Anna-Stiina Heiskanen

The European Water Framework Directive at the age of 10: A critical review of the achievements with recommendations for the future.

The European Water Framework Directive (WFD), which was adopted in 2000, changed water management in all member states of the European Union fundamentally, putting aquatic ecology at the base of management decisions. Here we review the successes and problems encountered with implementation of the WFD over the past 10years and provide recommendations to further improve the implementation process. We particularly address three fields: (i) the development of assessment methods (including reference conditions, typologies and intercalibration); (ii) the implementation of assessment systems in monitoring programmes; and (iii) the consequences for river basin management plans (such as the design, monitoring and success of restoration measures). The development of assessment methods has been a transparent process and has resulted in improved and more standardised tools for assessing water bodies across Europe. The process has been more time consuming, and methods are more complex, than originally expected. Future challenges still remain, including the estimation of uncertainty of assessment results and a revision of rules in combining the results obtained with different Biological Quality Elements. A huge amount of monitoring data is now being generated for WFD purposes. Monitoring data are not centrally stored and thus poorly accessible for purposes beyond the WFD. Future challenges include enhanced data accessibility and the establishment of a Europe-wide central monitoring network of reference sites. The WFD river basin management plans base management decisions on the response of aquatic organisms to environmental stress. In contrast to the effects of degradation, the biotic response to restoration is less well-known and poorly predictable. The timescale of the WFD (obtaining good ecological status in all surface waters by 2027) is over-ambitious. Future challenges include long-term monitoring of restoration measures to understand the requirements for ecosystems to recover and prioritisation of measures according to re-colonisation potential.

Good Environmental Status of marine ecosystems: What is it and how do we know when we have attained it?

The European Marine Strategy Framework Directive (MSFD) requires EU Member States (MS) to achieve Good Environmental Status (GEnS) of their seas by 2020. We address the question of what GEnS entails especially with regard to the level at which targets are set (descriptors, criteria, indicators), to scales for assessments (regional, sub-divisions, site-specific), and to difficulties in putting into practice the GEnS concept. We propose a refined and operational definition of GEnS, indicating the data and information needed to all parts of that definition. We indicate the options for determining when GEnS has been met, acknowledge the data and information needs for each option, and recommend a combination of existing quantitative targets and expert judgement. We think that the MSFD implementation needs to be less complex than shown for other similar directives, can be based largely on existing data and can be centred on the activities of the Regional Seas Conventions.

Overview of Integrative Assessment of Marine Systems: The Ecosystem Approach in Practice

Traditional and emerging human activities are increasingly putting pressures on marine ecosystems and impacting their ability to sustain ecological and human communities. To evaluate the health status of marine ecosystems we need a science-based, integrated Ecosystem Approach, that incorporates knowledge of ecosystem function and services provided that can be used to track how management decisions change the health of marine ecosystems. Although many methods have been developed to assess the status of single components of the ecosystem, few exist for assessing multiple ecosystem components in a holistic way. To undertake such an integrative assessment, it is necessary to understand the response of marine systems to human pressures. Hence, innovative monitoring is needed to obtain data to determine the health of large marine areas, and in an holistic way. Here we review five existing methods that address both of these needs (monitoring and assessment): the Ecosystem Health Assessment Tool; a method for the Marine Strategy Framework Directive in the Bay of Biscay; the Ocean Health Index; the Marine Biodiversity Assessment Tool; and the Nested Environmental status Assessment Tool. We have highlighted their main characteristics and analyzing their commonalities and differences, in terms of: use of the Ecosystem Approach; inclusion of multiple components in the assessment; use of reference conditions; use of integrative assessments; use of a range of values to capture the status; weighting ecosystem components when integrating; determine the uncertainty; ensure spatial and temporal comparability; use of robust monitoring approaches; and address pressures and impacts. Ultimately, for any ecosystem assessment to be effective it needs to be: transparent and repeatable and, in order to inform marine management, the results should be easy to communicate to wide audiences, including scientists, managers and policymakers.

Sedimentation and particulate nutrient dynamics along a coastal gradient from a fjord-like bay to the open sea

Seasonal changes of total particulate material (TPM), particulate organic carbon (POC), nitrogen (PON) and phosphorus (PTP) concentrations in the water column, in sediment traps and on the sediment surface were studied in the SW coast of Finland, Baltic Sea, from March to November 1992. Sampling was carried out along a coastal gradient from the fjord-like, semi-enclosed Pojo Bay to the outer archipelago and open sea area. In Pojo Bay, TPM sedimentation rates were high and relatively constant, and had low organic carbon contents throughout the seasonal cycle. Resuspension was estimated to contribute > 90% of total sedimentation of POC and PON. Clear seasonality in sedimentation with high settling rates of primary organic material in spring, low sedimentation rates during summer and a considerable increase of resuspension during autumn was found in the outer archipelago and open sea. The C:N:P ratios of suspended, settled and sediment surface material indicated greater sedimentary loss of N (as compared to P and C) and closer coupling between pelagial and benthos in the archipelago and open sea area than in Pojo Bay. The sedimentation of P was 20–50% more effective (as compared to N and C) in Pojo Bay than elsewhere. These results indicate that the shift of planktonic nutrient limitation (from P to N limitation) is enhanced due to the more efficient sedimentation of the main limiting element along the estuarine gradient. The primary sedimentation of organic carbon (approximating export flux from the pelagic system) during the whole study period was estimated to be 30–48% of the total net primary production. This indicates that despite the differences in the salinity, nutrient dynamics and planktonic community structure along the coastal gradient, a relatively constant fraction of the annual primary production is exported from the pelagic system by sedimentation.

Dissolved iron:phosphate ratio as an indicator of phosphate release to oxic water of the inner and outer coastal Baltic Sea

Pore water concentrations and benthic fluxes of dissolved Fe, P and N were measured at two coastal basins in the Gulf of Finland, northern Baltic Sea, during a seasonal cycle. The bioturbated inner coastal basin, where exchange of near-bottom water is efficient, had a better ability to retain P in sediments than the outer basin, where near-bottom water O2 concentration decreases during summer. Under the presence of O2 high pore water dissolved Fe:P ratio (>3.6 w:w) in surface layer of the sediment, measured especially in winter, indicated negligible or low P-release and high N:P ratio in the efflux. On the contrary, low Fe:P ratio (<3.6), measured in summer and autumn, indicated high efflux of P and low N:P flux ratio. The low dissolved Fe:P ratio suggested that there was not enough diffusing Fe to form Fe3+ oxide-rich layer in the oxic surface zone of the sediments or near-bottom water to bind the P diffusing from the sediment. However, in sediments bioturbated by the abundant bivalve Macoma baltica, small efflux of P were measured almost throughout the study period. Thus, the Fe:P ratio cannot alone explain the P-release in bioturbated sediments. The low N:P ratio in the efflux measured in summer and autumn partly explains the measured low N:P ratio in the near-bottom water and thus N limitation of primary production in the Gulf. Additionally, it is evident that the release of P in the Gulf itself is of great importance for the trophic state of the Gulf of Finland.

Carbon flow patterns in the planktonic food web of the Gulf of Riga, the Baltic Sea : a reconstruction by the inverse method

We used the inverse method to reconstruct a carbon flux model for the planktonic food web of the southern part of the Gulf of Riga, the Baltic Sea. The model was based on data from three field campaigns (3–12 May 1995; 28 June–7 July 1994; 26 August–3 September 1993). The carbon flow model indicated very different channelling of gross primary production (GPP) in the three different periods. In spring 55% of GPP was channelled to detritus, while in summer 35% was exudated and channelled to dissolved organic carbon (DOC). In autumn, 42% of GPP was channelled to the zooplankton compartments. The model suggested high bacterial respiration rates and low bacterial growth efficiencies (6%) in spring and autumn. During these periods large decreases in DOC were anticipated to occur due to bacterial respiration. In summer the model suggested that bacterial respiration rate was low and that the bacterial growth efficiency was high (60%). During this period a net accumulation of DOC apparently occurred. Respiration was the most important loss of organic carbon in all seasons, corresponding on average to 152, 59 and 391% of GPP daily in spring, summer and autumn, respectively. Daily sedimentation rates of particulate organic carbon (POC) were consistently low (<3% d−1), removing 13–29% of GPP daily. The sedimented material consisted mainly of amorphous detritus. This indicates that in spite of the relatively high level of eutrophication, the planktonic system in the Gulf of Riga has a high short-term carbon retention and recycling capacity, and little POC is lost from the upper water column through sedimentation.

Seasonal stages of phytoplankton community structure and sinking loss in the Gulf of Riga

In this paper, we present the biomass, species composition and sinking losses of phytoplankton and heterotrophic flagellates obtained during three seasonal stages (May 1995; June–July 1994; August 1993) from the Gulf of Riga — a eutrophied, semi-enclosed area in the Baltic Sea. The Gulf was characterised by intensive dinoflagellate (mainly Peridiniella catenata) dominated spring bloom (2700–7600 μg l−1 wet weight) while the diatom Thalassiosira baltica contributed most (80–90%) to the settling phytoplankton biomass (up to 6.5 g m−2 day−1). The mineral nutrients were abundant during the bloom and it is suggested that the differential sedimentation of species was caused by physical factors (thermal stratification of the water column). The phytoplankton biomass in summer (780–2600 μg l−1) was dominated by high abundance of filamentous cyanobacterium Aphanizomenon flos-aquae, autotrophic nanoflagellates and picoplankton. The primary vertical flux of phytoplankton (<1 g m−2 day−1) was mainly due to non-motile species and aggregate-bound picoplankton and A. flos-aquae. Below the pycnocline, resuspended dormant diatom populations caused a significant (up to 1 g m−2 day−1) secondary flux. Large heterotrophic dinoflagellates (Gyrodinium/Gymnodinium) were abundant (up to 500 μg l−1) in the middle layers and associated to ammonium regeneration. The early autumn stage was a post cyanobacterial bloom situation with relatively low phytoplankton abundance (330–860 μg l−1) dominated by A. flos-aquae and nanoflagellates. Also, the sedimentation of phytoplankton was lowest (up to 340 mg m−2 day−1). Our results indicate high seasonal differences in the phytoplankton community structure and sedimentation. However, the high within-season temporal variability overrules the variability between different areas of the southern part of the Gulf.

Bridging the Gap between Policy and Science in Assessing the Health Status of Marine Ecosystems

Human activities, both established and emerging, increasingly affect the provision of marine ecosystem services that deliver societal and economic benefits. Monitoring the status of marine ecosystems and determining how human activities change their capacity to sustain benefits for society requires an evidence-based Integrated Ecosystem Assessment approach that incorporates knowledge of ecosystem functioning and services). Although there are diverse methods to assess the status of individual ecosystem components, none assesses the health of marine ecosystems holistically, integrating information from multiple ecosystem components. Similarly, while acknowledging the availability of several methods to measure single pressures and assess their impacts, evaluation of cumulative effects of multiple pressures remains scarce. Therefore, an integrative assessment requires us to first understand the response of marine ecosystems to human activities and their pressures and then develop innovative, cost-effective monitoring tools that enable collection of data to assess the health status of large marine areas. Conceptually, combining this knowledge of effective monitoring methods with cost-benefit analyses will help identify appropriate management measures to improve environmental status economically and efficiently. The European project DEVOTES (DEVelopment Of innovative Tools for understanding marine biodiversity and assessing good Environmental Status) specifically addressed these topics in order to support policy makers and managers in implementing the European Marine Strategy Framework Directive. Here, we synthesize our main innovative findings, placing these within the context of recent wider research, and identifying gaps and the major future challenges.

Seasonal and spatial variation of suspended and sedimented nutrients (C, N, P) in the pelagic system of the Gulf of Riga

Abstract The temporal and spatial variation of suspended and sedimented C, N and P in the pelagic system in the central and southern part of the eutrophicated Gulf of Riga were investigated during late spring, summer and early autumn from 1993–1995. The temporal variability at a central station was as high or greater than the spatial variability. Thus no discernible influence of the highly eutrophicated river Daugava on the plankton dynamics and the pelagic–benthic coupling of the Gulf of Riga was observed. High sedimentation rates of carbon-rich organic material were recorded at the end of the spring bloom, while P and N were retained on average 5 and 1.2 times more effectively, respectively, than C in the pelagic system. Low sedimentation rates of P, indicating effective recycling in the mixed surface layer, were typical for most of the productive season. The low C/N ratios of the settled material during summer were probably caused by accumulation of heterotrophic dinoflagellates into the sediment traps rather than due to increased vertical export of N. It is suggested that the major supply of organic matter to the benthos is determined by the time window characterised by low heterotrophic diversity and biomass in early spring. The trophic complexity of the planktonic community in the southern and central Gulf of Riga with its continuous discharge of nutrients by large rivers such as Daugava, results in a high buffering capacity of the pelagic system towards external perturbations such as increased nutrient supply.

Impact of climatic variability on parameters used in typology and ecological quality assessment of surface waters—implications on the Water Framework Directive

In most cases the negative impacts of climate change to aquatic ecosystems cannot be mitigated by measures in the river basin management. Ignoring climate change by the Water Framework Directive may have strong implications for the typology and quality assessment systems used for water bodies. As a result of climate change, water bodies, especially those located near the type boundaries may change their type. Compared to typology characteristics, water quality parameters are even more labile and may be easily affected by climate change. The paper exemplifies that the anticipated deterioration of water quality within the time frame relevant for WFD implementation may be large enough to endanger the fulfillment of the set water quality objectives. The review of the river basin characterization every six years, as required by the WFD, might also include re-evaluation of reference conditions according to the changes observed at pristine reference sites. As a consequence, the restoration targets (i.e., the good ecological status) would also need to be evaluated periodically.