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  • 1.
    Bell, Russel T
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Stensdotter, Ulrika
    Pettersson, Kurt
    Istvanovics, Vera
    Pierson, Don C
    Microbial dynamics and phosphorus turnover in Lake Erken1998In: Archiv Fur Hydrobiologie Spec. Issues: Advances in Limnology, Vol. 51, p. 1-20Article in journal (Refereed)
  • 2.
    Blenckner, Thorsten
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Adrian, Rita
    Arvola, Lauri
    Järvinen, Marko
    Nõges, Peeter
    Nõges, Tiina
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    The impact of climate change on lakes in northern Europe2010In: The impact of climate change on European lakes / [ed] D.G. George, Springer , 2010, p. 339-358Chapter in book (Other academic)
  • 3.
    Blenckner, Thorsten
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Malmaeus, Mikael
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Pettersson, Kurt
    Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Norr Malma feldstation.
    Climatic change and the risk of lake eutrophication2006In: Verh. Int. Verein. Limnol., Vol. 29, p. 1837-1841Article in journal (Refereed)
    Abstract [en]

    Climatic variation and change affect the dynamics of nutrients and ecosystem processes.

    The aim is to quantitatively evaluate changes in phosphorus dynamics resulting from a climate warming in lakes. Long-term data and the results of a regional climate model, a physical lake model and a phosphorus model generated for three Swedish lakes with different morphometry and trophic status were analysed. The analysis of the long-term data and the models varied greatly with respect to the variability and the response of the phosphorus dynamics to past and future climate scenarios. The risk of lake eutrophication will be discussed.

  • 4.
    FORSELL, Lena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    PETTERSSON, Kurt
    ON THE SEASONAL MIGRATION OF THE CYANOBACTERIUM GLOEOTRICHIA-ECHINULATA IN LAKE ERKEN, SWEDEN, AND ITS INFLUENCE ON THE PELAGIC POPULATION1995In: MARINE AND FRESHWATER RESEARCH, ISSN 1323-1650, Vol. 46, no 1, p. 287-293Article in journal (Refereed)
    Abstract [en]

    The quantity and distribution of colonies of Gloeotrichia echinulata migrating from the sediments into the water column were studied in Lake Erken by the use of inverted traps. The epilimnetic population and the phosphorus status of the epilimnetic coloni

  • 5.
    Goedkoop, Willem
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Pettersson, Kurt
    Seasonal changes in sediment phosphorus forms in relation to sedimentation and benthic bacterial biomass in Lake Erken. Seasonal changes in sediment phosphorus forms in relation to sedimentation and benthic bacterial biomass in2000In: Hydrobiologia, Vol. 431, no 1, p. 41-50Article in journal (Refereed)
    Abstract [en]

    Surficial sediment and sedimenting material were sampled during spring and summer 1991 in Lake Erken. Sediment was analyzed for redox potential, P concentrations and bacterial biomass. Sedimentation and chlorophyll a concentrations of sedimenting matter w

  • 6.
    Håkanson, Lars
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. LUVA.
    Malmaeus, Mikael
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. LUVA.
    Karlsson, Magnus
    Pettersson, Kurt
    Faculty of Science and Technology, Biology, Department of Ecology and Evolution.
    Stigebrandt, Anders
    Walin, Gösta
    Regeringens miljöexperter ansvariga för Östersjöns kris.: DN-debatt2005Other (Other (popular scientific, debate etc.))
  • 7.
    Istvanovics, Vera
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Pettersson, Kurt
    Phosphorus release in relation to composition and isotopic exchangeability of sediment phosphorus1998In: Archiv fuer Hydrobiologie Spec. Issues: Advances in Limnology, Vol. 51, p. 91-104Article in journal (Refereed)
  • 8.
    KAHLERT, Maria
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    PETTERSSON, Kurt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    The impact of substrate and lake trophy on the biomass and nutrient status of benthic algae.2002In: Hydrobiologia, Vol. 489, p. 161-169Article in journal (Refereed)
  • 9.
    Karlsson-Elfgren, Irene
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology, Limnology.
    Rydin, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Hyenstrand, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Pettersson, Kurt
    Recruitment and pelagic growth of Gloeotrichia echinulata (Chyanophyceae) in Lake Erken2003In: Journal of Phycology, ISSN 0022-3646, E-ISSN 1529-8817, Vol. 39, no 6, p. 1050-1056Article in journal (Refereed)
    Abstract [en]

    Different parameters in the life cycle of the colony forming cyanobacterium Gloeotrichia echinulata (J.E. Smith) Richter was evaluated in Lake Erken, Sweden. Recruitment of colonies from the sediments and pelagic abundance were measured during 2 years. These data were then used in a model to evaluate and estimate parameters of the life cycle. In our study, recruitment alone only contributed to a small part (<5%) of the maximum G. echinulata abundance that occurred during late summer. However, recruitment from shallow sediments forms the important seed for the pelagic population. Together with measured rates of migration from the sediment, variations in either pelagic colony division rate or pelagic residence time could explain variations in the measured abundance of G. echinulata in situ.

  • 10.
    Kisand, Veljo
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Pettersson, Kurt
    Induction of bacterial and algal exoenzymes during summer in Lake Erken1998In: Archiv fuer Hydrobiologie Spec. Issues: Advances in Limnology, Vol. 51, p. 115-121Article in journal (Refereed)
  • 11.
    Moore, Karen
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Pierson, Donald
    Weyhenmeyer, Gesa
    Pettersson, Kurt
    High-frequency monitoring of colored dissolved organic matter (CDOM) fluorescence in the Swedish river HedströmmenManuscript (Other academic)
  • 12.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Blenckner, Thorsten
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Physical and chemical properties determine zebra mussel invasion success in lakes2011In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 669, no 1, p. 227-236Article in journal (Refereed)
    Abstract [en]

    To address the question whether the abundance of an invasive species can be explained by physical and chemical properties of the invaded ecosystems, we gathered density data of invasive zebra mussels and the physical and chemical data of ecosystems they invaded. We assembled published data from 55 European and 13 North American lakes and developed a model for zebra mussel density using a generalized additive model (GAM) approach. Our model revealed that the joint effect of surface area, total phosphorus and calcium concentrations explained 62% of the variation in Dreissena density. Our study indicates that large and less productive North American lakes can support larger local populations of zebra mussels. Our results suggest that the proliferation of an exotic species in an area can partially be explained by physical and chemical properties of the recipient environment.

  • 13.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Blenckner, Thorsten
    Eklöv, Peter
    Pettersson, Kurt
    Why is an invasive species more successful in some areas than others? A comparison of zebra mussel density in North American and European lakesIn: Article in journal (Refereed)
  • 14.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Non-lethal predator effects on the feeding rate and prey selection of the exotic zebra mussel (Dreissena polymorpha)2007In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 116, no 8, p. 1289-1298Article in journal (Refereed)
    Abstract [en]

    Predators may induce changes in prey feeding that indirectly influence both the impact of prey on resource abundances and their interactions with other species in their community. We evaluated whether clearance and excretion (faeces plus pseudofaeces) of phytoplankton by zebra mussels were affected by the presence of predatory cues from roach (Rutilus rutilus) and signal crayfish (Pasifastacus leniusculus). We found that non-lethal effects of predators can alter zebra mussel clearance rate and thus the impact of zebra mussels on phytoplankton. Risk cues released by both predators had similar negative effects on clearance rate of zebra mussels and cascading positive indirect effects on phytoplankton resources. Predation risk had a stronger effect on zebra mussels' clearance rate of cyanobacteria and diatoms than cryptophytes and chrysophytes. The presence of predators did not significantly affect the rate at which zebra mussels expelled and excreted phytoplankton, although there was a tendency for more chlorophyll to be expelled and excreted in the presence of predators. Our results contribute to the growing evidence that predators indirectly affect resource dynamics and food web structure through their non-lethal effects on consumers. Our results suggest that exotic species such as zebra mussels can show behavioural responses to both native (e.g., roach) and exotic (e.g., crayfish) predators.

  • 15.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Stoichiometric constraints do not limit successful invaders: zebra mussels in Swedish lakes2009In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 4, no 4, p. e5345-Article in journal (Refereed)
    Abstract [en]

    Background: Elemental imbalances of carbon (C): nitrogen (N): phosphorus (P) ratios in food resources can constrain the growth of grazers owning to tight coupling between growth rate, RNA allocation and biomass P content in animals. Testing for stoichiometric constraints among invasive species is a novel challenge in invasion ecology to unravel how a successful invader tackles ecological barriers in novel ecosystems.Methodology/Principal Findings: We examined the C:P and N:P ratios and the condition factor of a successful invader in lakes, the zebra mussel (Dreissena polymorpha), collected from two Swedish lakes. Concurrently, we analyzed the elemental composition of the food (seston) and tissue of the mussels in which nutrient composition of food and mussels varied over time. Zebra mussel condition factor was weakly related to the their own tissue N:P and C:P ratios, although the relation with the later ratio was not significant. Smaller mussels had relatively lower tissue N:P ratio and higher condition factor. There was no difference in C:P and N:P ratios between seston and mussels' tissues. Our results indicated that the variation in nutrient stoichiometry of zebra mussels can be explained by food quality and quantity. Conclusions/Significance: Our study suggests that fitness of invasive zebra mussels is not constrained by nutrient stoichiometry which is likely to be important for their proliferation in novel ecosystems. The lack of imbalance in C:P and N:P ratios between seston and mussels along with high tissue C:P ratio of the mussel allow them to tolerate potential P limitation and maintain high growth rate. Moreover, zebra mussels are able to change their tissue C:P and N:P ratios in response to the variation in elemental composition of their food. This can also help them to bypass potential nutrient stoichiometric constraints. Our finding is an important step towards understanding the mechanisms contributing to the success of exotic species from stoichiometric principles.

  • 16.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
    Pettersson, Kurt
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Effect of zebra mussel , an exotic freshwater species, on seston stoichiometry2008In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590Article in journal (Refereed)
  • 17.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Effects of the zebra mussel, an exotic freshwater species, on seston stoichiometry2008In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 53, no 5, p. 1973-1987Article in journal (Refereed)
    Abstract [en]

    We examined the effect of the zebra mussel, Dreissena polymorpha, an exotic species, on seston stoichiometry by conducting laboratory experiments in which we varied nutrient composition of seston and mussels over time. Zebra mussels altered the stoichiometry of seston through removal of particulate organic nutrients and changed the stoichiometry of the dissolved nutrient pool through nutrient excretion. Grazers had stronger effects on carbon : phosphorus (C : P) and nitrogen (N) : P ratios than on the C:N ratio of seston. Elemental residence time in tissue and high mass-specific nutrient excretion by small mussels caused small mussels to be more efficient nutrient recyclers than larger mussels. Zebra mussels reduced P availability through enhancing C: P and N: P molar ratios of seston during the period extending from June to August, when P was limited in the lake, and increased the C:N molar ratio of seston in June, when N was at the minimum level in the lake. C: P and N: P molar ratios for zebra mussel tissue were higher in August and somewhat in September than in all other months. N was retained more efficiently than P in Dreissena tissue. Nutrient mass-specific uptake rate was higher than excretion rate by zebra mussels.

  • 18.
    Naddafi, Rahmat
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Eklöv, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    The effect of seasonal variation in selective feeding by zebra mussels (Dreissena polymorpha) on phytoplankton community composition2007In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 52, no 5, p. 823-842Article in journal (Refereed)
    Abstract [en]

    To investigate the impact of zebra mussels (Dreissena polymorpha) on phytoplankton community composition, temporal variability in selective feeding by the mussels was determined from April to November 2005 in a natural lake using Delayed Fluorescence (DF) excitation spectroscopy. Selective grazing by zebra mussels varied in relation to seasonal phytoplankton dynamics; mussels showed a consistent preference for cryptophytes and avoidance of chlorophytes and cyanobacteria. Diatoms, chrysophytes and dinoflagellates responded differentially to zebra mussel grazing depending on their size. Analysis of excreted products of the zebra mussels revealed that in addition to chlorophytes and cyanobacteria, phytoplankton >50 μm and very small phytoplankton (≤7 μm) were largely expelled in pseudofaeces. The zebra mussel is a selective filter-feeder that alters its feeding behaviour in relation to phytoplankton composition to capture and ingest high quality phytoplankton, especially when phytoplankton occur in preferred size ranges. Flexibility of zebra mussel feeding behaviour and variation in susceptibility among phytoplankton groups to mussel ingestion indicate that invading zebra mussels could alter phytoplankton community composition of lakes and have important ecosystem consequences.

  • 19.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Mechanisms for internal loading of phosphorus in lakes1998In: HYDROBIOLOGIA, ISSN 0018-8158, Vol. 374, p. 21-25Article in journal (Refereed)
    Abstract [en]

    Lake sediments play an important role in the phosphorus metabolism in lakes. The impact depends on the tendencies to retain and to release phosphorus. The internal loading will often determine the eutrophication status of the lake and the time lag for rec

  • 20.
    Pettersson, Kurt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Forsell, Lena
    Hasselrot, Anders T
    Horizontal distribution patterns during a cyanobacterial bloom1995In: WATER SCIENCE AND TECHNOLOGY, ISSN 0273-1223, Vol. 32, no 4, p. 139-142Article in journal (Refereed)
    Abstract [en]

    A hierarchical sampling was performed in order to give a picture of the horizontal distribution of cyanobacterial colonies. It showed how the importance of different scales in distance changed during the summer bloom of Gloeotrichia echinulata in the mode

  • 21.
    Pettersson, Kurt
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Limnologi.
    Hyenstrand, Per
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Limnologi.
    Early spring development of phytoplankton in Lake Erken, Sweden, as monitored by delayed fluorescence2005In: Verh. Internat. Verein. Limnol, Vol. 29, p. 377-381Article in journal (Refereed)
    Abstract [en]

    A new technique, delayed fluoresence, developed within the EC-project ”Phytoplankton on line”, was used to follow the phytoplankton succession under the ice and through the ice-breakup in Lake Erken, Sweden. The monitoring was done automatically with high frequency measurements. A complementary weekly monitoring of chlorophyll a, phytoplankton composition and nutrient concentrations was performed and used to interprete the results.

    An interesting diurnal pattern of delayed fluorescence was shown under the ice and getting stronger as the light conditions improved through the melting of the snow and ice cover. Peaks in fluorescence occured in early morning and in late afternoon-evening.

  • 22. Pierson, D. C.
    et al.
    Weyhenmeyer, Gesa A.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Arvola, L.
    Benson, B.
    Blenckner, Thorsten
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Kratz, T.
    Livingstone, D. M.
    Markensten, H.
    Marzec, G.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Weathers, K.
    An automated method to monitor lake ice phenology2011In: Limnology and Oceanography: Methods, ISSN 1541-5856, E-ISSN 1541-5856, Vol. 9, p. 74-83Article in journal (Refereed)
    Abstract [en]

    A simple method to automatically measure the date of ice-on, the date of ice-off, and the duration of lake ice cover is described. The presence of ice cover is detected by recording water temperature just below the ice/water interface and just above the lake bottom using moored temperature sensors. The occurrence of ice-on rapidly leads to detectible levels of inverse stratification, defined as existing when the upper sensor records a temperature at least 0.1 degrees C below that of the bottom sensor, whereas the occurrence of ice-off leads to the return of isothermal mixing. Based on data from 10 lakes over a total of 43 winter seasons, we found that the timing and duration of inverse stratification monitored by recording temperature sensors compares well with ice cover statistics based on human observation. The root mean square difference between the observer-based and temperature-based estimates was 7.1 d for ice-on, 6.4 d for ice-off, and 10.0 d for the duration of ice cover. The coefficient of determination between the two types of estimates was 0.93, 0.86, and 0.91, respectively. The availability of inexpensive self-contained temperature loggers should allow expanded monitoring of ice cover in a large and diverse array of lakes. Such monitoring is needed to improve our ability to monitor the progression of global climate change, and to improve our understanding of the relationship between climate and ice cover over a wide range of temporal and spatial scales.

  • 23.
    Rengefors, Karin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Anderson, Donald M
    Pettersson, Kurt
    Phosphorus uptake by resting cysts of the marine dinoflagellate Scrippsiella trochoidea1996In: JOURNAL OF PLANKTON RESEARCH, ISSN 0142-7873, Vol. 18, no 9, p. 1753-1765Article in journal (Refereed)
    Abstract [en]

    Resting cysts of the marine dinoflagellate Scrippsiella trochoidea were produced under phosphorus (P)-deficient conditions, separated from vegatative cells, and incubated for 28 days in darkness at 4 and 20 degrees C in P-enriched and P-deplete medium. Th

  • 24.
    Rengefors, Karin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Pettersson, Kurt
    Blenckner, Thorsten
    Anderson, Donald M
    Species-specific alkaline phosphatase activity in freshwater spring phytoplankton: Application of a novel method2001In: Journal of plankton research, ISSN 0142-7873, Vol. 23, no 4, p. 435-443Article in journal (Refereed)
    Abstract [en]

    For the first time, in situ alkaline phosphatase activity (APA) was studied at the species level in a natural spring community of freshwater phytoplankton. This was achieved by utilizing a substrate called enzyme labeled fluorescence (ELF), which forms fl

  • 25.
    Rodrigo, Maria A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Pierson, Don C
    Pettersson, Kurt
    Kaup, Enn
    Padisák, Judit
    Sinking and floatingrates of of natural phytoplankton assemblages in Lake Erken.1998In: Archiv fur Hydrobiologie Spec. Issues: Advances in Limnology, Vol. 51, p. 143-156Article in journal (Refereed)
  • 26. Schroeder, Fabian
    et al.
    Traunspurger, Walter
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Peters, Lars
    Temporal changes in periphytic meiofauna in lakes of different trophic states2012In: Journal of limnology, ISSN 1129-5767, E-ISSN 1723-8633, Vol. 71, no 1, p. 216-227Article in journal (Refereed)
    Abstract [en]

    Meiofaunal organisms in the periphyton of stony hard-substrates (epilithon) were studied in three Swedish lakes with different trophic states (oligo-, meso- and eutrophic) with respect to seasonal successions in abundance, biomass, and production. Over a period of 2 years, the meiofaunal population of all three lakes fluctuated greatly, with densities varying up to nine-fold within a season. In the oligotrophic lake, a significant decrease in meiofauna in winter was striking, whereas in the other two lakes, richer in nutrients, there was a pronounced peak in early summer Although the lakes, on average, did not differ in epilithic organic and inorganic material, the differences in meiofaunal abundance, biomass, and production were significant. Correlation analysis revealed that altogether the meiofaunal biomass was positively related to the lakes trophic state (total phosphorus), while the meiofaunal abundance and production along the trophic spectrum displayed a humped-shape distribution, with maximum values measured in the mesotrophic Lake Erken (1324 ind cm(-2) and 2249 mu g DW cm(-2) y(-1)). Nematodes were the dominant meiofaunal group in the epilithon of all three lakes, accounting for up to 58% in abundance, 33% in biomass and 55% in production of the whole meiofaunal community. However their relative importance tended to decrease with increasing trophic state. Beside nematodes, rotifers, oligochaetes, copepods and tardigrades were also found in large numbers in the epilithon. Overall, the results demonstrated that, due to their high abundance, biomass, and production, meiofaunal organisms play an important role in epilithic communities.

  • 27.
    Weyhenmeyer, Gesa A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Blenckner, Thosten
    Pettersson, Kurt
    Changes of the plankton spring outburst related to the North Atlantic Oscillation1999In: LIMNOLOGY AND OCEANOGRAPHY, ISSN 0024-3590, Vol. 44, no 7, p. 1788-1792Article in journal (Refereed)
    Abstract [en]

    Changes in the timing, composition, and intensity of freshwater phytoplankton blooms are known to have an impact on water quality and aquatic ecosystem functions. Factors provoking these changes are, therefore, of major importance. In Lake Erken in southe

  • 28.
    Weyhenmeyer, Gesa A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolutionary Biology.
    Pettersson, Kurt
    Padisak, Judit
    Quantitative relationships between planktonic biomass and organic/inorganic resuspended particle matter.1998In: Arch. Hydrobiol. Spec. Issues Advanc. Limnol., Vol. 51, p. 201-212Article in journal (Refereed)
  • 29.
    Yang, Yang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Colom-Montero, William
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pierson, Don
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Water column stability and summer phytoplankton dynamics in a temperate lake (Lake Erken, Sweden)2016In: INLAND WATERS, ISSN 2044-2041, E-ISSN 2044-205X, Vol. 6, no 4, p. 499-508Article in journal (Refereed)
    Abstract [en]

    Phytoplankton development in aquatic ecosystems is caused by interactions among multiple environmental factors. Physical processes, particularly development of thermal stratification, have been proposed to be important factors for regulating phytoplankton composition and abundance during summer. This study examined the temporal pattern of thermal stratification during summer in Lake Erken, Sweden, based on 21 years of historical data spanning 23 years and investigated the role played by water stability on phytoplankton development. Water column stability indexes were calculated from high frequency measurements during periods of summer thermal stratification. Clustering and ordination analyzed the dissimilarities between communities during different periods and extracted the significant environmental gradients controlling phytoplankton succession. Wind introduced the major external disturbance to Lake Erken during summer and played an important role for the progression of thermocline depth. Species-specific thermal stability preference or tolerance determined the response of individual species to the stratification and constitutes a mechanism of species selection in phytoplankton dynamics. Lake Erken is an unstably stratified lake during summer, caused by wind-induced turbulence and internal seiches. Adaptation to these unstable conditions is the major determinant of phytoplankton dynamics. Hydrodynamic variability, characterized by different stability indexes in early, mid, and late summer, was the key factor regulating phytoplankton dynamics, directly by changing phytoplankton distribution and indirectly by altering both the light and nutrient availability in the epilimnion.

  • 30.
    Yang, Yang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Pettersson, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics.
    Padisák, Judit
    Repetitive baselines of phytoplankton succession in an unstably stratified temperate lake (Lake Erken, Sweden): a long-term analysis2016In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 764, no 1, p. 211-227Article in journal (Refereed)
    Abstract [en]

    The seasonal development of phytoplankton is a sequence of consecutive events with waxes and wanes of biomass and compositional shifts. This study analyzed 16 years data in Lake Erken, Sweden and revealed four baselines of phytoplankton succession with their underlying drivers. Results showed that there were two diatom-dominated phases annually. The vernal community was dominated by centric diatoms larger than 15 A mu m (functional groups B and C) which were fast-growing diatoms being highly efficient in the use of nutrients. The autumn community was comprised mainly meroplanktonic mixing-dependent Aulacoseira granulata and Fragilaria sp. (MP and P) or/and large centric diatoms (B). Between the two mixing-phases with diatoms, a Gloeotrichia echinulata (H 2) bloom occurred due to its preference for a stratified water column with elevated water temperatures and high light availability. The summer stratification in Lake Erken was weak and short, thus, favoring meroplanktonic diatoms to peak once the lake turned over in early autumn. Lake Erken represents an intermediate case between a highly mixed polymictic lake and a lake with strong summer stratification, where the observed stratification patterns allowed the development of an autumn diatom phase similar, by extent, to the vernal one and mainly dominated by meroplanktonic diatoms.

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