MARS Deliverables

Read and download the results from MARS. Also have a look at the MARS fact sheets, which are are designed as “quick feeds” written in a non-technical language of brief and concise style, not exceeding two pages in length.


Milestone 17 Task 8.1

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MARS Communication and dissemination strategy

The main objective of MARS communication and dissemination is to provide clear answers to major stakeholders on how to manage water bodies exposed to multiple pressures. To close the gap between science and policy and avoid information overload, the MARS dissemination strategy aims to combine target groups, suitable products and arenas for dialogue / communication. The key stakeholders are river basin managers (particularly in the 16 case study catchments), National Environment Agencies responsible for WFD implementation, WFD-CIS groups and MAES freshwater group, DG Environment and EEA.

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MARS Deliverable D1.1

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Overview of external projects relevant to MARS and detailed plans on how to cooperate with them; detailed communication strategy; production and publication of the project website

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Deliverable D1.1 summary

The implementation of successful external communication is a key to achieving the main objectives of the MARS project. In particular, the cooperation with related EU funded research projects plays a central role. In the first project months, a list of external projects relevant to MARS was prepared, aiming at maintaining this list over the full project duration.

Amongst these external activities we identified three partner projects of specific importance to MARS, as their aims particularly match with the objectives of our project: GLOBAQUA, SOLUTIONS and OpenNESS. The contact with these projects was established at an early stage, inviting the coordinators to the MARS kick-off workshop in February 2014. Extensive consultations with each project coordinator resulted in detailed plans for cooperation. These plans are descripted in this report.

Another objective of the MARS communication and dissemination is to provide clear answers to major stakeholders on how to manage water bodies exposed to multiple pressures. To close the gap between science and policy, and to avoid information overload, the MARS dissemination strategy aims to combine target groups, suitable products and arenas for dialogue and communication. The key stakeholders are river basin managers (particularly in the 16 case study catchments), national environmental agencies responsible for WFD implementation, WFD-CIS groups and MAES freshwater group, DG Environment and EEA.

As an external information channel for a broader audience a project website was set up, together with state-of-the-art communication tools and intranet facilities for storing all project-relevant files. A popular science blog, reaching up to 3,000 readers per month, with weekly posts was successfully taken over from the BioFresh project, and is now operated by the project. Additionally, new and social media channels are fed to reach the public.

Finally, the draft for a general information platform for the freshwater scientific community is presented. In this contribution we present a future outlook on establishing a ‘global network for freshwater scientists’, targeting at the sustainable onward use of already developed tools and data collections. The principal objective is to merge and synthesise the available information generated by various EU funded projects related to freshwater research.


MARS Deliverable 2.1

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Four manuscripts on the multiple stressor framework:

Part 1: Review of multiple stressors and their effects on European surface waters
Part 2: Cook-book for ecosystem service assessment and valuation in European water resource management
Part 3: Framework to select indicators of multi-stressor effects for European river basin management
Part 4: Report on the MARS scenarios of future changes in drivers and pressures with respect to Europe’s water resources

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Deliverable D2.1 summary

This deliverable is composed of four chapters describing products of the MARS project, which will contribute to harmonize the outcome of the experiments (WP3), of the catchment modelling (WP4) and of the large-scale data analysis (WP5). All these work areas address the effects of multiple stressors on water resources and aquatic ecosystems, but are using different approaches, targeting different stressor combinations and response variables. To ensure that the outcome is suited for a meta-analysis across approaches, scales, stressors and variables several underlying procedures were harmonized; that’s what this deliverable is about.

Part 1: Review of multiple stressors and their effects on European surface waters
Part 1 reviews the effects of multiple stressors on rivers, lakes, groundwaters and coastal ecosystems, based on a thorough literature analysis. Despite the existence of a huge conceptual knowledge base in aquatic ecology, only few studies provide quantitative evidence on multiple stress effects. Two-stressor combinations were addressed most frequently. Over all biological groups analyzed, the strength of the pressure-response relationships increased with increasing number of stressors considered in lakes and rivers, but the response remained unclear in transitional and coastal waters. Biological groups responded generally very differently to increasing complexity of stress.

Part 2: Cook-book for ecosystem service assessment and valuation in European water resource management
Part 2 first addresses current approaches towards ecosystem service assessment and valuation and provides an overview of ecosystem services evaluated in the MARS experiments, catchment models and large-scale data analysis. Finally, a procedure towards ecosystem service assessment to be applied in MARS is described, which comprises four steps: Scoping of the analysis, development of the integrated assessment framework, biophysical quantification of ecosystem services, and economic valuation of ecosystem services. The procedure is exemplified for a number of case study catchments.

Part 3: Framework to select indicators of multi-stressor effects for European river basin management
Part 3 describes a set of “benchmark indicators”, i.e. response variable to be addressed in the experiments, catchment modelling and large-scale data analysis. These indicators allow for a streamlined analysis of multi-stressor effects across the different spatial scales and environmental conditions targeted in MARS. The benchmark indicators mainly comprise simple metrics and indices of abiotic and biotic ecosystem properties, covering physico-chemical, hydrological and riparian features of the water body and selected attributes of its biological community. The indicators are known to respond to anthropogenic pressure. They are applicable in various geographical contexts and to different water categories and types of water bodies.

Part 4: Report on the MARS scenarios of future changes in drivers and pressures with respect to Europe’s water resources
Part 4 describes storylines outlining future changes regarding (i) main drivers in the economy, (ii) economic growth, (iii) policies regarding the environment, and (iv) public concern about the environment and protection of ecosystem services. This contribution establishes the baseline for simulating future scenarios at both basin and European scale. Various future climatic and socio- economic scenarios were chosen to define three storylines at the European level. Several projects and modeling tools were reviewed with the aim of identifying quantitative data fitting the selected storylines. Suitable data were collated and can now be used by the subsequent MARS work packages to drive the simulations of the three storylines.


MARS Deliverable 3.B

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Manuscript on time series analyses from the Mediterranean region

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D3.B summary

This deliverable investigates the impacts of changes in hydrology and nutrients on ecosystem structure and function of Mediterranean shallow lakes by using long term monitoring data of two lakes (Lakes Mogan and Eymir) and paleolimnological records of six lakes from Turkey. The first two papers are on Lakes Eymir and Mogan, which are two inter-connected lakes in Central Anatolia situated in a cold dry steppe climate. Both papers used 20 years of monitoring data. Manuscript 1 focused on annual and seasonal water and nutrient (TP, SRP, DIN, TN) budgets of the two lakes and highlighted the impacts of water balance on eutrophication of Mediterranean shallow lakes. It was published in Science for the Total Environment in April 2016. Manuscript 2 focused on understanding the impacts of nutrient concentrations and hydrological conditions (e.g. water level fluctuation and hydraulic retention time) on lake restoration efforts, which included sewage effluent diversion and biomanipulation in a relatively deep and shallow Mediterranean lake.

This paper is out online in February 2017 in the open access journal Water. The third and fourth manuscirpts provide long-term paleoecological data to infere the impact of past environmental changes using a paleolimnological approach with single or multiple proxies. In Manuscript 3, the Cladocera sub-fossils community assemblage was used to explain ecological changes that took place in three Anatolian lakes (Lakes Eymir, Mogan and Gölhisar), which are located in Mediterranean climatic zones. Sub-fossil cladoceran remains provide a good indicator of key environmental changes including water level, eutrophication and salinization. This manuscript has been published in Hydrobiologia in November 2015. Manuscript 4 used multi- proxy data of Cladocera, Diatom, pigment, plant macrofossil as well as XRF-determined minerals to trace the impacts of lake-level changes on benthic-pelagic primary and secondary productions over the last 50-100 years in three Turkish shallow lakes. It was published in Palaeogeography, Palaeoclimatology, Palaeoecology in March 2016.


MARS Deliverable 3.1

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Manuscripts on time series and temperature effects

Part 1: D3.1-1: Manuscripts on time series analysis in the north temperate region
Part 2: D3.1-2: Manuscripts on temperature effects on shallow lakes based on existing experimental data

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D3.1 summary

Part 1

This deliverable consists two manuscripts (MS) of lake time-series analysis in north-temperate region of Europe.

1st MS ‘Is fish able to regulate filamentous blue-green dominated phytoplankton?’ submitted to ‘Hydrobiologia’, analyzes >40-year data on biota, fish catches, hydrochemistry, hydrology, and meteorological parameters in Lake Võrtsjärv, a large and shallow eutrophic lake in Estonia. The lake has intensive commercial fisheries with well documented catches for all commercial fish species. The impact of commercial fisheries on the ecological status of lakes has been poorly studied and in most cases fish as a biological quality element is omitted in water bodies with commercial fisheries. Based on our previous knowledge we assumed that the effect of different fisheries management strategies in Võrtsjärv on water quality is negligible due to the weakly operating grazing food chain. Present study showed, however, that predatory fish (pikeperch) could have a cascading impact down the food web in this lake that has to be considered in fisheries management. As we showed, the recently introduced legal requirement to sort and report on small fish in fishery statistics has caused extensive back-release of small fish by fishermen and was one of the likely reasons why the amount of small fish, including small bream, has sharply increased in the lake. The fishery management measures that could increase small plankti- and benthivorous fish biomass have to be avoided as having a cascading negative effect on the ecosystem health of Lake Võrtsjärv.

2nd MS ‘Climate change, cyanobacteria blooms and ecological status of lakes: a Bayesian network approach’ accepted for publication in ‘Ecological Modelling’ addresses eutrophication and harmful cyanobacterial blooms as major challenges for management of aquatic ecosystems, which are expected to be reinforced by climate change. A Bayesian network (BN) modelling approach was applied to assess the impact of future scenarios of climate change and land-use management to ecological status incorporating cyanobacteria biomass as one of the indicators. The BN was able to model effects of climate change and management on ecological status of case study Lake Vansjø in Norway, by combining scenarios, process-based model output, monitoring data and the national lake assessment system. The results showed that the benefits of better land-use management were partly counteracted by future warming under these scenarios. BN demonstrated the importance of including more biological indicators in the modelling of lake status. E.g. the inclusion of cyanobacteria biomass allowed better predict the ecological status compared to assessment by phytoplankton biomass alone. Thus, the BN approach can be a useful supplement to process-based models for water resource management.

Part 2

The balance between gross primary production (GPP) and ecosystem respiration (ER) determines the metabolic status of lakes. As an integrative quantity, the metabolic status is an important indicator of lake function and can have a decisive influence on the role of lakes in regional and global matter cycling. Lake metabolism is influenced by environmental conditions such as light, mixing depth, nutrients and temperature – drivers predicted to be affected by climate change.

This delivery include result from two comprehensive experimental studied conducted to improve our understanding of these driving factors on the metabolic status of shallow lakes and their role in the carbon cycle. In both studies the focus is on the effects of nutrients at contrasting climate conditions. One of the studies is published in Global Change Biology (IF 8.02) in December 2015 and the other is under review after revision in the same journal.

Paper 1 (under review). This study is a pan-European space-for-time mesocosm experiment running from May until November 2011 (run as part of the REFRESH project, finished during the MASRS project) and involved six lakes, covering a temperature gradient from Sweden to Greece. The experiment comprised two nutrient levels (mesotrophic or eutrophic) crossed with two water levels (1 and 2 m) to simulate different light regimes and mixing depths. In situ GPP and ER were estimated using the O2 free-water method. GPP and ER were significantly higher in the eutrophic mesocosms than in mesotrophic mesocosms, whereas the shallow mesocosms had significantly higher volumetric metabolic rates but lower area-based metabolic rates than the deep mesocosms. GPP and ER increased exponentially with temperature. Temperature gains of ~0.53 eV for GPP and ~0.65 eV for ER were comparable with those predicted by metabolic theory. All systems switched from autotrophy to heterotrophy over the investigated temperature range. The threshold temperature for the switch in metabolic status was, however, lower under mesotrophic (~16 °C) than eutrophic conditions (~22 °C). Contrary to expectations, no significant interactions between temperature, nutrients and depth were observed for GPP and ER. Overall, we quantified the differential temperature sensitivity of GPP and ER and found that trophic state is crucial for how much warming a system can tolerate before it switches from net auto- to net heterotrophy. Paper 2 published in December 2015). This study focuses on greenhouse gas (GHG) emissions, based on the fact that fresh waters make a disproportionately large contribution to greenhouse gas (GHG) emissions, with shallow lakes being particular hotspots. How GHG fluxes from shallow lakes are altered by climate change may have profound implications for the global carbon cycle. Empirical evidence for the temperature dependence of the processes controlling GHG production in natural systems is largely based on the correlation between seasonal temperature variation and seasonal change in GHG fluxes. However, ecosystem-level GHG fluxes could be influenced by factors, which whilst varying seasonally with temperature are actually either indirectly related (e.g. primary producer biomass) or largely unrelated to temperature, for instance nutrient loading. As part of the Danish Climate change effect project (CRES) and MARS a one year study of GHG emission was conducted in the longest running shallow-lake mesocosm system. This system consists of twenty-four fully mixed, outdoor, flow- through mesocosms (diameter 1.9 m, water depth 1 m, retention time ~2.5 months). The one year GHG study run in 2013 demonstrated that nutrient concentrations override temperature as a control of both the total and individual GHG flux. Furthermore, testing for temperature treatment effects at low and high nutrient levels separately showed only one, rather weak, positive effect of temperature (CH4 flux at high nutrients). In contrast, at low nutrients, the CO2 efflux was lower in the elevated temperature treatments, with no significant effect on CH4 or N2O fluxes. Further analysis identified possible indirect effects of temperature treatment. For example, at low nutrient levels increased macrophyte abundance was associated with significantly reduced fluxes of both CH4 and CO2 for both total annual flux and monthly observation data. As macrophyte abundance was positively related to temperature treatment, this suggests the possibility of indirect temperature effects, via macrophyte abundance, on CH4 and CO2 flux. These findings indicate that fluxes of GHGs from shallow lakes may be controlled more by factors indirectly related to temperature, in this case nutrient concentration and the abundance of primary producers. Thus, at ecosystem scale response to climate change may not follow predictions based on the temperature dependence of metabolic processes.

These studies revealed strong variation in GPP, ER and GHG depending on nutrient level, trophic structure and climate to various extent and clearly also show that metabolic metrics can be very useful integrating indicators of multi-stressor effects in shallow lake ecosystems.


MARS Deliverable 3.2

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Manuscripts on experimental results

This deliverable contains abstracts of published and submitted manuscripts on experimental results within WP 3.2 (rivers & lakes).

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D3.2 summary - river manuscripts

This deliverable contains abstracts of published and submitted manuscripts on experimental results within WP 3.2 (rivers).

Manuscript 1 investigates the effects of a two months experimentally induced extreme low-flow scenario on the physical, biological, and functional characteristics in a macrophyte- rich lowland stream. A significant decline in the stream wetted habitat area, an increase in water temperature, and an increase in the accumulation of fine organic matter with reduced flow, but no significant changes in dissolved oxygen or benthic chlorophyll a concentrations was identified.

For Manuscript 2 an experiment in large outdoor flumes was conducted to assess the effects of low flow, fine sedimentation, and nutrient enrichment on the structure of the benthic macroinvertebrate community in riffle and run habitats of lowland streams. For most taxa, a negative effect of low flow on abundance in the riffle habitat was found, whereas the effect was partly mitigated by fine sedimentation and by nutrient enrichment. In contrast, fine sediment in combination with low flow rapidly affected macroinvertebrate composition in the run habitat, with decreasing abundances of many species.

Manuscript 3 describes the response of benthic algae species composition, traits, biovolume and Chl-a concentration to low flow in combination with nutrient enrichment and fine sedimentation. Experiments were conducted in large outdoor stream flumes. Strong responses in the benthic algae community to sudden changes in low flow and fine sedimentation were observed, mediating rapid species turnover with a decreased algal biovolume and increased abundance of large, motile species.

The objective of the study presented in Manuscript 4 was to assess the single and combined effects of hydropeaking and cold thermopeaking on the drift of aquatic macroinvertebrates in experimental flumes. It was found that hydropeaking induced significantly higher drift rates of most macroinvertebrate taxa, whereas combined hydropeaking and cold thermopeaking revealed reduced total drift rates.

Manuscript 5 presents results on the interactive effects of higher flow velocity and nutrient enrichment for an oligotrophic stream periphyton community. The results showed a significant lower biomass development in the hydropeaking treatment, compared to the no- hydropeaking treatment. Nutrient subsidy effects were not observed, because the biomass development of periphyton was highly diminished through the pulsed flow velocity increase.

Fish passage performance was investigated in a study presented in Manuscript 6 where a full-scale experimental vertical slot fishway under two different slot configurations (C1 & C2) was used. Results show that the chub performed a higher number of upstream movements in C2, while for the barbel, a large-bodied potamodromous bottom-oriented fish, the performance was similar in both configurations.

The study presented in Manuscript 7 analysed the responses of potamodromous fish facing combinations of a primary stressor (two levels of connectivity reduction due to water scarcity) and a secondary stressor (three levels of oxygen depletion due to increase organic load of anthropogenic nature). Results show that at the unconnected level the primary stressor (lack of connectivity) overrode the effect of the secondary stressor (oxygen depletion), but when connectivity existed oxygen depletion caused a reduction of fish movements with decreasing oxygen concentrations.

Manuscript 8 focused on the response of macroinvertebrate drift to single and combined effects of water scarcity and dissolved oxygen (DO) depletion over two seasons (winter and spring). Results showed that both stressors individually and together had a significant effect on macroinvertebrate drift ratio for both seasons. Single stressor effects showed that macroinvertebrate drift decreased with flow velocity reduction and increased with DO depletion, in both winter and spring experiments. Combined stressors interaction induced a positive synergistic drift effect for both seasons.

Four more manuscripts were submitted presenting experimental studies on fish movement and on effects of flow events and nutrient addition on stream periphyton and macroinvertebrates. Several further manuscripts are in preparation and are listed in this deliverable.

D3.2 summary - lake manuscripts

This deliverable contains abstracts of published and submitted manuscripts on experimental results within WP 3.2 (lakes) conducted in Denmark, UK and Germany. The experiments included studies of effects of a heatwave and pulsed N-dosing (Denmark), combined impact of nutrient addition, warming and extreme rainfall events (UK) and extreme effects on mixing and of browning (Germany). The experiment in Germany was started one year later than planned as there were problems with permissions. The results from this experiment are therefore online in the pipeline (see planned papers at page 27-28).
Heat wave experiment in experimental ponds in Denmark: A one-month heating experiment (+5oC) was conducted in mid-summer in existing experimental ponds (since August 2003) having two nutrient levels crossed with three temperatures and four replicates of each.

Manuscript 1 focuses on effects on the fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). It was published online in Freshwater Biology in April 2017.

Manuscript 2 focuses on effects on growth of two species of submerged macrophytes, Elodea canadensis and Potamogeton crispus, pre-adapted to different temperature. The paper was published in Climate Research in December 2015.
Pulse-dosing of Nitrogen in experimental ponds in Denmark: The effects of a N pulse on N processing and storage in shallow lake ecosystems based on a K15NO3 pulse addition (increased in NO3-concentration from c. 0.1 to 2 mg N/L) were studied in twelve mesocosms with relatively low nutrient levels (same systems as mentioned above).

In Manuscript 3 the dosed NO3 was followed for five months in the primary and secondary producers and turnover and loss rates were calculated. It was published online in Freshwater Biology in May 2017.

Manuscript 4 focuses on how periphyton (on inert substrata), epiphyton and epipelon biomass responded to a nitrogen (N) pulse, an approximately tenfold enrichment of the NO3-pool, under three contrasting warming scenarios. It was published online in Hydrobiologia in March 2017. Multiple stress experiment in UK mesocosms: investigating the combined impact of nutrient addition, warming and extreme rainfall events on shallow lake environments. The first two papers are on biological responses, specific metrics of water quality (chlorophyll a and cyanobacteria) and fish. The third paper uses outcomes from the experiment for methodological advancement in UV spectroscopic analysis for estimating freshwater DOM.

Manuscript 5 focuses on the response of phytoplankton and cyanobacteria, both metrics of water quality, to the combined effect of the three stressors, asking whether warming and nutrient enrichment exacerbate the effect of one another (synergistic) as predicted, and whether this interaction may be altered by significant biomass loss as a result of extreme rainfall events. The paper aims to provide mechanistic insight of the process underlying these responses. This manuscript will be submitted to Global Change Biology by August 2017.

Manuscript 6 tests the short term effect of extreme rainfall events on fish stress levels and whether responses to environmental perturbations were modified by conditions within the mesocoms, warming and nutrient enrichment, alone and in combination. This manuscript is due for submission by the end of June 2017.

Manuscript 7 uses the response of algae to future environmental scenarios in lakes to estimate extinction coefficients in the UV range of algae derived DOM. These estimates will be used to update current models based on UV spectroscopic analysis for estimating freshwater DOM. This manuscript is currently under review in Inland Waters, submitted March 2017.


MARS Deliverable D4.1

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Case study synthesis

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D4.1 summary

Deliverable D4.1 is a synthesis report of the 16 regional case studies being undertaken in WP4 (Multi-stressors at the river basin scale. The report is composed of 3 parts.

Part 1: Task 4.2 - Southern Basins region
Part 1 reports the background to, and results and conclusions from Task 4.2 on four case studies from the Southern Basins region. The four Southern Basins included in this report are: Lower Danbe (Romania); Lake Beyşehir (Turkey), Pinios (Greece), Sorraia (Portugal). In fact, the Southern group includes also the Nervión case study (Spain), which however will be reported in another Deliverable of MARS due to the special focus of the work on estuaries. The work described in this report was undertaken between February 2013 and July 2016.

Part 2: Task 4.3 - Central Basins region
Part 2 reports the background to, and results and conclusions from Task 4.3 on the 6 case studies from the Central Basins region. The six Central Basins are: the Drava (Austria); Elbe, Haval and Saale (Germany), Odense (Denmark); Thames (United Kingdom); Regge and Dinkel (Nederland); and, the Ruhr (Germany). The work described in this report was undertaken between February 2013 and July 2016.

Part 3: Task 4.4 - Northern Basins region
Part 3 reports the background to, and results and conclusions from Task 4.4 on the 6 case studies from the Northern Basins region. The Northern Basins are: the Otra and the Vansjø-Hobøl Norway), the Kokemäenjoki river basin, the Lepsämänjoki and Lake Pääjärvi catchments (Finland), lake Võrtsjärv (Estonia) and the Welsh basins (Wales). The work described in this report was undertaken between February 2013 and July 2016.


MARS Deliverable D4.2

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Manuscripts on stressor effects at the river basin level

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D4.2 Overview

In the previous report (D4.1, September 2016) we have developed predictive linkages between indicators of environmental quality and ecosystem services, and different types of pressures, single or multiple, across river basins from all over Europe, in a latitudinal and a west-east gradient, and having very different conditions of climate and land use drivers. Using such predictive linkages resulting both from empirical data treatment and process based modelling, and following a common approach for climatic scenario changes, downscaled to region level, we have studied the future evolution of indicators and services. Furthermore, we have looked into the programs of measures that are being implemented in each country and we attempted to understand how will be the responses of the indicators of quality and services, according to such implementation. The studies performed in these 16 basins have a great potential for common applications and studies, and these are being developed in the moment.
Although the hydrological and nutrient process-based models that were used and calibrated at each basin scale mostly contain liaisons between the different water compartments, these studies were mostly focused in surface waters and in the indicators of quality that were developed for the Water Framework Directive, as also the information from monitoring taking pace for the last decade, or in previous times. Many issues remain to be studied, related with interfaces between water compartments and also with the biotic aspects of the pressures, also important for some communities and in some cases.
This Deliverable (D4.2) is composed of five reports, dealing with stressor effects at the river basin level. These reports cover special aspects of the linkage between ecosystem compartments, multiple pressures and the responses of particular elements, notably the interface between terrestrial and aquatic environments represented by the riparian transitional ecosystems (D4.2-1), stressor propagation between surface waters and groundwaters (D4.2-2) and estuarine waters (D4.2-3), or deal with particular biological stressor effects when such are added to the more common chemical and physical stressors (D4.2-4 and D4.2-5). Most of these reports use different case studies (D4.2-1, D4.2-2 and D4.2-4) from MARS to pool data and experiences for a common target. The other two focus on the stressor propagation in transitional waters in the example of the estuary of Nervion (D4.2-3) and finally two other are related with biotic pressures, i.e. fisheries management and pathogens (D4.2-4 and D4.2-5). All of these studies will be adapted/are being prepared for publication submission.

The Deliverable 4.2. is therefore composed of five reports, with the non-technical summaries following this introduction:

D4.2-1: Riparian-to-catchment management options for stressor reduction and service enhancement

D4.2-2: Stressor propagation through surface-groundwater linkages and its effect on aquatic systems

D4.2-3: Stressor propagation through inland-transitional linkages and management consequences

D4.2-4: Fisheries as a source and target of multiple stressors

D4.2-5: Multiple-stressor risks for pathogens

D4.2-1 summary

D4.2-1: Riparian-to-catchment management options for stressor reduction and service enhancement

Riparian management is considered a key management option to improve lotic ecosystem status, functioning and services. Vegetated riparian buffer strips can retain nitrogen from sub-surface runoff, and phosphorous and fine sediments from surface runoff. Thus, they can reduce and mitigate the effects of diffuse pollution by agricultural and other land uses. However, the effectiveness of riparian buffers, to a large extent, depends on the location within the stream continuum, as well as on the land use conditions further upstream of the buffered stream sections. Catchment-scale effects can counteract riparian management effects. Here, we synthesise the evidence of riparian management options in light of catchment-scale pressures. We reviewed 53 management studies addressing both scales and developed a conceptual model to highlight management options with and without conflicts among management scales.

D4.2-2 summary

D4.2-2: Stressor propagation through surface- groundwater linkages and its effect on aquatic systems

The good ecological status of Europe’s freshwaters is still lacking. This paper reviews the role of groundwater in these systems and demonstrates that it is an important factor to include in surface water management. Groundwater influences streamflow, water chemistry and water temperature and connects rivers and streams with their catchment and thus functions as a pathway for stressors to reach the surface water. A new ‘Groundwater DPS’ framework is proposed which shows how groundwater fits in the system of a stressed aquatic ecosystem. The functioning of this framework is demonstrated using examples from four different European lowland catchments: the Thames, Odense, Regge and Dinkel catchments. The importance of groundwater varies between scales, between catchments and within catchments. The Groundwater DPS will aid water managers in understanding the importance of groundwater in their management areas and promotes the consideration of groundwater in future water management practices.

D4.2-3 summary

D4.2-3: Stressor propagation through inland- transitional linkages and management consequences

The MARS project (Managing Aquatic ecosystems and water Resources under multiple Stress) supports water managers and policy makers at the water body, river basin and European scales in the implementation of the Water Framework Directive (WFD) (Hering et al., 2015). It aims to address how a complex mix of stressors, for example resulting from urban and agricultural land use, water power generation and climate change, impacts European rivers, lakes, groundwater and estuaries, and what implications these stressor combinations have for ecological services, such as water provision (Ferreira et al., 2016).

One of the three scales of investigation within the MARS project, includes the study of 16 river basins throughout Europe, which have been investigated to characterise relationships between multiple stressors and ecological responses, functions and ecosystem services (Ferreira et al., 2016). Results of these studies are being synthesized and jointly analysed in the context of stressor combinations, climate scenarios and water and catchment management responses (including restoration scenarios), and how these can affect the ecological status, ecological functions and ecosystem services.
To assess the complex multi-stressor scenarios, it is necessary to test and improve existing modelling techniques including process-based models and empirical/statistical models; and to up-scale and generalize the results of the case studies, and contribute with these improved models to guide River Basin Management Plans (RBMP) and the best Programs of Measures (PoM) to achieve a good ecological status (Ferreira et al., 2016).

The modelling process follows the MARS conceptual modelling framework that can provide a holistic approach to modelling multi-stressors across different scales. This approach manages to combine the use of a risk assessment framework, a DPSIR scheme and the ecosystem service cascade in a joint modelling framework that enables to investigate the impacts of multiple stressors on biotic/abiotic state and on ecosystem services (Ferreira et al., 2016; Feld et al., 2016).

Within MARS the climate change scenarios were based upon GFDL-ESM2M and IPSL- CMA-LR climate models, which were used for generating precipitation and temperature scenarios for two climate scenarios (RCP 4.5, RCP 8.5), available for period of 2006-2099. The period of 2006-2015 was used in general as the reference period and monthly linear correction was applied to observed climate data and scenarios outputs covering this period (for details, see Ferreira et al., 2016).
In addition, three different storylines were developed for future land use scenarios. In each basin, these storylines were downscaled according to specific characteristics of land use and programs of measures to be undertaken for the purpose of achieving a better ecological status.

The storylines were:

- Storyline 1 – ‘Techno world’ (economic focus): In this scenario, economic growth is the main focus. Higher economic growth accompanied increase in energy demands and resources which brings agricultural expansion. However, environmental measures will be applied to mitigate human disturbance.

- Storyline 2 – ‘Consensus’ (green focus): In this scenario, economic growth is as it is today. More efforts put in to promote sustainable use of sources. A lot of effort applied to promote conservation and to restore degraded ecosystems.

- Storyline 3 – ‘Fragmented world’ (Survival of the fittest): In this scenario, there is an increase in economic development, in some cases also considering a big economic crisis (recession). There is no room almost for environmental issues.

In order to study this, we used one of the case studies, which is the Nervión-Ibaizabal catchment (hereafter Nervión), especially focusing in the estuary, as a transitional system. Here, we have investigated: (i) the links between pressures, recovery of the system and provision of cultural ecosystem services (i.e. recreational fishing and bathing waters); (ii) the future climate change scenarios for these services; and (iii) the management implications.

D4.2-4 summary

D4.2-4: Fisheries as a source and target of multiple stressors

This deliverable consists of the manuscript ‘Fisheries impacts on lake ecosystem structure in the context of changing climate and trophic state’ by Tiina Nõges (EMU), Orlane Anneville (INRA), Jean Guillard (INRA), Juta Haberman (EMU), Ain Järvalt (EMU), Marina Manca (CNR), Giuseppe Morabito (CNR), Michela Rogora (CNR), Stephen J. Thackeray (NERC), Pietro Volta (CNR), Ian J. Winfield (NERC), Peeter Nõges (EMU) that was submitted to Journal of Limnology (http://www.jlimnol.it/index.php/jlimnol) on March 8, 2017.

We analysed case studies from five European lake basins of differing trophic states (Lake Võrtsjärv, two basins of Windermere, Lake Geneva and Lake Maggiore) with long-term limnological and fisheries data. Decreasing phosphorus concentrations (re-oligotrophication) and increasing water temperatures have been reported in all five lake basins, while phytoplankton concentration has decreased only slightly or even increased in some cases. To examine possible ecosystem-scale effects of fisheries we analysed correlations between fish and fisheries data, and other food web components and environmental factors.

Re-oligotrophication over different ranges of the trophic scale induced different fish responses. Although a general model predicted increasing fish production and biomass with increasing trophic state, parameters other than phosphorus including fisheries pressure and the balance between predatory and non-predatory fish species explained a significant part of the observed variability in fish abundance. In the deeper lakes Geneva and Maggiore, we found a stronger link between phytoplankton and planktivorous fish and thus a more important cascading top-down effect than in other lakes. This connection makes careful ecosystem-based fisheries management extremely important for maintaining high water quality in such systems. We also demonstrated that increasing water temperature may favour piscivores at low phosphorus loading, but suppresses them at high phosphorus loading and may thus either enhance or diminish the cascading top- down control over phytoplankton with strong implications for water quality.

D4.2-5 summary

D4.2-5: Multiple-stressor risks for pathogens

A wide variety of disease-causing pathogenic microorganisms, including bacteria, are spread and transmitted via water. There are many potential sources of waterborne diseases in freshwater environments, although the main recognised routes are via direct contamination of water by faeces from both humans and animals, as well as by pathogens that can survive and are distributed by sewage treatment processes. Understanding the dynamics of both pathogenic bacteria and bacteria associated with faeces and sewage infrastructure can be helpful in determining the sources of bacteria and how they interact with freshwater environments.

Many freshwaters are experiencing a high degree of degradation in the form of interacting stressors such as elevated nutrients, chemical pollution, modified morphology and flows, as well as increases in algal bloom frequency and intensity. It is important to understand how these multiple stressors, particularly those associated with climate change, interact to affect pathogen abundance and dynamics. This study used DNA sequencing to investigate the microbial composition of a lowland river, the river Thames, UK, that is experiencing multiple stressors, at a weekly resolution over a two-year period.

It aimed to examine whether new molecular approaches, such as high throughput sequencing of the 16S rRNA bacterial gene, could provide more targeted indication of pathogenic bacteria loads rather than proxies, such as Faecal Indicator Organisms (FIOs). Families and genera of bacteria were selected to act as indicators of pollution from faeces, sewage infrastructure and a group of potentially pathogenic bacteria. Strong seasonal dynamics in abundance were observed, with most faecal and sewage indicators increasing in abundance during the winter months. Of the potential pathogen indicators, no confirmed pathogens were identified to species level, but closely related genera were present in low abundance, or if in higher abundance, were more likely associated with pathogens or parasites of natural populations of aquatic wildlife.

These results indicate that whilst faecal and sewage indicators show that contamination via these routes is occurring in the river Thames, it is not associated with high loads of pathogen species. Future studies covering a wider range of sites are recommended to identify potential hotspots associated with agriculture or sewage treatment.


MARS Deliverable 5.1

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Five Reports on stressor classification and effects at the European scale

Deliverable 5.1 is composed of 5 reports, the first report D5.1-1 contains 3 parts.

D5.1-1 Part 1: Multi-stressors on surface water and effects on ecological status
D5.1-1 Part 2: Analysis of pressure - response relations: classification of multiple pressures on broad river types
D5.1-1 Part 3: Multiple stressors and groundwater status analysis and statistical modelling at the European scale

D5.1-2: Relation of low flows, E-flows, and Ecological Status
D5.1-3: Impact of multi-stressors on ecosystem services and their monetary value
D5.1-4: Effects of multiple stressors on ecosystem structure and services of phytoplankton and macrophytes in European lakes
D5.1-5: New functional diversity indices allowing assessing vulnerability in abiotic multi-stressor context

The deliverable will be public as soon as a accompanying paper is published, for the moment it is available on demand, please contact us.

D5.1-1 Part 1 summary

Multi-stressors on surface water and effects on ecological status

Humans have increased the discharge of pollution, altered water flow regime and modified the morphology of rivers. All these actions have resulted in multiple pressures on freshwater ecosystems, undermining their biodiversity and ecological functioning. The European Union has adopted an ambitious water policy to reduce pressures and achieve a good ecological status for all water bodies. However, assessing multiple pressures on aquatic ecosystems and understanding their combined impact on the ecological status is challenging, especially at the large scale, though crucial to the planning of effective policies. Here, for the first time, we quantify multiple human pressures and their relationship with the ecological status for all European rivers. We considered ecological data collected across Europe and pressures assessed by pan-European models, including pollution, hydrological and hydromorphological alterations. We estimated that in one third of EU’s territory rivers are in good ecological status. We found that better ecological status is associated with the presence of natural areas in floodplains, while urbanisation and nutrient pollution are important predictors of ecological degradation. We explored scenarios of improvement of rivers ecological status for Europe. Our results strengthen the need to halt urban land take, curb nitrogen pollution and maintain and restore nature along rivers.

D5.1-1 Part 2 summary

Analysis of pressure - response relations: classification of multiple pressures on broad river types

For this deliverable a unique and comprehensive collation of input data were derived. Information from different data sources, in varying formats, spatial resolution, comprising information on hydrology, physico-chemical water quality, geo-morphological characteristics, ecological status and other, were harmonized and merged to an extended database. The data were derived for about 100,000 sub-catchments (FECs) covering Europe, EFTA states and further, hydrologically connected areas to the east.
From this database pressure indicators were deduced and statistically compared to the ecological status reported by the EU-countries. An important and novel indicator is the impact of hydrological alteration on major flow characteristic like base flow, floods or duration of low flows. These were derived by comparing modelled flows for current conditions and for seminatural conditions. The goal was identifying the most explanatory pressure indicators impeding a good ecological status. First, the general statistics on the distribution of all pressure indicators were conducted,
secondly, the pressure indicators were compared to the ecological status as assessed in 1st River Basin Management Plan (RBMP). Importance of pressures for supporting good ecological state varies a lot among river types and regions in Europe. On large rivers, chemical stressors, percentage of broad leaved forest and share of agricultural land in floodplain are three most important pressures. On lowland, medium to large rivers, high flow hydrological characteristics become very important also. Share of coniferous forest in floodplain is important pressure in mid altitude rivers, whereas base flow and oxygen demanding substances are important for highland rivers.

Our results also suggest, that diffuse pollution of nutrients and decrease of riparian vegetation at present do not support good ecological status mainly in the Mediterranean and Atlantic regions. In the Central and Baltic region, the most important cause for a deterioration of ecological status is the combination of diffuse pollution of nutrients and hydrological alterations. In the Eastern Continental region all three types of pressures, namely, hydrological, morphological and chemical are equally important.

Classification of multiple pressures on European broad rive types presented here is closely related to JRC work (Grizzetti et al., 2017) and NTUA work (MARS, 2017) in the same work package of the MARS project. JRC has unveiled patterns between human pressures and ecological status of European rivers in non - stratified manner. NTUA has analysed relation of low flows and ecological flows (E-flows) to ecological status and contributed data for hydrological pressures. This contribution is very important, since in our study we indeed show that hydrological pressures are very important, and in some regions and river types even prevail over morphological pressures.

Our results serve as an input to scenario analysis tool at the European scale (namely work package 7.4) and will be expanded with additional data and expert knowledge.

D5.1-1 Part 3 summary

Multiple stressors and groundwater status analysis and statistical modelling at the European scale

The aim of the work is to analyse groundwater status and stressors (pressures) relevant for groundwater using available data at European scale reported by European countries (WISE- WFD and WISE-SoE datasets managed by the EEA). In particular, a definition of spatial extent of ground waters in poor status, acting single stressors (pollution, abstraction, saltwater intrusion) and stressor combinations including an identification of prevailing pollutants causing failure of good groundwater status. The aim of the statistical analysis is to use simple statistical models to investigate the large-scale pressures on the chemical status and quantitative status of groundwater reported by European Union Member states. In particular, to see if it is possible to use these models to investigate and understand any interactions between different pressures on groundwater status.

The analysis of stressors and status shows that prevailing stressor causing failure of good groundwater status is pollution, followed by groundwater abstraction. Pollution in combination with groundwater abstraction appears to be most common stressor combination in Europe. Salt water intrusion is almost always associated with groundwater abstraction or/and pollution, but it does not take place in all coastal areas. The most common type of groundwater pollutants are agrochemicals (nutrients and pesticides) affecting whole Europe and especially agricultural areas. When assessing pesticide pollution at European scale, one must take into account a bias induced by various monitoring strategies used by countries, there is lack of comparable data on pesticide metabolites that may occur more frequently and in higher concentrations than parent pesticides. EU WFD common implementation strategy does not assure sufficient harmonization of monitoring strategies among EU member states preventing comparable pan-European assessments.

The study demonstrated how ‘data-led’ methods, such as stepwise regression, can be used to suggest and estimate models of groundwater status. However, we note that they should be used with caution as such approaches can include spurious relationships which result from not accounting for multiple hypothesis tests. Only limited interactions have been investigated to date, however, there is some evidence for a synergistic interaction between arable farming and winter precipitation (when the regression does not include country as a random effect) on the chemical status of groundwater. There is, however, less confidence in the results of models of groundwater quantitative status which appears, as may be expected, to be largely driven by weather variables.

D5.1-2 summary

Relation of low flows, E-flows, and Ecological Status

The present report ‘Relation of low flows, E-flows, and Ecological Status’ presents a European scale analysis of hydrologic data at the resolution of the Functional Elementary Catchment (FEC). Simulated daily time-series of river flows from the PCR-GLOBWB global model were used based on a hypothetic near-natural scenario where water abstractions from water bodies do not exist and an anthropogenic scenario with water abstractions occurring.The latter practically represents the reality. Many hydrologic indicators expressing the characteristics of the rivers’ hydrologic regime were calculated for all FECs with the Indicators of Hydrologic Alteration (IHA) methodology and software package and the deviations of the indicators’ values between the two scenarios were used as proxy metrics of hydrologic alteration or hydrologic stress of rivers. Regressions between indicators with the rather limited dataset of EQR values of two BQEs (macroinvertebrates and phytobenthos) showed insignificant or very weak relationships when processed with the entire dataset for Europe or separately for each of the 20 Broad River Types (BRTs). However, by conducting two examples at smaller scales (catchment or region) with better ecological response datasets clearer relationships were found.

Hydrologic alteration metrics were averaged per BRT without reference to any ecological response not showing remarkable hydrologic stress in certain BRTs or considerable differences in the degree of alteration among the various BRTs. Clearer results could be indicated by mapping the hydrologic alteration on Europe’s geographical background. The mapped indicators, especially some of those connected with low flow conditions were the most informative showing that Southern Europe is more hydrologically stressed due to groundwater abstractions for irrigation. In the rest of Europe hydrologic conditions change less frequently within a single year and a multi-year period.

The determination of a minimum ecological flow connected with good ecological status needs further research with updated datasets, but the water community can already take advantage of the results produced herein to obtain a view of hydrologic stress in Europe, identify significant hydrologic stress on a local basis and try to interpret the impacts of this stress on river’s ecology with the use of appropriate response data.

D5.1-3 summary

Impact of multi-stressors on ecosystem services and their monetary value

Which are the ecosystem services (i.e. the contribution of nature to human well-being) provided by European rivers, lakes, and coastal waters? Can we map and quantify them? Do enhanced ecosystem conditions and biodiversity support higher benefits for people? These are the questions addressed in this research.
We quantify the main ecosystem services provided by aquatic ecosystems at the European scale, including fish provisioning, water provisioning, water purification, erosion prevention, flood protection, coastal protection, and recreation. These services are provided by aquatic ecosystems, such as lakes, rivers, groundwater and coastal waters. We show European maps of ecosystem service capacity, flow (actual use), sustainability or efficiency and, when possible, benefit.

Our results indicate that the ecosystem services are mostly positively correlated with the ecological status of European water bodies (that is a measure of the ecosystem integrity and biodiversity), except for water provisioning, which strongly depends on the climatic and hydrographic characteristics of river basins. We also highlight how provisioning services can act as pressures on the aquatic ecosystems. Based on the relationship between ecosystem status and delivery of services, we explore qualitatively the expected changes of ecosystem services under scenarios of increase in different pressures.
Finally, we perform an economic valuation of the ecosystem services provided by European lakes, considering the current conditions and scenarios of improvement of the ecological status. Using a benefit transfer approach, we estimate that the average economic value of ecosystem services delivered by a European lake is 2.92 million EUR per year. We also demonstrated that the ecological status of lake has an impact on valuation. The expected benefit from restoring all European lakes into at least a moderate ecological status is estimated to be 5.9 billion EUR per year, which corresponds to 11.7 EUR per person and per year.

Quantifying and valuing ecosystem services helps to recognise all the benefits that humans receive from nature, offering stronger arguments to protect and restore ecosystems and thus fostering the implementation of the European water policy. This study offers scientific evidence to this aim.

D5.1-4 summary

Effects of multiple stressors on ecosystem structure and services of phytoplankton and macrophytes in European lakes

The aim of this deliverable was to assess the impacts of multiple stressors on lake ecosystems at the European scale. We have examined ecological responses of two main biological groups (quality elements), namely algae (phytoplankton) and other aquatic plants (macrophytes), to a range of stressor combinations in large populations of lakes. Moreover, the impacts of future multiple stressor scenarios - future climate and nutrient concentrations - have been assessed for a phytoplankton communtity index.

While nutrients are a key stressor in all regions of Europe, MARS also focuses on the following key environmental changes for specific regions: water scarcity and flow alterations (Southern Europe); changes in hydrology and morphology (Central Europe); and changes in hydrology and temperature (Northern Europe). More specifically, the stressors that have been investigated in this report are related to increased air temperature and precipitation, hydropower and water abstraction for irrigation and public water supply, hydrological changes (flushing or water level changes), salinisation, or increase in humic substances (“brownification”). We have analysed effects on ecological status (ecological quality ratio values), and in addition a set of indicators of environmental stressors for both biological quality elements. For phytoplankton, the main indicators analysed were chl-a, abundance of cyanobacteria (a group of potentially harmful algae) and PTI (phytoplankton trophic index). For macrophytes, the main indicators were the water-drawdown index (WIc) for regulated lakes, a proportion of macrophyte coverage (%PVI), and other indices based on specific species or species groups. Interactions within the lake community, including also zooplankton (small crustaceans), were addressed by analysis of data from mesocosms across Europe. Potential effects of multiple stressors on ecosystem services (e.g. nutrient retention, nutritional value of fish, and cultural services to lake visitors) have also been investigated by case studies and national datasets. The main large-scale data sources used in our studies include the European Environment Agency's WISE-SoE datasets (Waterbase), data compiled during previous EU projects (WISER), and national monitoring data. Moreover, information on lake and catchment characteristics (such as land use) was obtained from the MARS geodatabase. The natural characteristics of lakes (such altitude, surface area, mean depth, alkalinity and humic level) were explicitly considered in most of the studies, either as co- variables or as determinands of lake types.

The analysis of EEA's water quality data in combination with land use data showed that, not surprisingly, total phosphorus (P) concentration in lakes clearly increased and Secchi depth (transparency) generally decreased with increasing proportion of arable and pasture lands in lake catchments across Europe. Total P was the stressor that correlated best with ecological status of phytoplankton, while Secchi depth better explained the ecological status of macrophytes. Climatic variables such as air temperature and precipitation, in contrast, had apparently no effect on the ecological status. This result does not contradict that climate change may cause additional stress for lake ecosystem. Instead, the space-for-time approach (using geographic variation in climate as a substitute for temporal variation) in these analyses may not be the most appropriate for detecting real effects of climate change. For the individual phytoplankton indicators (cyanobacteria and PTI), interactions between effects of nutrients and climatic stressors (temperature and/or precipitations) were found for some of the lakes or lake types. For example, the analysis of time series indicated that cyanobacteria are most favoured by nutrient stress in lakes of low nutrient status and sensitive to summer rainfall in short residence time lakes. However, the studies also revealed large variation in the combined stressor effects among the different lakes types. It was therefore difficult to generalise such results across lake types. For the PTI index (Northern Europe), the strongest interaction between nutrients and temperature stress was found for lowland siliceous lakes. We used this empirical relationship to predict the future PTI scores for this lake type under the MARS future climate scenarios. According to our model, increased temperature and precipitation will result in higher PTI scores, indicating impaired ecological status. In the short term (2030), however, climate-induced changes in PTI will probably not be sufficient to change the ecological status class of lakes (e.g., from Good to Moderate).

The analysis of Mediterranean (Turkish) lakes suggest that warming together with expected changes in land use in this regions may result in higher salinisation and eutrophication with more frequent cyanobacteria blooms and loss of biodiversity. Consequently, under such conditions, the ecosystem services potential (e.g. drinking and irrigation water, biodiversity etc.) are likely to be deteriorated if not lost completely. To counteract, stricter control of nutrients emissions and human use of water is urgently needed.

The interactions between nutrients and climatic stressors could most clearly be interpreted from the experimental data based on former mesocosm experiments. For example, these experimental results indicate that global climate warming might favour growth of macrophytes at moderate water level decrease southern regions, even under relatively eutrophic conditions. However, if the water level decrease becomes so extreme that macrophytes are directly negatively affected, and longer and intense drought periods become more common, the combined effects of eutrophication and extreme water level reductions may adversely affect the development of macrophytes. In contrast, warmer temperatures in northern regions may hamper macrophyte growth due to increased precipitation and, thus increased water levels and nutrient loading.

The MARS project have resulted in much new information on the combined effect of eutrophication and climate change and their interactions on trophic structure and dynamics - showing that combined effects through a series of cascading events can lead to deterioration in water quality and ecological status - there are still some knowledge gaps to be filled. Knowledge on differences in interactions along altitude, latitude and other biogeographical gradients are needed before firm and safe conclusions relevant for managers and WFD can be drawn. We also need more knowledge on the resilience of lake community structure and dynamics to extreme climatic events such as heat waves, drought, and heavy rainfall, since we can expect an increase of such events.

D5.1-5 summary

New functional diversity indices allowing assessing vulnerability in abiotic multi-stressor context

A community hosted by an ecosystem composed of species sharing the same characteristics i.e. species showing the same response to the environment and/or species with the same impact on their environment, can be defined as a community with high functional redundancy. Such community is supposed to be less vulnerable to species loss and the ecosystem functioning is also supposed to be less impacted than when communities are composed of species with different functional characteristics.

In this work, we first described the fish communities of lakes, rivers and estuaries of France, Spain and Portugal using species richness and functional diversity. Functional diversity was a measure of the extent of complementary among species considering five characteristics previously define by different sources (literature, available database): fish size, vertical position in the water body, spawning habitat, trophic group, and swimming mode. For the three aquatic systems, the number of species and functional diversity was generally higher in northern and western France than in the Mediterranean areas; this geographical pattern was explained by historical events (recolonization after the last glacial period). Higher functional diversity found in estuaries compared to lakes and rivers was explained by the importance of the connectivity between adjacent environments.

Analysing correlations between functional redundancy and species richness, results suggest that higher taxonomic richness in freshwater ecosystems is likely to increase the stability and resilience of fish assemblages after environmental disturbance because of higher species redundancy whereas it is not the case in estuaries.

Studying the impact of species loss following different scenarios, we also demonstrated that, in rivers and estuaries, rare species support singular ecological functions not shared by dominant species. Our results suggest also that functional diversity of fish assemblages in rivers can be more affected by environmental disturbances than in lakes and estuaries.
Finally, using functional redundancy and taxonomic vulnerability, we proposed a composite index of functional vulnerability, minimised for highly redundant assemblages composed of species with low extinction risk. Fish communities of estuarine ecosystems appear less vulnerable to species loss in comparison with assemblages of lakes and rivers. Although these latter systems obtained comparable scores, the functional vulnerability was not influenced by the same component. Fish assemblages in lakes are often redundant but composed of a large part of vulnerable species, whereas river assemblages are in general poorly redundant but composed of species with low intrinsic vulnerability. This new score is proposed to be used in conservation perspective to define management priorities.


MARS Deliverable 5C

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Report on legacy and tipping points in large rivers

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D5.C summary

Large rivers have always been in the focus of human attention. Ancient and modern civilisations have arisen, prospered and dwindled on their banks, leaving us with the myths and legends that their waters provoked. Large rivers are of major economic relevance as providers of substantial services like, most notably drinking water, food, energy and transport. Large rivers have been altered since centuries and have undergone dramatic human-induced changes. Thus, large rivers are among the most stressed ecosystems worldwide.

In large rivers the stability as well as the disturbance amplitude trigger integral ecosystem functions and determine where and when which habitats are available within a temporal context. Thus, the basis for a sufficient understanding on the effects of stressors and their role in faunal changes strongly depends on the understanding of the ecosystem processes and their interlinkages which determine ecosystem functioning. This deliverable addresses the historical development of stressors in large European rivers and their legacy on the faunal elements, which have been typical in those rivers. Nowadays rare potamontypic Plecoptera, aquatic insects, have been chosen to act as umbrella-species reflecting ecosystem health.

The analyses showed a common development of the major stressors damming, navigation and neozoa in large rivers during the second half of the 20th century, which can be observed for other economical and societal factors too. The major regulation with corresponding channelization effects have been already finished at the beginning of the 20th century. However, those channelization effects have been emphasised by measures related to damming and to the improvement of large river navigability.

We found a considerable shrink in the distribution area of selected indicator species, namely of the aquatic insect order Plecoptera, the stoneflies. The analyses identified few refugia in Central France (Loire, Allier), Austria/Hungary (Raba, Lafnitz) and Hungary/Romania (Tisza) where a combination of several species still can be found after 1990. These systems show some communalities like natural discharge and sediment regimes. Even though neozoans have invaded them, unbroken dynamic processes seem to lessen their negative effect on indigenous faunas. Losses are identified in many river systems, especially in Scandinavia and Spain. Even though the analyses are related to uncertainties due to data gaps, the general trend seems plausible.

Especially invasive species in consequence of inland navigation tremendously changed the faunal composition of aquatic insect assemblages. Biological reference communities are lost for most large rivers since long times and cannot be described empirically. To establish ecological integer ecosystems as demanded by the Water Framework Directive, the few river systems, which still sustain typical large river species, must serve as reference to restore hydrologically and sedimentologically dynamic habitats.


MARS Deliverable 5D

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Report on the position of exotic species in the context of estuaries, rivers and lakes multi-stressors and regarding ecosystem services

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D5.D summary

Non-native species, i.e. species occurring outside of their native range, have been recognised as a major threat for ecosystem functioning. Indeed, the number of non-native species introduced at all continents to support human activities or needs has increased during the last decades and several non-native species are now spread worldwide, e.g. mosquitofish species or salmonids. Aquatic ecosystems are particularly sensitive to these introductions. Numerous evidences were provided concerning their impact on native biota, at different levels of organisation (genetic, individual, population, community and ecosystem). Invasion biology is a complex discipline as the success of establishment of non-native species in new locations is driven by numerous factors that depend on the local context. Local environmental conditions, species tolerance, native biota and life history traits were hypothesised as key factors controlling the invasion success of an introduced species.

The main objective of this study was to assess the impacts of non-native species on fish assemblages all along the freshwater-marine continuum at large scale in Europe. We thus considered lakes, rivers and estuaries of France, Spain and Portugal. The status of each species was defined at the national level (native, translocated or exotic) and served to assess the relative abundance of non-native species in fish assemblages. In order to understand the ability of non-native species to colonise new areas, we compared their characteristics to those of the native species through two components of functional diversity: specificity and originality.

Results showed that estuaries were very different from lakes and rivers, with less non-native species. All were freshwater species with low occurrence and low abundances (Lepomis gibbosus, Ameiurus melas, Sander lucioperca. Silurus glanis, Carassius carassius, Cyprinus carpio). In contrast, in lakes and rivers, non-native fish species occurred in about 25% of fish assemblages, although with heterogeneous distributions across systems. Lakes were approximately four times more affected by the occurrences of non-native species than rivers. In France, Portugal and Spain, almost 1/3 of the regional species pools were composed of non-native fish species, with the pikeperch (Sander lucioperca), the pumpkinseed (Lepomis gibbosus), the largemouth bass (Micropterus salmoides) and the European catfish (Silurus glanis) being the most common non-native species encountered. With the exception of some particular locations, when non-native species were present, they only accounted for a small proportion of local fish abundances (on average 16.78% of catches). We also observed that the non-native species pool was overall more functionally original and specialized than the native species pool. This pattern suggests that non-native fish species exhibit functional traits that tend to differ from those of native species, which is consistent with previous observations. Moreover, this highlights the role played by non-native species in the functional richness of some assemblages, especially on the Iberian Peninsula, where local species and functional richness were generally low.

A majority of non-native fish species investigated is known to be of interest, either for commercial or recreational fishing and, consequently, they have a high economic value. This observation is especially true on the Iberian Peninsula, where approximately half of the fished species represent non-native species. However, some of these non-native species with fishing interest are also known to deteriorate water quality, i.e. to increase nutrients and thus contributing to eutrophication of reservoirs. The management of non-native species (removal, control, etc.) should be integrated within an ecosystem service assessment framework, to weight the cost/benefits of given actions.


MARS Deliverable D6.1

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Synthesis of stressor interactions and indicators

D6.1-1: Stressor interactions and most sensitive indicators of impact at the species, ecosystem and land- scape scale that are relevant to sustaining eco- system services and human benefits
D6.1-2: Synthesis of stressor interactions and indicators: Manuscript on evaluation of methods for diagnosing cause of deteriorations in ecological status
D6.1-3: Recommendations for more integrated river basin management and gaps in tools

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D6.1-1 summary

Currently, practical management of water bodies focuses on the control of single stressors which are assumed to be dominant. Work by the MARS project and others using ecosystem scale and experimental observations has demonstrated that the relationships between primary stressors and ecological response indicators can be confounded through interactions with secondary pressures, giving rise to a potentially novel approach in the management of water bodies to achieve ecological recovery: the multi-stressor-response approach.

Little is known about the commonality of multiple stressor effects on ecological and ecosystem service indicators and whether these vary in space and time. This information is needed to support large scale multiple-stressor management approaches, for example, to off-set the effects of climate change through abatement of nutrient stressors.
This report addressed knowledge gaps in this field by developing a standard quantitative assessment of data analysis across MARS experiments, long-term monitoring, and river basin spatial monitoring case studies, providing a comprehensive comparison of responses from mesocosm to Europe in scale.

The common analysis approach allowed for quantification of interaction strength and forms between three widespread stressor combinations found across Europe: (1) nutrients and high temperatures, (2) nutrients and low flow, and (3) nutrients and high flow.

To synthesise multi-stressor interactions, we developed a simple and standardised analysis workflow to quantify the interacting effects of nutrient stress and one other stressor on a range of ecological responses in a consistent manner. We requested that individual analysts across the project team complete the analysis on their own datasets and report the results for syntheses. Therefore, the analysis workflow was designed to be as simple as possible and to generalise across a range of potential response variable types and study designs. Some analysts sub-setted their data set to explore the sensitivity of the relationships between multiple stressor and indicators across different spatial and - temporal scales.  
In total we obtained results from 47 analyses completed within 12 separate studies. Of these, 43 originated in northern and central Europe while just four analyses were from Southern Europe. In addition to nutrient stress as the most common primary stressor, the most common secondary stressors examined were high temperature and high flow. Indicators of phytoplankton responses were most commonly reported, followed by fish, with few studies of invertebrates and macrophytes.  Given the large number of studies examining the abundance of cyanobacteria, and to a lesser extent fish abundance, results were also considered in relation to the ecosystem services of water supply, recreational value and fisheries.

Statistically significant responses to nutrient stress (i.e. the primary stressors) were found in 85% of analyses (40 out of 47) while significant responses to the secondary stressors were apparent in only 38% of analyses (18 of 47). Responses to the secondary stressors were most commonly detected in  analyses of temperature and morphology, but were rarely detected in analyses of high or low flow. 4 Classifying overall interaction types based on both stressor effects resulted in roughly equivalent tallies among the three types of interaction considered: 18 antagonistic effects, 13 opposing effects and 16 synergistic effects across all analyses. For phytoplankton only, the results were 10 antagonistic effects, 11 opposing effects and 11 synergistic effects. There was little sign of clear differences in interaction types among the types of secondary stressor or across ecosystem type. However, this comparison was hampered by the relatively small sample size and the fact that a relatively low proportion of analyses yielded statistically significant interaction terms. Of the 47 modelled interactions, only 8 (17%) achieved statistical significance at P < 0.05 and these did not show a clear tendency towards any one of the interaction types.

Our study highlights that experimental approaches often provide the clearest signal of stressor interactions. They do not, however, provide a comprehensive understanding of how stressors interact in the real-world, over varying sites and stressor gradients; for this monitoring data are more relevant.

The range of responses in stressor interactions across all our case-studies highlight that it is often difficult to predict how two stressors may interact at a given site and both synergistic and antagonistic responses may be possible for the same stressor combination at sites with different characteristics or different levels of stress. Sometimes the significance of stressor effects, both acting singly or in combination, may be masked by other covariates either in different seasons or years (e.g. effects of nutrients may be masked by high flow in rivers) or at sites of differing typology (e.g. deep lakes may differ in sensitivity from shallow lakes). We offer recommendations on improving the analytical approach to detect the effects of interacting stressors in this context. An improved understanding of the impact of stressor reduction is vital to evaluate the success of potential management options and underpin practical MARS guidance on river basin management planning (RBMP). Unfortunately, the data collated here do not allow examination of stressor abatement responses. We do, however, review evidence on stressor abatement and offer some considerations with respect to developing recovery concepts within future work.

D6.1-2 summary

Aim of this study was to analyse a large set of bioassessment metrics to identify and quantify stressor-specific metric responses reacting to one group of stressors but not to another.  
We hypothesise that stressor-specific responses occur when the individual stressors show independent ‘modes of action’ (i.e. the specific stress-induced changes of environmental factors that modify the ecological niches of the species constituting the biological community).

The data used comprised three biological groups (macrophytes, benthic invertebrates, fish) covering three broad river types in Western and Central Germany. The stressor groups under investigation were physico-chemical, hydromorphological and hydrological stress.  

We performed linear variation partitioning to reduce the large set of metrics to a set of candidates for further non-linear analyses using a combination of boosted regression tree modelling and variation partitioning.  
The linear analyses revealed 16 candidate metrics that met our criteria, most of them for the medium to large lowland rivers. Macrophyte- and fish-based metrics were most relevant. In a geographically and methodologically more precise data subset, invertebrate metrics revealed more promising models than in the broader data set.  
Subsequent non-linear modelling resulted in two truly stressor-specific metrics, both based on invertebrate data: The Index of Biocoenotic Region (specifically indicating hydromorphological stress) and the Share of alien species (specifically indicating physico-chemical stress).  

We concluded that the biological community generally responds to stressors in rather an integrative than a specific way, but stressor-specific metrics can be identified. Future research on diagnostic metrics should focus on quantifying those stressor parameters that represent individual ‘modes of action’.

D6.1-3 summary

This report is the Deliverable presenting the results for the 4th aim in relation to the work package task 6.4 entitled ‘Integrated River basin management: evaluation of the MARS conceptual model’.

Within task 6.4 an evaluation was made on the current river basin management practises for dealing with multiple stressors and how existing river basin management plans can be improved by incorporating elements of the MARS conceptual model and the MARS Tools (WP7). We reflect on these current practises and evaluate the MARS conceptual model and MARS Tools as an aid to daily water management on a local level. In particular, we focused on two key European policy/management questions: the benefits of sustaining ecological flows and the value of green infrastructure for natural water retention measures (flood regulation and drought mitigation) in relation to other water management questions, strategies and practises. These two topics are seen only as examples, as many other aspects of RBMPs could also be assessed.

Using a structured questionnaire and a workshop with WP4 case-study partners, their associated river basin managers, and a wider group of river basin managers from our applied partners and elsewhere in Europe, we were able to obtain an overview of the current practises in setting river basin management plans and selection of measures in relation to the multiple stressor challenges throughout Europe. The main aim of the questionnaire was to get a better understanding of the following questions:

  • How does daily water management practice deal with the selection of cost-effective measures, for water bodies exposed to multiple stressors?
  • Is knowledge on pressure interactions and biological response taken into account when selecting and prioritizing the measures?
  • How can MARS best contribute to a potential gap in knowledge and tools from the perspective of the stakeholders?

We specifically challenged the workshop participants to link their current practises to the topics relevant within the MARS project and linked this to the potential need and usage of tools that could help identify the role of multi-stressor challenges within their daily management practises. With this information we defined how the conceptual model could be used in practice and what gaps in indicators or tools are currently hampering daily practise.


MARS Deliverable D8.4

Deliverable 8.4 fact sheets

Fact sheets

Version 2, updated March 2016

The MARS project puts emphasis on practical outputs and the dissemination of scientific findings, allowing to establish strong linkages between the scientists and the practitioners 'on the ground'. One particular aim of the MARS communication and dissemination strategy is to encourage the scholars to leave their ‘ivory tower’ and to propagate their knowledge in a digestible format. The fact sheets are designed as “quick feeds” for a diverse target-audience, including academics, administrators, practitioners and policy-makers. Each fact sheet is written in a non-technical language of brief and concise style, not exceeding two pages in length.

  • Fact sheet #01: Multiple stresses and freshwater ecosystem service provision: the MARS ‘cookbook’ methodology
  • Fact sheet #02: Freshwater Information Platform – www.freshwaterplatfrom.eu
  • Fact sheet #03: MARS scenarios and storylines
  • Fact sheet #04: Multiple stresses on Europe’s freshwaters: emerging challenges for science, policy and management
  • Fact sheet #05: Freshwaterblog: A tool for wide range dissemination
  • Fact sheet #06: HyTEC: investigating the effects of pulse releases of water from hydropower on aquatic life
  • Fact sheet #07: Provisioning Freshwater Ecosystem Services
  • Fact sheet #08: Regulating and Maintaining Freshwater Ecosystem Services
  • Fact sheet #09: Cultural Freshwater Ecosystem Services
  • Fact sheet #10: Storylines: writing the future for effective water management – Fragmented World
  • Fact sheet #11: Storylines: writing the future for effective water management – Consensus World
  • Fact sheet #12: Storylines: writing the future for effective water management – Techno World

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Access all fact sheets individualy

Deliverable D8.4 summary

Europe's surface waters are affected by multiple stressors, ranging from water pollution of urban point and agricultural diffuse sources to habitat alteration by river engineering and maintenance management. Effective multi-stressor mitigation not only requires in-depth knowledge on the causal pathways to convey practical management solutions, but also appropriate dissemination and communication strategies to impart the existing knowledge, to generate understanding and to distribute relevant evidence.

Multi-stressor settings and their effects on the ecosystem are complex and often complicated to grasp, even for the experts familiar with this topic. When, for instance, multiple stressors act simultaneously, interactions often occur that either exacerbate the impact on the ecosystem compared to the sum of the single stressor effects (so-called "synergistic effects"), or weaken the impact on the ecosystem (so-called “antagonistic effects”). Insights into these interactions are of paramount importance to water managers as the choice of appropriate management strategies depends on this knowledge.

The MARS project thus puts emphasis on practical outputs and the dissemination of scientific findings, allowing to establish strong linkages between the scientists and the practitioners 'on the ground'. One particular aim of the MARS communication and dissemination strategy is to encourage the scholars to leave their ‘ivory tower’ and to propagate their knowledge in a digestible format. Especially the freshwater blog run by the project already proved effective in this regard.

The report at hand forms an essential part of the MARS strategy to communicate the project’s key-approaches and -messages generated from the various research strands conducted in MARS. The fact sheets that constitute the core of this report are designed as “quick feeds” for a diverse target-audience, including academics, administrators, practitioners and policy-makers. Each fact sheet is written in a non-technical language of brief and concise style, not exceeding two pages in length. A set of high-resolution illustrations relevant in the particular context accompanies each fact sheet. These illustrations either visualize thematic contents or generate corporate design for specific MARS products.

The fact sheets are placed at a central position on the MARS public website (go to fact sheets) to allow for easy internet access. The publication of this deliverable will be featured in a post on the Freshwater Blog. Furthermore, the individual fact sheets will be circulated via email to the MARS consortium and external contacts, including members of the target-audience specified above.

We intend to update this document during the future course of MARS, collating fact sheets and illustrations of all relevant MARS achievements. The following provides a selection of topics that will be addressed in the document’s updates, envisaged for project month 48 (January 2018):

  • Selected MARS experiments and case-study catchments;
  • MARS tools;
  • MARS key deliverables.