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  • 1.
    Al Jawaheri, Raad
    et al.
    Halmstad University, School of Business, Engineering and Science.
    Sahlén, Göran
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Negative impact of lake liming programmes on the species richness of dragonflies (Odonata): a study from southern Sweden2017In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 788, no 1, p. 99-113Article in journal (Refereed)
    Abstract [en]

    Liming programmes aiming to restore fish populations are being implemented in many acidified aquatic systems in northern Europe. We studied Odonata communities in 47 forest lakes in SW Sweden, 13 that are currently being limed, and 8 that have previously been limed. Thirty-one species were recorded, with the highest mean number in untreated lakes, followed by previously treated lakes and currently treated lakes. Species communities differed between untreated and limed lakes, but only few rare species found in the untreated lakes were absent in the treated lakes. Likewise, species known to thrive in acid environments were either rare or showed no preferences. Comparing the number of records of odonate species within a large regional area to the proportion of lakes inhabited in our study, we found that seven of the most commonly observed species occurred less frequently in limed lakes than in the untreated ones, including two of the three most common taxa. Reduced species numbers in limed lakes might be due to conditions on other trophic levels, including fish predation. We argue that Odonata should be considered when developing new biological indices of water quality, although the causes of the observed occurrence patterns need to be studied further. © 2016 Springer International Publishing Switzerland

  • 2. Andersson, A
    et al.
    Wallberg, P
    Nordback, J
    Bergqvist, P A
    Selstam, Eva
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Effect of nutrient enrichment on the distribution and sedimentation of polychlorinated biphenyls (PCBs) in seawater1998In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 377, p. 45-56Article in journal (Refereed)
    Abstract [en]

    The effect of nutrient enrichment on the distribution of polychlorinated biphenyl's (PCBs) in the microbial food web and the residence time of PCBs in seawater was studied in an experimental mesocosm system. Two 5 m high temperature and light controlled mesocosm tubes (empty set = 0.5 m) were filled with seawater from the northern Baltic Sea. Inorganic phosphorus and nitrogen were added daily to one mesocosm, while the other served as a control. Experiments were conducted at 5, 10 and 20 degrees C. Three C-14-labelled PCBs of different degree of chlorination were added to subsamples of the mesocosms: 4-chlorobiphenyl (MCB), IUPAC # 3, 2,2',5,5'-tetrachlorobiphenyl (TCB), IUPAC # 52 and 2,2',4,4',5,5'-hexachlorobiphenyl (HCB) IUPAC # 153. The biomasses and growth rates of the microorganisms as well as the sedimentation rate of particulate organic material increased with nutrient enrichment. The size distribution of the microorganisms changed with nutrient status, from dominance of picoplankton (< 2 mu m) in the control towards increased importance of micro (> 10 mu m) and nanoplankton (2-10 mu m) in nutrient enrichment. The specific growth rate of the bacterial community was found to be more temperature dependent than that of the phytoplankton community. The relative proportion of PCBs in the > 2 mu m fraction was observed to be in the order MCB < TCB < HCB, while the opposite distribution prevailed in the < 2 mu m fraction. We hypothesize that this is due to the combined effect of the different K-ow values of the PCBs and a different composition of the particulate organic carbon in the > 2 mu m and < 2 mu m fractions (e.g. different lipid composition). The residence time of the PCBs in the mesocosm generally decreased with nutrient enrichment, but was dependent on the degree of chlorination of the PCB. Our results indicate that the transport of organic pollutants up through the food web is more important in nutrient poor than in nutrient rich waters and that the importance of sedimentation is higher in eutrophic ecosystems.

  • 3.
    Andersson, Lotta
    et al.
    SMHI, Core Services.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Modelling of human and climatic impact on nitrogen load in a Swedish river 1885-19942003In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 497, no 1-3, p. 63-77Article in journal (Refereed)
    Abstract [en]

    Changes in environmental conditions within a river basin in South Central Sweden (1400 km(2)) and impacts on riverine nitrogen (N) transport were evaluated. A historical database was compiled and the process-based HBV-N model used to estimate flow normalised N loads in 1885, 1905, 1927, 1956, 1976, and 1994, using a standard climatological record (1985-1994). The study shows the value of process-based modelling in environmental impact assessment, by making it possible to assess and integrate the effect of a number of factors, both with regard to human impact and natural climatic variability. Factors taken into account include: the effects of land use, agricultural practices, atmospheric deposition, human dietary intake, use of flush toilets, lowering of lakes, building of dams, and climatic variability. For all years studied, agriculture was the overriding source of N, and changes in riverine N over time mainly reflected changes in land use and agricultural practices. In spite of decreasing N-leaching from agriculture, the net load remained fairly constant between 1885 and 1927, due to reduced N retention. Drainage of agricultural land had a dominating impact on reducing N retention, which increased the N loads, while the effects of the lowering of lake levels and dam building were less pronounced. Household N emission per capita was higher in 1994 than in 1927, as the increased consumption of meat and dairy products alone resulted in a higher increase of the emission than was compensated for with wastewater treatment improvement. In addition, introduction of flush toilets increased the emission from households. In total, the net load in 1976 was twofold higher than that in 1885, 1905 and 1927, due to increased leaching from agriculture, wastewater emission, and atmospheric deposition on lake surfaces. Finally, the impact of climatological variability was assessed, using a 110-yr climatological record. The choice of 10-yr period of climatological data was the factor that had the largest impact on calculated N load.

  • 4.
    Andersson, Per
    et al.
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Torssander, Peter
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Ingri, Johan
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Sulphur isotope ratios in sulphate and oxygen isotopes in water from a small watershed in central Sweden1992In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 235-236, no 1, p. 205-217Article in journal (Refereed)
    Abstract [en]

    During 1988-89 water samples for sulphur and oxygen isotope measurements were collected in the Lake Mjösjön watershed (7.3 km2), central Sweden. Samples included: precipitation, throughfall, lakewater, shallow groundwater and inlet and outlet streams. The δ34S of sulphate in precipitation ranged from + 6.41‰ in winter to + 3.88‰ in summer, the higher winter values attributed to seasonal differences in the kinetic and equilibrium isotope fractionation during oxidation of atmospheric sulphur dioxide to sulphate. The δ34S in rain samples and in pine and spruce throughfall were similar, indicating no gain of sulphur from the trees. In the inflowing stream, the δ34S value increased as discharge decreased, from + 5.57‰ in spring to + 26.21‰ in summer, indicating bacterial sulphate reduction. The fluctuations in the inlet water were damped by the lake and in the outlet water, only a small decrease in the δ34S value during spring discharge was observed. During winter 1988-89, the near surface waters in the lake showed the same δ34S as snow indicating that meltwater governs the isotopic composition. During the winter, the δ34S in the near bottom waters increased while oxygen decreased due to bacterial sulphate reduction in the sediments. This also caused an increase in the alkalinity in the near bottom waters. Based on the δ18O data the water within the watershed is derived largely from meteoric water. During spring discharge, meltwater governs the inflow and outflow stream while additional groundwater influences occurred during the drier period. Most sulphur is derived from atmospheric deposition and the δ34S in sulphate increased during passage through the watershed due to bacterial sulphate reduction.

  • 5. Arnott, Russell N.
    et al.
    Cherif, Mehdi
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bryant, Lee D.
    Wain, Danielle J.
    Artificially generated turbulence: a review of phycological nanocosm, microcosm, and mesocosm experiments2021In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 848, p. 961-991Article, review/survey (Refereed)
    Abstract [en]

    Building on a summary of how turbulence influences biological systems, we reviewed key phytoplankton-turbulence laboratory experiments (after Peters and Redondo in Scientia Marina: Lectures on plankton and turbulence, International Centre for Coastal Resources, Barcelona, 1997) and Peters and Marrase (Marine Ecology Progress Series 205:291-306, 2000) to provide a current overview of artificial turbulence generation methods and quantification techniques. This review found that most phytoplankton studies using artificial turbulence feature some form of quantification of turbulence; it is recommended to use turbulent dissipation rates (epsilon) for consistency with physical oceanographic and limnological observations. Grid-generated turbulence is the dominant method used to generate artificial turbulence with most experiments providing quantified epsilon values. Couette cylinders are also commonly used due to the ease of quantification, albeit as shear rates not epsilon. Dinoflagellates were the primary phytoplanktonic group studied due to their propensity for forming harmful algal blooms (HAB) as well as their apparent sensitivity to turbulence. This study found that a majority of experimental setups are made from acrylate plastics that could emit toxins as these materials degrade under UV light. Furthermore, most cosm systems studied were not sufficiently large to accommodate the full range of turbulent length scales, omitting larger vertical overturns. Recognising that phytoplankton-turbulence interactions are extremely complex, the continued promotion of more interdisciplinary studies is recommended.

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  • 6. Bakker, Elisabeth S.
    et al.
    Sarneel, Judith
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Gulati, Ramesh D.
    Liu, Zhengwen
    van Donk, Ellen
    Restoring macrophyte diversity in shallow temperate lakes: biotic versus abiotic constraints2013In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 710, no 1, p. 23-37Article in journal (Refereed)
    Abstract [en]

    Although many lake restoration projects have led to decreased nutrient loads and increased water transparency, the establishment or expansion of macrophytes does not immediately follow the improved abiotic conditions and it is often unclear whether vegetation with high macrophyte diversity will return. We provide an overview of the potential bottlenecks for restoration of submerged macrophyte vegetation with a high biodiversity and focus on the biotic factors, including the availability of propagules, herbivory, plant competition and the role of remnant populations. We found that the potential for restoration in many lakes is large when clear water conditions are met, even though the macrophyte community composition of the early 1900s, the start of human-induced large-scale eutrophication in Northwestern Europe, could not be restored. However, emerging charophytes and species rich vegetation are often lost due to competition with eutrophic species. Disturbances such as herbivory can limit dominance by eutrophic species and improve macrophyte diversity. We conclude that it is imperative to study the role of propagule availability more closely as well as the biotic interactions including herbivory and plant competition. After abiotic conditions are met, these will further determine macrophyte diversity and define what exactly can be restored and what not.

  • 7.
    Bengtsson, Mia M.
    et al.
    Ernst Moritz Arndt Univ Greifswald, Inst Microbiol, Felix Hausdorff Str 8, D-17489 Greifswald, Germany.
    Attermeyer, Katrin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. WasserCluster Lunz, Dr Carl Kupelwieser Promenade 5, A-3293 Lunz Am See, Austria.
    Catalan, Nuria
    Catalan Inst Water Res ICRA, Emili Grahit 101, Girona 17003, Spain.
    Interactive effects on organic matter processing from soils to the ocean: are priming effects relevant in aquatic ecosystems?2018In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 822, no 1, p. 1-17Article, review/survey (Refereed)
    Abstract [en]

    Organic matter (OM) is degraded during transport from soils to oceans. However, there are spatial and temporal variabilities along the aquatic continuum, which hamper the development of carbon cycling models. One concept that has been applied in this context is the priming effect (PE), describing non-additive effects on OM degradation after mixing sources of contrasting bioavailability. Studies on the aquatic PE report divergent results from positive (increased OM degradation rates) to neutral, to negative (decreased OM degradation rates) effects upon mixing. Here, we aim to condense the outcomes of these studies on aquatic PE. Based on a literature review, we discuss differences in the reported PEs across freshwater and marine ecosystems, identifying system-specific features that could favour non-additive effects on OM degradation. Using a quantitative meta-analysis approach, we evaluated the occurrence, direction (positive vs. negative) and magnitude of aquatic PE. The meta-analysis revealed a mean PE of 12.6%, which was not significantly different from zero across studies. Hence, mixing of contrasting OM sources in aquatic ecosystems does not necessarily result in a change in OM degradation rates. Therefore, we suggest to focus on molecular and microbial diversity and function, which could provide a better mechanistic understanding of processes driving OM interactions.

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  • 8.
    Bergfur, Jenny
    et al.
    Department of Aquatic Sciences and Assessment, Swedish Agricultural University, Uppsala, Sweden; The Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen, UK .
    Johnson, Richard K
    Department of Aquatic Sciences and Assessment, Swedish Agricultural University, Uppsala, Sweden.
    Sandin, Leonard
    Department of Aquatic Sciences and Assessment, Swedish Agricultural University, Uppsala, Sweden.
    Goedkoop, Willem
    Department of Aquatic Sciences and Assessment, Swedish Agricultural University, Uppsala, Sweden.
    Effects of nutrient enrichment on C and N stable isotope ratios of invertebrates, fish and their food resources in boreal streams2009In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 628, p. 67-79Article in journal (Refereed)
    Abstract [en]

    Carbon and nitrogen stable isotopes are frequently used to study energy sources and food web structure in ecosystems, and more recently, to study the effects of anthropogenic stress on aquatic ecosystems. We investigated the effect of nutrient enrichment on  d13C and d15N in fine (FPOM), coarse (CPOM) particulate organic matter, periphyton, invertebrates and fish in nine boreal streams in south-central Sweden. In addition, we analysed the diet of benthic consumers using stable isotope data. Increases in d15N of periphyton (R2 = 0.88), CPOM (0.78), invertebrates (0.92) and fish (0.89) were related to nutrient enrichment. In contrast, d13C signatures did not change along the nutrient gradient. Our results show that d15N has potential as a sensitive indicator of nutrient enrichment in boreal streams. Carbon and nitrogen isotopes failed to elucidate putative diets of selected aquatic consumers. Indeed, comparison of low- and high-impact sites showed that d13C of many consumers were found outside the ranges of basal resource d13C. Moreover, ranges of basal resource d13C and d15N overlapped at both low and high sites, making discrimination between the importance of allochthonous and autochthonous production difficult. Our findings show that a fractionation rate of 3.4% is not always be appropriate to assess trophic interactions, suggesting that more studies are needed on fractionation rates along gradients of impairment.

  • 9.
    Bergström, Ann-Kristin
    et al.
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Deininger, A.
    Jonsson, Anders
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Karlsson, Jan
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Vrede, T.
    Effects of nitrogen enrichment on zooplankton biomass and N:P recycling ratios across a DOC gradient in northern-latitude lakes2021In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 848, no 21, p. 4991-5010Article in journal (Refereed)
    Abstract [en]

    We used data from whole-lake studies to assess how changes in food quantity (phytoplankton biomass) and quality (phytoplankton community composition, seston C:P and N:P) with N fertilization affect zooplankton biomass, community composition and C:N:P stoichiometry, and their N:P recycling ratio along a gradient in lake DOC concentrations. We found that despite major differences in phytoplankton biomass with DOC (unimodal distributions, especially with N fertilization), no major differences in zooplankton biomass were detectable. Instead, phytoplankton to zooplankton biomass ratios were high, especially at intermediate DOC and after N fertilization, implying low trophic transfer efficiencies. An explanation for the observed low phytoplankton resource use, and biomass responses in zooplankton, was dominance of colony forming chlorophytes of reduced edibility at intermediate lake DOC, combined with reduced phytoplankton mineral quality (enhanced seston N:P) with N fertilization. N fertilization, however, increased zooplankton N:P recycling ratios, with largest impact at low DOC where phytoplankton benefitted from light sufficiently to cause enhanced seston N:P. Our results suggest that although N enrichment and increased phytoplankton biomass do not necessarily increase zooplankton biomass, bottom-up effects may still impact zooplankton and their N:P recycling ratio through promotion of phytoplankton species of low edibility and altered mineral quality.

  • 10.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Deininger, A.
    Jonsson, Anders
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Vrede, T.
    Effects of nitrogen enrichment on zooplankton biomass and N:P recycling ratios across a DOC gradient in northern-latitude lakes2021In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 848, no 21, p. 4991-5010Article in journal (Refereed)
    Abstract [en]

    We used data from whole-lake studies to assess how changes in food quantity (phytoplankton biomass) and quality (phytoplankton community composition, seston C:P and N:P) with N fertilization affect zooplankton biomass, community composition and C:N:P stoichiometry, and their N:P recycling ratio along a gradient in lake DOC concentrations. We found that despite major differences in phytoplankton biomass with DOC (unimodal distributions, especially with N fertilization), no major differences in zooplankton biomass were detectable. Instead, phytoplankton to zooplankton biomass ratios were high, especially at intermediate DOC and after N fertilization, implying low trophic transfer efficiencies. An explanation for the observed low phytoplankton resource use, and biomass responses in zooplankton, was dominance of colony forming chlorophytes of reduced edibility at intermediate lake DOC, combined with reduced phytoplankton mineral quality (enhanced seston N:P) with N fertilization. N fertilization, however, increased zooplankton N:P recycling ratios, with largest impact at low DOC where phytoplankton benefitted from light sufficiently to cause enhanced seston N:P. Our results suggest that although N enrichment and increased phytoplankton biomass do not necessarily increase zooplankton biomass, bottom-up effects may still impact zooplankton and their N:P recycling ratio through promotion of phytoplankton species of low edibility and altered mineral quality.

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  • 11.
    Blenckner, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Models as tools for understanding past, recent and future changes in large lakes.2008In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 599, p. 177-182Article in journal (Refereed)
    Abstract [en]

    Large lakes currently exhibit ecosystem responses to environmental changes such as climate and land use changes, nutrient loading, toxic contaminants, hydrological modifications and invasive species. These sources have impacted lake ecosystems over a number of years in various combinations and often in a spatially heterogeneous pattern. At the same time, many different kinds of mathematical models have been developed to help to understand ecosystem processes and improve cost-effective management. Here, the advantages and limitations of models and sources of uncertainty will be discussed. From these considerations and in view of the multiple environmental pressures, the following emerging issues still have to be met in order to improve the understanding of ecosystem function and management of large lakes: (1) the inclusion of thresholds and points-of-no-return; (2) construction of general models to simulate biogeochemical processes for a large number of lakes rather than for individual systems; (3) improvement of the understanding of spatio-temporal variability to quantify biogeochemical fluxes accurately; and (4) inclusion of biogeochemical linkages between terrestrial and aquatic ecosystems in model approaches to assess the effects of external environmental pressures such as land-use changes. The inclusion of the above-mentioned issues would substantially improve models as tools for the scientific understanding and cost-effective management of large lakes that are subject to multiple environmental pressures in a changing future.

  • 12.
    Blenckner, Thorsten
    et al.
    Stockholm University, Stockholm Resilience Centre.
    Noges, Tiina
    Tranvik, Lars
    Pettersson, Kurt
    Naddafi, Rahmat
    Preface2011In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 660, no 1, p. 1-2Article in journal (Refereed)
  • 13.
    Blindow, Irmgard
    et al.
    Ernst Moritz Arndt University of Greifswald, Germany .
    Hargeby, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Hilt, Sabine
    Leibniz Institute Freshwater Ecol and Inland Fisheries, Germany .
    Facilitation of clear-water conditions in shallow lakes by macrophytes: differences between charophyte and angiosperm dominance2014In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 737, no 1, p. 99-110Article in journal (Refereed)
    Abstract [en]

    A number of mechanisms result in a feedback between water clarity and macrophytes and, consequently, the occurrence of alternative stable states in shallow lakes. We hypothesize that bottom-up mechanisms and interactions within the benthic food web are more important in a charophyte-dominated clear-water state, while top-down mechanism and interactions in the planktonic food web prevail at angiosperm dominance. Charophytes, which dominate at lower nutrient concentrations and develop higher densities than most angiosperms, can have a higher influence on sedimentation, resuspension, and water column nutrients. During dominance of dense submerged vegetation like charophytes, zooplankton can be hampered by low food quality and quantity and by high predation pressure from juvenile fish, which in turn are favoured by the high refuge potential of this vegetation. Grazing pressure from zooplankton on phytoplankton can therefore be low in charophytes, but the main feedback in angiosperm-dominated ecosystems. Charophytes offer a higher surface than most angiosperms to periphyton, which favors benthic invertebrates. These support macrophytes by grazing periphyton and constitute a central link in a trophic cascade from fish to periphyton and macrophytes. To test these hypotheses, more experiments and field measurements comparing the effect of charophytes and angiosperms on water clarity are needed.

  • 14.
    Bohman, Irene
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Herrmann, Jan
    University of Kalmar, School of Pure and Applied Natural Sciences.
    The timing for winter-growing shredder species and leaf litter turnover rate in an oligotrophic lake, SE Sweden2006In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 556, no 1, p. 99-108Article in journal (Refereed)
    Abstract [en]

    Small freshwater systems often depend on allochthonous organic subsidies to sustain productivity. Benthic invertebrates consuming coarse detritus maintain the energy flow by conveying dead organic matter into prey items and increase the food availability for other consumers. Compared to lotic systems, the dynamics of coarse detritus decomposition has not received much attention in lakes. The objectives of this study were to investigate the seasonality of leaf litter turnover and the timing of abundance of potential shredder species in a typical oligotrophic boreal lake. Leaf litter was experimentally exposed in litterbags in the littoral zone in Lake Välen from autumn to late spring two consecutive years. The weight loss rate of leaf litter initially followed the same pattern during both winter periods, but was markedly influenced by freezing in late winter the second year. Further, the seasonal variation patterns in abundance in litterbags were quite different among the potential shredder species. Only the limnephilid caddis larvae showed a density variation pattern possible to connect to the weight loss of leaf litter in litterbags. Otherwise frequent detritivores such as Asellus aquaticus and Leptophlebia marginata displayed lowest density in litterbags during the main weight loss period. However, after the long ice period the second winter the remaining leaf litter seemed to be consumed by A. aquaticus. With increasing knowledge of the initial leaf breakdown process and the guild of shredders in lakes, the decomposition rate may also in this habitat become a useful instrument when evaluating the impact from perturbations on ecosystem function.

  • 15.
    Bryhn, Andreas Christoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    A morphometrically based method for predicting water layer boundaries in meromictic lakes2009In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 636, no 1, p. 413-419Article in journal (Refereed)
    Abstract [en]

    Many general mass-balance models that simulate processes in one or two water layers have been successfully constructed, tested and used to predict effects from remediating lake pollution and other environmental disturbances. However, these models are poorly suited for meromictic lakes which consist of yet another water layer. In order to determine a cross-systems based algorithm for the depth of the boundary between the two lowest layers (D crit2; in m), data from 24 three-layer lakes were analysed, and this depth could be predicted from the maximum depth and the lake surface area. The resulting model was tested with good results against independent data from 6 lakes which were not used for model development. Furthermore, D crit2 was predicted at a considerably lower depth than the theoretical wave base (a previously defined functional separator between the two top layers) in 110 out of 113 meromictic lakes. This indicates that the equation for D crit2 estimated in this study may be used for developing general mass-balance models for a large number of lakes which contain three stable water layers.

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  • 16. Brönmark, Christer
    et al.
    Brodersen, Jakob
    Chapman, Ben B.
    Nicolle, Alice
    Nilsson, P. Anders
    Lund University.
    Skov, Christian
    Hansson, Lars-Anders
    Regime shifts in shallow lakes: the importance of seasonal fish migration2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 646, p. 91-100Article in journal (Refereed)
    Abstract [en]

    Shallow eutrophic lakes commonly existin two alternative stable states: a clear-water state anda turbid water state. A number of mechanisms,including both abiotic and biotic processes, buffer therespective states against changes, whereas othermechanisms likely drive transitions between states.Our earlier research shows that a large proportion of zooplanktivorous fish populations in shallow lakesundertake seasonal migrations where they leave thelake during winter and migrate back to the lake inspring. Based on our past research, we propose anumber of scenarios of how feedback processesbetween the individual and ecosystem levels mayaffect stability of alternative stable states in shallowlakes when mediated by fish migration. Migrationeffects on shallow lakes result from processes atdifferent scales, from the individual to the ecosystem.Our earlier research has shown that ecosystemproperties, including piscivore abundance and zoo-plankton productivity, affect the individual state of zooplanktivorous fish, such as growth rate or condi-tion. Individual state, in turn, affects the relativeproportion and timing of migrating zooplanktivorousfish. This change, in turn, may stabilize states orcause runaway processes that eventually lead to stateshifts. Consequently, such knowledge of processescoupled to seasonal migration of planktivorous fishshould increase our understanding of shallow lakedynamics.

  • 17.
    Brönmark, Christer
    et al.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Weisner, Stefan E. B.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Indirect effects of fish community structure on submerged vegetation in shallow, eutrophic lakes: an alternative mechanism1992In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 243/244, no 1, p. 293-301Article in journal (Refereed)
    Abstract [en]

    The loss of submerged macrophytes during eutrophication of shallow takes is a commonly observed phenomenon. The proximate reason for this decline is a reduction of available light due to increasing phytoplankton and/or epiphyton biomass. Here we argue that the ultimate cause for the transition from a macrophyte-dominated state to a phytoplankton-dominated state is a change in fish community structure. A catastrophic disturbance event (e.g. winterkill) acting selectively on piscivores, cascades down food chains, eventually reducing macrophyte growth through shading by epiphyton, an effect that is reinforced by increasing phytoplankton biomass. The transition back from the phytoplankton to the macrophyte state depends on an increase in piscivore standing stock and a reduction of planktivores. A conceptual model of these mechanisms is presented and supported by literature data and preliminary observations from a field experiment. © 1992 Kluwer Academic Publishers.

  • 18.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Comparing static and dynamic incubations in primary production measurements under different euphotic and mixing depths2019In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 827, no 1, p. 155-169Article in journal (Refereed)
    Abstract [en]

    Since phytoplankton production is usually estimated from static incubations (fixed depths or light levels), a mesocosm study was performed to evaluate the significance of mixing depth, mixing intensity and load of humus of natural phytoplankton assemblages. Vertically rotated (dynamic) incubations usually gave higher results than static incubations in humus-rich water. Mixing intensity was of significant importance in one of 2years tested, but strong interaction effects with humus complicated the explanation. Differences in primary production between dynamic incubations did not fully reflect the received PAR dose, and increased humus and increased mixing depth increased the photo-assimilation efficiency. Different single-depth incubations did not provide a shortcut method to measure water-column primary production with high accuracy. Results diverged from theoretical estimates based on recent combined photo-biological and physical environmental models. The large variability in responses to mixing is supposed to reflect species-specific adaptations and pre-history regarding quantity (photons) and quality (spectral distribution) of the optical environment in an assemblage of different species. The proportional abundance of each species with its specific characters will therefore strongly influence bulk primary production. Due to such variable responses, clear guidelines for a best practice in primary production measurements cannot be given, based on the present results.

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  • 19.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Productivity related to ambient photon flux for phytoplankton communities under different turbid conditions2019In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 837, no 1, p. 109-115Article in journal (Refereed)
    Abstract [en]

    Phytoplankton productivity standardized to chlorophyll a and photon flux (mg C mg chl. a(-1) mol photons(-1)) of natural communities from northern Bothnian Sea under dynamic (vertically rotating) incubations and different optical conditions was studied during four mesocosm experiments between April 2013 and April 2016. The standardized productivity showed a positive exponential relationship with calculated optical depth (P<0.001 in all four cases) although a considerably weaker one for one of the series where the community was pre-adapted to the same optical condition as used in the measurements. This series also showed a lower regression slope than the three non-adapted series, which in turn showed identical regression slopes, thus indicating a similar response on the standardized productivity to short-term changes in average ambient photon flux and mixing depth. These results indicate that phytoplankton communities in environments with episodic inflow and mixing of humus-rich water can partly compensate for the reduced photon flux by increased production efficiency.

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  • 20.
    Båmstedt, Ulf
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Martinussen, Monica B.
    Institute of Marine Research, Bergen, Norway .
    Ecology and behavior of Bolinopsis infundibulum (Ctenophora; Lobata) in the Northeast Atlantic2015In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 759, no 1, p. 3-14Article in journal (Refereed)
    Abstract [en]

    Results from field surveys with net sampling and video profiling, combined with laboratory experiments on feeding and growth, revealed the ecological function of Bolinopsis infundibulum in northern temperate coastal waters. B. infundibulum reaching a peak abundance of around 250 ctenophores m(-2), in mid-May, followed by a dramatic reduction over the next few weeks, presumably explained by predation from the ctenophore Beroe cucumis. The field data on maximum individual body height in the population indicated an instantaneous growth rate of 0.129 d(-1). Newly hatched cydippid larvae showed an average instantaneous growth rate of 0.240 d(-1) over 4 weeks, whereas ctenophores in the size range of 4.4-9.8 mm height gave instantaneous growth rates between 0.10 and 0.20 d(-1). B. infundibulum disappeared from surface water in mid-June, but big individuals were found in deeper water, where they preyed on copepods. The results indicate that the new generation of the year was recruited from February onwards. Laboratory predation and digestion experiments showed a continuous increase in predation rate with increased prey abundance, throughout the tested range of 5-400 copepods l(-1), and a digestion time increasing from 39 min with a single copepod ingested to 73 min with 8 copepods ingested.

  • 21.
    Carreira, Bruno M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology. Univ Lisbon, cE3c, Fac Ciencias, Bloco C2, P-1749016 Lisbon, Portugal;Univ South Bohemia, Fac Sci, Dept Ecosyst Biol & Soil & Water Res Infrastruct, Branisovska 1760, Ceske Budejovice 37005, Czech Republic.
    Segurado, Pedro
    Univ Lisbon, Ctr Estudos Florestais, Inst Super Agron, P-1349017 Lisbon, Portugal.
    Laurila, Anssi
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Rebelo, Rui
    Univ Lisbon, cE3c, Fac Ciencias, Bloco C2, P-1749016 Lisbon, Portugal.
    Heat waves trigger swift changes in the diet and life-history of a freshwater snail2020In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 847, no 4, p. 999-1011Article in journal (Refereed)
    Abstract [en]

    Extreme climatic events, such as heat waves, may induce changes in nutrient acquisition by omnivorous ectotherms. Likely modulated by the intensity, frequency and duration of these events, dietary shifts during heat waves may threaten the stability of freshwaters. We investigated the effects of heat wave duration on diet assimilation and life-history traits of the freshwater gastropod Radix balthica. We compared the magnitude of the effects of a short (1 week) and a long heat wave (7 weeks) on the assimilation of animal- and plant-based diets, measuring performance in terms of growth rate and reproduction. We hypothesized that heat waves should increase the proportion of plant material assimilated on the mixed diet and change the performance of snails on the animal and plant-based diets. Both heat waves increased the assimilation of plant material on the mixed diet and growth rate, with minor negative effects on reproduction. However, responses were disproportional to heat wave duration, as the short heat wave elicited swift and relatively stronger responses. Our findings showcase the role of phenotypic plasticity in aiding ectotherms to cope with increased thermal stress and acclimate. Temporarily changing the strength of trophic interactions, heat waves may alter community dynamics in freshwater habitats.

  • 22.
    Catalán, Núria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Herrero Ortega, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Gröntoft, H.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Hilmarsson, T. G.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Wu, Pianpian
    Levanoni, Oded
    Bishop, K.
    Garcia Bravo, Andrea
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Effects of beaver impoundments on dissolved organic matter quality and biodegradability in boreal riverine systems2017In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 793, no 1, p. 135-148Article in journal (Refereed)
    Abstract [en]

    Beaver impoundments modify the structure of river reaches and lead to changes in ecosystem function and biogeochemical processes. Here, we assessed the changes in dissolved organic matter (DOM) quality and the biodegradation patterns in a set of beaver systems across Sweden. As the effect of beaver impoundments might be transient and local, we compared DOM quality and biodegradability of both pond and upstream sections of differentially aged beaver systems. Newly established dams shifted the sources and DOM biodegradability patterns. In particular, humic-like DOM, most likely leached from surrounding soils, characterized upstream sections of new beaver impoundments. In contrast, autochthonous and processed compounds, with both higher biodegradation rates and a broader spectrum of reactivities, differentiated DOM in ponds. DOM in recently established ponds seemed to be more humic and less processed compared to older ponds, but system idiosyncrasies determined by catchment particularities influenced this ageing effect.

  • 23. Catalán, Núria
    et al.
    Obrador, Biel
    Pretus, Joan Lluís
    Ecosystem processes drive dissolved organic matter quality in a highly dynamic water body2014In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117Article in journal (Refereed)
  • 24.
    Cuenca-Cambronero, M.
    et al.
    Univ Vic, Cent Univ Catalonia, Aquat Ecol Grp, Vic 08500, Spain..
    Blicharska, Malgorzata
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Natural Resources and Sustainable Development.
    Perrin, J. -a.
    ISARA, Dept Agroecol & Environm, Lyon, France..
    Davidson, T. A.
    Aarhus Univ, Dept Ecosci, Silkeborg, Denmark..
    Oertli, B.
    Univ Appl Sci & Arts Western Switzerland, HEPIA, HES SO, Geneva, Switzerland..
    Lago, M.
    Ecol Inst, Berlin, Germany..
    Beklioglu, M.
    Middle East Tech Univ, Biol Dept, Limnol Lab, Dumlupinar Bulvari 1, TR-06800 Cankaya, Ankara, Turkiye..
    Meerhoff, M.
    Aarhus Univ, Dept Ecosci, Silkeborg, Denmark.;Univ Republ, Ctr Univ Reg Este CURE, Dept Ecol & Gest Ambiental, Maldonado, Uruguay..
    Arim, M.
    Univ Republ, Ctr Univ Reg Este CURE, Dept Ecol & Gest Ambiental, Maldonado, Uruguay..
    Teixeira, J.
    Univ Porto, Interdisciplinary Ctr Marine & Environm Res, CIIMAR, Matosinhos, Portugal..
    De Meester, L.
    Katholieke Univ Leuven, Lab Aquat Ecol Evolut & Conservat, Louvain, Belgium.;Leibniz Inst Freshwater Ecol & Inland Fisheries, Berlin, Germany.;Free Univ Berlin, Inst Biol, Berlin, Germany..
    Biggs, J.
    Freshwater Habitats Trust, Bury Knowle House, Headington, England..
    Robin, J.
    ISARA, Dept Agroecol & Environm, Lyon, France..
    Martin, B.
    Randbee Consultants, Malaga, Spain..
    Greaves, H. M.
    UCL, Environm Change Res Ctr, Dept Geog, Pond Restorat Res Grp, London, England..
    Sayer, C. D.
    UCL, Environm Change Res Ctr, Dept Geog, Pond Restorat Res Grp, London, England..
    Lemmens, P.
    Katholieke Univ Leuven, Lab Aquat Ecol Evolut & Conservat, Louvain, Belgium.;Leibniz Inst Freshwater Ecol & Inland Fisheries, Berlin, Germany..
    Boix, D.
    Univ Girona, Inst Aquat Ecol, GRECO, Girona, Spain..
    Mehner, T.
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Berlin, Germany..
    Bartrons, M.
    Univ Vic, Cent Univ Catalonia, Aquat Ecol Grp, Vic 08500, Spain..
    Brucet, S.
    Univ Vic, Cent Univ Catalonia, Aquat Ecol Grp, Vic 08500, Spain.;Catalan Inst Res, Adv Studies, ICREA, Barcelona, Spain..
    Challenges and opportunities in the use of ponds and pondscapes as Nature-based Solutions2023In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 850, no 15, p. 3257-3271Article in journal (Refereed)
    Abstract [en]

    Ponds and "pondscapes" (networks of ponds) are crucial habitats for biodiversity and for delivering multiple benefits to humans, so-called "Nature's Contribution to People", such as climate mitigation and adaptation to climate change, creation, and maintenance of habitat for biodiversity, water purification, flood mitigation and cultural benefits (e.g., recreational possibilities). However, ponds are not often considered as Nature-based Solutions to provide all these benefits. In addition, there is insufficient knowledge on how to manage and restore ponds to maximise their role to increase the resilience of ecosystems and society to climate change. To facilitate improved implementation of ponds as Nature-based Solutions for the delivery of a wide range of Nature Contributions to People, it is important to generate and integrate biodiversity, ecosystems, societal, economic and policy knowledge. Hence, there is a need for evidence-based guidance to support the broader use of ponds. Here, we review the role of ponds and pondscapes in delivering Nature's Contributions to People and provide an overview of the challenges and opportunities for their broader implementation as Nature-based Solutions. Finally, we propose a conceptual framework that can help the implementation of pond Nature-based Solutions, and that outlines future research needs.

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  • 25.
    Das, Supriyo Kumar
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Routh, Joyanto
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Roychoudhury, Alakendra N.
    Val Klump, J.
    Ranjan, Rajesh Kumar
    Phosphorus dynamics in shallow eutrophic lakes: an example from Zeekoevlei, South Africa2009In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 619, p. 55-66Article in journal (Refereed)
    Abstract [en]

    Zeekoevlei is the largest freshwater lake in South Africa and has been suffering from hyper-eutrophic conditions since last few decades. We have used total P (TP), dissolved phosphate (PO4 (3-)), organic P (OP), calcium (Ca) and iron (Fe) bound P fractions to investigate the relevant physical, chemical and biological processes responsible for sedimentation and retention of P and to study phosphorus (P) dynamics in this shallow lake. In addition, redox proxies (V/Cr and Th/U ratios) are used to study the prevailing redox conditions in sediments. Adsorption by CaCO3 and planktonic assimilation of P are found to control P sedimentation in Zeekoevlei. Low concentration of the labile OP fraction in surface sediments restricts the release of P by bacterial remineralisation. Low molar Ca/P and Fe/P ratios indicate low P retention capacity of sediments, and P is most likely released by desorption from wind-induced resuspended sediments and mixing of pore water with the overlying water column.

  • 26.
    Das, Supriyo Kumar
    et al.
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Routh, Joyanto
    Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
    Roychoudhury, Alakendra N.
    Department of Geological Sciences, University of Cape Town, Rondebosch, South Africa.
    Val Klump, J.
    Department of Biological Sciences and Department of Geosciences, Great Lakes WATER Institute, University of Wisconsin-Milwaukee, Milwaukee, USA.
    Ranjan, Rajesh Kumar
    School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.
    Phosphorus dynamics in shallow eutrophic lakes: an example from Zeekoevlei, South Africa2009In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 619, p. 55-66Article in journal (Refereed)
    Abstract [en]

    Zeekoevlei is the largest freshwater lake in South Africa and has been suffering from hyper-eutrophic conditions since last few decades. We have used total P (TP), dissolved phosphate (PO4 (3-)), organic P (OP), calcium (Ca) and iron (Fe) bound P fractions to investigate the relevant physical, chemical and biological processes responsible for sedimentation and retention of P and to study phosphorus (P) dynamics in this shallow lake. In addition, redox proxies (V/Cr and Th/U ratios) are used to study the prevailing redox conditions in sediments. Adsorption by CaCO3 and planktonic assimilation of P are found to control P sedimentation in Zeekoevlei. Low concentration of the labile OP fraction in surface sediments restricts the release of P by bacterial remineralisation. Low molar Ca/P and Fe/P ratios indicate low P retention capacity of sediments, and P is most likely released by desorption from wind-induced resuspended sediments and mixing of pore water with the overlying water column.

  • 27.
    Degerman, Rickard
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Lefébure, Robert
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Byström, Pär
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Larsson, Stefan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Andersson, Agneta
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Food web interactions determine energy transfer efficiency and top consumer responses to inputs of dissolved organic carbon2018In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 805, no 1, p. 131-146Article in journal (Refereed)
    Abstract [en]

    Climate change projections indicate increased precipitation in northern Europe, leading to increased inflow of allochthonous organic matter to aquatic systems. The food web responses are poorly known, and may differ depending on the trophic structure. We performed an experimental mesocosm study where effects of labile dissolved organic carbon (DOC) on two different pelagic food webs were investigated, one having zooplankton as highest trophic level and the other with planktivorous fish as top consumer. In both food webs, DOC caused higher bacterial production and lower food web efficiency, i.e., energy transfer efficiency from the base to the top of the food web. However, the top-level response to DOC addition differed in the zooplankton and the fish systems. The zooplankton production increased due to efficient channeling of energy via both the bacteria land the phytoplankton pathway, while the fish production decreased due to channeling of energy mainly via the longer and less efficient bacterial pathway. We conclude that the added DOC either acted as a subsidy by increasing the production of the top trophic level (mesozooplankton), or as a sink causing decreased top consumer production (planktivorous fish).

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  • 28.
    Dessborn, Lisa
    et al.
    Kristianstad University, School of Education and Environment.
    Elmberg, Johan
    Kristianstad University, School of Education and Environment.
    Nummi, Petri
    Department of Forest Ecology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Joensuu Game and Fisheries Research.
    Sjöberg, Kjell
    Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences, Umeå.
    Hatching in dabbling ducks and emergence in chironomids: a case of predator-prey synchrony?2009In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 636, no 1, p. 319-329Article in journal (Refereed)
    Abstract [en]

    It has been hypothesized that dabbling ducks (Anas spp.) time breeding to coincide with annual regional peaks in emerging dipterans, especially Chironomidae, which are important prey for newly hatched ducklings. However, this hypothesis has never been evaluated in a replicated lake-level study, including year effects in emergence patterns. We collected duck and invertebrate data from 12 lakes during the nesting seasons 1989-1994 in a watershed in southern Finland. The oligotrophic study lakes are typical of the boreal Holarctic, as are the three focal duck species: mallard Anas platyrhynchos L., widgeon Anas penelope L and teal Anas crecca L. Hatching of ducklings showed a clear peak in relation to ambient phenology (annual ice-out date of lakes), whereas chironomid emergence was more erratic and showed no clear peak at the lake level, although total watershed-level emergence was somewhat higher before and long after the duck hatching peak. Thus, we find no evidence that ducklings hatch in synchrony with abundance peaks of emerging chironomids. There was large within-year temporal variation in chironomid emergence among lakes, but this was not correlated with ambient temperature. The rank of individual lakes with respect to the abundance of emerging chironomids was consistent among as well as within years, a predictability that ought to make adaptive lake choice by ducks possible. On the lake level, there was a positive correlation between the total amount of emerging chironomids and brood use. We argue that emergence patterns of chironomids on typical boreal lakes are neither compressed nor predictable enough to be a major selective force on the timing of egg-laying and hatching in dabbling ducks. Despite spatial (among-lake) patterns of abundance of emerging chironomids being predictable within and among years, the observed pattern of brood use suggests that other factors, e.g. habitat structure, also affect lake choice.

  • 29.
    Dudley, Bernard J.
    et al.
    Centre for Ecology and Hydrology, Bush Estate, Penicuik.
    Dunbar, Michael
    Centre for Ecology and Hydrology, Wallingford, Oxon.
    Penning, Ellis
    Deltares, Delft.
    Kolada, Agnieszka
    Institute of Environmental Protection - National Research Institute, Warsaw.
    Hellsten, Seppo K.
    Finnish Environment Institute (SYKE), University of Oulu.
    Oggioni, Alessandro
    Institute for Electromagnetic Sensing of the Environment CNR - IREA, Via Bassini.
    Bertin, Vincent
    Irstea, UR REBX, 50 Avenue de Verdun.
    Ecke, Frauke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Søndergaard, Martin
    Institute of Bioscience, Aarhus University.
    Measurements of uncertainty in macrophyte metrics used to assess European lake water quality2013In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 704, no 1, p. 179-191Article in journal (Refereed)
    Abstract [en]

    Uncertainty is an important factor in ecological assessment, and has important implications for the ecological classification and management of lakes. However, our knowledge of the effects of uncertainty in the assessment of different ecological indicators is limited. Here, we used data from a standardized campaign of aquatic plant surveys, in 28 lakes from 10 European countries, to assess variation in macrophyte metrics across a set of nested spatial scales: countries, lakes, sampling stations, replicate transects, and replicate samples at two depth-zones. Metrics investigated in each transect included taxa richness, maximum depth of colonisation and two indicators of trophic status: Ellenberg’s N and a metric based on phosphorus trophic status. Metrics were found to have a slightly stronger relationship to pressures when they were calculated on abundance data compared to presence/absence data. Eutrophication metrics based on helophytes were found not to be useful in assessing the effects of nutrient pressure. These metrics were also found to vary with the depth of sampling, with shallower taxa representing higher trophic status. This study demonstrates the complex spatial variability in macrophyte communities, the effect of this variability on the metrics, and theimplications to water managers, especially in relation to survey design.

  • 30.
    Ecke, Frauke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering. Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, 750 07, Uppsala, Sweden.
    Hellsten, Seppo
    Finnish Environment Institute (SYKE), University of Oulu, P.O. Box 413, 90014, Oulu, Finland.
    Mjelde, Marit
    Norwegian Institute for Water Research, Gaustadalléen 21, 0349, Oslo, Norway.
    Kuoppala, Minna
    Finnish Environment Institute (SYKE), University of Oulu, P.O. Box 413, 90014, Oulu, Finland.
    Schlacke, Sabine
    Research Centre for European Environmental Law, Faculty of Law, University of Bremen, Universitätsallee GW1, 28353, Bremen, Germany.
    Potential conflicts between environmental legislation and conservation exemplified by aquatic macrophytes2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 656, no 1, p. 107-115Article in journal (Refereed)
    Abstract [en]

    It is important that legislation on water quality issues of freshwaters is not in conflict with nature conservation purposes. So far, it is however unknown how the assessment of ecological status according to for example the Water Framework Directive (WFD) of the European Community relates to the status of lakes according to the Habitat Directive (HD) or to national environmental objectives including, e.g., the protection of important wetland areas and red-listed species. We used lake macrophyte classification schemes of Norway, Sweden, and Finland and a total of 1,014 lakes to evaluate the possible conflict between these directives and national legislation. The classification schemes represent mainly trophic indices penalizing lakes with elevated phosphorous concentrations. In general, high ecological status according to the WFD did not mean high number of red-listed species or high status according to the HD or other national environmental objectives. In Sweden 78%, in Norway 47%, and in Finland 29% of lakes with red-listed species were classified as lakes of moderate or worse ecological status based on the macrophyte classification scheme. These lakes thus did not fulfill the demands of the WFD. Restoration of surface water toward fulfilling the demands requires in practice a reduction of the trophic status. This might potentially result in for example the loss of red-listed species. To avoid such potential conflicts, we primarily suggest revising the national quality assessment systems toward implicitly incorporating nature conservation aspects, e.g., the number of red-listed species in a multi-metric assessment system.

  • 31. Eckert, Ester M.
    et al.
    Cancellario, Tommaso
    Bodelier, Paul L. E.
    Declerck, Steven A. J.
    Diwen, Liang
    Samad, Sainur
    Winder, Monika
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Zhou, Libin
    Fontaneto, Diego
    A combination of host ecology and habitat but not evolutionary history explains differences in the microbiomes associated with rotifers2023In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 850, no 17, p. 3813-3821Article in journal (Refereed)
    Abstract [en]

    The holobiont concept places emphasis on the strict relationship between a host and its associated microbiome, with several studies supporting a strong effect of the quality of the microbiome on the host fitness. The generalities of the holobiont have been questioned for several invertebrates, including zooplankton. Here we assess the role of host ecology, habitat, and evolutionary history to explain the differences in the microbiomes associated with rotifers, across a broad taxonomic spectrum and from different habitats. The analyses of 93 rotifer-associated microbiomes from 23 rotifer host species revealed that a combination of effects from the host ecology and its habitat seem to be stronger than host phylogenetic distances in explaining differences in microbial composition of the microbiomes. This pattern is in line with the idea of habitat filtering being a stronger explanation than co-evolution in shaping the relationship between a microbiome and its rotifer host. 

  • 32.
    Elmberg, Johan
    et al.
    Kristianstad University, School of Education and Environment.
    Dessborn, Lisa
    Kristianstad University, School of Education and Environment.
    Englund, Göran
    Department of Ecology and Environmental Science, Umeå University.
    Presence of fish affects lake use and breeding success in ducks2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 641, no 1, p. 215-223Article in journal (Refereed)
    Abstract [en]

    Several previous studies indicate that presence of fish has negative effects on waterbirds breeding on lakes, owing either to competition for common invertebrate prey or fish predation on ducklings/chicks. However, others have reported results to the contrary and it remains unresolved what factors trigger, inhibit, and modulate fish-waterbird interactions. The present study was designed to test the effect of fish presence per se, with a minimum of variation in possibly confounding environmental variables. Thus, after stratifying for area, depth, altitude, pH, and total phosphorus we compared 13 lakes with and 12 without fish (mainly pike Esox lucius and perch Perca fluviatilis) with respect to (i) general species richness of waterbirds, (ii) species-specific utilization and breeding success of two dabbling ducks (mallard Anas platyrhynchos and teal Anas crecca) and a diving duck (goldeneye Bucephala clangula). General species richness of waterbirds was higher on fishless lakes. Overall use (bird days) and brood number of teal and goldeneye were higher on fishless lakes. The latter also had more benthic and free-swimming prey invertebrates compared to lakes with fish. Mallard use, mallard brood number, and abundance of emerging insects did not differ between lake groups. Generalized linear models including fish presence as factor and considering seven environmental variables as covariates, confirmed that all waterbird variables except mallard days and broods were negatively correlated to fish presence. There was also a residual positive relationship of lake area on general species richness, teal days, and teal broods. Our data demonstrate a stronger effect of fish presence on diving ducks and small surface feeding ducks than on large surface-feeding ducks. We argue that observed patterns were caused by fish predation on ducks rather than by fish-duck competition for common prey.

  • 33. Elmberg, Johan
    et al.
    Dessborn, Lisa
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Presence of fish affects lake use and breeding success in ducks2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 641, no 1, p. 215-223Article in journal (Refereed)
    Abstract [en]

    Several previous studies indicate that presence of fish has negative effects on waterbirds breeding on lakes, owing either to competition for common invertebrate prey or fish predation on ducklings/chicks. However, others have reported results to the contrary and it remains unresolved what factors trigger, inhibit, and modulate fish-waterbird interactions. The present study was designed to test the effect of fish presence per se, with a minimum of variation in possibly confounding environmental variables. Thus, after stratifying for area, depth, altitude, pH, and total phosphorus we compared 13 lakes with and 12 without fish (mainly pike Esox lucius and perch Perca fluviatilis) with respect to (i) general species richness of waterbirds, (ii) species-specific utilization and breeding success of two dabbling ducks (mallard Anas platyrhynchos and teal Anas crecca) and a diving duck (goldeneye Bucephala clangula). General species richness of waterbirds was higher on fishless lakes. Overall use (bird days) and brood number of teal and goldeneye were higher on fishless lakes. The latter also had more benthic and free-swimming prey invertebrates compared to lakes with fish. Mallard use, mallard brood number, and abundance of emerging insects did not differ between lake groups. Generalized linear models including fish presence as factor and considering seven environmental variables as covariates, confirmed that all waterbird variables except mallard days and broods were negatively correlated to fish presence. There was also a residual positive relationship of lake area on general species richness, teal days, and teal broods. Our data demonstrate a stronger effect of fish presence on diving ducks and small surface feeding ducks than on large surface-feeding ducks. We argue that observed patterns were caused by fish predation on ducks rather than by fish-duck competition for common prey.

  • 34.
    Elmberg, Johan
    et al.
    Department of Wildlife Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Department of Applied Ecology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Evo Game Research Station.
    Sjöberg, Kjell
    Department of Wildlife Ecology, Swedish University of Agricultural Sciences, Umeå.
    Do intruding predators and trap position affect the reliability of catches in activity traps?1992In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 239, no 3, p. 187-193Article in journal (Refereed)
    Abstract [en]

    Forty lakes in Sweden and Finland were sampled in 1990 with activity traps to evaluate the effects of trapped predators on invertebrate catch. Vertebrate (fish, newts) and invertebrate (leeches, dragonflies, water beetles, backswimmers and water scorpions) predators were considered separately. Invertebrate predators affected neither the abundance nor the taxonomic diversity of the catches. Vertebrate predators had no effect on the abundance but reduced the taxonomic diversity of the catches significantly. Thus, vertebrate predators are a possible source of bias in activity trap catches, but oily concerning taxonomic diversity. Within the depth gradient studied (0.25-0.75 m), trap position (suspended in mid-water versus on the bottom) did not affect the percentages of nektonic and benthic invertebrates in the catches. The relative abundance of all taxa was similar in the catches from different trap positions, but the relative abundance of the most numerous taxa as well as the diversity of the catches differed between trap positions. We conclude that both mid-water and bottom traps are suitable for monitoring aquatic invertebrates, and that bottom traps may be preferred for practical reasons.

  • 35.
    Elmberg, Johan
    et al.
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Sjöberg, Kjell
    Department of Animal Ecology, Swedish University of Agricultural Sciences, Umeå.
    Nummi, Petri
    Department of Applied Zoology, University of Helsinki.
    Pöysä, Hannu
    Finnish Game and Fisheries Research Institute, Evo Game Research Station.
    Patterns of lake acidity and waterfowl communities1994In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 279-280, no 1, p. 201-206Article in journal (Refereed)
    Abstract [en]

    Breeding waterfowl communities were studied in 28 lakes in three areas in North Europe, along gradients of acid precipitation and alkalinity that result in lake conditions ranging from unaffected to strongly acidified. Acidic lakes had generally sparser and less complex vegetation, and fewer invertebrates were caught in activity traps. There was neither correlation between pH and waterfowl species richness (genus Anas, family Anatidae, and waterfowl sensu latu tested separately), nor between pH and waterfowl diversity (Simpson's index). Further, pH and waterfowl population density (genus Anas, family Anatidae, and waterfowl sensu latu) were not correlated, but when functional rather than taxonomic groups were considered, pH and relative abundance of fish-eating species (Gaviidae and Podicipedidae) were correlated. However, the relative abundance of Bucephala clangula, a diving duck that may compete with fish for food, was not correlated with pH. Although individual species may be affected, community level responses of waterfowl to acidity are either absent or hard to detect at our sites.

  • 36.
    Enefalk, Åsa
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Bergman, Eva
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Effects of fine wood on macroinvertebrate drift in four boreal forest streams2016In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 765, no 1, p. 317-327Article in journal (Refereed)
    Abstract [en]

    Most studies of stream wood have focused on pieces a parts per thousand yen0.1 m diameter. However, this approach may overlook an important feature of small streams, where wood < 0.1 m can constitute the majority of wood pieces. We examined the effect of fine wood (FW) on local drift of stream macroinvertebrates. The study was carried out at seven sites in four boreal forest streams, from early June to mid-August 2011. This was done by anchoring bundles of FW at each site and measuring drift upstream and downstream of each bundle. We hypothesized that FW would increase drift density, biomass and diversity of aquatic invertebrates. Ten weeks after FW addition, aquatic drift density was higher downstream than upstream of FW bundles, while drift biomass and drift diversity did not differ significantly downstream and upstream of FW.

  • 37. Euclide, Peter T.
    et al.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Stockwell, Jason D.
    Partial diel vertical migration in an omnivorous macroinvertebrate, Mysis diluviana2017In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 787, no 1, p. 387-396Article in journal (Refereed)
    Abstract [en]

    Partial migration, whereby only a portion of a population migrates, has just recently received attention in aquatic systems. Partial diel vertical migration (DVM) has received even less attention but could significantly influence our understanding of trophic interactions and nutrient movement in open water systems. Recent work in the Baltic Sea shows differences in isotope composition between benthic and pelagic Mysis salemaai sampled at night, suggesting that partial DVM may be fixed at the individual level. Historic observations of North American M. diluviana suggest partial DVMin this species, but this behavior has largely been ignored in the literature. We used length, occurrence of gravid females, and body delta C-13, delta N-15, delta S-34, and C:N ratio as markers to test for differences among adult M. diluviana collected from benthic and pelagic habitats at night in Lake Champlain, USA. We found differences in body length and occurrence of gravid females between pelagic- and benthic-caught M. diluviana and differences in C: N between pelagic-and benthic-caught non-gravid individuals, consistent with life stage and body condition hypotheses for partial migration. Partial DVM of M. diluviana could have significant impacts on population assessments which could bias food web models used in basic research and management.

  • 38.
    Gaillard, Marie-Jose
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Dearing, John A
    El-Daoushy, F
    Enell, M
    Håkansson, H
    A multidisciplinary study of Lake Bjäresjö (S Sweden): land-use history, soil erosion, lake trophy and lake-level fluctuations during the last 3000 years1991In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 214, p. 107-114Article in journal (Refereed)
    Abstract [en]

    The lake Bjaresjosjon, Southern Scania, Southern Sweden, was studied in the context of the project 'The cultural landscape of the past 6000 years in Southern Sweden'. Pollen, plant macrofossils, diatoms, physical and chemical analysis, magnetic measurements and radiometric methods (Pb-210, C-14) have been used to study palaeoecological changes, i.e. climate, land use, lake trophy and soil erosion during the past 3000 years. This multidisciplinary study shows striking responses of diatom communities, physical and chemical characteristics, sediment yields and magnetic parameters to land-use changes and lake-level fluctuations. Moreover, the latter are closely related to the settlement history at the site, inferred from archaeological records and historical sources. Before 650 AD, the limnological development was affected mainly by lake-level fluctuations, but partly also by human impact (extensive forest clearings and dominant pastoral farming). With the expansion of arable farming (around 650 AD), human impact on the landscape was the major factor influencing soil erosion processes in the catchment and limnological changes in the lake.

  • 39.
    Gilek, Michael
    et al.
    Stockholms universitet.
    Littorin, Bengt
    Saetre, Peter
    Spatial patterns of abundance and growth of Mytilus edulis on boulders in the Northern Baltic Sea proper2001In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 452, no 1-3, p. 59-68Article in journal (Refereed)
    Abstract [en]

    Small scale spatial patterns of abundance, growth and condition of the mussel Mytilus edulis on sub-littoral boulders (approx. 1-2 m high) were investigated at the island of Asko in the northern Baltic proper. The effect of side (exposed/sheltered with respect to wave action and sunlight) of boulder and position (up/down) on boulder was investigated. A large spatial variability in abundance of M. edulis between boulders and between various sites within boulders were found. The highest numbers of mussels were found on the wave exposed side, near the top of boulders. Shell growth was favoured by a sheltered side and a down position. The body condition (meat weight/shell weight) of mussels was, on the other hand, affected only by position, the condition of mussels being better at the up position. Consequently, there seems to be temporal differences in the condition for growth within a spatial position. The body condition of the mussels was best near the top of boulders in the spring, but long-term shell growth was favoured by a sheltered side and a down position. This may reflect changes in the composition and availability of food during the year with phytoplankton as the major food source during the spring bloom and resuspension of benthic production and detritus as relatively more important during the rest of the year.

  • 40.
    Gosselin, Marie-Pierre
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences.
    Petts, G. E.
    Univ Westminster, London W1R 8AL, England..
    Maddock, I. P.
    Univ Worcester, Inst Sci & Environm, Henwick Grove WR2 6AJ, Worcs, England..
    Mesohabitat use by bullhead (Cottus gobio)2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 652, no 1, p. 299-310Article in journal (Refereed)
    Abstract [en]

    Habitat composition and connectivity within a stream vary with changing flows but the influence of changing flow on habitat use by fish is not well understood. Meso- and microhabitat surveys were used to investigate habitat use by bullhead (Cottus gobio Linnaeus) in response to discharge variation in a small tributary of the Upper Severn, England. Mesohabitat mapping surveys were carried out over a range of summer flows (0.016-0.216 m(3) s(-1)) and were coupled with direct underwater observations (snorkelling) of fish location. Five mesohabitat types-glides, runs, riffles, chutes and pools-were present in the reach at all flows surveyed and 'backwaters' were found at three flows. The macro-morphology of the reach comprised six riffle-pool sequences divided into 27 mesohabitats with the maximum diversity (23 mesohabitats) at intermediate flows (Q (43)) and only 15 mesohabitats at Q (95). Despite low numbers of fish (N = 78), bullhead displayed a strong association (51% of the fish) with glides-relatively deep habitats having high rates of velocity increase with flow. However, 54% of the fish were observed in two large, persistent mesohabitats, a glide (34%) and a pool (20%), both located below a faster flowing mesohabitat. Habitat use curves based upon micro-habitat data showed bullhead favoured low velocities (< 0.30 m s(-1)), depths less than 0.30 m and a cobble substratum. This study illustrates the value of cross-scale investigations in linking fish ecology, flow and physical habitat variability and suggests mesohabitat size, persistence and arrangement may influence fish distribution.

  • 41.
    Gunnarsson, Gunnar
    et al.
    Kristianstad University, Sweden.
    Kjeller, Elsie
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Kristianstad University, Sweden.
    Holopainen, Sari
    Univ Helsinki, Finland.
    Djerf, Henric
    Kristianstad University, Sweden.
    Elmberg, Johan
    Kristianstad University, Sweden.
    Poeysae, Hannu
    Univ Eastern Finland, Finland.
    Söderquist, Pär
    Kristianstad University, Sweden.
    Waldenström, Jonas
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    The hub of the wheel or hitchhikers?: The potential influence of large avian herbivores on other trophic levels in wetland ecosystems2024In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 851, p. 107-127Article in journal (Refereed)
    Abstract [en]

    Goose and swan populations have increased concurrently with environmental degradation of wetlands, such as eutrophication, vegetation losses, and decrease in biodiversity. An important question is whether geese and swans contribute to such changes or if they instead benefit from them. We collected data from 37 wetlands in southern Sweden April - July 2021 to study relationships between geese, swans and other waterbird guilds, macrophytes, invertebrates, as well as physical and water chemistry variables. Neither goose nor swan abundance was negatively correlated with other trophic levels (abundance, richness, or cover). On the contrary, goose or swan abundances were positively related to abundances of surface and benthic feeding waterbirds, cover of specific macrophytes, and to invertebrate richness and abundance. Moreover, invertebrates (number of taxa or abundance) were positively associated with abundance of several waterbird guilds and total phosphorous with surface feeders, whereas water colour was positively (surface feeders) or negatively (benthic feeders) related. We conclude that waterbirds are more abundant in productive wetlands and that geese and swans do not show clear deleterious effects on other trophic levels included in this study. However, patterns may be masked at the species level, which should be addressed in further studies, complemented with experimental studies of grazing impact.

  • 42.
    Gylle, A. Maria
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Nygård, Charlotta A.
    Cty Adm, Dept Environm, S-87186 Harnosand, Sweden .
    Svan, Carina I.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pocock, Tessa
    Heliospectra AB, S-50630 Boras, Sweden.
    Ekelund, Nils G. A.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Photosynthesis in relation to D1, PsaA and Rubisco in marine and brackish water ecotypes of Fucus vesiculosus and Fucus radicans (Phaeophyceae)2013In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 700, no 1, p. 109-119Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate photosynthetic differences between the marine, Norwegian Sea ecotype and the brackish, Bothnian Sea ecotype of F. vesiculosus and F. radicans and to see whether photosynthetic differences could be connected with the relative amounts of D1 protein (PSII), PsaA (PSI) protein and/or Rubisco. For this purpose, we tested if a higher photosynthetic maximum (P (max)) in the Atlantic Ocean ecotype of F. vesiculosus relative to the Baltic Sea ecotype, and an increase of the P (max) in Baltic Sea ecotype of F. vesiculosus at higher salinity, could be due to an increase in the relative amounts of Rubisco. The proteins have been evaluated on a relative basis. Immunoblot signals showed that the amount of Rubisco was higher in both ecotypes of F. vesiculosus than in F. radicans, but no differences could be detected between the two ecotypes of F. vesiculosus. The results suggest an uneven photosystem protein stoichiometry in Fucus, with more of the PSI protein PsaA relative to the PSII protein D1. The difference in P (max) between the two ecotypes of F. vesiculosus might be related to the difficulties for the algae to adapt to the environment in Bothnian Sea.

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  • 43.
    Gylle, Maria
    et al.
    Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, 851 70, Sundsvall, Sweden.
    Nygård, Charlotta
    Department of Environment, County Administration Västernorrland, 871 86, Härnösand, Sweden.
    Svan, Carina I
    Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University, 851 70, Sundsvall, Sweden.
    Pocock, Tessa
    Heliospectra AB, Armbågavägen 3, 506 30, Borås, Sweden.
    Ekelund, Nils
    Department of Natural Sciences, Engineering and Mathematics, Mid Sweden University.
    Photosynthesis in relation to D1, PsaA and Rubisco in marine and brackish water ecotypes of  Fucus vesiculosus  and Fucus radicans  (Phaeophyceae).2013In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 700, no 1, p. 109-119Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate photosynthetic differences between the marine, Norwegian Sea ecotype and the brackish, Bothnian Sea ecotype of F. vesiculosus and F. radicans and to see whether photosynthetic differences could be connected with the relative amounts of D1 protein (PSII), PsaA (PSI) protein and/or Rubisco. For this purpose, we tested if a higher photosynthetic maximum (P max) in the Atlantic Ocean ecotype of F. vesiculosus relative to the Baltic Sea ecotype, and an increase of the P max in Baltic Sea ecotype of F. vesiculosus at higher salinity, could be due to an increase in the relative amounts of Rubisco. The proteins have been evaluated on a relative basis. Immunoblot signals showed that the amount of Rubisco was higher in both ecotypes of F. vesiculosus than in F. radicans, but no differences could be detected between the two ecotypes of F. vesiculosus. The results suggest an uneven photosystem protein stoichiometry in Fucus, with more of the PSI protein PsaA relative to the PSII protein D1. The difference in P max between the two ecotypes of F. vesiculosus might be related to the difficulties for the algae to adapt to the environment in Bothnian Sea.

  • 44.
    Hansen, Joakim P.
    et al.
    Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre.
    Snickars, Martin
    Applying macrophyte community indicators to assess anthropogenic pressures on shallow soft bottoms2014In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 738, no 1, p. 171-189Article in journal (Refereed)
    Abstract [en]

    Vegetated soft bottoms are under pressure due to a number of anthropogenic stressors, such as coastal exploitation and eutrophication. The ecological value of these biotopes has gained recognition through international conventions and the EU directives, which request methods for assessment of the environmental status of coastal areas. However, currently there is no appropriate method for assessing the status of shallow vegetated soft bottoms in the northern Baltic Sea. Therefore, we developed a macrophyte community index and tested its response in relation to important pressures (eutrophication and boating activity) and natural gradients (topographic openness, depth and salinity) on shallow bays in the northern Baltic Sea. The macrophyte index, and hence the proportion of sensitive to tolerant species, decreased with increasing phosphorus concentration, turbidity and level of boating activity, while the cumulative cover of macrophytes only showed a negative trend in response to increasing turbidity. Juvenile fish abundance was positively related to the index, indicating importance of sensitive macrophyte species for ecosystem functioning. As the index was tested in a wide geographic area, and showed a uniform response across natural gradients, it is a promising tool for assessment of environmental status that may be applied also in other vegetated soft-bottom areas.

  • 45.
    Hansson, Lars-Anders
    et al.
    Institute of Ecology, Lund University, Ecology Building, Lund, Sweden.
    Nicolle, Alice
    Institute of Ecology, Lund University, Ecology Building, Lund, Sweden.
    Bronmark, Christer
    Institute of Ecology, Lund University, Ecology Building, Lund, Sweden.
    Hargeby, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Lindstrom, Ake
    Institute of Ecology, Lund University, Ecology Building, Lund, Sweden.
    Andersson, Gunnar
    Institute of Ecology, Lund University, Ecology Building, Lund, Sweden.
    Waterfowl, macrophytes, and the clear water state of shallow lakes2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 646, no 1, p. 101-109Article in journal (Refereed)
    Abstract [en]

    The importance of lake ecosystems for waterfowl remains a topic of debate. In order to assess how temporal variations in lake features, specifically shifts between alternative stable states, may interact with the waterfowl fauna, we performed a long-term (22 years) study of the shallow Lake Krankesjon, southern Sweden. Lower total numbers of waterfowl occurred during periods with low macrophyte cover and turbid water, than when submersed macrophytes flourished and the water was clear. Some specific functional groups of waterfowl, such as herbivores, invertebrate, and fish feeders, showed a positive relation to clear water and high macrophyte cover. Hence, our data suggest that some migratory waterfowl may select lakes based on water quality, thereby adjusting their large-scale migratory routes. On the other hand, omnivorous waterfowl exhibited their highest abundances during turbid conditions. Furthermore, waterfowl not primarily relying on food from the lake showed no response to fluctuations in turbidity or macrophyte cover, but followed regional trends in population dynamics. In our study lake, L. Krankesjon, we estimated that waterfowl remove less than 3% of the macrophyte biomass during a stable clear-water state with lush macrophyte beds. However, during transition periods between alternative stable states, when macrophyte biomass is lower and the plants already stressed, the consumption rate of waterfowl may have a stronger effect on lake ecosystem functioning.

  • 46. Hauptmann, Demian
    et al.
    Myrstener, Maria
    Spatial and temporal patterns of stream nutrient limitation in an Arctic catchment2023In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 850, no 7, p. 1699-1713Article in journal (Refereed)
    Abstract [en]

    Arctic stream biofilm responses to ongoing climate-related changes in physical and chemical conditions have major implications for stream food webs and biogeochemical cycles. Yet, such effects have rarely been studied outside summer months or at sub-catchment scales in the Arctic. We used deployments of nutrient diffusing substrates (NDS) to assess the spatial (20 deployments) and seasonal patterns (10 deployments) and physical and chemical drivers of nutrient limitation within an Arctic stream catchment. Results show that nutrient limitation of autotrophic processes was common during summer, but that light inhibited biomass accrual under the ice in winter. Alongside single N, P and C responses, co-limitation dominated the overall pattern of limitation over time and across the catchment. However, the primary limiting nutrient to autotrophs changed from N to P in parts of the catchment with higher N concentrations. As Arctic studies are often conducted at individual sites during summer, these may miss shifts in the drivers of stream productivity that arise from variable nutrient, temperature, and light regimes. Our results caution against focusing on one single most important limiting nutrient, as we found that this can shift seasonally and over small spatial scales in this Arctic catchment.

  • 47.
    Hauptmann, Demian
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Climate Impact Research Centre, Umeå University, Umeå, Sweden.
    Myrstener, Maria
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Climate Impact Research Centre, Umeå University, Umeå, Sweden; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Spatial and temporal patterns of stream nutrient limitation in an Arctic catchment2023In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 850, no 7, p. 1699-1713Article in journal (Refereed)
    Abstract [en]

    Arctic stream biofilm responses to ongoing climate-related changes in physical and chemical conditions have major implications for stream food webs and biogeochemical cycles. Yet, such effects have rarely been studied outside summer months or at sub-catchment scales in the Arctic. We used deployments of nutrient diffusing substrates (NDS) to assess the spatial (20 deployments) and seasonal patterns (10 deployments) and physical and chemical drivers of nutrient limitation within an Arctic stream catchment. Results show that nutrient limitation of autotrophic processes was common during summer, but that light inhibited biomass accrual under the ice in winter. Alongside single N, P and C responses, co-limitation dominated the overall pattern of limitation over time and across the catchment. However, the primary limiting nutrient to autotrophs changed from N to P in parts of the catchment with higher N concentrations. As Arctic studies are often conducted at individual sites during summer, these may miss shifts in the drivers of stream productivity that arise from variable nutrient, temperature, and light regimes. Our results caution against focusing on one single most important limiting nutrient, as we found that this can shift seasonally and over small spatial scales in this Arctic catchment.

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  • 48. Hilt, Sabine
    et al.
    Wanke, Thomas
    Scharnweber, Kristin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Brauns, Mario
    Syväranta, Jari
    Brothers, Soren
    Gaedke, Ursula
    Köhler, Jan
    Lischke, Betty
    Mehner, Thomas
    Contrasting response of two shallow eutrophic cold temperate lakes to a partial winterkill of fish2015In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 749, no 1, p. 31-42Article in journal (Refereed)
    Abstract [en]

    Food-web effects of winterkill are difficult to predict as the enhanced mortality of planktivorous fish may be counterbalanced by an even higher mortality of piscivores. We hypothesised that a winterkill in a clear and a turbid shallow lake would equalise their fish community composition, but seasonal plankton successions would differ between lakes. After a partial winterkill, we observed a reduction of fish biomass by 16 and 43% in a clear-water and a turbid small temperate lake, respectively. Fish biomass and piscivore shares (5% of fish biomass) were similar in both lakes after this winterkill, but young-of-the-year (YOY) abundances were higher in the turbid lake. Top-down control by crustaceans was only partly responsible for low phytoplankton biomass at the end of May following the winterkill in both lakes. Summer phytoplankton biomass remained low in the clear-water lake despite high abundances of YOY fish (mainly roach). In contrast, the crustacean biomass of the turbid lake was reduced in summer by a high YOY abundance (sunbleak and roach), leading to a strong increase in phytoplankton biomass. The YOY abundance of fish in shallow eutrophic lakes may thus be more important for their summer phytoplankton development after winterkill than the relative abundance of piscivores.

  • 49. Hooge, Matthew
    et al.
    Wallberg, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Todt, Christiane
    Maloy, Aaron
    Jondelius, Ulf
    Tyler, Seth
    A revision of the systematics of panther worms (Hofstenia spp., Acoela), with notes on color variation and genetic variation within the genus2007In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 592, p. 439-454Article in journal (Refereed)
    Abstract [en]

    Species of the genus Hofstenia are voracious predators and among the largest and most colorful of the Acoela. They are known from Japan, the Red Sea, the North Atlantic islands of Bermuda and the Bahamas, and the Caribbean and in a variety of habitats including the rocky intertidal, among Thalassia sea grass, on filamentous algae and decaying mangrove leaves. Certain color morphs associated with each of these habitats seem to have confused the taxonomy of the group. While brown-and-white banding and spotting patterns of Hofstenia miamia and Hofstenia giselae are distinctive for species associated with mangrove leaves and Thallasia sp. and are likely to be cryptic for these specific environments, we find some evidence to suggest that the coloration is mimicry of a nudibranch with aposematic coloration. The common plan in these patterns is one with three variously solid or spotted lighter cross bands on a dark background. Our examination of museum type material and live specimens of Hofstenia collected from Bahamas, Belize, Bermuda, and Panama revealed no internal morphological differences between the Hofstenia species occurring in the Caribbean. Similarly, our analyses of 18S and 28S molecular sequence data revealed no significant differences among specimens. Accordingly, we declare that Hofstenia giselae is a junior synonym of Hofstenia miamia, the three- banded panther worm.

  • 50. Härlin, Mikael
    Tree-thinking and nemertean systematics, with a systematization of the Eureptantia1998In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 365, no 1-3, p. 33-46Article in journal (Refereed)
    Abstract [en]

    I review how some influential nemertean systematistshave perceived and illustrated phylogenetic trees andargue that the nineteenth century nemerteantaxonomists still influence many contemporarynemertean taxonomists to a high degree. By showing hownineteenth century systematics differs from moremodern views on trees, I hope to convey the advantagesof a cladistic approach to tree-thinking and nemerteansystematics. Furthermore I propose a systematizationof the Eureptantia that illustrates the cladisticapproach to tree-thinking but, more importantly, isalso a better representation of eureptantic phylogenythan previous classifications.

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