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Reservoirs provide diverse water-related services such as storage for energy production, water supply, irrigation, flood protection and provision of minimum flow during dry periods. When reservoirs are meant catering for multi-purposes, trade-offs and synergies between services provided need to be considered through their proper management and operation. This chapter reviews multipurpose multiunit reservoir systems including their optimum management and tools and decision support systems available for that.

Peri-urban areas are characterized by multifunctional land-use patterns forming a mosaic of built-up and agricultural areas. They are critical for providing food and other agricultural products, livelihood opportunities and multiple ecosystem services, which makes them transformative where urban and rural spaces blend. We analyzed land use changes in a peri-urban micro-watershed in Southern India by using Google Earth data to understand the micro-level spatio-temporal dynamics. This study aims at understanding the peri-urban agriculture and landscape changes as related to the change in use of wastewater and groundwater for irrigation. The temporal dynamics of peri-urban system including the changes in built-up, paragrass, paddy rice and vegetable cultivation, groundwater and wastewater irrigated areas in the watershed were evaluated. The detected changes indicate that, as a consequence of urban pressures, agricultural landscapes are being converted into built-up areas and, at the same time, former barren land is converted to agricultural plots. The mapped land use data are used in landscape change modelling for predicting the peri-urban agricultural dynamics and the driving factors in the watershed. Combined with the mapping and modelling approaches for land use change analysis, our results form the basis for integrated resources management in the wastewater influenced peri-urban systems.

The German Federal Ministry of Education and Research (BMBF) has supported numerousresearch projects on Integrated Water Resources Management (IWRM) within the fundinginitiative “Integrated Water Resources Management“ from 2006 to 2015, with partners fromuniversities, research institutes and commercial enterprises. The scientific accompanying project“Networking the BMBF-funding activity on Integrated Water Resources Management” hasencouraged dialogue between all actors in science, politics, administration, economy and civilsociety in order to achieve synergy effects from the various activities. Important synergies haveresulted from the founding of the BMBF funding initiative “Global change and the HydrologicalCycle“ (GLOWA) for example, and “Research for the sustainable development of the megacitiesof tomorrow“. One of the accompanying project‘s aims is to initiate and support, compile andprepare content-driven dialogue on cross-cutting topics.This paper encompasses and summarises current concepts and core issues of capacitydevelopment as a core element in the realisation of Integrated Water Resources Managementin developing countries. We present findings from workshops and working groups which tookplace from 2009 to 2013. The necessity and goals for conducting capacity development will bepresented first, followed by a brief overview of the literature on conceptional approaches in orderto derive the necessary demands for an implementation strategy for capacity development. Theresults of a survey on current capacity development strategies in 17 joint research projects willbe presented, and conclusions drawn for the structuring of future concepts.

1.We studied the effect of size-selective predation on the outcome of competition between two differently sized prey species in a homogenous environment. 2. Using a physiologically structured population model, we calculated equilibrium food concentrations for a range of predation scenarios defined by varying maximum predation intensity and size-selectivity, the latter being characterized by the neutral selection length (NSL), where negative selection of small prey size-classes turns into positive selection of larger prey. We parameterized the model according to the well-studied example of fish predation on two differently sized cladoceran species, Daphnia pulicaria and Daphnia galeata. 3.Although the larger D. pulicaria was principally the better competitor for food, competitive superiority shifted to the smaller D. galeata under certain predation scenarios. The lowest predation intensity needed to induce a shift from D. pulicaria to D. galeata was found at NSL values in between the sizes at maturity of both species. 4.Analysing the per capita mortality rates as a result of the underlying parameters of the mortality model, NSL and maximum predation intensity, revealed that the tolerable mortality rate of daphnids decreased as NSL increases towards values close to the size at maturity. This effect was most pronounced in D. pulicaria, thus explaining a higher vulnerability of the larger species to size-selective predation. 5.A reduction of the size at maturity in the smaller species (D. galeata) as a phenotypic response to the presence of fish resulted not only in an increased capability to withstand predation, but also in competitive dominance shifts over the larger D. pulicaria at lower predation intensities and a much wider range of NSL as a trait-mediated indirect effect. 6.Overall, our results demonstrate that shifts in dominance of differently sized herbivores under size-selective predation regimes may be facilitated by the demonstrated alteration in competitive, 1.We studied the effect of size-selective predation on the outcome of competition between two differently sized prey species in a homogenous environment. 2. Using a physiologically structured population model, we calculated equilibrium food concentrations for a range of predation scenarios defined by varying maximum predation intensity and size-selectivity, the latter being characterized by the neutral selection length (NSL), where negative selection of small prey size-classes turns into positive selection of larger prey. We parameterized the model according to the well-studied example of fish predation on two differently sized cladoceran species, Daphnia pulicaria and Daphnia galeata. 3.Although the larger D. pulicaria was principally the better competitor for food, competitive superiority shifted to the smaller D. galeata under certain predation scenarios. The lowest predation intensity needed to induce a shift from D. pulicaria to D. galeata was found at NSL values in between the sizes at maturity of both species. 4.Analysing the per capita mortality rates as a result of the underlying parameters of the mortality model, NSL and maximum predation intensity, revealed that the tolerable mortality rate of daphnids decreased as NSL increases towards values close to the size at maturity. This effect was most pronounced in D. pulicaria, thus explaining a higher vulnerability of the larger species to size-selective predation. 5.A reduction of the size at maturity in the smaller species (D. galeata) as a phenotypic response to the presence of fish resulted not only in an increased capability to withstand predation, but also in competitive dominance shifts over the larger D. pulicaria at lower predation intensities and a much wider range of NSL as a trait-mediated indirect effect. 6.Overall, our results demonstrate that shifts in dominance of differently sized herbivores under size-selective predation regimes may be facilitated by the demonstrated alteration in competitive

A large number and wide variety of lake ecosystem models have been developed and published during the past four decades. We identify two challenges for making further progress in this field. One such challenge is to avoid developing more models largely following the concept of others (‘reinventing the wheel’). The other challenge is to avoid focusing on only one type of model, while ignoring new and diverse approaches that have become available (‘having tunnel vision’). In this paper, we aim at improving the awareness of existing models and knowledge of concurrent approaches in lake ecosystem modelling, without covering all possible model tools and avenues. First, we present a broad variety of modelling approaches. To illustrate these approaches, we give brief descriptions of rather arbitrarily selected sets of specific models. We deal with static models (steady state and regression models), complex dynamic models (CAEDYM, CE-QUAL-W2, Delft 3D-ECO, LakeMab, LakeWeb, MyLake, PCLake, PROTECH, SALMO), structurally dynamic models and minimal dynamic models. We also discuss a group of approaches that could all be classified as individual based: super-individual models (Piscator, Charisma), physiologically structured models, stage-structured models and trait-based models. We briefly mention genetic algorithms, neural networks, Kalman filters and fuzzy logic. Thereafter, we zoom in, as an in-depth example, on the multi-decadal development and application of the lake ecosystem model PCLake and related models (PCLake Metamodel, Lake Shira Model, IPH-TRIM3D-PCLake). In the discussion, we argue that while the historical development of each approach and model is understandable given its ‘leading principle’, there are many opportunities for combining approaches. We take the point of view that a single ‘right’ approach does not exist and should not be strived for. Instead, multiple modelling approaches, applied concurrently to a given problem, can help develop an integrative view

A large number and wide variety of lake ecosystem models have been developed and published during the past four decades. We identify two challenges for making further progress in this field. One such challenge is to avoid developing more models largely following the concept of others (‘reinventing the wheel’). The other challenge is to avoid focusing on only one type of model, while ignoring new and diverse approaches that have become available (‘having tunnel vision’). In this paper, we aim at improving the awareness of existing models and knowledge of concurrent approaches in lake ecosystem modelling, without covering all possible model tools and avenues. First, we present a broad variety of modelling approaches. To illustrate these approaches, we give brief descriptions of rather arbitrarily selected sets of specific models. We deal with static models (steady state and regression models), complex dynamic models (CAEDYM, CE-QUAL-W2, Delft 3D-ECO, LakeMab, LakeWeb, MyLake, PCLake, PROTECH, SALMO), structurally dynamic models and minimal dynamic models. We also discuss a group of approaches that could all be classified as individual based: super-individual models (Piscator, Charisma), physiologically structured models, stage-structured models and trait-based models. We briefly mention genetic algorithms, neural networks, Kalman filters and fuzzy logic. Thereafter, we zoom in, as an in-depth example, on the multi-decadal development and application of the lake ecosystem model PCLake and related models (PCLake Metamodel, Lake Shira Model, IPH-TRIM3D-PCLake). In the discussion, we argue that while the historical development of each approach and model is understandable given its ‘leading principle’, there are many opportunities for combining approaches. We take the point of view that a single ‘right’ approach does not exist and should not be strived for. Instead, multiple modelling approaches, applied concurrently to a given problem, can help develop an integrative view, A large number and wide variety of lake ecosystem models have been developed and published during the past four decades. We identify two challenges for making further progress in this field. One such challenge is to avoid developing more models largely following the concept of others (‘reinventing the wheel’). The other challenge is to avoid focusing on only one type of model, while ignoring new and diverse approaches that have become available (‘having tunnel vision’). In this paper, we aim at improving the awareness of existing models and knowledge of concurrent approaches in lake ecosystem modelling, without covering all possible model tools and avenues. First, we present a broad variety of modelling approaches. To illustrate these approaches, we give brief descriptions of rather arbitrarily selected sets of specific models. We deal with static models (steady state and regression models), complex dynamic models (CAEDYM, CE-QUAL-W2, Delft 3D-ECO, LakeMab, LakeWeb, MyLake, PCLake, PROTECH, SALMO), structurally dynamic models and minimal dynamic models. We also discuss a group of approaches that could all be classified as individual based: super-individual models (Piscator, Charisma), physiologically structured models, stage-structured models and trait-based models. We briefly mention genetic algorithms, neural networks, Kalman filters and fuzzy logic. Thereafter, we zoom in, as an in-depth example, on the multi-decadal development and application of the lake ecosystem model PCLake and related models (PCLake Metamodel, Lake Shira Model, IPH-TRIM3D-PCLake). In the discussion, we argue that while the historical development of each approach and model is understandable given its ‘leading principle’, there are many opportunities for combining approaches. We take the point of view that a single ‘right’ approach does not exist and should not be strived for. Instead, multiple modelling approaches, applied concurrently to a given problem, can help develop an integrative view

We studied costs and benefits of life history shifts of water fleas (genus Daphnia) in response to infochemicals from planktivorous fish. We applied a dynamic energy budget model to investigate the resource allocation patterns underlying the observed life history shifts and their adaptive value under size selective predation in one coherent analysis. Using a published data set of life history shifts in response to fish infochemicals we show that Daphnia invests less energy in somatic growth in the fish treatment. This observation complies with theoretical predictions on optimal resource allocation. However, the observed patterns of phenotypic plasticity cannot be explained by changes in resource allocation patterns alone because our model-based analysis of the empirical data clearly identified additional bioenergetic costs in the fish treatments. Consequently, the response to fish kairomone only becomes adaptive if the intensity of size selective predation surpasses a certain critical level. We believe that this is the first study that puts resource allocation, energetic costs, and adaptive value of predator induced life-history shifts – using empirical data – into one theoretical framework., We studied costs and benefits of life history shifts of water fleas (genus Daphnia) in response to infochemicals from planktivorous fish. We applied a dynamic energy budget model to investigate the resource allocation patterns underlying the observed life history shifts and their adaptive value under size selective predation in one coherent analysis. Using a published data set of life history shifts in response to fish infochemicals we show that Daphnia invests less energy in somatic growth in the fish treatment. This observation complies with theoretical predictions on optimal resource allocation. However, the observed patterns of phenotypic plasticity cannot be explained by changes in resource allocation patterns alone because our model-based analysis of the empirical data clearly identified additional bioenergetic costs in the fish treatments. Consequently, the response to fish kairomone only becomes adaptive if the intensity of size selective predation surpasses a certain critical level. We believe that this is the first study that puts resource allocation, energetic costs, and adaptive value of predator induced life-history shifts – using empirical data – into one theoretical framework.

Mismatches between predator and prey due to climate change have now been documented for a number of systems. Ultimately, a mismatch may have far-reaching consequences for ecosystem functioning as decoupling of trophic relationships results in trophic cascades. Here, we examine the potential for climate change induced mismatches between zooplankton and algae during spring succession, with a focus on Daphnia and its algal food. Whereas the development of an overwintering population of daphnids may parallel shifts in phytoplankton phenology due to climate warming, changes in the photoperiod–temperature interaction may cause the emerging population of daphnids to hatch too late and mismatch their phytoplankton prey. A decoupling of the trophic relationship between the keystone herbivore Daphnia and its algal prey can result in the absence of a spring clear water phase. We extended an existing minimal model of seasonal dynamics of Daphnia and algae and varied the way the Daphnia population is started in spring, i.e., from free swimming individuals or from hatching resting eggs. Our model results show that temperature affects the timing of peak abundance in Daphnia and algae, and subsequently the timing of the clear water phase. When a population is started from a small inoculum of hatching resting eggs, extreme climate warming (+6°C) results in a decoupling of trophic relationships and the clear water phase fails to occur. In the other scenarios, the trophic relationships between Daphnia and its algal food source remain intact. Analysis of 36 temperate lakes showed that shallow lakes have a higher potential for climate induced match–mismatches, as the probability of active overwintering daphnids decreases with lake depth. Future research should point out whether lake depth is a direct causal factor in determining the presence of active overwintering daphnids or merely indicative for underlying causal factors such as fish predation and macrophyte cover., Mismatches between predator and prey due to climate change have now been documented for a number of systems. Ultimately, a mismatch may have far-reaching consequences for ecosystem functioning as decoupling of trophic relationships results in trophic cascades. Here, we examine the potential for climate change induced mismatches between zooplankton and algae during spring succession, with a focus on Daphnia and its algal food. Whereas the development of an overwintering population of daphnids may parallel shifts in phytoplankton phenology due to climate warming, changes in the photoperiod–temperature interaction may cause the emerging population of daphnids to hatch too late and mismatch their phytoplankton prey. A decoupling of the trophic relationship between the keystone herbivore Daphnia and its algal prey can result in the absence of a spring clear water phase. We extended an existing minimal model of seasonal dynamics of Daphnia and algae and varied the way the Daphnia population is started in spring, i.e., from free swimming individuals or from hatching resting eggs. Our model results show that temperature affects the timing of peak abundance in Daphnia and algae, and subsequently the timing of the clear water phase. When a population is started from a small inoculum of hatching resting eggs, extreme climate warming (+6°C) results in a decoupling of trophic relationships and the clear water phase fails to occur. In the other scenarios, the trophic relationships between Daphnia and its algal food source remain intact. Analysis of 36 temperate lakes showed that shallow lakes have a higher potential for climate induced match–mismatches, as the probability of active overwintering daphnids decreases with lake depth. Future research should point out whether lake depth is a direct causal factor in determining the presence of active overwintering daphnids or merely indicative for underlying causal factors such as fish predation and macrophyte cover.

Global average surface temperatures are expected to rise by about 1.4–5.8°C from the present until the year 2100. This temperature increase will affect all ecosystems on earth. For shallow lakes—which can be either in a clear water or a turbid state—this climate change will expectedly negatively affect water transparency though the prediction is far from conclusive and experimental investigations elucidating the potential climatic effects on shallow lakes are still rare. The aim of this study was to further shape and sharpens hypotheses on the impact of climate change on shallow lakes by applying an existing and well-calibrated ecosystem model, PCLake. We focused on asymptotic model behaviour for a range of temperature and loading scenarios in a factorial design. We conclude that climate change will likely lead to decreased critical nutrient loadings. Combined with an expected increase in the external nutrient loading, this will increase the probability of a shift from a clear to a turbid state. As the model predicts a higher summer chlorophyll-a concentration, a stronger dominance of cyanobacteria during summer and a reduced zooplankton abundance due to climate change, the turbid state itself is likely to become even more severe., Global average surface temperatures are expected to rise by about 1.4–5.8°C from the present until the year 2100. This temperature increase will affect all ecosystems on earth. For shallow lakes—which can be either in a clear water or a turbid state—this climate change will expectedly negatively affect water transparency though the prediction is far from conclusive and experimental investigations elucidating the potential climatic effects on shallow lakes are still rare. The aim of this study was to further shape and sharpens hypotheses on the impact of climate change on shallow lakes by applying an existing and well-calibrated ecosystem model, PCLake. We focused on asymptotic model behaviour for a range of temperature and loading scenarios in a factorial design. We conclude that climate change will likely lead to decreased critical nutrient loadings. Combined with an expected increase in the external nutrient loading, this will increase the probability of a shift from a clear to a turbid state. As the model predicts a higher summer chlorophyll-a concentration, a stronger dominance of cyanobacteria during summer and a reduced zooplankton abundance due to climate change, the turbid state itself is likely to become even more severe.

According to the size-efficiency hypothesis (SEH) larger bodied cladocerans are better competitors for food than small bodied species. In environments with fish, however, the higher losses of the large bodied species due to size-selective predation may shift the balance in favor of the small bodied species. Here we present a theoretical framework for the analysis of the competitive abilities of zooplankton species that takes both competition and predation into account in one coherent analysis. By applying the conceptually well-understood framework of physiologically structured population models we were able to predict the relative difference in predation rates necessary to cause a shift in dominance of the large-bodied species (Daphnia pulicaria) to the small-bodied species (D. galeata). These predictions depend only on seven easily interpretable parameters per species: size at birth, size at maturity and maximum size, age at maturity, maximal clutch size, egg development time and finally the half-saturation constant for food. The critical equilibrium mortality of D. pulicaria was 0.16 d1 at food concentrations close to the critical food concentration of D. galeata, i.e. D. pulicaria will win the competition as long as its mortality rate is below 0.16 d1. At higher food concentrations the differential mortality curve (plotting equilibrium mortalities of both species against each other) approached a linear function with a slope of one and an intercept equal to the difference in maximal population birth rates. The prediction of critical predation rates was independent of the ingestion rate of the cladocerans and the algal carrying capacity and food regeneration rate of the environment although the mechanism works through competition for a shared algal food resource. We interpret these findings in terms of the relative predation risk large and small-bodied cladocerans will face in various freshwater ecosystems., According to the size-efficiency hypothesis (SEH) larger bodied cladocerans are better competitors for food than small bodied species. In environments with fish, however, the higher losses of the large bodied species due to size-selective predation may shift the balance in favor of the small bodied species. Here we present a theoretical framework for the analysis of the competitive abilities of zooplankton species that takes both competition and predation into account in one coherent analysis. By applying the conceptually well-understood framework of physiologically structured population models we were able to predict the relative difference in predation rates necessary to cause a shift in dominance of the large-bodied species (Daphnia pulicaria) to the small-bodied species (D. galeata). These predictions depend only on seven easily interpretable parameters per species: size at birth, size at maturity and maximum size, age at maturity, maximal clutch size, egg development time and finally the half-saturation constant for food. The critical equilibrium mortality of D. pulicaria was 0.16 d1 at food concentrations close to the critical food concentration of D. galeata, i.e. D. pulicaria will win the competition as long as its mortality rate is below 0.16 d1. At higher food concentrations the differential mortality curve (plotting equilibrium mortalities of both species against each other) approached a linear function with a slope of one and an intercept equal to the difference in maximal population birth rates. The prediction of critical predation rates was independent of the ingestion rate of the cladocerans and the algal carrying capacity and food regeneration rate of the environment although the mechanism works through competition for a shared algal food resource. We interpret these findings in terms of the relative predation risk large and small-bodied cladocerans will face in various freshwater ecosystems.

Life history shifts in daphnids in response to fish infochemicals are generally interpreted as an adaptive response to positive size-selective predation. This interpretation does, however, not hold for larval and small juvenile planktivorous fish, which due to gape limitation, feed on small and medium sized prey. In a life table experiment we show that daphnids exposed to infochemicals excreted by small gape-limited perch and larger perch changed their life history in the same direction, irrespective of the contrasting size-selection of the fish. However, responses to fish infochemicals were strongly influenced by food conditions for daphnids. In the high food treatments size at maturity was in the presence of fish infochemicals, whereas age at maturity remained unchanged. Under low food conditions, size at maturity was generally smaller compared with the high food situation, but unaffected by fish infochemicals. By contrast, age at maturity, which was increased at low food levels, was significantly lower in fish treatments compared with the control. We conclude that life history responses of daphnids to gape-limited fish can indeed be maladaptive, but only in situations of high food availability. This combination of factors is, however, rather unlikely because gape-limited fish usually occur in late spring during the clear water phase when daphnids are severely food limited. We thus hypothesize that the costs of this maladaptive response under negative size-selective predation will be low under field conditions and the selective advantage under positive size-selective predation later in the season will outweigh these costs., Life history shifts in daphnids in response to fish infochemicals are generally interpreted as an adaptive response to positive size-selective predation. This interpretation does, however, not hold for larval and small juvenile planktivorous fish, which due to gape limitation, feed on small and medium sized prey. In a life table experiment we show that daphnids exposed to infochemicals excreted by small gape-limited perch and larger perch changed their life history in the same direction, irrespective of the contrasting size-selection of the fish. However, responses to fish infochemicals were strongly influenced by food conditions for daphnids. In the high food treatments size at maturity was in the presence of fish infochemicals, whereas age at maturity remained unchanged. Under low food conditions, size at maturity was generally smaller compared with the high food situation, but unaffected by fish infochemicals. By contrast, age at maturity, which was increased at low food levels, was significantly lower in fish treatments compared with the control. We conclude that life history responses of daphnids to gape-limited fish can indeed be maladaptive, but only in situations of high food availability. This combination of factors is, however, rather unlikely because gape-limited fish usually occur in late spring during the clear water phase when daphnids are severely food limited. We thus hypothesize that the costs of this maladaptive response under negative size-selective predation will be low under field conditions and the selective advantage under positive size-selective predation later in the season will outweigh these costs.

The midsummer decline (MSD) of daphnids has been attributed to a range of factors related to either resource availability or predation. However, the relative magnitude and importance of each of these factors remained unknown. Therefore, we quantified simultaneously, but independently, both consumptive mortality due to predation and non-consumptive mortality of Daphnia galeata due to senescence, disease, food limitation as well as limiting physical or chemical factors between May and July 1998 in Bautzen Reservoir, Germany. These losses were balanced by the population gains by recruitment. The predation pressure exerted by age-0 fish, by older zooplanktivorous fish and by carnivorous zooplankton did not completely account for the observed mortality pattern of D. galeata that caused the MSD. Non-consumptive mortality in the field was calculated from recruitment patterns estimated from field samples and from age-specific survival probabilities of Daphnia offspring according to lifetable experiments. The results suggest a high non-consumptive mortality during the clear-water phase which is comparable to the magnitude of consumptive losses and may give a possible explanation for the remaining part of Daphnia mortality. By integrating all data concerning the initial abundance in early May as well as population gains and losses of daphnids, a balance sheet was drawn up for four years of investigation (1995-1998). The differences between the cumulated positive and negative book values corresponded well to the actually observed Daphnia abundance in Bautzen Reservoir at the transition period to an MSD of every year. Generally, the hypothesis is supported that an MSD should be expected if the period with bottom-up limitation during the clear-water phase overlaps strongly with top-down effects whereby in detail the following combination of conditions should be fulfilled: (i) a high biomass of age-0 percids in May/June, (ii) an early start of Daphnia consumption by carnivorous z, The midsummer decline (MSD) of daphnids has been attributed to a range of factors related to either resource availability or predation. However, the relative magnitude and importance of each of these factors remained unknown. Therefore, we quantified simultaneously, but independently, both consumptive mortality due to predation and non-consumptive mortality of Daphnia galeata due to senescence, disease, food limitation as well as limiting physical or chemical factors between May and July 1998 in Bautzen Reservoir, Germany. These losses were balanced by the population gains by recruitment. The predation pressure exerted by age-0 fish, by older zooplanktivorous fish and by carnivorous zooplankton did not completely account for the observed mortality pattern of D. galeata that caused the MSD. Non-consumptive mortality in the field was calculated from recruitment patterns estimated from field samples and from age-specific survival probabilities of Daphnia offspring according to lifetable experiments. The results suggest a high non-consumptive mortality during the clear-water phase which is comparable to the magnitude of consumptive losses and may give a possible explanation for the remaining part of Daphnia mortality. By integrating all data concerning the initial abundance in early May as well as population gains and losses of daphnids, a balance sheet was drawn up for four years of investigation (1995-1998). The differences between the cumulated positive and negative book values corresponded well to the actually observed Daphnia abundance in Bautzen Reservoir at the transition period to an MSD of every year. Generally, the hypothesis is supported that an MSD should be expected if the period with bottom-up limitation during the clear-water phase overlaps strongly with top-down effects whereby in detail the following combination of conditions should be fulfilled: (i) a high biomass of age-0 percids in May/June, (ii) an early start of Daphnia consumption by carnivorous z

The aim of the present study was to analyse and compare the feeding behaviour of large perch (>25 cm total length) in two lakes of different state and corresponding differences in food availability. Investigations were conducted in the Bautzen Reservoir, Germany, (biomanipulated, macrophyte cover, The aim of the present study was to analyse and compare the feeding behaviour of large perch (>25 cm total length) in two lakes of different state and corresponding differences in food availability. Investigations were conducted in the Bautzen Reservoir, Germany, (biomanipulated, macrophyte cover

The population dynamics of D. galeata was studied during the period May–July of 5 successive years in Bautzen Reservoir (Germany). Sampling intervals of 3–4 days and knowledge of the egg–age distribution made it possible to calculate recruitment of the population for each sampling interval. In every year, high Daphnia densities and high Secchi depth readings (clear-water stage) were recorded in spring. In two of the 5 years, Daphnia abundance remained on a high level throughout summer, whereas in the remaining 3 years a midsummer decline of Daphnia was observed. Birth rates declined while the abundance increased in spring in every year but the timing of this decline in relation to abundance and the onset of the clear-water stage revealed no obvious pattern, distinguishing between years with or without a midsummer decline. However, cumulative recruitment did reveal a clear pattern: in years without a midsummer decline, cumulative recruitment increased slowly, but continually, starting from a low level in early May. By contrast, in years with a midsummer decline, recruitment increased strongly during one week in May, starting from a relatively high density level (>30 ind. l-1). This quick increase was followed by extended periods with low recruitment. Consequently, in these years the population was dominated by a strong peak-cohort of about the same age during the clear-water stage. If all members of this cohort, while approaching their maximum life-span, die off during a short time interval, this may have a pronounced effect on the initiation of a midsummer decline. From an extensive literature search, evidence is provided that the findings of this study represent a demographic mechanism which is of general importance for the initiation of a midsummer decline in temperate waters [KEYWORDS: Daphnia galeata, recruitment, reproduction, midsummer decline, clear-water stage], The population dynamics of D. galeata was studied during the period May–July of 5 successive years in Bautzen Reservoir (Germany). Sampling intervals of 3–4 days and knowledge of the egg–age distribution made it possible to calculate recruitment of the population for each sampling interval. In every year, high Daphnia densities and high Secchi depth readings (clear-water stage) were recorded in spring. In two of the 5 years, Daphnia abundance remained on a high level throughout summer, whereas in the remaining 3 years a midsummer decline of Daphnia was observed. Birth rates declined while the abundance increased in spring in every year but the timing of this decline in relation to abundance and the onset of the clear-water stage revealed no obvious pattern, distinguishing between years with or without a midsummer decline. However, cumulative recruitment did reveal a clear pattern: in years without a midsummer decline, cumulative recruitment increased slowly, but continually, starting from a low level in early May. By contrast, in years with a midsummer decline, recruitment increased strongly during one week in May, starting from a relatively high density level (>30 ind. l-1). This quick increase was followed by extended periods with low recruitment. Consequently, in these years the population was dominated by a strong peak-cohort of about the same age during the clear-water stage. If all members of this cohort, while approaching their maximum life-span, die off during a short time interval, this may have a pronounced effect on the initiation of a midsummer decline. From an extensive literature search, evidence is provided that the findings of this study represent a demographic mechanism which is of general importance for the initiation of a midsummer decline in temperate waters [KEYWORDS: Daphnia galeata, recruitment, reproduction, midsummer decline, clear-water stage]

Background. An increasing diversity of public, voluntary sector and private providers offer services for the mentally ill in the ongoing process of psychiatric reform. Good service description is one important prerequisite for mental health service research. Aims 1) To describe service provision for the mentally ill in five European centres using the European Service Mapping Schedule (ESMS); and 2) to discuss the use of the instrument in describing service provision. Methods. All services providing care for people with severe mental illness in five European catchment areas (in Amsterdam, the Netherlands; Copenhagen, Denmark; London, UK; Santander, Spain; Verona, Italy) were identified through various sources. The identified services were classified, and service provision was quantified in accordance with the ESMS manual. Descriptive information was obtained. Results. We identified from 10 to 45 different services for catchment areas of between 50,000 (Copenhagen) and 560,000 (Santander) population run by three to 16 providers. They varied in aims, staffing and functioning. Hospital and non-hospital residential services, community-based services, and social support agencies were available in all sites. There was substantial variation across centres in the range, number and activities of services. Collecting comparable data sets on all service types, particularly for day and structured activity services and outpatient and community services required substantial effort. Conclusion. Operationalised description of mental health services across Europe is possible but requires further refinement.