of low eutrophicated environments, appear strongly reduced. Marked differences in the macrophyte dominance and in the bio-physico-chemical variables which characterise the main environmental conditions of the Venice lagoon support the different distribution and composition of macrofaunal communities. Seaweed stations appear mainly governed by the seasonal cycles of these un-rooted macrophytes which, by alternating periods of production and decomposition, are responsible for the drastic reduction of macrofauna biodiversity and biomass. Conversely, seagrass stations exhibit a better oxidisation of the environment and show conditions more favourable for macrofauna colonisation, especially in the presence of macrophytes which are characterised by very well developed below-ground systems such as Cymodocea nodosa.     

Implications of the revision to the bathing water directive for local authorities in the Solent

This paper focuses on the revision to the Bathing Water Directive and its likely implications for local authorities in the United Kingdom. It outlines the proposal and its current status in European negotiation and the likely outcome. It then details the work the Solent Forum, in particular a subgroup that focuses on water quality, the Solent Water Quality Association, has done in relation to the proposed revision and their implications for coastal local authorities. Initially, this group considered what the implications for coastal local authorities might be through a national conference and has since concentrated on ensuring authorities at the local level are prepared for the enhanced responsibilities the changes will place on them. This has been achieved through individual project work related to ensuring beach management plans are in place for incidents of non-compliance, undertaking research at local beaches to understand the needs of the public vis-a-vis information, and hosting national events to share best practice.     

白令海峡夏季流量的年际变化及其成因

白令海峡是连接太平洋和北冰洋的唯一通道,穿过海峡的海水体积通量在年际尺度上的变化主要取决于海峡南北两侧的海面高度差,白令海峡的入流对北冰洋海洋过程有重要的意义。利用SODA资料计算夏季白令海峡海水体积通量,对其年际变化及成因进行分析。结果表明夏季白令海峡的体积通量主要是正压地转的;当体积通量为正距平时,楚科奇海、东西伯利亚海、拉普捷夫海以及波弗特海南部海面高度为负距平,同时,白令海陆架海面高度为正距平;对这些海域的Ekman运动、上层海洋温度、盐度和垂直流速进行分析,发现海面高度异常与海峡体积通量的这种关系主要是与海面气压异常分布所产生的Ekman运动有关。当白令海峡的体积通量为正距平时,北冰洋中央海面气压为正距平,白令海海盆海面气压为负距平。这种气压的异常分布在一定程度上解释了上层海洋运动、海水温盐结构与白令海峡入流的关系,从而把夏季大尺度大气环流和白令海峡体积通量的年际变化联系了起来。     

Regulation of the fishing activities in the lagoon of Venice,Italy: Results from a socio-economic study

In the last years, the overall fish industry in the lagoon of Venice has shown a gradual decline. In order to better understand this process, we carry out a socio-economic questionnaire next to the fisherman population. Questionnaire contains significant qualitative and quantitative data that allow us to evaluate the social and the cultural profile of the respondents, including information with respect to the different technological fishing characteristics involved, type and amount of the species harvested as well as the overall productivity of the activity. Furthermore, the questionnaire contains an economic valuation exercise so as to assess in monetary terms the preferences of the fishermen with respect to different alternative policy options that may characterize a future regulation of this economic activity. Estimation results show that fishermen welcome any regulation initiative that is characterized by: (1) banning all fishing activities during the night, (2) allocating fishing concessions areas to each fishermen in a way that minimize the distance between the fishing area and the harbor, and (3) by introducing of a labeling mechanism that certifies the origin of the product. Moreover, the underlying economic valuation mechanism reveals to sensitive to respondent's motivational profile, including the overall trust and confidence that fisherman community places on the current institutional bodies. This result reveals to be of particular significance when attempting the design of an efficient, widely supported regulation of the fishing activity in the lagoon of Venice.     

Analysis of the inter-annual variability and southward expansion of red tides in the Zhejiang coastal waters from 1981 to 2018

A time series dataset spanning 39 years(1981-2018) on red tide events in Zhejiang coastal waters was used to study the characteristics of inter-annual spatial and temporal variations. A distinct inter-annual pattern characterized by low frequency, explosive growth and fluctuating decline stages was found over the studied time scale. Most red tide events occurred in parallel to the bathymetric contour, and 95.4% were located to the west of the 50 m isobath. Additionally, the high-incidence area o...     

阿拉伯海东南海域盐度收支的季节变化

采用SODA海洋同化产品的月平均资料,本文分析了阿拉伯海东南海域表层盐度的季节变化特征,发现局地海面淡水通量不能解释盐度的变化。两个典型区域的表层海水盐度收支分析表明,海洋的平流输送是造成阿拉伯海东南海域盐度冬季降低、夏季升高的主要原因,而淡水通量仅在夏季印度西侧沿岸区域造成盐度降低。冬季,东北季风环流将孟加拉湾北部的低盐水沿同纬度输送到阿拉伯海,然后向北输送,使表层海水盐度降低;夏季,西南季风环流把阿拉伯海西北部的高盐水向南、向东输送,使阿拉伯海东南海域盐度升高。受地理位置因素的影响,阿拉伯海东南海域表层盐度的变化冬季明显强于夏季。     

南海盐度锋的年际变化特征分析

为了探究南海表层5 m盐度锋的年际变化特征,应用50年(1958—2007年)的SODA月平均资料,采用均方差和经验正交函数进行研究。结果表明,盐度锋年际变化显著的区域集中在北部湾、海南岛以东、南海北部、吕宋海峡、东马来西亚西北部和越南最南端;第一模态和第二模态时间系数变化趋势均表明南海盐度锋强度在逐渐减小;前者呈单极子型空间分布,后者空间分布型则为偶极子型。第一模态时间系数功率谱分析表明该模态存在3—5年和7—16年的周期,Morlet小波分析显示1965—2000年该模态主要存在4年、9年和12年左右的周期。第一模态确立的3个负位相中心区域(海南岛以东、吕宋海峡和越南最南端)的均值变化趋势一致,强度都在逐渐增大,具有同位相变化特征;第二模态时间系数功率谱分析表明该模态存在3年、5年和8—12年的周期。Morlet小波分析表明1962—2001年期间该模态存在3年、5年和9—12年的周期。第二模态找出的两个正负位相中心分别在东马来西亚西北部和南海北部,前者盐度锋强度在逐渐减小,而后者强度却在持续增大,强度的年际变化呈现反位相变化特征。     

Some statistical properties of the inter-annual variability of the relative transparency of Black Sea waters

The Secchi disk data-base compiled in the Black Sea from 1992 to 1993 has been investigated. The space-time variability of statistical properties (RMS deviations and trends) of the series of inter-annual anomalies of the relative water transparency is described. Translated by Vladimir A. Puchkin.     

Applicability and intercalibration of macrophyte quality indices to characterise the ecological status of Mediterranean transitional waters: the case of the Venice lagoon

In the framework of the WFD 2000/60/EC intercalibration process the updated versions of the EEI and R‐MaQI, proposed by Italy and Greece for the transitional waters, have been applied to the macrophytes of the Venice lagoon to test their comparability and relationships with the pressure gradients. Submerged macrophytes were collected during spring 2007 at 60 sites spread within the lagoon. At each site, five random samples were collected and the total coverage of benthic macrophytes in the field was estimated based on a number of tests of the bottom. To assess seagrass epiphytes, five shoots were collected for each replicate. Physico‐chemical data were collected in the water column at 14 sites selected to reflect the main hydro‐geomorphological and trophic gradients of the lagoon. The analyses performed indicated that the two metrics appeared to be weakly intercalibrated and only the 30% of the sampling sites displayed the same quality class. The main differences fell into the Moderate and Low classes and the two indices provided discordant results in the intermediate and confined areas of the lagoon. In contrast, the two indices showed good affinity in the marine areas of inlets, which are characterised by seagrass meadows and late‐successional macroalgae. Similar results were evidenced also in a redundancy analysis by the different relationships between quality classes and the physico‐chemical gradients. The main reason for this seems to be the heterogeneity of species–environment relationships inside the groups of species on which the indices are based. Critical aspects of methodological differences and applicability of the macrophyte indices proposed by Italy and Greece for the transitional waters of the Mediterranean eco‐region are discussed.     

北黄海冬季温盐年际变化时空模态与气候响应

根据1977-2012年历年2 月份北黄海断面表底层温度、盐度观测资料,采用旋转经验正交函数（REOF）、跃变分 析、最大熵谱分析和延迟相关分析等方法,分析了断面温度、盐度年际变化时空模态和机制。断面表底层温度、盐度时空模 态主要有两种：开阔海型和近岸（近海） 型。温度、盐度模态的时间分量变化主要有准周期变化和线性趋势变化,温度模态 时间分量存在显著线性升高趋势。历年2月平均气温年际变化主要影响开阔海型温度模态,历年1 月经向伪风应力和年际变 化主要影响近岸型温度模态。盐度模态主要受渤南（鲁北）水和辽南水盐度年际变化影响,受渤南（鲁北） 水影响的盐度模 态,模态时间分量存在显著线性升高趋势;受辽南水影响的盐度模态,模态时间分量存在显著线性降低趋势,其中模态线性 升高的斜率大于模态线性降低的斜率。     

Interannual salinity variations in the Tsushima Strait and its relation to the Changjiang discharge

Interannual salinity variations in the Tsushima Strait are investigated on the basis of historical hydrographic data. The EOF analysis revealed that the most dominant mode is the in-phase salinity variation between the eastern and western channels. The time coefficients of the EOF first mode in summer show a negative correlation with the Changjiang discharge, which indicates that salinity in the Tsushima Strait tends to decrease over summer, related to a large discharge of the Changjiang. The eigenvectors of the first mode are larger in the eastern channel than those in the western channel, though the low salinity water mainly flows through the western channel. This is because the low salinity water spreads into the eastern channel as well as the western channel over summers with a large discharge of the Changjiang. The out-of-phase salinity variation between the channels is extracted as the EOF second mode; this is the predominant variation in the western channel. The time coefficients of the second mode in summer show no significant correlations to the volume transports through the western channel and the transport differences between channels. A relationship between the EOF second mode and variations in the wind stress over the East China Sea is suggested.