A weight of evidence approach for quality assessment of sediments impacted by an oil spill: The role of a set of biomarkers as a line of evidence

In an attempt to incorporate both line of evidence (LOE) and classical weight of evidence (WOE) approaches for the assessment of sediment quality, a set of biomarkers were analyzed in target tissues of two invertebrate species after 28 days of exposure to sediments impacted by oil (derived from the tanker Prestige (2002)). The integration of biomarkers with sediment contamination, acute toxicity and benthic alteration parameters provides an “early warning” tool which not only indicates the environmental quality of an area, but also constitutes an advisory tool for potential ecological risks. The selected biomarkers provide information about the first biological responses due to the presence of contaminants in the environment providing predictable reports about further effects to the ecosystem. The present study demonstrates that the use of a set of biomarkers as part of a WOE approach designed to assess contaminated sediments contributes added value to the classical LOE and allows characterization of the environmental status of the studied area in a more precise and accurate way.     

Can additional abundance indices improve harvest control rules for New Zealand rock lobster (Jasus edwardsii) fisheries?

Although New Zealand rock lobster (Jasus edwardsii) fisheries can be assessed with a sophisticated Bayesian length‐based model, these assessments are expensive and time consuming; they cannot be conducted for each area every year. Harvest control rules are increasingly important management tools in New Zealand rock lobster fisheries. Recent work has developed and evaluated procedures for rebuilding or maintaining lobster stocks based on criteria agreed by stakeholders. Most management procedures depend on a single abundance index, often catch per unit of effort (CPUE). When management procedures react slowly to changes in vulnerable biomass, allowable catches get out of phase with the stock, causing large oscillations in both catches and CPUE. Lags between data and management actions and “latent years” are features of rules that reduce responsiveness. This study explores ways to improve the responsiveness of harvest control rules by using additional data to predict changes in vulnerable biomass. Four data sets are examined: CPUE trends, pre‐recruit indices, puerulus settlement indices, and size frequencies. Only pre‐recruit indices, which were explored with a simple delay‐difference model based on parameter estimates from recent assessments, appeared to have immediate potential for use in improving management procedures.     

Estimating extreme water level probabilities: A comparison of the direct methods and recommendations for best practise

Over the past five decades, several approaches for estimating probabilities of extreme still water levels have been developed. Currently, different methods are applied not only on transnational, but also on national scales, resulting in a heterogeneous level of protection. Applying different statistical methods can yield significantly different estimates of return water levels, but even the use of the same technique can produce large discrepancies, because there is subjective parameter choice at several steps in the model setup. In this paper, we compare probabilities of extreme still water levels estimated using the main direct methods (i.e. the block maxima method and the peaks over threshold method) considering a wide range of strategies to create extreme value dataset and a range of different model setups. We primarily use tide gauge records from the German Bight but also consider data from sites around the UK and Australia for comparison. The focus is on testing the influence of the following three main factors, which can affect the estimates of extreme value statistics: (1) detrending the original data sets; (2) building samples of extreme values from the original data sets; and (3) the record lengths of the original data sets. We find that using different detrending techniques biases the results from extreme value statistics. Hence, we recommend using a 1-year moving average of high waters (or hourly records if these are available) to correct the original data sets for seasonal and long-term sea level changes. Our results highlight that the peaks over threshold method yields more reliable and more stable (i.e. using short records leads to the same results as when using long records) estimates of probabilities of extreme still water levels than the block maxima method. In analysing a variety of threshold selection methods we find that using the 99.7th percentile water level leads to the most stable return water level estimates along the German Bight. This is also valid for the international stations considered. Finally, to provide guidance for coastal engineers and operators, we recommend the peaks over threshold method and define an objective approach for setting up the model. If this is applied routinely around a country, it will help overcome the problem of heterogeneous levels of protection resulting from different methods and varying model setups.     

Long-term monitoring using resident and caged mussels in Boston Harbor yield similar spatial and temporal trends in chemical contamination

Measurements of chemical contaminants in caged (transplanted) and resident mussel populations have become a routine tool for monitoring and assessing the status and trends of coastal water quality. However, few long-term data sets are available to assess the comparability and efficacy of these two monitoring approaches. Three long-term independent data sets exist for Boston Harbor: the National Mussel Watch program has analyzed resident blue mussels (Mytilus edulis) from the Boston Harbor/Massachusetts Bay region for over twenty years, the Massachusetts Water Resources Authority has annually deployed caged (transplanted) mussels (M. edulis) to assess bioaccumulation potential of sewage effluent discharged under its NPDES permit for over fourteen years, and the GulfWatch program has analyzed resident blue mussel populations for over twelve years. Together, these data provide consistent and comparable information on temporal and spatial changes in chemical contamination in Boston Harbor as steps were taken to reduce contaminant loading. The data also demonstrate the complementary nature of resident and caged (transplanted) mussels for assessing contaminant trends even when the basic approaches and sampling frequency differ. These fifteen-year data sets demonstrate contaminant concentrations in mussels from Boston Harbor are similar and with few exceptions have significantly decreased since the early 1990s. The observed trends also demonstrate broad scale improvements to the quality of Boston Harbor and expand understanding of the response of coastal systems to interventions that reduce the load of chemicals to the ocean.     

基于高通量测序技术的北冰洋典型环境原生生物多样性研究进展

原生生物指可独立生存的单细胞或群体真核生物,其多样性高、结构功能复杂、分布广泛,是海洋微型浮游生物群落的重要组成部分,在维持海洋生态系统结构与功能中发挥着重要作用。早期使用显微镜、流式细胞术等传统方法对原生生物多样性的研究具有若干局限性,随着分子生物学技术的发展,测序技术（尤其高通量测序）为深入研究原生生物多样性、群落组成、时空变化及甄别其环境驱动因素等做出重要贡献。北冰洋是受全球气候变暖影响最为严重的大洋,作为水体生态系统的重要组成者,原生生物所受影响仍待深入探讨。因此,探究北冰洋典型环境（如海水、海冰、融池等）中原生生物的群落组成、动态变化等,有助于了解全球变暖过程中北冰洋生态系统的变化。然而,由于极地自然环境恶劣、样品采集困难等原因,北冰洋原生生物多样性的相关研究十分欠缺,许多研究空白亟待补充。本文对基于高通量测序技术的北冰洋原生生物多样性研究进行了文献搜集与整理,以期为全球变化背景下原生生物多样性研究提供参考。     

A weight-of-evidence approach to assessing the ecological impact of organotin pollution in Dutch marine and brackish waters; combining risk prognosis and field monitoring using common periwinkles (Littorina littorea)

In the present study an integrated ecological risk assessment based on multiple lines of evidence (LOEs) was evaluated in order to better assess the risk from TBT in Dutch harbours and open coastal waters. On the basis of spatial distributions of measured tributyltin (TBT) concentrations in sediments and suspended matter, predictions of the intersex index (ISI) in Littorina littorea and the ecological risk expressed as the Potentially Affected Fraction (PAF) of species were made. The results were compared to actual ISI measurements and presence of L. littorea in the field. The PAF calculated on the basis of TBT levels for open coastal waters ranged from 4.2% to 15.3%; for harbours it ranged from 3.5% to 26.9%. Significant intersex levels were observed only in waters where the risk was calculated above 10% PAF. This study suggests that the absence of L. littorea from some harbours with high ecological risk values can be explained by high TBT concentrations. A call is made for the use of integrated approaches like weight-of-evidence (WOE) to help practitioners improve ecological risk assessment.     

Calibration of a two-dimensional hydrodynamics model

This paper reports the approach and results of calibrating a two-dimensional hydrodynamics model. The model was applied to Humboldt Bay, California, and calibrated with synoptic tidal data at four locations. The model calibration was done by using both a trial-and-error approach and a parameter identification (PI) method. For the given finite-difference grid resolution and field observations, the calibration attempt revealed that the two methods produced two different sets of parameters, but with almost identical comparisons between the model solutions and observations. The study results indicate that the appropriate range of model parameter values can be more efficiently identified by parameter identification method, and the best calibration strategy is to use both methods conjunctively.     

Orientation of Sandhoppers Under Natural Conditions in Repeated Trials: an Analysis Using Longitudinal Directional Data

Zonal recovery is a prompt escape towards the sea performed by sandhoppers under stressful environmental conditions. Differences in habitat features, meteorological conditions during the tests and morphological characteristics of the individuals are all factors affecting orientation. This paper deals with the temporal variation of the orientation of a sandhopper sample, taking into account the effect of some environmental and morphological variables on these changes. The directions chosen by single animals in repeated trials under natural conditions were analysed, using longitudinal circular data. The longitudinal analysis highlights several details about three different kinds of intrapopulation variation due to: sun, wind and eye left/right asymmetry. A clear link between the successive directional responses is demonstrated as well as modulation of behaviour with time: the animals stabilise orientation towards a certain direction in successive trials. The use of longitudinal sets of data in orientation studies produces a good synthesis of directional behaviour, due to several advantages of this kind of analysis. These include the fact that the association between successive behaviours and variability through repeated trials is taken into account; a progressive improvement, due to the integration of information from previous experiences, can be detected; the role of the main cues and factors affecting orientation is more accurately defined; and more parsimonious statistical models can be used to fit the data.     

Mean–Standard Deviation Representation of Sonar Images for Echo Detection: Application to SAS Images

This paper addresses the detection of underwater mines echoes with application to synthetic aperture sonar (SAS) imaging. A detection method based on local first- and second-order statistical properties of the sonar images is proposed. It consists of mapping the data onto the mean-standard deviation plane highlighting these properties. With this representation, an adaptive thresholding of the data enables the separation of the echoes from the reverberation background. The procedure is automated using an entropy criterion (setting of a threshold). Applied on various SAS data sets containing both proud and buried mines, the proposed method positively compares to the conventional amplitude threshold detection method. The performances are evaluated by means of receiver operating characteristic (ROC) curves.     

Quantitative evaluation of the time-line reduction performance in high definition marine magnetic surveys

The effectiveness of the time reduction procedure is the critical problem for the informative contents evaluation in the high definition (HD) geomagnetic marine surveys. The use of magnetogradiometers is a good solution for the time-reduction in the regional offshore studies but often, for technical reasons, this is not a practicable method in the very detailed coastal, canal or harbour surveys where the use of coastal base stations may be preferable. On the other hand the uncertainty of the full transferability of the coastal magnetograms to large areas of marine surveys can disrupt the time-reduced data sets by a geomagnetic residual time component. The phenomenon is related to the distance from the coastal observatory and to the homogeneity of the local magnetic characteristics of the crust. The maximum applicability distance of the time-line correction (TL) is qualitatively evaluated and is shown to be inconsistent with geomagnetic marine surveys in high definition. In this work we show a quantitative method to evaluate the stability of the coastal observatory magnetograms over the nearby marine area, together with the numerical degree of precision of the correction. The method is based on a double survey of the same profile (timer track: TT) at two different times. The surveys produce two different row data sets where the difference is related only to the geomagnetic time variations. Using the coastal observatory magnetograms we time-reduce the two data sets: if the coastal observatory magnetograms are fully coherent in the whole survey area the difference between the two reduced data sets will be zero. However, if the time variations measured in the observatory are inadequate in amplitude or phase to model the corresponding time variations in the surveyed profile (TT), the discrepancy between the time reduced data sets will not be zero. Similar TTs starting with various course from the base station permit the surveyed area to be split into sectors with variable degree of time coherence and to assign a degree of precision to the time-reduced survey.     

A multi‐stock,length‐based assessment model for New Zealand rock lobster (Jasus Edwardsii)

We describe a multi‐stock, length‐based Bayesian assessment model for New Zealand spiny lobster (Jasus edwardsii) fisheries. This model allows simultaneous modelling of two or more stocks with a mixture of common and stock‐specific parameters: recruitment is always stock‐specific, but any other parameter can be specified as either common or stock‐specific. Common parameters are estimated from a wider base than they would be in a single‐stock model. The model's time step is flexible and can be changed during the period being modelled to accommodate better data quality in recent data. Other options include the capacity to estimate movements among stocks, allow density‐dependent growth, and choose among likelihood functions for the various data sets, between finite and instantaneous fishing dynamics and between two forms of selectivity curve.     

基于BP网络对模拟声呐信号分类

针对常规的主动声呐调查设备,在简单海洋分层模型的基础上,模拟了多波束类单频信号、侧扫类单频信号、Ch irp调频信号和混合信号4类声呐接收信号,并针对接收信号特征构造了3层BP网络模型,将隐藏层神经元数目设为可调节;利用时间域脉冲宽度和水深与频率域功率谱密度相结合的特征参量,成功地对模拟信号进行了分类。采用改进的BP网络模型,用训练成功的BP网络对102个检测信号进行了分类测试,结果表明,分类成功率较高,可达76%~84.6%,因而利用BP网络可以对不同类别设备的模拟声呐接收信号进行分类。     

安德拉水位计测量中水位值计算的误差分析和估算

在安德拉水位计的实际应用中,除由压力测量引起的水位测量误差外,在水位数据的计算中,也存在着误差因素。本文分析了这些因素的误差分量,并粗略地估算了它们的大小;由此提出了参与水位值计算的几个主要订正参数的选值方法。     

Availability of offloading from an LNG barge

Long-term data sets are discussed for three locations – a southern North Sea location, where sea states are typically dominated by wind-sea conditions, a Northwest Shelf of Australia location, where sea states are often a mix of wind-sea and swell conditions, and a Guinea Gulf location offshore Nigeria, where sea states are dominated by swell. Various types of sea state statistics that have application to availability studies are presented; but databases of these type that also include wind and current data can also be used to estimate response parameters, which can give a more direct assessment of availability, and some example statistics of these are also given. Finally, the availability of offloading an FLNG barge to carrier is evaluated for each of the data sets, for specific operability criteria. Two types of operability criteria are used in the availability evaluations, and the results compared.     

A Bayesian method for the estimation of return values of wave heights

Bayesian statistics offer a novel means of estimating return values of wave heights and hence of establishing design criteria for offshore structures. The Bayesian method has significant advantages over the classical method since it enables all types of uncertainty (physical, parameter, distribution) associated with the design wave prediction to be handled in a consistent manner in the same analysis.The basic principles of the Bayesian method for drawing inferences are outlined step-by-step. It is shown how Bayesian estimators of return values for wave heights are established by taking an expectation over all parameters and contending distributions. When the Bayesian procedure is applied to large data sets, such as wave data sets, computational difficulties could be encountered, making a “remedial” procedure necessary. However, the Bayesian procedure has been used successfully with wave data sets from the northern North Sea. Furthermore, the associated remedial procedure is such that the program can be made suitable for many existing computers, e.g. desk computers.     

Data Uncertainty Estimation in Matched-Field Geoacoustic Inversion

This paper examines a variety of approaches to treating unknown data uncertainties in matched-field geoacoustic inversion. Both optimal parameter estimation via misfit minimization and parameter uncertainty estimation via Gibbs sampling are considered. The misfit is based on the likelihood function for Gaussian-distributed errors, which requires specification of the data variance at each frequency. Unfortunately, independent knowledge of variance is rarely available due to unknown theory errors. Many applications of matched-field minimization implicitly assume that variance effects are uniform over frequency; however, this can be a poor assumption as theory errors generally vary with frequency. Parameter uncertainty estimation to date has used fixed maximum-likelihood (ML) variance estimates, which does not account for the variance uncertainty in estimating parameter uncertainties. This paper considers two new approaches to treating data uncertainty in matched-field inversion: Including variances explicitly as additional (nuisance) parameters in the inversion, and treating variances as implicit unknowns by constraining the misfit according to an ML variance formulation (this includes variance uncertainty without increasing the number of unknown parameters). All of the above approaches are compared for realistic synthetic test cases and for shallow-water acoustic data measured in the Mediterranean Sea as part of the PROpagation channel SIMulator experiment (PROSIM'97).     

现有波群因子的统计研究

自Goda于1970年提出谱峰度参量Qp以来,迄今表征波群强度的因子己有十多种.对文中提及的较常用的11种因子即以后被称为现有波群因子,各作者都强调自己的优点,但何者为较好,直至目前尚无客观的评价.依据从三个测点获得的111组数据对现有波群因子予以检验,若某一因子在较短的记录长度内有连续三个值且其中最大值和最小值满足:(最大值减最小值)不大干0.005,则被称为稳定的波群因子;若这种因子又满足三个条件,即它在任一序数中出现的次数最多、在整条记录中出现的总次数最多和在整条记录的最初1280s内出现率最大,则被称为较佳波群因子.就检验的个例而言,(波高的)平均连长(L₁)和波高与周期的相关系数［R_HT(0)]就是这种因子.将这两个因子连结起来,今后称之为联合波群因子.因此,建议以此联合波群因子表征波群强度将会较前人采用的单因子的为好.     

A small-scale spatial analysis system for maritime Australia

Within the field of resource and environmental management, the paramount value of a spatial analysis system is as a tool for regionalising a case-area in diverse directed ways, each being useful for (i) increasing scientific understanding of that area (intellectualisation) or (ii) for allocating operational categories (for example, funding categories, regulatory categories) differentially between parts of the case-area (called operations support or policy support). Success in serving these scientific and administrative values depends in turn upon two primary attributes of the spatial analysis system and a larger number of secondary attributes. These primary attributes are (i) the range and quality of geocoded data sets held in store or able to be accessed and (ii) the range of spatial analysis techniques which can be called upon for operating on stored data sets. Secondary attributes influencing a spatial analysis system's value include its accessibility to potential users, its ease of use, the judgment and experience of its users and the quality of its cartographic and other outputs. The present paper is a status report on the Australian Coastal And Marine Resources Information System, CAMRIS, a spatial analysis system developed as a demonstration for Australia. CAMRIS contains or can access raw and value-added data sets which comprehensively cover both terrestrial and marine components of the Australian maritime estate. Onshore, for the immediate coastal strip, data held or accessible include geocoded data on vegetation, geology, landform, wetland and coastline type, land use, climate and population. For coastal drainage basins, data sets include river networks, river flows, wetland attributes, soils, geology, elevation, vegetation, mineral deposits, beach attributes, population and bird distributions. Nearshore data include geocoded data on estuary attributes, island attributes, seagrass beds and marine protected areas. Offshore (oceanic) geocoded data held or accessible include bathymetry, sea surface temperature and salinity/dissolved oxygen profiles, together with a variety of geophysical records including gravity, magnetics, seismic track lines, substrates, waves, winds, storms, tides and cyclones. While raw data are stored as such whenever available, many of these data sets are in value-added form, held perhaps as a surface or choropleth or as a function of primary data items. A range of spatial analysis techniques is routinely available for application to CAMRIS data sets including those within the SPANS, Arc Info, and Idrisi geographic information systems, the S Plus exploratory data analysis package, and specialist in-house packages such as PATN for multivariate positive classification and LUPIS for resource allocation and normative classification. CAMRIS demonstration studies in various stages of completion address: (1) selection of coastal and marine protected areas; (2) identification of priority areas for the management of land-based marine pollution; (3) planning for coastal population growth; and (4) synoptic impacts of climatic change in the coastal zone. Further candidate studies being considered include mariculture prospects and proactive management of oil spills and leaks. An important indicator of success for the CAMRIS project would be for it to be seen as a prototype for a properly-funded multi-agency national maritime (coastal and marine) spatial analysis system. Australia, with one of the worlds largest and most diverse maritime estates and with a small population imposing increasing pressures on that estate, needs powerful policy and operations support tools.     

The global structural response model for multi-deck ships in concept design phase

This paper is an attempt to contribute to the improvement of an analysis model within overall structural synthesis procedure for the multi-deck ships. The paper is organized in two parts: modeling principles and model validation. Principles of the proposed generic model formulation on the global and sub-structure levels are given in detail while the load model is briefly summarized. The basic building blocks (macro-elements and gross-elements) for the modeling of ordinary stiffened panels, combining numerical and analytical approaches, are presented and discussed w.r.t. requirements for a multi-deck structure. Different surrogates (sets of elements and ordinary macro-elements) used for equivalent modeling of large side openings are evaluated, since the reduced shear stiffness of superstructure sides has large influence on the hull girder stress distributions along the entire cross section height. The generic ship models developed using outlined principles and the basic building blocks are further validated through complex examples of a large cruise ship and a livestock carrier. On the global level, the accuracy of the generic model w.r.t. the longitudinal stress distribution over ships height is compared with a standard full ship FE model. The results confirmed that the suggested structural modeling principles, based on the generic FE model can be applied for the fast investigation of different structural topological/geometrical concepts as well as for the ordinary scantling/material optimization.