Simple tools for assessing water quality and trophic status in transitional water ecosystems

In this study we have developed an index for assessing trophic status and water quality in transitional aquatic ecosystems of Southern Europe. The index has been developed from the water quality index of the U.S. National Sanitation Foundation and integrates the main causal factors (inorganic nutrients), the key biological elements (primary producers) and indicator of effects (oxygen) of eutrophication. Six main variables have been used: relative coverage of benthic phanerogams and opportunistic macroalgae species, and concentrations of dissolved oxygen, phytoplankton chlorophyll-a, dissolved inorganic nitrogen and phosphorus. Non-linear functions are used to transform each measured variable into its quality value. Each quality value is then multiplied by a weighting factor, to take into account the relative contribution of each variable to the overall water quality. Finally, the index value is calculated as the sum of the weighted quality values, ranging from 0 (poorest state) to 100 (best condition). The index has been tested and validated in six transitional water ecosystems which differ in anthropogenic pressures and eutrophication levels, for which data sets were available from 1989 to 2004: Sacca di Goro (Northern Adriatic Sea, Italy), Lesina Lagoon (Southern Adriatic Sea, Italy), Ria Formosa (Algarve, Southern Portugal), Mar Menor (Murcia, Southern Spain), Etang de Thau (Herault, Southern France) and Gulf of Gera (Lesvos Island, Greece). The index assessments have been compared with evaluations from the IFREMER (French Research Institute for the Exploitation of the Sea) classification scheme (France) and the trophic index TRIX (Italy), which are currently used for national monitoring of coastal waters and lagoons. Based on the conclusions of this study we suggest to use the index for monitoring water quality in shallow coastal transitional waters, where benthic vegetation controls primary productivity, which makes indices based on phytoplankton only (e.g., TRIX) unsuitable.     

滆湖入湖河流春季大型底栖动物群落结构及水质生物学评价

分别于2018年4月和2019年4月对滆湖入湖河流底栖动物开展调查,并利用生物指数对水质进行生物学评价。结果表明:共鉴定滆湖入湖河流底栖动物28种,以重度耐污种霍甫水丝蚓(优势度为0.46)和中等耐污种铜锈环棱螺(优势度为0.11)占据绝对优势。生物多样性方面以鹤溪河最高,湟里河、扁担河次之,夏溪河及入湖河口最低,水生植物分布是影响各区域底栖动物多样性的重要因素。卡尔森营养状态指数(TSI)与水质污染等级生物评价结果基本一致,以新孟河延伸拓浚工程沿线为界,鹤溪河、夏溪河、湟里河中上游河段处于中度富营养化水平,水体为轻-中污染状态,而下游河段、扁担河及入湖河口处于重度富营养化水平,水体为中-重污染状态。     

Improvement of the ecological water qualification system of rivers based on the first results of the Hungarian phytobenthos surveillance monitoring

Results of an ecological quality ratio-based qualification system, developed on the basis of the analysis of 1,161 benthic diatom dataset of the Hungarian national database, are presented herein. Using Kohonen’s Self Organising Map technique, the 25 Hungarian physiographic river types were pooled into six larger distinct categories (diatom river groups). Diatom metrics were tested for their sensitivity to the targeted stressors (nutrients, COD hydromorphological alteration) in each group. The strongest relationships were found in the case of the IPS, SI and TI indices; therefore the average of these metrics (IPSITI) was proposed as a national multimetric index for Hungarian streams. Based on IPSITI values, the ratio of moderate to worse quality water was the highest in those groups containing small rivers. In the case of large, lowland and mid-altitude rivers with fine sediment, the good and moderate ecological status was more characteristic. Applicability of the IPSITI seems to be very useful in case of small- and medium-sized rivers. For these rivers, the index showed a significant relationship with nutrients and organic pollutants. In the case of very large rivers, the stressor–index relationships were not significant because of the insufficient number of samples and the small range of stressors.     

珊瑚藻类对南麂列岛潮间带底栖生物群落多样性的影响

为了解南麂列岛潮间带珊瑚藻类对于其他大型藻类和底栖动物的影响, 在南麂列岛国家级海洋自然保护区布设了4条潮间带断面, 于2012年5月至2013年2月对其生物状况进行了逐季调查, 分别分析了中低潮区大型藻类、非珊瑚藻大型藻类、底栖动物的物种多样性和均匀度, 并计算了大型底栖动物的功能多样性指数Rao's Q。主要结果如下: (1)共采集和鉴定出大型藻类52种, 其中珊瑚藻科藻类有5种; (2)珊瑚藻类在高潮区没有分布, 在中低潮区均占据优势, 占潮间带藻类生物量的68.9%。四季中低潮区大型藻类的Shannon-Wiener多样性指数范围为1.638-4.044, 非珊瑚藻大型藻类的多样性指数范围为1.495-3.809, 底栖动物为5.289-6.917; 大型藻类的Pielou均匀度指数范围为0.819-0.971, 非珊瑚藻大型藻类的均匀度指数范围为0.830-0.973, 底栖动物为0.967-0.988; (3)大型藻类物种多样性和均匀度指数的降低与珊瑚藻类优势度的增加相关, 但珊瑚藻类优势度与底栖动物物种多样性指数、均匀度指数和功能多样性指数均没有显著相关性; (4)底栖动物功能多样性与珊瑚藻类优势度均呈低潮区高于中潮区的变化规律, 但相关性分析表明两者间并无直接联系。推测珊瑚藻类通过竞争占据了其他藻类的生存空间, 从而降低了南麂列岛潮间带大型藻类的物种多样性和均匀度。底栖动物则因其自身生活特点而使得珊瑚藻类的扩张未能影响其多样性水平。     

Using aquatic macrophyte community indices to define the ecological status of European lakes

Defining the overall ecological status of lakes according to the Water Framework Directive (WFD) is to be partially based on the species composition of the aquatic macrophyte community. We tested three assessment methods to define the ecological status of the macrophyte community in response to a eutrophication pressure as reflected by total phosphorus concentrations in lake water. An absolute species richness, a trophic index (TI) and a lake trophic ranking (LTR) method were tested at Europe-wide, regional and national scales as well as by alkalinity category, using data from 1,147 lakes from 12 European states. Total phosphorus data were used to represent the trophic status of individual samples and were plotted against the calculated TI and LTR values. Additionally, the LTR method was tested in some individual lakes with a relatively long time series of monitoring data. The TI correlated well with total P in the Northern European lake types, whereas the relationship in the Central European lake types was less clear. The relationship between total P and light extinction is often very good in the Northern European lake types compared to the Central European lake types. This can be one of the reasons for a better agreement between the indices and eutrophication pressure in the Northern European lake types. The response of individual lakes to changes in the abiotic environment was sometimes represented incorrectly by the indices used, which is a cause of concern for the use of single indices in status assessments in practice.     

Performance of different biotic indices assessing the ecological status of rivers in the Central Himalaya

Biotic indices based on benthic macroinvertebrates are increasingly being used to assess the ecological quality of running water worldwide. In Nepal in the central Himalaya, five biotic indices have been developed in succession over the last decade to assess the ecological status of rivers, namely: the NEPbios, BRSbios, GRSbios, HKHbios, and NEPbios-Extended. The implementation of control and protection policies should be based on indices with proven reliability. Such reliability refers to the ability of the index to detect the correct status about the health of the assessed environment. So in the present study, we compare the performance of these five indices to determine the most robust, reliable biotic index for Nepal. In total, 248 biological samples belonging to first- to sixth-order streams were analyzed. Each sampling site was preclassified in situ using a screening protocol and later validated with physicochemical parameters to reflect the actual field condition. Overall, the GRSbios proved to be the most reliable, followed by the NEPbios-Extended, HKHbios, NEPbios, and BRSbios. The results were further validated by the ROC (Receiver Operating Characteristic) curve method. The study recommends applying the GRSbios to ecologically assess rivers in Nepal. In addition, we discuss modifying the GRSbios method to consider the future impacts of global change.     

Nitrogen cycling in coastal marine ecosystems

It is generally considered that nitrogen availability is one of the major factors regulating primary production in temperate coastal marine environments. Coastal regions often receive large anthropogenic inputs of nitrogen that cause eutrophication. The impact of these nitrogen additions has a profound effect in estuaries and coastal lagoons where water exchange is limited. Such increased nutrient loading promotes the growth of phytoplankton and fast growing pelagic macroalgae while rooted plants (sea-grasses) and benthic are suppressed due to reduced light availability. This shift from benthic to pelagic primary production introduces large diurnal variations in oxygen concentrations in the water column. In addition oxygen consumption in the surface sediments increases due to the deposition of readily degradable biomass. In this review the physico-chemical and biological factors regulating nitrogen cycling in coastal marine ecosystems are considered in relation to developing effective management programmes to rehabilitate seagrass communities in lagoons currently dominated by pelagic macroalgae and/or cyanobacteria.     

莱州湾多毛类底栖动物生态特征及其对环境变化的响应

研究了2010年莱州湾15个站位的多毛类底栖动物群落生态特征及其对主要海水化学、沉积物环境变化的响应,并与1998年的相关研究进行了对比,以期对莱州湾生态质量现状进行健康评价。结果表明:与1998年相比,2010年底栖动物种类组成和生物多样性发生了较大的变化,底栖动物中绝对优势种为小头虫(Capitellacapitata)。夏季,H’与硝酸盐、石油类、重金属铅、铜、锌、铬呈负相关,说明多毛类动物多样性随着富营养化程度的提高而相应降低,营养物质氮的大量输入,重金属的污染,对莱州湾多毛类动物群落产生了一定负面影响。ABC曲线和BOPA指数结果显示,底栖动物的丰度优势度曲线高于生物量曲线,表明莱州湾底栖动物群落处于重度扰动状态,并且以小头虫为主的多毛类动物显著增加预示了莱州湾已经受到了一定程度的污染。加强海水养殖管理,合理利用海洋生物资源,对底栖动物群落的稳定性和环境的可持续利用具有重要意义。     

A multimetric diatom index to assess the ecological status of coastal Galician rivers (NW Spain)

There are many rivers in northwest Spain as a consequence of the mountainous landscape and the granitic geology subjected to Atlantic influences. Water and epilithic diatoms samples were collected at 72 sites in Galicia flowing into the Atlantic Ocean and Cantabrian Sea in summer 2002–2003 and spring 2004. These sites included minimally disturbed sites, defined as reference sites, and impacted sites which were influenced by different human pressures. We used the diatom assemblages to calculate diatom indices using the Omnidia software, but we also developed new metrics based on the similarity of species composition in reference sites. The response of the metrics was tested in relation to physicochemical variables. We developed a diatom multimetric index (MDIAT) as a combination of metric values. The sensitivity of the MDIAT to organic and nutrient stressors supports the use of this index to classify the ecological status of Galician rivers. The MDIAT showed higher correlations with some variables and nutrients than the individual metrics. According to the MDIAT, 69% of the sites sampled in Galician coastal rivers achieve good ecological status. The MDIAT has been developed specifically for Galician granitic rivers (NW Spain), and has been intercalibrated at the European level in the Central Baltic Rivers GIG. Our study validates the application of this multimetric index to evaluate the water quality in coastal Galician rivers.     

Integrated ecosystem health assessment based on eco-exergy theory: A case study of the Jiangsu coastal area

The main objective of ecosystem health management is to preserve the capacity of ecosystems to respond to disturbances and future changes. We proposed a set of ecological indicators for coastal ecosystem health assessment using physical stressors such as total suspended matter, chemical stressors including nutrients and heavy metal pollutants, community structure metrics including species richness, diversity and evenness, and ecosystem level eco-exergy indicators. The results of our case study indicate that the health status of the Jiangsu coastal ecosystem is limited by environmental stressors and factors that affect the community species diversity. The health status of nektonic and benthic communities is reflected by water quality and sediment physicochemical properties, respectively. The results of our case study demonstrate that the integrated ecological health indicator system can provide a comprehensive assessment that corresponds with the current health of coastal ecosystems and a reliable theoretical basis for regional coastal management.     

Ecological status assessment of European lakes: a comparison of metrics for phytoplankton, macrophytes, benthic invertebrates and fish

Data on phytoplankton, macrophytes, benthic invertebrates and fish from more than 2000 lakes in 22 European countries were used to develop and test metrics for assessing the ecological status of European lakes as required by the Water Framework Directive. The strongest and most sensitive of the 11 metrics responding to eutrophication pressure were phytoplankton chlorophyll a, a taxonomic composition trophic index and a functional traits index, the macrophyte intercalibration taxonomic composition metric and a Nordic lake fish index. Intermediate response was found for a cyanobacterial bloom intensity index (Cyano), the Ellenberg macrophyte index and a multimetric index for benthic invertebrates. The latter also responded to hydromorphological pressure. The metrics provide information on primary and secondary impacts of eutrophication in the pelagic and the littoral zone of lakes. Several of these metrics were used as common metrics in the intercalibration of national assessment systems or have been incorporated directly into the national systems. New biological metrics have been developed to assess hydromorphological pressures, based on aquatic macrophyte responses to water level fluctuations, and on macroinvertebrate responses to morphological modifications of lake shorelines. These metrics thus enable the quantification of biological impacts of hydromorphological pressures in lakes.     

The role of microphytobenthos on shallow coastal lagoons: a modelling approach

Ria Formosa is a Region of Restricted Exchange given its limited connection to coastal water circulation. Furthermore, it is subject to several anthropogenic activities that can lead to an increase in nutrients and potentially to eutrophication. Previous studies have shown the importance of the benthic compartment, specifically the microphytobenthos (MPB) in this shallow coastal lagoon. The dCSTT–MPB model [new version of the dynamic Comprehensive Studies Task Team (dCSTT) model] here described couples the benthic and pelagic compartments. Due to the shallowness of the system, the benthic microalgae are one of the most important primary producers of the system. Preliminary results of the model show a large biomass of benthic microalgae, which strongly influences the pelagic chlorophyll concentration by resuspension. However, algae concentrations in the water column are relatively small due to the high flushing rate of the lagoon. The MPB community is mainly supported by nutrients in the pore water. A sensitivity analysis (SA) has revealed that the factors associated with the benthic compartment were the most important and sensitive to changes. Porosity, benthic chlorophyll recycling, loss of MPB due to grazing and the yield of microphytobenthic chlorophyll from nitrogen were some of the most sensitive parameters, as well as the ones associated with decay of particulate organic nitrogen. The development of our dCSTT–MPB model has itself provided insights into benthic function.     

河流岸带湿地沉积物重金属分布对植被物种多样性和底栖动物群落特征的影响

河流岸带湿地栖息地完整性对河流水环境、水生态和水文的安全与健康具有重要意义,为探究河流岸带湿地表层沉积物重金属分布特征及其对植被和底栖动物的影响,对滦河干流上中下游河段表层沉积物、植物群落和底栖动物调查分析,采用生物毒性效应系数法和综合潜在生态风险指数法评价沉积物重金属污染特征,采用植被物种多样性指数和底栖动物完整性指数评价滦河植物和底栖动物群落特征,探究岸带湿地沉积物重金属空间分布与植被及底栖动物群落特征之间关系。结果表明,滦河表层沉积物总体呈清洁水平,但不同河段重金属空间分布差异较大,下游重金属生态危害系数和潜在生态风险指数高于上中游。湿地物种调查共识别维管束植物219种,大型无脊椎底栖动物105种,综合评价结果表明下游植物群落物种多样性和底栖动物群落完整性低于上中游。滦河下游岸带湿地沉积物重金属对生物群落具有生物毒性和潜在的生态风险,降低了植被物种多样性和底栖动物群落完整性。大型底栖动物完整性指数能够综合反映底栖动物群落结构特征变化,对河岸带湿地生态健康评价和监测具有重要意义。     

不同底栖生物指数在福建省近岸海域的适用性

将3个底栖生物指数AZTI海洋生物指数(AMBI)、多毛类机会种和端足目动物指数(BOPA)、底栖动物多毛类和端足目指数(BPA)和Shannon多样性指数(H)应用于福建省近岸海域4个典型海湾和1个河口的生态质量评价,评估这4个指数在研究区的适用性.结果表明: 4个指数的评价结果差异较大,评价等级完全相同的站位仅有4个,占总评价站数的8.7%;AMBI将76.1%的站位评价为等级“良”,BOPA将89.1%的站位评价为等级“优”,BPA和H的评价结果等级梯度变化明显;对于海湾,BOPA、BPA和AMBI与营养盐因子活性磷酸盐(DIP)和无机氮(DIN)无显著相关性,不能响应研究区的富营养化压力;而H与DIN呈显著负相关.对于河口,BOPA、BPA和AMBI与DIP和DIN均呈显著正相关,且随着与入海口距离的减小,7个断面生态质量评价等级没有明显变化,不能识别河口高强度的富营养化压力,评价结果偏高;而H与DIN呈显著负相关,且随着与入海口距离的减小,7个断面生态质量评价等级呈现提高的趋势.总体上,BOPA、BPA和AMBI在福建近岸海域的适用性较低,而H更合适该研究区,能够响应研究区主要的环境压力.     

Can a benthic diatom community complement chemical analyses and discriminate between disturbed and undisturbed saline wetland habitats? A study of seven soda pans in Serbia

Soda pans are protected in the European Union as Natura 2000 areas in the category of “Pannonic saline steppes and marshes”. There are at least six soda pans of reference status in Serbia and only a half have strict legal protection. The number of similar, but disturbed (modified) habitats that could be reconstructed is still unknown. We conducted sampling in five natural and two disturbed soda pans aiming to compare a difference in physical and chemical water properties and benthic diatom communities. In addition, we tried to apply recently developed Diatom Index for Soda Pans (DISP) and Trait-based index (TBI) to test the applicability of taxonomic and trait-based approaches in ecological status assessment of soda pans in the southern part of the Carpathian Basin. In contrast to natural soda pans, lower pH and nutrients levels were recorded in disturbed pans. A total of 86 taxa of benthic diatoms, including 11 new for diatom flora of Serbia, were identified. A lower species richness and Shannon index was recorded in natural soda pans. Nitzschia austriaca, N. supralitorea, Navicula veneta and N. wiesneri were dominant diatoms in soda pans of the reference status. Both diatom indices were in average lower in disturbed pans, and this difference was statistically significant for DISP index. We concluded that two indices, supplemented with indicator values for some local diatom species, can be a promising tool for soda pan conservation in this part of the Carpathian Basin.

     

Comparing macroinvertebrate indices to detect organic pollution across Europe: a contribution to the EC Water Framework Directive intercalibration

With the EC Water Framework Directive (WFD) the ecological status of a water body is defined by comparing the observed biological community composition present with near-natural reference conditions. The ecological status is then classified into five quality classes (high, good, moderate, poor and bad). It is of great importance that `good ecological status' has the same meaning within the European Union, since water bodies not measuring up to these standards have to be improved. Therefore, the Ecological Quality Ratios (EQR) at high-good, and good-moderate quality class boundaries will be intercalibrated. Each country has to report physical, chemical, and biological data from two sites at each of these boundaries and since most data exist for benthic macroinvertebrates, this quality element will be of great importance in the intercalibration process. The aim of this study was therefore to compare the results of different benthic macroinvertebrate metrics used to assess the impact of organic pollution (including eutrophication) (one of the major human impacts on European streams). A selection of the data sampled in the AQEM project was evaluated, where benthic macroinvertebrate- and abiotic data from four countries (Austria, the Czech Republic, Portugal and Sweden) and seven `stream types' were included. An organic pollution (including eutrophication) gradient was defined using Principal Component Analysis and the boundaries for high-good and good-moderate ecological status set by the partners from each country were used to define arbitrary class boundaries. The Average Score Per Taxon (ASPT) was well correlated with the stress gradient in most stream types, whereas the Saprobic Index worked clearly better than ASPT in those countries (Austria and the Czech Republic) where macroinvertebrates are generally identified to lower (species) as opposed to a higher (genus or family) level of identification. Defining harmonised class boundaries is difficult; this process has to consider the natural differences between stream types (e.g. in the reference values of metrics) but has to eliminate different perceptions of ecological quality.     

环境污染对小清河口大型底栖动物多样性的影响

利用2008年7月小清河口和黄河口各8个站位的底栖动物调查资料,运用多种多样性指数对两河口底栖动物群落多样性特征进行了比较,并运用Spearman相关分析分析了14个环境因素和底栖动物群落多样性特征的相关关系。结果显示,小清河口共有大型底栖动物4门6纲17目35科37属38种,平均分类差异指数为85.7,分类差异变异指数为585.6,黄河口共有大型底栖动物6门9纲24目42科45属48种,平均分类差异指数为89.3,分类差异变异指数为435.8。小清河口的多样性指数(H’)仅约为黄河口的1/3。Spearman相关分析表明,H’与铵盐、硝酸盐、铜和汞含量呈负相关性,说明底栖动物群落多样性随着富营养化程度的提高而相应降低,营养物质氮的大量输入和重金属的污染对小清河口大型底栖动物群落产生了一定负面影响。ABC曲线法分析显示,小清河口底栖动物的丰度优势度曲线与生物量优势度曲线相交,表明小清河口底栖动物群落处于中度干扰状态;BOPA指数显示,小清河口8个站位中有4个站位受到不同程度的环境污染,生活污水和工业废水的排放可能对小清河口底栖动物生态特征带来巨大影响,加强工业和生活污水排放管理,强化清洁生产,加强工业污染源的治理力度,对恢复小清河流域水质、改善生态环境具有重要意义。     

Application of signal detection theory approach for setting thresholds in benthic quality assessments

The European Marine Strategy Framework Directive requires EU Member States to prepare national strategies and manage their seas to achieve good environmental status (GES) by 2020. There are many multimetric indices proposed as indicators of the ecological quality of the benthic environment. Their functionality and utility are extensively discussed in the literature. Different frameworks are suggested for comparative assessments of indicators with no agreement on a standardized way of selecting the most appropriate one. In the current study, we apply signal detection theory (SDT) to evaluate the specificity and sensitivity of the Benthic Quality Index (BQI), its response to the eutrophication pressure, and its performance under the effects of estuarine water outflow. The BQI showed acceptable response to total nitrogen, total phosphorus and chlorophyll-a concentrations in the study area. Based on the results, we suggest using SDT for setting GES thresholds in a standardized way. This aids a robust assessment of the environmental status and supports differentiation between the quality classes.