Multimetric assessment of freshwater macroinvertebrate communities in Flanders, Belgium

One of the objectives of the European Water Framework Directive (WFD; EU, 2000) is to attain a good status for all surface waters in the European Union by the end of 2015. To this end, the ecological status of natural surface waters should be assessed, based on a number of biological quality elements which depend on the category of surface water (rivers, lakes, transitional waters or coastal waters). For each of these elements, member states must choose or develop a classification method, taking into account a set of parameters depending on the quality element and on the surface water category (EU, 2000). The assessment system must be differentiated among the types of water bodies within a category. The method must be in agreement with an Ecological Quality Ratio (EQR) showing relative proportion of the index compared to the reference conditions. This EQR ranges from zero to one, respectively corresponding to a bad and a very good ecological status. This interval is divided into five classes reflecting bad, poor, moderate, good and high ecological status (EU, 2000). For the categories rivers and lakes, one of the relevant biological quality elements is the “benthic invertebrate fauna” (EU, 2000), commonly referred to as macroinvertebrates. For this quality element, the parameters “taxonomic composition and abundance”, “ratio of disturbance sensitive to insensitive taxa” and “diversity” should be taken into account. In Flanders, Belgium, the Belgian Biotic Index (BBI; De Pauw and Vanhooren, 1983), based on macroinvertebrates, has been applied in routine monitoring schemes by the Flemish Environment Agency (VMM) since 1989, confirming the reliability and robustness of this biological quality index. However, with respect to the application of this index for rivers and lakes within a WFD context, not all technical requirements are met by the BBI. The abundance, which is one of the relevant parameters imposed by the WFD, is not taken into account in the BBI calculation, and this index is not explicitly based on a reference condition approach. Furthermore, it is not a type-specific method, in other words, all types of rivers are evaluated by means of the same criteria, and the BBI was intended as an assessment system for watercourses only, not for lakes (De Pauw and Vanhooren, 1983). Two general problems are identified that are associated with taxonomic resolution in water quality assessment based on macroinvertebrates. These are explored by means of analysis of the BBI index calculation method. A first difficulty is caused by possible changes in taxonomy over time, giving rise to inconsistencies in index calculation. A second problem is due to the introduction of exotic species. Both problems can introduce a bias in calculation of the index. To avoid this problem in future assessment methods, it is proposed to use a taxa list to which no changes are made except for the addition of newly introduced exotic species. Since the BBI does not meet all the requirements of the WFD, a new index, the Multimetric Macroinvertebrate Index Flanders (MMIF) for assessing rivers and lakes is proposed. This index is developed using the database of macroinvertebrate samples provided by the VMM. The MMIF is calculated based on macroinvertebrate community data obtained using the same sampling and identification procedure as the BBI. The index calculation is a type-specific multimetric system based on five equally weighted metrics, which are taxa richness, number of Ephemeroptera, Plecoptera and/or Trichoptera taxa, number of other sensitive taxa, the Shannon-Wiener diversity index, and the mean tolerance score. The final index value is expressed as an EQR ranging from zero for bad status to one for high status. The MMIF combines the robustness of the BBI and the long-term experience in Flanders with the flexibility of multimetric indices, while at the same time taking into account the technical requirements of the WFD. To ensure that boundary values for the national biological assessment methods are comparable along all member states in Europe, regional intercalibration exercises were envisaged by the WFD for each quality element and for each category of water body. For river macroinvertebrates, the relevant regional intercalibration exercise for Flanders was coordinated by the so-called Central-Baltic Geographical Intercalibration Group (CB-GIG, 2006). Flanders contributed to this intercalibration exercise, using VMM sampling data, in order to compare the Flemish boundary values to those of the other participating countries and regions and, if necessary, to adjust them to ensure inclusion in the intercalibration decision of the European Commission (EU, 2007). This exercise for river macroinvertebrates essentially consisted in a regression of each participating member states’ national method against a common, generally applicable index. This regression is carried out separately by each member state using a national dataset. Based on the obtained regression equation, each country converts its national boundary values into values on the scale of the common index for subsequent comparison. The mean value of the converted national boundaries is calculated and the rescaled national boundaries should be within a certain range of this mean value in order to be considered as comparable (CB-GIG, 2006). Two major problems emerged with regard to the Flemish contribution. First, the derivation of reference values for the metrics of the common index was not possible using field data because no reference sites are present in Flanders. To overcome this problem, an alternative and transparent way of deriving reference values was used in order to have reference values comparable to those of the other member states (Gabriels, 2007). The second problem concerned the boundary values, which clearly fell below the comparability interval. Therefore, alternative boundary values were proposed. This adjustment of the MMIF class boundaries for rivers was formally accepted by the steering group of the intercalibration exercise (CB-GIG, 2007). The adjusted values were adopted in the draft version of the intercalibration decision of the European Commission (EU, 2007), of which the official publication is foreseen for the end of 2007

Implications of taxonomic modifications and alien species on biological water quality assessment as exemplified by the Belgian Biotic Index method

In this paper, some important problems related to taxonomic resolution in water quality assessment by means of macroinvertebrates are discussed. Most quality indices based on macroinvertebrates only require identification up to genus or family level. Although this can be seen as a practical trade-off between taxonomic precision and time constraints and financial resources, it can result in biased assessment scores for certain stream types. An additional difficulty of identification levels other than species is caused by possible changes in taxonomy over time. A given genus may indeed have been split up into two or more genera or a species could be assigned to a different genus. These changes may alter biotic index values calculated over time, due to a change in number of taxa or replacement of one taxon by another one having a different tolerance class. An additional problem is caused by the invasion of exotic species. The genus Corbicula for instance is currently invading Belgian watercourses in increasing numbers. Since no Belgian Biotic Index (BBI) tolerance class is defined for Corbicula, this may cause inconsistencies in index calcu-lations as well. In order to eliminate these, a semi-fixed taxa list, including a tolerance class for each taxon, for BBI calculation is proposed

Seasonal Predictability of Daily Rainfall Characteristics in Central Northern Chile for Dry-Land Management

The seasonal predictability of daily winter rainfall characteristics relevant to dry-land management was investigated in the Coquimbo region of central northern Chile, with focus on the seasonal rainfall total, daily rainfall frequency, and mean daily rainfall intensity on wet days at the station scale. Three approaches of increasing complexity were tested. First, an index of the simultaneous El Nino–Southern Oscillation (ENSO) was regressed onto May–August (MJJA) observed precipitation; this explained 32% of station-averaged rainfall-amount variability, but performed poorly in a forecasting setting. The second approach used retrospective seasonal forecasts made with three general circulation models (GCMs) to produce downscaled seasonal rainfall statistics by means of canonical correlation analysis (CCA). In the third approach, a nonhomogeneous hidden Markov model (nHMM) driven by the GCM’s seasonal forecasts was used to model stochastic daily rainfall sequences. While the CCA is used as a downscaling method for the seasonal rainfall characteristics themselves, the nHMM has the ability to simulate a large ensemble of daily rainfall sequences at each station from which the rainfall statistics were calculated. Similar cross-validated skill estimates were obtained using both the CCA and nHMM, with the highest correlations with observations found for seasonal rainfall amount and rainfall frequency (up to 0.9 at individual stations). These findings were interpreted using analyses of observed rainfall spatial coherence, and by means of synoptic rainfall states derived from the HMM. The downscaled hindcasts were then tailored to meteorological drought prediction, using the standardized precipitation index (SPI) based on seasonal values, the frequency of substantial rainfall days (>15 mm; FREQ15) and the daily accumulated precipitation deficit. Deterministic hindcasts of SPI showed high hit rates, with high ranked probability skill score for probabilistic hindcasts of FREQ15 obtained via the nHMM

Funções de pedotransferência relacionadas à variabilidade espacial da retenção de água em solos de várzea

The estimation of non available soil variables through the knowledge of other related measured variables can be achieved through pedotransfer functions (PTF) mainly saving time and reducing cost. Great differences among soils, however, can yield non desirable results when applying this method. This study discusses the application of developed PTFs by several authors using a variety of soils of different characteristics, to evaluate soil water contents of two Brazilian lowland soils. Comparisons are made between PTF evaluated data and field measured data, using statistical and geostatistical tools, like mean error, root mean square error, semivariogram, cross-validation, and regression coefficient. The eight tested PTFs to evaluate gravimetric soil water contents (Ug) at the tensions of 33 kPa and 1,500 kPa presented a tendency to overestimate Ug 33 kPa and underestimate Ug1,500 kPa. The PTFs were ranked according to their performance and also with respect to their potential in describing the structure of the spatial variability of the set of measured values. Although none of the PTFs have changed the distribution pattern of the data, all resulted in mean and variance statistically different from those observed for all measured values. The PTFs that presented the best predictive values of Ug33 kPa and Ug1,500 kPa were not the same that had the best performance to reproduce the structure of spatial variability of these variables.A estimativa de variáveis do solo não disponíveis, por meio do conhecimento de outras variáveis medidas, pode ser obtida com o uso de funções de pedotransferência (FPT) com economia de tempo e custos. Entretanto, havendo grande diferença entre os solos, o uso desse método pode conduzir a resultados indesejáveis. Neste estudo é discutida a aplicação de FPTs desenvolvidas por alguns autores usando solos de diferentes características, para avaliar a retenção de água em dois solos de várzea brasileiros. As comparações foram feitas entre os dados medidos e estimados pelas FPTs, usando ferramentas estatísticas e da geoestatística, como erro médio, raiz quadrada do erro médio, semivariogramas, validação cruzada e coeficiente de regressão. As oito FPTs testadas para avaliar o conteúdo gravimétrico de água no solo (Ug) sob as tensões de 33 e 1.500 kPa apresentaram tendência em superestimar Ug 33 kPa e em subestimar Ug 1.500 kPa. As FPTs foram classificadas de acordo com seu desempenho e também em relação ao seu potencial em descrever a estrutura de variabilidade espacial do conjunto de dados medidos. Embora nenhuma das FPTs tenha alterado o padrão de distribuição dos dados, todas resultaram em média e variância estatisticamente diferentes daquelas verificadas para o conjunto dos valores medidos. As FPTs com melhor capacidade preditiva dos valores de Ug33 kPa e Ug1.500 kPa não foram as mesmas que tiveram o melhor desempenho para reproduzir a estrutura de variabilidade espacial dessas variáveis.ICTP (Trieste-Italy)Ghent University (Ghent-Belgium)CNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)EMBRAPA - Clima Temperad

The contribution of the European Society for Soil Conservation (ESSC) to scientific knowledge, education and sustainability

Soil is an integral component of the global environmental system which supports the quality and diversity of terrestrial life on Earth. Therefore, it is vital to consider the processes and impacts of soil degradation on society, especially on the provision of environmental goods and services, including food security and climate change mitigation and adaptation. Scientific societies devoted to soil science play significant roles in reducing soil degradation and promoting soil conservation by advancing scientific knowledge, education and environmental sustainability. The ESSC was founded on 4 November 1988, with the aims to: 1. Support research on soil degradation, soil protection and soil and water conservation. 2. Provide a network for the exchange of knowledge about soil degradation processes and soil conservation research and practises. 3. Produce publications on major issues relating to soil degradation and soil and water conservation. 4. Advise regulators and policy-makers on soil issues, especially soil degradation, protection and conservation. The societal challenges that can be addressed through better soil protection, advancing knowledge and scientific approaches to soil protection and sustainable management, mean the ESSC embraces the on-going development, application, review and constructive criticism of highly innovative scientific soil conservation methods. In this context, the ESSC analyses and publicizes the roles and functions of soil in natural and human-modified systems and the functional optimization of soils to ensure sustainable environmental protection. “The thin layer of soil that forms a patchy covering over the continents controls our own existence and that of every other animal of the land” (Rachel Carson (1962) in ‘Silent Spring’).European Society for Soil Conservatio