Hafok AB

Stenhamra, Sweden
Stenhamra, Sweden

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Schiele K.S.,Leibniz Institute for Baltic Sea Research | Darr A.,Leibniz Institute for Baltic Sea Research | Zettler M.L.,Leibniz Institute for Baltic Sea Research | Berg T.,MariLim Aquatic Research GmbH | And 9 more authors.
Ecological Indicators | Year: 2016

Evaluating the state of benthic communities has played an important role in water quality assessments. Indices incorporating species sensitivities, richness and densities are commonly applied. In Europe, the importance of benthic indices has increased in the last years with the implementation of the European Marine Strategy Framework Directive (MSFD) which at the same time demands the applicability of an index across regional scales. To date, environmental variability is rarely considered in benthic indices and most sensitivity rankings have the disadvantages of static values (i.e. the same value in all areas), expert judgement and a limited geographical range. This study presents species sensitivity values calculated along environmental gradients for the Baltic Sea. Sensitivities were calculated according to the procedure of the Benthic Quality Index (BQI). We created a matrix of subregions, classes of salinity, depth and gear to identify comparable subsets for data analysis. Altogether, 19 subsets were defined within the Baltic Sea basins. Sensitivity values were calculated for 329 species out of a total of 678 species that were recorded in this study. Sensitivity values of taxa vary between subsets as it was expected for different environmental conditions. Most sensitivity values can be assigned to species occurring in euhaline and polyhaline waters. Distribution of species with high and low sensitivity values differed along the salinity gradient. In euhaline waters more species with high sensitivity values occurred than species with low sensitivity values, while in mesohaline waters the ratio of high and low sensitivity values among species was almost equal. In oligohaline waters more species with lower sensitivity values were present. For the first time, sensitivity values were calculated for a large number of species using the same method for the entire Baltic Sea. This results in a Baltic-wide comprehensive set of sensitivity values based on a dataset across subregional borders, and divided along environmental gradients and gear type. The same principles can be applied to transient waters from rivers to coastal lagoons as well as to other environments with gradients of, e.g. hydrodynamic characteristics. Publicly available sensitivity values will increase transparency and support the improvement of state assessments under the MSFD. © 2015 Elsevier Ltd.


Ramos E.,University of Cantabria | Juanes J.A.,University of Cantabria | Galvan C.,University of Cantabria | Neto J.M.,University of Coimbra | And 13 more authors.
Estuarine, Coastal and Shelf Science | Year: 2012

According to requirements for intercalibration of assessment methods of vegetation quality elements along the North East Atlantic region, within the scope of the European Water Framework Directive (WFD), a better classification system of coastal regions is needed. To accomplish that goal, a quantitative classification approach was launched in order to establish common typologies for assessment of this biological quality element. This was preliminarily based on a physical classification of the coastal waters that included two consecutive steps, a first one devoted to the establishment of "biotypes" (large areas), and a latter one dealing with recognition of the variability within biotypes (" subtypological variants"). The NEA region coastline was subdivided into 550 consecutive stretches (40 km long). Then, physical variables (sea surface temperature, photosynthetically active radiation, wave exposure, tidal range and salinity) were calculated in reference points of each stretch, 5. km from the coast. This information was based mostly on satellite acquired data, using specific procedures proposed in this work. Physical typologies of NEA coastal waters were obtained by statistical analyses. Five different biotypes were selected (i.e. coastal sectors of the European coast) by national experts as baseline information to be used on intercalibration of assessment methods for vegetation within the WFD. Variability of environmental conditions on those biotypes was also analyzed and compared with previous classifications carried out at the national scale. Results from this study showed the feasibility of this methodological approach as a useful tool for assessment of the actual homogeneity of coastal environments. © 2011 Elsevier Ltd.


Nystrom Sandman A.,University of Stockholm | Nystrom Sandman A.,AquaBiota Water Research | Wikstrom S.A.,University of Stockholm | Wikstrom S.A.,AquaBiota Water Research | And 3 more authors.
Ecography | Year: 2013

Statistical modelling can be used to relate biological survey data to environmental factors, thereby providing a basis for predictive mapping of species or communities. Although environmental variables vary and influence biota at different scales, models are often fitted without discussion of how scale dependency influences the results. In this study, we analysed the relative importance of environmental factors for the distribution of aquatic species as a function of extent, using data on the cover of five common benthic species (four macrophytes and one animal), from 1731 sites along the Swedish Baltic Sea coast. We modelled the cover and distribution of the five species in relation to salinity, depth, slope, wave exposure and substrate in scale steps from 25 to 1500 km, and analysed the relative contribution of the environmental variables to each species model. The average total deviance explained by the models was generally quite high, and decreased with increasing scale for all macrophyte species, while it increased for the animal, the Baltic Sea blue mussel Mytilus edulis. The relative contribution of different environmental variables changed with scale, and responses also differed between species. The average contribution of salinity increased for all species when moving from local to Baltic Sea scale, and for the Baltic Sea blue mussel it was the single most important factor at the Baltic Sea scale. The average contribution of depth decreased with increasing scale for all species. However, regardless of scale, depth was the most important environmental factor to explain the distribution of all but one of the investigated macrophyte species. This shows that fine scale predictor variables can be of major importance also for species distribution models covering large areas. © 2012 The Authors.


Tornroos A.,Åbo Akademi University | Bonsdorff E.,Åbo Akademi University | Bremner J.,Center for Environment | Blomqvist M.,Hafok AB | And 3 more authors.
Journal of Sea Research | Year: 2015

Alterations to ecosystem function due to reductions in species richness are predicted to increase as humans continue to affect the marine environment, especially in coastal areas, which serve as the interface between land and sea. The potential functional consequences due to reductions in species diversity have attracted considerable attention recently but little is known about the consequence of such loss in natural communities. We examined how the potential for function is affected by natural reductions in taxon richness using empirical (non-simulated) coastal marine benthic macrofaunal data from the Skagerrak-Baltic Sea region (N. Europe), where taxon richness decreases 25-fold, from 151 to 6 taxa. To estimate functional changes we defined multiple traits (10 traits and 51 categories) on which trait category richness, functional diversity (FD) and number of taxa per trait category were calculated. Our results show that decrease in taxon richness leads to an overall reduction in function but functional richness remains comparatively high even at the lowest level of taxon richness. Although the taxonomic reduction was sharp, up to 96% of total taxon richness, we identified both potential thresholds in functioning and subtler changes where function was maintained along the gradient. The functional changes were not only caused by reductions in taxa per trait category, some categories were maintained or even increased. Primarily, the reduction in species richness altered trait categories related to feeding, living and movement and thus potentially could have an effect on various ecosystem processes. This highlights the importance of recognising ecosystem multifunctionality, especially at low taxonomic richness. We also found that in this system rare species (singletons) did not stand for the functional complexities and changes. Our findings were consistent with theoretical and experimental predictions and suggest that a large proportion of the information about alterations of function is found in measures such as functional diversity and number of taxa per trait category. © 2014 Elsevier B.V.


Gogina M.,Leibniz Institute for Baltic Sea Research | Nygard H.,Finnish Environment Institute | Blomqvist M.,Hafok AB | Daunys D.,Klaipeda University | And 7 more authors.
ICES Journal of Marine Science | Year: 2016

This study provides an inventory of the recent benthic macrofaunal communities in the entire Baltic Sea. The analyses of soft-bottom benthic invertebrate community data based on over 7000 locations in the Baltic Sea suggested the existence of 10 major communities based on species abundances and 17 communities based on species biomasses, respectively. The low-saline northern Baltic, characterized by silty sediments, is dominated by Monoporeia affinis, Marenzelleria spp., and Macoma balthica. Hydrobiidae, Pygospio elegans, and Cerastoderma glaucum dominate the community in sandy habitats off the Estonian west coast and in the southeastern and southern Baltic Sea. Deep parts of the Gulf of Finland and central Baltic Sea often experience hypoxia, and when oxygen levels in these regions recover, Bylgides sarsi was the first species to colonize. The southwestern Baltic Sea, with high salinity, has higher macrofaunal diversity compared with the northern parts. To spatially interpolate the distribution of the major communities, we used the Random Forest method. Substrate data, bathymetric maps, and modelled hydrographical fields were used as predictors. Model predictions were in good agreement with observations, quantified by Cohen's κ of 0.90 for the abundance and 0.89 in the wet weight-based model. Misclassifications were mainly associated with uncommon classes in regions with high spatial variability. Our analysis provides a detailed baseline map of the distribution of benthic communities in the Baltic Sea to be used both in science and management. © 2016 International Council for the Exploration of the Sea.


PubMed | University of Aarhus, University of Stockholm and Hafok AB
Type: Journal Article | Journal: Marine biology | Year: 2016

Coastal vegetation communities are important for primary production, biodiversity, coastal protection, carbon and nutrient cycling which, in combination with their sensitivity to eutrophication, render them potential indicators of environmental status for environmental policies like the EU Water and Marine Strategy Framework Directives. We evaluated one potential indicator for coastal vegetation, the cumulative cover at depths where the vegetation is light limited, by investigating its response to eutrophication along gradients in natural conditions. We used a large data set covering the Swedish coastline, spanning broad gradients in nutrient level, water clarity, seabed substrate, physical exposure and climate in addition to a salinity gradient from 0.5 to 30.5. Macroalgal cover increased significantly along gradients of declining nutrient concentration and increasing water clarity when we had accounted for diver effects, spatio-temporal sampling variability, salinity gradients, wave exposure and latitude. The developed empirical model explained 79% of the variation in algal cover across 130 areas. Based on this, we identified macroalgal cover as a promising indicator across the Baltic Sea, Kattegat and Skagerrak. A parallel analysis of soft-substrate macrophytes similarly identified significant increases in cover with decreasing concentrations of total nitrogen and increasing salinity, but the resulting empirical model explained only 52% of the variation in cover, probably due to the spatially more variable nature of soft-substrate vegetation. The identified general responses of vegetation cover to gradients of eutrophication across wide ranges in environmental settings may be useful for monitoring and management of marine vegetation in areas with strong environmental gradients.


Leonardsson K.,Swedish University of Agricultural Sciences | Blomqvist M.,Hafok AB | Magnusson M.,Marine Monitoring AB | Wikstrom A.,Marine Monitoring AB | And 2 more authors.
Marine Pollution Bulletin | Year: 2015

A challenging aspect of benthic quality indices used for assessing the marine environment has been to compile reliable measures of the species' sensitivity to disturbances. Sensitivity values and their uncertainties can be calculated, but a problem to cope with is that the results may depend on the actual proportion of samples from disturbed and undisturbed environments. Here we calculated sensitivity values for each species along an artificial disturbance gradient created by bootstrapping varying numbers of samples from disturbed and undisturbed environments. The values were increasing, decreasing, or more or less constant along this gradient. The lowest value with the lowest uncertainty was adopted as the species sensitivity value.Analyses of the uncertainties indicated that the accuracy rather than the precision might be a concern. We suggest a method to exclude species for which the uncertainty is outside predefined limits as a precaution to reduce bias in the environmental status classification. © 2015 The Authors.


Leonardsson K.,Swedish University of Agricultural Sciences | Blomqvist M.,Hafok AB | Rosenberg R.,Marine Monitoring AB | Rosenberg R.,Gothenburg University
Marine Pollution Bulletin | Year: 2016

The Benthic Quality Index, BQI, is widely used for benthic quality assessment. Here, we investigated if spatial variation in the BQI can be reduced by accounting for the environmental factors instead of having different boundaries for different salinity regimes between status classes in the EU Water Framework Directive and Marine Strategy Framework Directive. For this purpose we tested salinity, sediment structure, and depth in a regression model to test their contribution to variations in BQI. The spatial variation in BQI was better explained by depth than by salinity or sediment structure. The proposed assessment method uses the residuals from the regression model between BQI and depth. With this method the variance in BQI between samples was reduced by 50% to 75% in the majority of situations. A method to establish the boundary between good and moderate status and how to derive EQR-values according to the WFD is presented. © 2015.


PubMed | Swedish University of Agricultural Sciences, Hafok AB and Gothenburg University
Type: Journal Article | Journal: Marine pollution bulletin | Year: 2016

The Benthic Quality Index, BQI, is widely used for benthic quality assessment. Here, we investigated if spatial variation in the BQI can be reduced by accounting for the environmental factors instead of having different boundaries for different salinity regimes between status classes in the EU Water Framework Directive and Marine Strategy Framework Directive. For this purpose we tested salinity, sediment structure, and depth in a regression model to test their contribution to variations in BQI. The spatial variation in BQI was better explained by depth than by salinity or sediment structure. The proposed assessment method uses the residuals from the regression model between BQI and depth. With this method the variance in BQI between samples was reduced by 50% to 75% in the majority of situations. A method to establish the boundary between good and moderate status and how to derive EQR-values according to the WFD is presented.


PubMed | Swedish University of Agricultural Sciences, Hafok AB, Gothenburg University and Marine Monitoring AB
Type: Journal Article | Journal: Marine pollution bulletin | Year: 2015

A challenging aspect of benthic quality indices used for assessing the marine environment has been to compile reliable measures of the species sensitivity to disturbances. Sensitivity values and their uncertainties can be calculated, but a problem to cope with is that the results may depend on the actual proportion of samples from disturbed and undisturbed environments. Here we calculated sensitivity values for each species along an artificial disturbance gradient created by bootstrapping varying numbers of samples from disturbed and undisturbed environments. The values were increasing, decreasing, or more or less constant along this gradient. The lowest value with the lowest uncertainty was adopted as the species sensitivity value. Analyses of the uncertainties indicated that the accuracy rather than the precision might be a concern. We suggest a method to exclude species for which the uncertainty is outside predefined limits as a precaution to reduce bias in the environmental status classification.

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