Biology, Ecology and Management of Aquatic Plants, 1999
Dense beds of aquatic macrophytes often cause nuisance to boaters and swimmers, and may obstruct ... more Dense beds of aquatic macrophytes often cause nuisance to boaters and swimmers, and may obstruct water flow. Management of aquatic vegetation is, therefore, often aimed at reducing the biomass of the plants. If the nuisance is caused by exotic invasive species, there usually is no controversy with nature conservation aims. In shallow lakes, however, the interests of recreational users may conflict with nature conservation because the promotion of indigenous submerged vegetation is considered an important tool for lake restoration. Aiming at intermediate vegetation biomass seems a good solution for this controversy at first sight. However, we argue that such a compromise is often not the best policy from a welfare economic point of view. We present preliminary results of a graphical model, showing that the overall benefit for all ecosystem users may be minimal at the intermediate vegetation biomass. Furthermore, even if there is an optimal benefit at an intermediate macrophyte biomass, we argue that it is may not always be feasible to force the vegetation biomass to the desired level. Due to ecological feedback mechanisms, the system can have two alternative stable states: one with high vegetation biomass and one with little or no vegetation. It is concluded that it will often be better to realise a management strategy aimed at keeping some lakes (or parts of lakes) free of aquatic plants, whereas allowing others to be densely vegetated.
Promoting indigenous submerged macrophytes is considered an important measure to restore shallow ... more Promoting indigenous submerged macrophytes is considered an important measure to restore shallow lakes. On the other hand, dense stands of aquatic vegetation often cause nuisance for boating, swimming and by obstruction of water flow. Consequently, the interests of recreational users may conflict with nature conservation. At first sight, aiming lake management at intermediate vegetation biomass seems a good solution for this controversy. However, as can be shown with a simple economical model, such a compromise may not always be an optimal solution in terms of total welfare across all users of a lake. Here, we show that a management strategy aimed at moderate plant biomass can also be unfeasible for ecological reasons. This is shown by applying two very different models: a minimal logistic model of plant growth which is easy to understand, and the relatively complex and realistic simulation model Charisma which, among other things, includes the seasonal cycle and a detailed description of the dynamics of light availability for macrophytes. The qualitative results of both models were remarkably similar. If the ecosystem has no alternative stable states, it is possible to set vegetation to any desired sustainable level using an appropriate harvesting strategy. However, if an intermediate vegetation biomass is to be realized the costs of harvesting are high, because the yield is predicted to be maximal in that case. If the ecosystem has alternative stable states, harvesting becomes risky because the vegetation may collapse entirely below a certain, in practice unknown, biomass. Also, even moderate harvesting may reduce the resilience of the vegetated state, making the ecosystem more vulnerable to adverse conditions such as unfavorable weather conditions or bird grazing.
The European Water Framework Directive has been adopted by Member States to assess and manage the... more The European Water Framework Directive has been adopted by Member States to assess and manage the ecological integrity of surface waters. Specific challenges include harmonizing diverse assessment systems across Europe, linking ecological assessment to restoration measures and reaching a common view on 'good' ecological status. In this study, nine national macrophyte-based approaches for assessing ecological status were compared and harmonized, using a large dataset of 539 European lakes. A macrophyte common metric, representing the average standardized view of each lake by all countries, was used to compare national methods. This was also shown to reflect the total phosphorus (r = 0.32), total nitrogen (r = 0.22) as well as chlorophyll- (r = 0.35-0.38) gradients, providing a link between ecological data, stressors and management decisions. Despite differing assessment approaches and initial differences in classification, a consensus was reached on how type-specific macrophy...
Defining the overall ecological status of lakes according to the Water Framework Directive (WFD) ... more 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 W. E. Penning (&)
Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (... more Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (nonlinear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database
L. Kufel, A. Prejs & JI Rybak (eds), Shallow Lakes &#... more L. Kufel, A. Prejs & JI Rybak (eds), Shallow Lakes '95. c 1997 Kluwer Academic Publishers. Printed in Belgium. ... Macroinvertebrate communities in relation to submerged vegetation in two Chara-dominated lakes ... Marcel S. van den Berg1, Hugo Coops2, Ruurd Noordhuis2, ...
Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (... more Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (nonlinear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database A. Kolada selection and classification methods. This hampers a Europe-wide comparison of classified species lists as used for the status assessment within the WFD implementation process.
Water-birds were almost absent from Lake Veluwemeer during the 1970s and 1980s, due to low food a... more Water-birds were almost absent from Lake Veluwemeer during the 1970s and 1980s, due to low food availability related to eutrophication. Several restoration measures have resulted in the recolonization of the lake by Chara spp. during the 1990s. Bird numbers in autumn and winter have increased along with charophyte biomass. Linear regression analysis was used to relate bird numbers to the
S 0 3 0 4 -3 7 7 0 ( 0 1 ) 0 0 2 0 6 -6 276 E.H. van Nes et al. / Aquatic Botany 72 (2002) mixing... more S 0 3 0 4 -3 7 7 0 ( 0 1 ) 0 0 2 0 6 -6 276 E.H. van Nes et al. / Aquatic Botany 72 (2002) mixing, on the other hand, local alternative stable states are predicted to occur.
The Water Framework Directive is the first international legislation to require European countrie... more The Water Framework Directive is the first international legislation to require European countries to establish comparable ecological assessment schemes for their freshwaters. A key element in harmonising quality classification within and between Europe's river basins is an "Intercalibration" exercise, stipulated by the WFD, to ensure that the good status boundaries in all of the biological assessment methods correspond to similar levels of anthropogenic pressure. In this article, we provide a comprehensive overview of this international comparison, focusing on the assessment schemes developed for freshwater lakes. Out of 82 lake ecological assessment methods reported for the comparison, 62 were successfully intercalibrated and included in the EC Decision on intercalibration, with a high proportion of phytoplankton (18), macrophyte (17) and benthic fauna (13) assessment methods. All the lake assessment methods are reviewed in this article, including the results of intercalibration. Furthermore, the current gaps and way forward to reach consistent management objectives for European lakes are discussed.
The Water Framework Directive (WFD) has been published in 2000 and the process of its implementat... more The Water Framework Directive (WFD) has been published in 2000 and the process of its implementation has created a new paradigm in the understanding of ecological status of water bodies in Europe. The Directive explicitly requires that ecological status is assessed through the analysis of various characteristics of aquatic flora and fauna. An Intercalibration exercise is foreseen to identify and resolve significant inconsistencies between the ecological quality classifications of EU Member States to ensure that the obligation to reach good status has the same meaning throughout Europe. The results of the first Lake Intercalibration exercise (2003)(2004)(2005)(2006)(2007)(2008) are the setting of reference conditions and class boundaries for phytoplankton biomass metrics for all lake intercalibration types and all geographical regions of the EU. Work on macrophyte assessment methods has been carried out in the Alpine, Central/Baltic and Northern region, while only Alpine and Mediterranean countries have succeeded to develop and harmonize phytoplankton composition assessment methods. The aim of the second phase of intercalibration (2008)(2009)(2010)(2011) is to close these gaps and improve the comparability of the results in time for the second river basin management plans due in 2015.
L. Kufel, A. Prejs & JI Rybak (eds), Shallow Lakes &#... more L. Kufel, A. Prejs & JI Rybak (eds), Shallow Lakes '95. c 1997 Kluwer Academic Publishers. Printed in Belgium. ... Macroinvertebrate communities in relation to submerged vegetation in two Chara-dominated lakes ... Marcel S. van den Berg1, Hugo Coops2, Ruurd Noordhuis2, ...
1. The implementation of the Water Framework Directive requires EU member states to establish and... more 1. The implementation of the Water Framework Directive requires EU member states to establish and harmonize ecological status class boundaries for biological quality elements. In this paper, we describe an approach for defining ecological class boundaries that delineates shifts in lake ecosystem functioning and, therefore, provides ecologically meaningful targets for water policy in Europe. 2. We collected an extensive data set of 810 lake-years from nine Central European countries , and we used phytoplankton chlorophyll a, a metric widely used to measure the impact of eutrophication in lakes. Our approach establishes chlorophyll a target values in relation to three significant ecological effects of eutrophication: the decline of aquatic macrophytes, the dominance of potentially harmful cyanobacteria and the major functional switch from a clear water to a turbid state. 3. Ranges of threshold chlorophyll a concentrations are given for the two most common lake types in lowland Central Europe: for moderately deep lakes (mean depth 3–15 m), the greatest ecological shifts occur in the range 10–12 lg L À1 chlorophyll a, and for shallow lakes (<3 m mean depth), in the range 21–23 lg L À1 chlorophyll a. 4. Synthesis and applications. Our study provides class boundaries for determining the ecological status of lakes, which have robust ecological consequences for lake functioning and which, therefore, provide strong and objective targets for sustainable water management in Europe. The results have been endorsed by all participant member states and adopted in the European Commission legislation, marking the first attempt in international water policy to move from physico-chemical quality standards to harmonized ecologically based quality targets.
Novel markers for prostate cancer (PCa) are needed because current established markers such as pr... more Novel markers for prostate cancer (PCa) are needed because current established markers such as prostate-specific antigen lack diagnostic specificity and prognostic value. Proteomics analysis of serum from mice grafted with human PCa xenografts resulted in the identification of 44 tumor-derived proteins. Besides secreted proteins we identified several cytoplasmic proteins, among which were most subunits of the proteasome. Native gel electrophoresis and sandwich ELISA showed that these subunits are present as proteasome complexes in the serum from xenograft-bearing mice. We hypothesized that the presence of proteasome subunits and other cytoplasmic proteins in serum of xenografted mice could be explained by the secretion of small vesicles by cancer cells, so-called exosomes. Therefore, mass spectrometry and Western blotting analyses of the protein content of exosomes isolated from PCa cell lines was performed. This resulted in the identification of mainly cytoplasmic proteins of which several had previously been identified in the serum of xenografted mice, including proteasome subunits. The isolated exosomes also contained RNA, including the gene fusion TMPRSS2-ERG product. These observations suggest that although their function is not clearly defined cancer-derived exosomes offer possibilities for the identification of novel biomarkers for PCa.
... Optimum separation of SH peaks was obtained, using a reverse-phase C2/C18 HPLC ... s -1. Thes... more ... Optimum separation of SH peaks was obtained, using a reverse-phase C2/C18 HPLC ... s -1. These rates were used to draw the PI (photosynthesis-irradiance) curves, and ... In many algae, phytochelatins (poly-gammagluta-mylcysteinyl-glycines) are induced by heavy metals (Gek ...
Logistic regression was used to analyse the relationship between six submerged macrophyte taxa (C... more Logistic regression was used to analyse the relationship between six submerged macrophyte taxa (Chara spp., Potamogeton perfoliatus, Potamogeton pectinatus, Potamogeton pusillus, Myriophyllum spicatum, Alisma gramineum and sum of all species) and four environmental variables (turbidity, effective wind fetch, water depth and sediment silt percentage, including interactions and some quadratic terms). The models were based on intensive vegetation samples (total c. 72 000) and other monitoring data carried out in five Dutch shallow lakes in the IJsselmeer area from 1988 to 1998. Water depth and light extinction were the most important factors determining the occurrence of all studied species in Veluwemeer, while effective wind fetch had a moderate effect and sediment silt had only a minor effect on the occurrence. Water depth had a negative impact on all species, except A. gramineum, which showed an optimum response. Three species showed an optimum response at intermediate turbidity (M. spicatum, P. pusillus and P. pectinatus), whereas the other taxa were negatively related. Three species (Chara spp., P. perfoliatus and M. spicatum) were positively related to wind fetch or showed an optimum response at intermediate value, whereas P. pusillus, P. pectinatus and A. gramineum were negatively related. The models including interactions between the explanatory variables showed a high goodness of fit for Veluwemeer for Chara, P. pectinatus and M. spicatum (in more than 8 of 10 instances, a cell originally scored '1' are predicted to have a higher probability than the ones originally scored '0'). The models of the other species showed a moderate goodness of fit (between 6 and 8 of 10 instances correctly predicted). The models developed for Veluwemeer were valid for Chara in all the four other lakes (more than 8 of 10 instances correctly predicted), while the models of other species were valid in some instances. A succession of vegetation was recognised based on water depth and turbidity in Veluwemeer. P. perfoliatus and P. pectinatus dominated the shallow zones under turbid conditions, but a change to dominance by Chara occurred in clear water. Based on the observation of co-occurrence, competition has played an important role for the shift from P. pectinatus to Chara. Chara became dominant 2 years after initial colonisation of Chara in P. pectinatus beds. Competition between P. perfoliatus and Chara may have been of less importance, due to a more distinct habitat (deeper colonisation) of dense P. perfoliatus beds. The analysed species showed large differences in vegetation stability from year-to-year. Chara showed the highest year to year stability (c. 65% of the cells remained covered from one year to another), while A. gramineum showed the highest dynamics (c. 10% of the cells remained covered from one year to another). Species producing specialized vegetative propagules for over wintering showed a higher local stability than species without such propagules.
Biology, Ecology and Management of Aquatic Plants, 1999
Dense beds of aquatic macrophytes often cause nuisance to boaters and swimmers, and may obstruct ... more Dense beds of aquatic macrophytes often cause nuisance to boaters and swimmers, and may obstruct water flow. Management of aquatic vegetation is, therefore, often aimed at reducing the biomass of the plants. If the nuisance is caused by exotic invasive species, there usually is no controversy with nature conservation aims. In shallow lakes, however, the interests of recreational users may conflict with nature conservation because the promotion of indigenous submerged vegetation is considered an important tool for lake restoration. Aiming at intermediate vegetation biomass seems a good solution for this controversy at first sight. However, we argue that such a compromise is often not the best policy from a welfare economic point of view. We present preliminary results of a graphical model, showing that the overall benefit for all ecosystem users may be minimal at the intermediate vegetation biomass. Furthermore, even if there is an optimal benefit at an intermediate macrophyte biomass, we argue that it is may not always be feasible to force the vegetation biomass to the desired level. Due to ecological feedback mechanisms, the system can have two alternative stable states: one with high vegetation biomass and one with little or no vegetation. It is concluded that it will often be better to realise a management strategy aimed at keeping some lakes (or parts of lakes) free of aquatic plants, whereas allowing others to be densely vegetated.
Promoting indigenous submerged macrophytes is considered an important measure to restore shallow ... more Promoting indigenous submerged macrophytes is considered an important measure to restore shallow lakes. On the other hand, dense stands of aquatic vegetation often cause nuisance for boating, swimming and by obstruction of water flow. Consequently, the interests of recreational users may conflict with nature conservation. At first sight, aiming lake management at intermediate vegetation biomass seems a good solution for this controversy. However, as can be shown with a simple economical model, such a compromise may not always be an optimal solution in terms of total welfare across all users of a lake. Here, we show that a management strategy aimed at moderate plant biomass can also be unfeasible for ecological reasons. This is shown by applying two very different models: a minimal logistic model of plant growth which is easy to understand, and the relatively complex and realistic simulation model Charisma which, among other things, includes the seasonal cycle and a detailed description of the dynamics of light availability for macrophytes. The qualitative results of both models were remarkably similar. If the ecosystem has no alternative stable states, it is possible to set vegetation to any desired sustainable level using an appropriate harvesting strategy. However, if an intermediate vegetation biomass is to be realized the costs of harvesting are high, because the yield is predicted to be maximal in that case. If the ecosystem has alternative stable states, harvesting becomes risky because the vegetation may collapse entirely below a certain, in practice unknown, biomass. Also, even moderate harvesting may reduce the resilience of the vegetated state, making the ecosystem more vulnerable to adverse conditions such as unfavorable weather conditions or bird grazing.
The European Water Framework Directive has been adopted by Member States to assess and manage the... more The European Water Framework Directive has been adopted by Member States to assess and manage the ecological integrity of surface waters. Specific challenges include harmonizing diverse assessment systems across Europe, linking ecological assessment to restoration measures and reaching a common view on 'good' ecological status. In this study, nine national macrophyte-based approaches for assessing ecological status were compared and harmonized, using a large dataset of 539 European lakes. A macrophyte common metric, representing the average standardized view of each lake by all countries, was used to compare national methods. This was also shown to reflect the total phosphorus (r = 0.32), total nitrogen (r = 0.22) as well as chlorophyll- (r = 0.35-0.38) gradients, providing a link between ecological data, stressors and management decisions. Despite differing assessment approaches and initial differences in classification, a consensus was reached on how type-specific macrophy...
Defining the overall ecological status of lakes according to the Water Framework Directive (WFD) ... more 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 W. E. Penning (&)
Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (... more Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (nonlinear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database
L. Kufel, A. Prejs & JI Rybak (eds), Shallow Lakes &#... more L. Kufel, A. Prejs & JI Rybak (eds), Shallow Lakes '95. c 1997 Kluwer Academic Publishers. Printed in Belgium. ... Macroinvertebrate communities in relation to submerged vegetation in two Chara-dominated lakes ... Marcel S. van den Berg1, Hugo Coops2, Ruurd Noordhuis2, ...
Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (... more Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (nonlinear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database A. Kolada selection and classification methods. This hampers a Europe-wide comparison of classified species lists as used for the status assessment within the WFD implementation process.
Water-birds were almost absent from Lake Veluwemeer during the 1970s and 1980s, due to low food a... more Water-birds were almost absent from Lake Veluwemeer during the 1970s and 1980s, due to low food availability related to eutrophication. Several restoration measures have resulted in the recolonization of the lake by Chara spp. during the 1990s. Bird numbers in autumn and winter have increased along with charophyte biomass. Linear regression analysis was used to relate bird numbers to the
S 0 3 0 4 -3 7 7 0 ( 0 1 ) 0 0 2 0 6 -6 276 E.H. van Nes et al. / Aquatic Botany 72 (2002) mixing... more S 0 3 0 4 -3 7 7 0 ( 0 1 ) 0 0 2 0 6 -6 276 E.H. van Nes et al. / Aquatic Botany 72 (2002) mixing, on the other hand, local alternative stable states are predicted to occur.
The Water Framework Directive is the first international legislation to require European countrie... more The Water Framework Directive is the first international legislation to require European countries to establish comparable ecological assessment schemes for their freshwaters. A key element in harmonising quality classification within and between Europe's river basins is an "Intercalibration" exercise, stipulated by the WFD, to ensure that the good status boundaries in all of the biological assessment methods correspond to similar levels of anthropogenic pressure. In this article, we provide a comprehensive overview of this international comparison, focusing on the assessment schemes developed for freshwater lakes. Out of 82 lake ecological assessment methods reported for the comparison, 62 were successfully intercalibrated and included in the EC Decision on intercalibration, with a high proportion of phytoplankton (18), macrophyte (17) and benthic fauna (13) assessment methods. All the lake assessment methods are reviewed in this article, including the results of intercalibration. Furthermore, the current gaps and way forward to reach consistent management objectives for European lakes are discussed.
The Water Framework Directive (WFD) has been published in 2000 and the process of its implementat... more The Water Framework Directive (WFD) has been published in 2000 and the process of its implementation has created a new paradigm in the understanding of ecological status of water bodies in Europe. The Directive explicitly requires that ecological status is assessed through the analysis of various characteristics of aquatic flora and fauna. An Intercalibration exercise is foreseen to identify and resolve significant inconsistencies between the ecological quality classifications of EU Member States to ensure that the obligation to reach good status has the same meaning throughout Europe. The results of the first Lake Intercalibration exercise (2003)(2004)(2005)(2006)(2007)(2008) are the setting of reference conditions and class boundaries for phytoplankton biomass metrics for all lake intercalibration types and all geographical regions of the EU. Work on macrophyte assessment methods has been carried out in the Alpine, Central/Baltic and Northern region, while only Alpine and Mediterranean countries have succeeded to develop and harmonize phytoplankton composition assessment methods. The aim of the second phase of intercalibration (2008)(2009)(2010)(2011) is to close these gaps and improve the comparability of the results in time for the second river basin management plans due in 2015.
L. Kufel, A. Prejs & JI Rybak (eds), Shallow Lakes &#... more L. Kufel, A. Prejs & JI Rybak (eds), Shallow Lakes '95. c 1997 Kluwer Academic Publishers. Printed in Belgium. ... Macroinvertebrate communities in relation to submerged vegetation in two Chara-dominated lakes ... Marcel S. van den Berg1, Hugo Coops2, Ruurd Noordhuis2, ...
1. The implementation of the Water Framework Directive requires EU member states to establish and... more 1. The implementation of the Water Framework Directive requires EU member states to establish and harmonize ecological status class boundaries for biological quality elements. In this paper, we describe an approach for defining ecological class boundaries that delineates shifts in lake ecosystem functioning and, therefore, provides ecologically meaningful targets for water policy in Europe. 2. We collected an extensive data set of 810 lake-years from nine Central European countries , and we used phytoplankton chlorophyll a, a metric widely used to measure the impact of eutrophication in lakes. Our approach establishes chlorophyll a target values in relation to three significant ecological effects of eutrophication: the decline of aquatic macrophytes, the dominance of potentially harmful cyanobacteria and the major functional switch from a clear water to a turbid state. 3. Ranges of threshold chlorophyll a concentrations are given for the two most common lake types in lowland Central Europe: for moderately deep lakes (mean depth 3–15 m), the greatest ecological shifts occur in the range 10–12 lg L À1 chlorophyll a, and for shallow lakes (<3 m mean depth), in the range 21–23 lg L À1 chlorophyll a. 4. Synthesis and applications. Our study provides class boundaries for determining the ecological status of lakes, which have robust ecological consequences for lake functioning and which, therefore, provide strong and objective targets for sustainable water management in Europe. The results have been endorsed by all participant member states and adopted in the European Commission legislation, marking the first attempt in international water policy to move from physico-chemical quality standards to harmonized ecologically based quality targets.
Novel markers for prostate cancer (PCa) are needed because current established markers such as pr... more Novel markers for prostate cancer (PCa) are needed because current established markers such as prostate-specific antigen lack diagnostic specificity and prognostic value. Proteomics analysis of serum from mice grafted with human PCa xenografts resulted in the identification of 44 tumor-derived proteins. Besides secreted proteins we identified several cytoplasmic proteins, among which were most subunits of the proteasome. Native gel electrophoresis and sandwich ELISA showed that these subunits are present as proteasome complexes in the serum from xenograft-bearing mice. We hypothesized that the presence of proteasome subunits and other cytoplasmic proteins in serum of xenografted mice could be explained by the secretion of small vesicles by cancer cells, so-called exosomes. Therefore, mass spectrometry and Western blotting analyses of the protein content of exosomes isolated from PCa cell lines was performed. This resulted in the identification of mainly cytoplasmic proteins of which several had previously been identified in the serum of xenografted mice, including proteasome subunits. The isolated exosomes also contained RNA, including the gene fusion TMPRSS2-ERG product. These observations suggest that although their function is not clearly defined cancer-derived exosomes offer possibilities for the identification of novel biomarkers for PCa.
... Optimum separation of SH peaks was obtained, using a reverse-phase C2/C18 HPLC ... s -1. Thes... more ... Optimum separation of SH peaks was obtained, using a reverse-phase C2/C18 HPLC ... s -1. These rates were used to draw the PI (photosynthesis-irradiance) curves, and ... In many algae, phytochelatins (poly-gammagluta-mylcysteinyl-glycines) are induced by heavy metals (Gek ...
Logistic regression was used to analyse the relationship between six submerged macrophyte taxa (C... more Logistic regression was used to analyse the relationship between six submerged macrophyte taxa (Chara spp., Potamogeton perfoliatus, Potamogeton pectinatus, Potamogeton pusillus, Myriophyllum spicatum, Alisma gramineum and sum of all species) and four environmental variables (turbidity, effective wind fetch, water depth and sediment silt percentage, including interactions and some quadratic terms). The models were based on intensive vegetation samples (total c. 72 000) and other monitoring data carried out in five Dutch shallow lakes in the IJsselmeer area from 1988 to 1998. Water depth and light extinction were the most important factors determining the occurrence of all studied species in Veluwemeer, while effective wind fetch had a moderate effect and sediment silt had only a minor effect on the occurrence. Water depth had a negative impact on all species, except A. gramineum, which showed an optimum response. Three species showed an optimum response at intermediate turbidity (M. spicatum, P. pusillus and P. pectinatus), whereas the other taxa were negatively related. Three species (Chara spp., P. perfoliatus and M. spicatum) were positively related to wind fetch or showed an optimum response at intermediate value, whereas P. pusillus, P. pectinatus and A. gramineum were negatively related. The models including interactions between the explanatory variables showed a high goodness of fit for Veluwemeer for Chara, P. pectinatus and M. spicatum (in more than 8 of 10 instances, a cell originally scored '1' are predicted to have a higher probability than the ones originally scored '0'). The models of the other species showed a moderate goodness of fit (between 6 and 8 of 10 instances correctly predicted). The models developed for Veluwemeer were valid for Chara in all the four other lakes (more than 8 of 10 instances correctly predicted), while the models of other species were valid in some instances. A succession of vegetation was recognised based on water depth and turbidity in Veluwemeer. P. perfoliatus and P. pectinatus dominated the shallow zones under turbid conditions, but a change to dominance by Chara occurred in clear water. Based on the observation of co-occurrence, competition has played an important role for the shift from P. pectinatus to Chara. Chara became dominant 2 years after initial colonisation of Chara in P. pectinatus beds. Competition between P. perfoliatus and Chara may have been of less importance, due to a more distinct habitat (deeper colonisation) of dense P. perfoliatus beds. The analysed species showed large differences in vegetation stability from year-to-year. Chara showed the highest year to year stability (c. 65% of the cells remained covered from one year to another), while A. gramineum showed the highest dynamics (c. 10% of the cells remained covered from one year to another). Species producing specialized vegetative propagules for over wintering showed a higher local stability than species without such propagules.
Uploads
Papers by Marcel Berg