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  • 1.
    Ask, Jenny
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Reinikainen, Marko
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Variation in hatching success and egg production of Eurytemora affinis (Calanoida, Copepoda). from the Gulf of Bothnia, Baltic Sea, in relation to abundance and clonal differences of diatoms2006In: Journal of Plankton Research, Vol. 28, no 7, p. 683-694Article in journal (Refereed)
  • 2.
    Berglund, Johnny
    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).
    Müren, Umut
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Båmstedt, Ulf
    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).
    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).
    Efficiency of a phytoplankton-based and a bacterial-based food web in a pelagic marine system2007In: Limnology and Oceanography, Vol. 52, no 1, p. 121-131Article in journal (Refereed)
    Abstract [en]

    he food web efficiency in two contrasting food webs, one phytoplankton based and one bacteria based, was studied in a mesocosm experiment using seawater from the northern Baltic Sea. Organisms included in the experiment were bacteria, phytoplankton, protozoa, and mesozooplankton (copepods). A phytoplankton-based food web was generated by incubating at a high light level with the addition of nitrogen and phosphorus (NP). A bacteria-based food web was created by adding carbon, nitrogen, and phosphorus (CNP) and incubating at a lower light level. In the CNP treatment bacteria dominated the productivity (91%), while in the NP treatment phytoplankton were dominant producers (74%). The phytoplankton community in the NP treatment was dominated by autotrophic nanoflagellates. The food web efficiency, defined as mesozooplankton productivity per basal productivity (phytoplankton + bacteria), was 22% in the phytoplankton-based food web and 2% in the bacteria-based food web. This discrepancy could be explained by 1�xtra trophic levels in the bacteria-based food web where carbon passed through flagellates and ciliates before reaching mesozooplankton, while in the phytoplankton-based food web there was a direct pathway from phytoplankton to mesozooplankton. The results were supported by stable isotope analysis of mesozooplankton. We propose that climate change, with increased precipitation and river runoff in the Baltic Sea, might favor a bacteria-based food web and thereby reduce pelagic productivity at higher trophic levels.

  • 3.
    Båmstedt, U
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Fyhn, H J
    Martinussen, M B
    Mjaavatten, O
    Grahl-Nielsen, O
    Seasonal distribution, diversity and biochemical composition of appendicularians in Norwegian fjords2005In: Response of marine ecosystem to global change: Ecological impact of appendicularians, Contemporary , 2005, p. 227-254Chapter in book (Refereed)
  • 4.
    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.

  • 5.
    Båmstedt, Ulf
    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).
    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).
    Wikner, Johan
    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).
    Blomqvist, Sven
    Konsekvenser för Östersjöns biologi av förändrat klimat under 21:a århundradet2007Report (Other academic)
  • 6.
    Båmstedt, Ulf
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Brugel, Sonia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    A cost-precision model for marine environmental monitoring, based on time-integrated averages2017In: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 189, no 7, article id 354Article in journal (Refereed)
    Abstract [en]

    Ongoing marine monitoring programs are seldom designed to detect changes in the environment between different years, mainly due to the high number of samples required for a sufficient statistical precision. We here show that pooling over time (time integration) of seasonal measurements provides an efficient method of reducing variability, thereby improving the precision and power in detecting inter-annual differences. Such data from weekly environmental sensor profiles at 21 stations in the northern Bothnian Sea was used in a cost-precision spatio-temporal allocation model. Time-integrated averages for six different variables over 6 months from a rather heterogeneous area showed low variability between stations (coefficient of variation, CV, range of 0.6-12.4%) compared to variability between stations in a single day (CV range 2.4-88.6%), or variability over time for a single station (CV range 0.4-110.7%). Reduced sampling frequency from weekly to approximately monthly sampling did not change the results markedly, whereas lower frequency differed more from results with weekly sampling. With monthly sampling, high precision and power of estimates could therefore be achieved with a low number of stations. With input of cost factors like ship time, labor, and analyses, the model can predict the cost for a given required precision in the time-integrated average of each variable by optimizing sampling allocation. A following power analysis can provide information on minimum sample size to detect differences between years with a required power. Alternatively, the model can predict the precision of annual means for the included variables when the program has a pre-defined budget. Use of time-integrated results from sampling stations with different areal coverage and environmental heterogeneity can thus be an efficient strategy to detect environmental differences between single years, as well as a long-term temporal trend. Use of the presented allocation model will then help to minimize the cost and effort of a monitoring program.

  • 7.
    Båmstedt, Ulf
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Larsson, Henrik
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    An indoor pelagic mesocosm facility to simulate multiple water-column characteristics2018In: International Aquatic Research, ISSN 2008-4935, E-ISSN 2008-6970, Vol. 10, no 1, p. 13-29Article in journal (Refereed)
    Abstract [en]

    Mesocosms are important research tools in aquatic ecology because they close the gap between laboratory studies at the individual or lower organization level and field studies at the population and ecosystem level. However, most mesocosm studies regarding the pelagic environment do not consider the effects of physical factors like water-column stratification, turbulence and mixing. Neglecting such factors might bias the results compared to the natural system. Using a unique indoor mesocosm facility, we present results on how different water-column stratifications can be made and how they act as barriers for exchange between water layers. Turbulent mixing, simulated by vertically rotating incubation vessels, is shown to be of high importance for primary production, generating up to nine times higher production in humus-rich water than incubation vessels at fixed depths. Convective stirring is shown to be an attractive method for generating different turbulence conditions, and different temperature settings can be used to get turnover times from 84 h or more down to 17 min for a 5-m water parcel. We also demonstrate how an anoxic bottom layer can be achieved by stimulating heterotrophic bacteria through addition of bioavailable organic carbon.

  • 8.
    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.

  • 9.
    Båmstedt, Ulf
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Wikner, Johan
    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).
    Mixing depth and allochthonous dissolved organic carbon: controlling factors of coastal trophic balance2016In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 561, p. 17-29Article in journal (Refereed)
    Abstract [en]

    ABSTRACT: The interacting effects of different mixing depths and increased allochthonous dissolved organic carbon (DOC) on the ratio of heterotrophic to autotrophic production (i.e. trophic balance) was evaluated in a mesocosm study with a stratified water column. An autumn plankton community from the northern Bothnian Sea showed significantly decreased phytoplankton production and somewhat increased bacterial production with added DOC. In addition, increased mixing depth further reduced phytoplankton production. With a deep pycnocline and added DOC, the system became net-heterotrophic, with an average bacteria-to-phytoplankton production ratio of 1.24. With a deep pycnocline without added DOC, the trophic balance was changed to 0.44 (i.e. autotrophic). With a shallow pycnocline, the system remained net-autotrophic irrespective of DOC addition. We propose that increased precipitation in northern Europe due to climate change may result in changed density stratification and increased allochthonous DOC transport to the sea, leading to more heterotrophic coastal aquatic ecosystems. Such a scenario may entail reduced biological production at higher trophic levels and enhanced CO2 emission to the atmosphere.

  • 10. Calbet, Albert
    et al.
    Sazhin, Andrey F.
    Nejstgaard, Jens C.
    Berger, Stella A.
    Tait, Zachary S.
    Olmos, Lorena
    Sousoni, Despoina
    Isari, Stamatina
    Martinez, Rodrigo A.
    Bouquet, Jean-Marie
    Thompson, Eric M.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jakobsen, Hans H.
    Future Climate Scenarios for a Coastal Productive Planktonic Food Web Resulting in Microplankton Phenology Changes and Decreased Trophic Transfer Efficiency2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 4, p. e94388-Article in journal (Refereed)
    Abstract [en]

    We studied the effects of future climate change scenarios on plankton communities of a Norwegian fjord using a mesocosm approach. After the spring bloom, natural plankton were enclosed and treated in duplicates with inorganic nutrients elevated to pre-bloom conditions (N, P, Si; eutrophication), lowering of 0.4 pH units (acidification), and rising 3 degrees C temperature (warming). All nutrient-amended treatments resulted in phytoplankton blooms dominated by chain-forming diatoms, and reached 13-16 mu g chlorophyll (chl) a l(-1). In the control mesocosms, chl a remained below 1 mu g l(-1). Acidification and warming had contrasting effects on the phenology and bloom-dynamics of autotrophic and heterotrophic microplankton. Bacillariophyceae, prymnesiophyceae, cryptophyta, and Protoperidinium spp. peaked earlier at higher temperature and lower pH. Chlorophyta showed lower peak abundances with acidification, but higher peak abundances with increased temperature. The peak magnitude of autotrophic dinophyceae and ciliates was, on the other hand, lowered with combined warming and acidification. Over time, the plankton communities shifted from autotrophic phytoplankton blooms to a more heterotrophic system in all mesocosms, especially in the control unaltered mesocosms. The development of mass balance and proportion of heterotrophic/autotrophic biomass predict a shift towards a more autotrophic community and less-efficient food web transfer when temperature, nutrients and acidification are combined in a future climate-change scenario. We suggest that this result may be related to a lower food quality for microzooplankton under acidification and warming scenarios and to an increase of catabolic processes compared to anabolic ones at higher temperatures.

  • 11.
    Dahlgren, Kristin
    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).
    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).
    Larsson, Ulf
    Department of Systems Ecology, Stockholm University, 10691 Stockholm, Sweden.
    Hajdu, Susanna
    Department of Systems Ecology, Stockholm University, 10691 Stockholm, Sweden.
    Båmstedt, Ulf
    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).
    Planktonic production and carbon transfer efficiency along a north-south gradient in the Baltic sea2010In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 409, p. 77-94Article in journal (Refereed)
    Abstract [en]

    A 1 yr study was conducted along a brackish-water production gradient to enhance the understanding of factors governing pelagic food web function. This was achieved by measuring carbon transfer efficiency (TE) from the basal resource to an intermediate trophic level. TE was defined as mesozooplankton carbon consumption rate divided by production at the basal trophic level, which is composed of phytoplankton and bacteria. A north–south transect in the Baltic Sea was used as a model system, with 2 stations each in the Bothnian Bay, Bothnian Sea and Baltic Proper being sampled 5 to 8× during 2006. In addition, data from monitoring programmes were used, which comprised 10 to 22 samplings stn–1. TE was expected to be governed by the size distribution of phytoplankton and due to the nutrient gradient, we expected to find an optimal cell size, and thus also a high TE, in the intermediate-productive Bothnian Sea. The basal production during summer/autumn increased 5-fold from north to south, while the mesozooplankton carbon consumption rate exhibited a peak inthe Bothnian Sea, being ~3× higher than in both Bothnian Bay and Baltic Proper. TE was found to be intermediate in the Bothnian Bay (average: 0.8), highest in the Bothnian Sea (1.6), and lowest in the Baltic Proper (0.2). We suggest that the variation in carbon transfer efficiency can be explained by the composition of the phytoplankton community, the abundance balance between copepods and cladocerans, as well as the species composition of mesozooplankton in relation to the size structure of phytoplankton.

  • 12.
    Dahlgren, Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Olsen, Bernt Rydland
    Troedsson, Christofer
    Båmstedt, Ulf
    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).
    Seasonal variation in wax ester concentration and gut content in a Baltic Sea copepod [Limnocalanus macrurus (Sars 1863)]2012In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 34, no 4, p. 286-297Article in journal (Refereed)
    Abstract [en]

    Limnocalanus macrurus from Bothnian Bay in the northern part of the Baltic Sea was studied during the ice-free period (AprilDecember) in order to understand its life history and feeding biology. Our data on the population dynamics indicated that reproduction occurred during the ice-covered period, during which lipid storage was reduced to a minimum. From spring to late summer, the lipid reserve increased by a factor of 3, while the gonads of adult females were immature during this period, continuing to December as indicated by the small size of the eggs. Average stomach fullness was always ca. 50 indicating continuous feeding activity. A newly developed denaturing high-performance liquid chromatography method was used to analyse the gut contents over the study period. More than 30 taxa (at different taxonomic levels) could be identified. However, phytoplankton was only represented by one taxon (Diatomophycea), and was restricted to July. Thus, adult L. macrurus seems to have a strongly carnivorous feeding preference in the northern Baltic Sea.

  • 13.
    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).

  • 14. Dinasquet, J.
    et al.
    Titelman, J.
    Moller, L. F.
    Setala, O.
    Granhag, L.
    Andersen, T.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Haraldsson, M.
    Hosia, A.
    Katajisto, T.
    Kragh, T.
    Kuparinen, J.
    Schroter, M. -L
    Sondergaard, M.
    Tiselius, P.
    Riemann, L.
    Cascading effects of the ctenophore Mnemiopsis leidyi on the planktonic food web in a nutrient-limited estuarine system2012In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 460, p. 49-61Article in journal (Refereed)
    Abstract [en]

    Increasing biomasses of gelatinous zooplankton presumably have major implications for the structure and function of marine food webs at large; however, current data on lower trophic levels are scarce, as most studies have focused on the immediate effects on zooplankton and fish larvae only. We examined the short-term impact of larvae and adults of the invasive ctenophore Mnemiopsis leidyi on a summer planktonic food web in the estuarine southern Baltic Sea, with special emphasis on the microbial loop. Grazing by M. leidyi reduced the mesozooplankton biomass, followed by increased dinoflagellate biomass in treatments with M. leidyi. While chlorophyll a increased most in the treatments with M. leidyi, small phytoplankton and ciliates decreased in all treatments. M. leidyi had a slight effect on bacterial abundance, but not on bacterial production, ectoenzymatic activities, or community composition. Undetectable levels of phosphate and a gradual accumulation of dissolved organic carbon during the experiment suggested a malfunctioning microbial loop scenario. The experiment shows that direct and indirect short-term effects of M. leidyi on the estuarine food web are limited to higher trophic levels and indicates that top-down and bottom-up consequences of M. leidyi expansions on the microbial loop will likely depend on local nutrient conditions.

  • 15. Grubisic, Lorena M.
    et al.
    Brutemark, Andreas
    Weyhenmeyer, Gesa A.
    Wikner, Johan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Bertilsson, Stefan
    Effects of stratification depth and dissolved organic matter on brackish bacterioplankton communities2012In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 453, p. 37-48Article in journal (Refereed)
    Abstract [en]

    Bacterioplankton growth is often directly or indirectly controlled by external energy subsidies via organic matter inputs or solar radiation. We carried out a mesocosm experiment to assess how bacterioplankton communities responded to elevated levels of dissolved organic matter (DOM) and experimentally controlled stratification depth. The month-long experiment consisted of 2500 l mesocosms subjected to 4 experimental manipulations in triplicate: the stratification depth was set to either 1.5 or 3.5 m, with or without experimental addition of ambient levels of chromophoric DOM. DOM addition had a significant effect on bacterial community composition as assessed by terminal restriction fragment length polymorphism of amplified 16S rRNA genes. In contrast, there were no effects of the DOM amendment on bacterial biomass or production. Mixing depth and the coupled effective light climate in the photic zone also had a significant effect on bacterial community composition. Furthermore, shallow mixing depth was associated with enhanced primary production, whereas DOM addition had a negative effect on phyto plankton biomass and productivity. Our results suggest that bacterial community composition is coupled to primary production under the studied coastal nutrient regime, and point to a key role of DOM quality in controlling bacterioplankton communities.

  • 16. Haraldsson, Matilda
    et al.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Tiselius, Peter
    Titelman, Josefin
    Aksnes, Dag L.
    Evidence of Diel Vertical Migration in Mnemiopsis leidyi2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 1, p. e86595-Article in journal (Refereed)
    Abstract [en]

    The vertical distribution and migration of plankton organisms may have a large impact on their horizontal dispersal and distribution, and consequently on trophic interactions. In this study we used video-net profiling to describe the fine scale vertical distribution of Mnemiopsis leidyi in the Kattegat and Baltic Proper. Potential diel vertical migration was also investigated by frequent filming during a 24-hour cycle at two contrasting locations with respect to salinity stratification. The video profiles revealed a pronounced diel vertical migration at one of the locations. However, only the small and medium size classes migrated, on average 0.85 m h(-1), corresponding to a total migration distance of 10 m during 12 h. Larger individuals (with well developed lobes, approx. >27 mm) stay on average in the same depth interval at all times. Biophysical data suggest that migrating individuals likely responded to light, and avoided irradiance levels higher than approx. 10 mu mol quanta m(-2) s(-1). We suggest that strong stratification caused by low surface salinity seemed to prohibit vertical migration.

  • 17. Hosia, A.
    et al.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Seasonal abundance and vertical distribution of siphonophores in western Norwegian fjords2008In: Journal of Plankton Research, Vol. 30, no 8, p. 951-962Article in journal (Refereed)
    Abstract [en]

    Seasonal abundance of siphonophores in Korsfjord and Fanafjord was studied by net sampling. Nanomia cara, Lensia conoidea and Dimophyes arctica were dominant species present throughout the year. Abundance of N. cara colonies peaked in late May and early June. Low numbers of relatively large colonies and high numbers of siphonulae were observed during winter. Dimophyes arctica and L. conoidea had a generation shift in March, when large over-wintering and small young polygastric colonies co-existed briefly before the former disappeared. Abundances were lowest during winter, and eudoxids were consistently more numerous than polygastric colonies for both species. Maximum abundances of polygastric D. arctica and L. conoidea occurred in early May and late June, respectively. Lensia conoidea may have more than one annual generation in Korsfjord. Vertical distributions of siphonophores were studied with an remotely operated vehicle in nine fjords. The distributions of agalmatid physonects, probably mostly N. cara, differed significantly between the fjords, with the weighted mean depths of the distributions ranging from 99 to 412 m. Results from Sognefjord suggested diel vertical migration. The bulk of the adult colonies in each fjord occurred below sill depth. Siphonophores were not observed at localities known to host persistent populations of Periphylla periphylla.

  • 18. Hosia, A.
    et al.
    Båmstedt, Ulf
    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).
    Seasonal changes in the gelatinous zooplankton community and hydromedusa abundances in Korsfjord and Fanafjord, western Norway2008In: Marine Ecology Progress Series, Vol. 351, p. 113-127Article in journal (Refereed)
    Abstract [en]

    Quantitative seasonal studies on gelatinous zooplankton in Norwegian fjords are scarce. We recorded the quantitative composition of the gelatinous zooplankton community in Korsfjord and Fanafjord during 1 yr. Thirty-six species or genera of hydromedusae, 7 species of siphonophores, 4 species of ctenophores and 2 species of scyphomedusae were recorded. Aglantha digitale was numerically dominant in both fjords. A separate video-profiling study on the vertical distribution of fully grown specimens of this species was made in Korsfjord and the adjacent Bjornafjord. Our data suggest 2 A. digitale generations yr(-1), with relatively low importance of the latter generation. The overwintering strategy includes autumn growth to full size and distribution at intermediate depth, mainly between 200 and 300 m. Siphonophores were prominent in the more oceanic Korsfjord, while Fanafjord was characterized by meroplanktonic hydromedusae. More species were recorded from Korsfjord, which may be partly attributed to the larger volume sampled and the higher probability of encountering oceanic visitors in this fjord. Korsfjord also harbored a community of deep-water hydromedusae absent from Fanafjord. The gelatinous community of both fjords was most numerous and species-rich from April to June. Spring maximum densities were higher in Fanafjord. During winter, gelatinous zooplankton was more abundant in Korsfjord, with eudoxids of Dimophyes arctica and Lensia conoidea forming the bulk of the community. Hydromedusa species appeared sequentially and differed in terms of maximum abundance attained and length of their presence in the plankton. Multivariate analyses revealed a clear seasonal succession for the gelatinous community of both fjords.

  • 19. Jacoby, Charles A.
    et al.
    Youngbluth, Marsh J.
    Frost, Jessica R.
    Flood, Per R.
    Uiblein, Franz
    Bamstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Pages, Francesc
    Shale, David
    Vertical distribution, behavior, chemical composition and metabolism of Stauroteuthis syrtensis (Octopoda: Cirrata) in the northwest Atlantic2009In: Aquatic Biology, ISSN 1864-7782, E-ISSN 1864-7790, Vol. 5, no 1, p. 13-22Article in journal (Refereed)
    Abstract [en]

    The cirrate octopod Stauroteuthis syrtensis is a mesopelagic species commonly collected in the North Atlantic. Individuals were observed at depths > 600 m and typically within 100 m of the bottom in three similar to 900 m deep canyons indenting the southern edge of Georges Bank. When first sighted, most octopods were floating passively with their webbed arms gathered into a small ball. When disturbed, they expanded their webs to form a 'balloon' shape, swam slowly by Sculling their fins, pulsed their webs like medusae and, in some cases, streamlined their arms and webs and moved away smoothly by rapidly sculling their fins. The bodies of 9 octopods comprised 92 to 95 % water, with tissue containing 9 to 22 % carbon (C) and 2 to 4 % nitrogen (N). These values were similar to those reported for medusae and ctenophores. Oxygen (O(2)) consumption rates of 4.6 to 25.8 mu mol 02 g(-1) C h(-1) were within ranges reported for medusae, ctenophores, and deep-water cephalopods. The stomachs of S. syrtensis, dissected immediately after capture, contained only the calanoid copepod Calan us finmarchicus. Calculations indicated that S. syrtensis need 1.3 to 30.1 ind. d(-1) of C. finmarchicus to meet their measured metabolic demand. Excretion rates (0.3 to 12.4 mu g NH(4)(+) g(-1) C h(-1) and 0.06 to 4.83 mu g PO(4)(3-) g(-1) C h(-1)) were at least an order of magnitude lower than rates reported for other octopods or gelatinous zooplankters. O:N ratios (11 to 366) suggested that S. syrtensis catabolized lipids, which may be supplied by C. finmarchicus. Vertical distribution, relatively torpid behavior and low metabolic rates characterized S. syrtensis as a benthopelagic and relatively passive predator on copepods.

  • 20. Klevjer, Thor A.
    et al.
    Kaartvedt, Stein
    Bamstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    In situ behaviour and acoustic properties of the deep living jellyfish Periphylla periphylla2009In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 31, no 8, p. 793-803Article in journal (Refereed)
    Abstract [en]

    The importance of jellyfish in marine systems is increasingly being recognized, and in some ecosystems, jellyfish may now be considered the top predator. We studied the behaviour of individuals of the deep-water schypozoan Periphylla periphylla in one such location, the Lurefjord, Norway. The study was performed using a combination of submersible acoustics (38 kHz), video and net methods, and the focus was on variation in behaviour and vertical distribution in relation to the diel cycle. A proportion of the population underwent synchronous vertical migrations, but P. periphylla were still recorded throughout the water column both day and night. The majority of individuals were swimming (vertically) at speeds < 2 cm s(-1) irrespective of the time of day. However, occasional vertical swimming events with speeds exceeding 10 cm s(-1) were recorded. Such events of elevated vertical speeds were of short duration, followed by subsequent periods of no vertical movements. Different size fractions appeared to have different patterns of vertical swimming activity, with smaller jellyfish swimming more continuously than the larger Periphylla. The echo strengths of the individual returns (target strength, TS) peaked at approximately -62 dB, and variability in TS for individuals was high, with the strongest echoes seen in deep water. The results show the feasibility of acoustic methods for studying the in situ behaviour and acoustic properties of these jellyfish, but also that acoustically weak jellyfish are only recorded close to the transducer or the acoustic axis, which will bias acoustic data on vertical size distribution and acoustic abundance estimates.

  • 21.
    Lefebure, Robert
    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).
    Degerman, Rickard
    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).
    Andersson, Agneta
    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).
    Eriksson, Lars-Ove
    Department of Wildlife, Fish and Environmental Studies, SLU, Umeå, Sweden.
    Båmstedt, Ulf
    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.
    Impacts of elevated terrestrial nutrient loads and temperature on pelagic food-web efficiency and fish production2013In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 19, no 5, p. 1358-1372Article in journal (Other academic)
    Abstract [en]

    Both temperature and terrestrial organic matter have strong impacts on aquatic food-web dynamics and production. Temperature affects vital rates of all organisms, and terrestrial organic matter can act both as an energy source for lower trophic levels, while simultaneously reducing light availability for autotrophic production. As climate change predictions for the Baltic Sea and elsewhere suggest increases in both terrestrial matter runoff and increases in temperature, we studied the effects on pelagic food-web dynamics and food-web efficiency in a plausible future scenario with respect to these abiotic variables in a large-scale mesocosm experiment. Total basal (phytoplankton plus bacterial) production was slightly reduced when only increasing temperatures, but was otherwise similar across all other treatments. Separate increases in nutrient loads and temperature decreased the ratio of autotrophic:heterotrophic production, but the combined treatment of elevated temperature and terrestrial nutrient loads increased both fish production and food-web efficiency. CDOM: Chl a ratios strongly indicated that terrestrial and not autotrophic carbon was the main energy source in these food webs and our results also showed that zooplankton biomass was positively correlated with increased bacterial production. Concomitantly, biomass of the dominant calanoid copepod Acartia sp. increased as an effect of increased temperature. As the combined effects of increased temperature and terrestrial organic nutrient loads were required to increase zooplankton abundance and fish production, conclusions about effects of climate change on food-web dynamics and fish production must be based on realistic combinations of several abiotic factors. Moreover, our results question established notions on the net inefficiency of heterotrophic carbon transfer to the top of the food web.

  • 22. Lopez-Urrutia, A
    et al.
    Harris, R P
    Acuña, J L
    Båmstedt, U
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Flood, P R
    Fyhn, H J
    Gasser, B
    Gorsky, G
    Irigoien, X
    Martinussen, M
    A comparison of appendicularian seasonal cycles in four contrasting European coastal environments2005In: Response of marine ecosystem to global change: Ecological impact of appendicularians, Contemporary Publishing International, Paris , 2005, p. 255-276Chapter in book (Refereed)
  • 23.
    Md Amin, Roswati
    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).
    Båmstedt, Ulf
    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).
    Nejstgaard, Jens C
    Skidaway Institute of Oceanography, USA.
    Di Capua, Iole
    Ecology and Evolution of Plankton, Stazione Zoologica, Italy.
    Partition of planktonic respiratory carbon requirements during a phytoplankton spring bloom2012In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 451, p. 15-29Article in journal (Refereed)
    Abstract [en]

    We studied the effect of variable phytoplankton biomass and dominance of the diatom Skeletonema marinoi on the planktonic community respiratory carbon requirement over a period of 14 days (14-28 April, 2008) in 3 different mesocosms filled with natural water at Espegrend marine biological field station by Raunefjord, Norway. The carbon requirement was measured on mesozooplankton (the calanoid copepod Calanus finmarchicus) and three different size fraction; <200 µm (dominated by microzooplankton), <15 µm (dominated by nanoplankton including most of the phytoplankton) and particles passing GF/C (dominated by bacterioplankton) by measuring oxygen consumption with an optode system with two SensorDish Readers. The respiratory carbon requirement showed no clear trend over time for any of the four groups. The mesozooplankton contributed the least to the total community carbon requirement, corresponding to less than 6% of primary production. In contrast, microzooplankton and nanoplankton consistently dominated the community carbon requirement, corresponding to > 50% of the primary production, while bacterioplankton showed an intermediate and variable contribution (ca <20% with a max of 50%). Feeding experiments on mesozooplankton (C. finmarchicus) two days before the peak in phytoplankton biomass, showed that the copepods ingested 2.4-4.3 times their respiratory carbon requirements, thus giving a high potential for growth. Respiratory carbon requirements of mesozooplankton were not significantly related to dominance or quantity of food available, whereas the respiratory carbon requirements of other groups were all related to the production of 22:6(n-3) fatty acid. The study confirms the important role of microorganisms in the biological carbon transformation through the food web during a phytoplankton spring bloom.

  • 24.
    Md Amin, Roswati
    et al.
    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.
    Koski, Marja
    National Institute of Aquatic Resources, Technical University of Denmark, Charlettenlund, Denmark.
    Bamstedt, 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.
    Vidoudez, Charles
    Departement of organismic and evolutionary biology, Harvard University, Cambridge, USA.
    Strain-related physiological and behavioral effects of Skeletonema marinoi on three common planktonic copepods2011In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 158, no 9, p. 1965-1980Article in journal (Refereed)
    Abstract [en]

    Three strains of the chain-forming diatom Skeletonema marinoi, differing in their production of polyunsaturated aldehydes (PUA) and nutritional food components, were used in experiments on feeding, egg production, hatching success, pellet production, and behavior of three common planktonic copepods: Acartia tonsa, Pseudocalanus elongatus, and Temora longicornis. The three different diatom strains (9B, 1G, and 7J) induced widely different effects on Acartia tonsa physiology, and the 9B strain induced different effects for the three copepods. In contrast, different strains induced no or small alterations in the distribution, swimming behavior, and turning frequency of the copepods. 22:6(n-3) fatty acid (DHA) and sterol content of the diet typically showed a positive effect on either egg production (A. tonsa) or hatching success (P. elongatus), while other measured compounds (PUA, other long-chain polyunsaturated fatty acids) of the algae had no obvious effects. Our results demonstrate that differences between strains of a given diatom species can generate effects on copepod physiology, which are as large as those induced by different algae species or groups. This emphasizes the need to identify the specific characteristics of local diatoms together with the interacting effects of different mineral, biochemical, and toxic compounds and their potential implications on different copepod species.

  • 25.
    Nydahl, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Tengberg, Anders
    Lundberg, Erik
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Wikner, Johan
    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).
    Precise microbial respiration rate in coastal waters by a contiuous multi-sample sensorManuscript (preprint) (Other academic)
  • 26. Olsen, Bernt Rydland
    et al.
    Dahlgren, Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Schander, Christoffer
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Rapp, Hans Tore
    Troedsson, Christofer
    PCR-DHPLC assay for the identification of predator-prey interactions2012In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 34, no 4, p. 277-285Article in journal (Refereed)
    Abstract [en]

    Denaturing high-performance liquid chromatography (DHPLC) is a relatively new method for separating amplicons in a mixture, and was recently developed for parasite detection in the blue crab Callinectes sapidus. That assay used a peptide nucleic acid (PNA) PCR hybridization blocking probe (PNAPCRDHPLC) to decrease the generic PCR bias of dominant templates (the host) in the mixture prior to separation on the DHPLC column, thus enhancing the less abundant parasite DNA. The same assay and rational can be used to investigate predatorprey interactions. However, in ecosystem studies with many predatorprey relationships, development of specific PNA-blocking probes for each predator would be too laborious. Here, we have developed a PCRDHPLC assay excluding the dominant predator amplicons in a first DHPLC run, followed by re-amplification of the non-predator retention volumes and further separation and characterization in a second DHPLC run. This assay generated data on the specific trophic interactions between the calanoid copepod Limnocalanus macrurus and its prey from a seasonal sampling programme. The assay provides an efficient way for an unbiased screening of predatorprey relationships, and although developed for L. macrurus in this study, the approach has wide applicability for any predatorprey interaction.

  • 27. Paffenhöfer, G A
    et al.
    Ianora, A
    Miralto, A
    Turner, J T
    Kleppel, G S
    d'Alcala, M R
    Casotti, R
    Caldwell, G S
    Pohnert, G
    Fontana, A
    Muller-Navarra, D
    Jonasdottir, S
    Armbrust, V
    Båmstedt, U
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Ban, S
    Bentley, M G
    Boersma, M
    Bundy, M
    Buttino, I
    Calbet, A
    Carlotti, F
    Carotenuto, Y
    d'Ippolito, G
    Frost, B
    Guisande, C
    Lampert, W
    Lee, R F
    Mazza, S
    Mazzocchi, M G
    Nejstgaard, J C
    Poulet, S A
    Romano, G
    Smetacek, V
    Uye, S
    Wakeham, S
    Watson, S
    Wichard, T
    Colloquium on diatom-copepod interactions2005In: Mar. Ecol. Progr. Ser., Vol. 286, p. 293-305Article in journal (Refereed)
  • 28. Paul, Carsten
    et al.
    Reunamo, Anna
    Lindehoff, Elin
    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.
    Bergkvist, Johanna
    Mausz, Michaela A.
    Larsson, Henrik
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Richter, Hannes
    Wangberg, Sten-Ake
    Leskinen, Piia
    Bamstedt, 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.
    Pohnert, Georg
    Diatom Derived Polyunsaturated Aldehydes Do Not Structure the Planktonic Microbial Community in a Mesocosm Study2012In: Marine Drugs, ISSN 1660-3397, E-ISSN 1660-3397, Vol. 10, no 4, p. 775-792Article in journal (Refereed)
    Abstract [en]

    Several marine and freshwater diatoms produce polyunsaturated aldehydes (PUA) in wound-activated processes. These metabolites are also released by intact diatom cells during algal blooms. Due to their activity in laboratory experiments, PUA are considered as potential mediators of diatom-bacteria interactions. Here, we tested the hypothesis that PUA mediate such processes in a close-to-field mesocosm experiment. Natural plankton communities enriched with Skeletonema marinoi strains that differ in their PUA production, a plankton control, and a plankton control supplemented with PUA at natural and elevated concentrations were observed. We monitored bacterial and viral abundance as well as bacterial community composition and did not observe any influence of PUA on these parameters even at elevated concentrations. We rather detected an alternation of the bacterial diversity over time and differences between the two S. marinoi strains, indicating unique dynamic bacterial communities in these algal blooms. These results suggest that factors other than PUA are of significance for interactions between diatoms and bacteria.

  • 29. Riemann, L
    et al.
    Titelman, J
    Båhmstedt, U
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Links between jellyfish and microbes in a jellyfish dominated fjord?2006In: Mar. Ecol. Progr. Ser, Vol. 325, p. 29-42Article in journal (Refereed)
  • 30. Sjoqvist, C.
    et al.
    Kremp, A.
    Lindehoff, Elin
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF). Department of Biology and Environmental Science, Centre for Ecology and Evolution in Microbial model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Egardt, J.
    Gross, S.
    Jönsson, M.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Larsson, Henrik
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Pohnert, G.
    Richter, H.
    Selander, E.
    Godhe, A.
    Effects of Grazer Presence on Genetic Structure of a Phenotypically Diverse Diatom Population2014In: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 67, no 1, p. 83-95Article in journal (Refereed)
    Abstract [en]

    Studies of predator-prey systems in both aquatic and terrestrial environments have shown that grazers structure the intraspecific diversity of prey species, given that the prey populations are phenotypically variable. Populations of phytoplankton have traditionally considered comprising only low intraspecific variation, hence selective grazing as a potentially structuring factor of both genetic and phenotypic diversity has not been comprehensively studied. In this study, we compared strain specific growth rates, production of polyunsaturated aldehydes, and chain length of the marine diatom Skeletonema marinoi in both grazer and non-grazer conditions by conducting monoclonal experiments. Additionally, a mesocosm experiment was performed with multiclonal experimental S. marinoi populations exposed to grazers at different levels of copepod concentration to test effects of grazer presence on diatom diversity in close to natural conditions. Our results show that distinct genotypes of a geographically restricted population exhibit variable phenotypic traits relevant to grazing interactions such as chain length and growth rates. Grazer presence affected clonal richness and evenness of multiclonal Skeletonema populations in the mesocosms, likely in conjunction with intrinsic interactions among the diatom strains. Only the production of polyunsaturated aldehydes was not affected by grazer presence. Our findings suggest that grazing can be an important factor structuring diatom population diversity in the sea and emphasize the importance of considering clonal differences when characterizing species and their role in nature.

  • 31. Sornes, T.A.
    et al.
    Hosia, A.
    Båmstedt, Ulf
    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).
    Aksnes, D.L.
    Swimming and feeding in Periphylla periphylla (Scyphozoa, Coronatae)2008In: Marine Biology, Vol. 153, no 4, p. 653-659Article in journal (Refereed)
    Abstract [en]

    Some western Norwegian fjords host extraordinarily abundant and persistent populations of the mesopelagic, coronate scyphomedusa, Periphylla periphylla. In these environments, from late autumn to spring, the medusae undertake regular diel vertical migrations into surface waters. From unique observations obtained with a remotely operated vehicle (ROV), including observations made without artificial light, we observed that 90% of the medusae swam with their tentacles in aboral position. Stomach content analyses of surface-collected specimens revealed that the medusae ate mainly calanoid copepods, but ostracods and large euphausiids were also prominent components of their diets. The clearance rate potential of P. periphylla, assessed from in situ observations and stomach contents, was comparable to that of similar-sized, epipelagic gelatinous species. Our findings suggest that P. periphylla behave as active predators in surface waters.

  • 32. Sornes, Tom A.
    et al.
    Aksnes, Dag L.
    Bamstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Youngbluth, Marsh J.
    Causes for mass occurrences of the jellyfish Periphylla periphylla: a hypothesis that involves optically conditioned retention2007In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 29, no 2, p. 157-167Article in journal (Refereed)
    Abstract [en]

    The mesopelagic coronate medusa Periphylla periphylla has been very abundant (20-320 individuals m(-2)), with as many as 2.5 individuals m(-3), for more than a decade in certain Norwegian fjords. These abundances are two to three orders of magnitude higher than reported from open ocean environments. Comparisons of the size, density and behavior of this jellyfish in three fjords (Lurefjorden, Sognefjorden and Halsafjorden) support the hypothesis that retention of P. periphylla is related to basin topography, light attenuation and photosensitivity. Furthermore, we hypothesize that the abundances of P. periphylla in Lurefjorden and Halsafjorden, but not in Sognefjorden, have been stimulated by increased light absorbance of water masses formed in the North Sea.

  • 33. Sotje, I.
    et al.
    Tiemann, H.
    Båmstedt, Ulf
    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).
    Trophic ecology and the related functional morphology of the deepwater medusa Periphylla periphylla (Scyphozoa, Coronata)2007In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, ISSN 10.1007/s00227-006-0369-2, Vol. 150, no 3, p. 329-343Article in journal (Refereed)
    Abstract [en]

    Remotely operated vehicle (ROV)-based field studies on the distribution and behaviour of Periphylla periphylla Péron and Lesueur (Ann Mus Hist Nat Marseille 14:316-366, 1809), from three Norwegian fjords have been combined with on-board experiments and morphological and histological studies in order to understand the trophic ecology of this species. Field studies from one of the fjords showed that the zooplankton biomass was negatively related with P. periphylla abundance, indicating a predatory effect. The majority of zooplankton biomass tended to be distributed above the aggregation of P. periphylla, which in turn showed highest abundance at 100-200 m depth. Observation on the orientation of medusae passing the ROV when descending down in the water column at dawn and dusk, showed no consistency with the theory of diel vertical migration. Estimated metabolic demand of P. periphylla indicated a daily predation impact on the prey assemblage of 13% as an average for the fjord. In situ behavioural observations showed that the dominant tentacle posture of large medusae was straight upward, with tentacles extended to the oral-aboral body axis. The hunting mode alternates between ambush and ramming, whereby tentacle posture minimises the water turbulence that may otherwise alarm the prey. The musculature of the tentacles is well developed, with an especially strong longitudinal muscle on the oral side, facilitating fast movement of the tentacle towards the mouth. In addition, ring-, radial-, and diagonal musculatures are also present. The diagonal is probably most important for the corkscrew retraction of the tentacle, used at the moment of prey capture. Results from laboratory experiments show that different body-parts of P. periphylla vary in sensitivity for chemical and mechanical stimuli, including hydrodynamic disturbance and vibration in the surrounding water. Feeding success is facilitated by combining the vibration-sense on the tentacle tips and the marginal lappets, the touch-sense on the tentacle bases and marginal lappets, and a taste control of the captured prey at the mouthlips.

  • 34. Tiemann, Henry
    et al.
    Soetje, Ilka
    Johnston, Blair D.
    Flood, Per R.
    Bamstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Documentation of potential courtship-behaviour in Periphylla periphylla (Cnidaria: Scyphozoa)2009In: Journal of the Marine Biological Association of the United Kingdom, ISSN 0025-3154, E-ISSN 1469-7769, Vol. 89, no 1, p. 63-66Article in journal (Refereed)
    Abstract [en]

    The distribution pattern and nocturnal surface behaviour of the deep-sea medusa Periphylla periphylla in a Norwegian fjord was studied. Medusa abundance, size distribution and condition were determined, using surface collections, net tows and ROV-based video profiles. Only larger, mature medusae reached the surface and aggregated into small groups of both sexes, whereas juvenile medusae remained in deeper waters. Observations on the behaviour and cytology of aggregated medusae suggested a mating strategy. We hypothesize that this behaviour is the by-product of a holopelagic life history, developed in a more oceanic deep environment with low species abundance, as surface aggregation increases the chance of encounter and mating.

  • 35. Titelman, J
    et al.
    Riemann, L
    Sørnes, T
    Griekspoor, P
    Båmstedt, U
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Turnover of dead jellyfish: stimulation and retardation of microbial activity2006In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 325, p. 43-58Article in journal (Refereed)
  • 36.
    Wikner, Johan
    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).
    Panigrahi, Satya
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nydahl, Anna
    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).
    Lundberg, Erik
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Båmstedt, Ulf
    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).
    Tengberg, Anders
    Göteborgs universitet.
    Precise continuous measurements of pelagic respiration in coastal waters with Oxygen Optodes2013In: Limnology and Oceanography: Methods, ISSN 1541-5856, E-ISSN 1541-5856, Vol. 11, p. 1-15Article in journal (Refereed)
    Abstract [en]

    An analytical setup for respiration rate measurements was developed and evaluated in pelagic water samples using a commercially available optical oxygen sensor (Optode (TM)). This setup required the development of a gas tight stopper to connect the sensors to a 1 dm(3) glass sample bottle, precise temperature control (+/- 0.05 degrees C), and proper stirring of samples. The detection limit and precision of the method was 0.3 mmol O-2 m(-3) d(-1). This was similar to the detection limit for the high-precision Winkler titration method reported in field studies. When compared with the Winkler method, the Optode sensor enabled operator-independent, high temporal resolution measurement of respiration, better coverage of plankton groups and detection of non-linear oxygen decline, without the need for wet chemistry. Respiration rates measured by the Optodes showed good accuracy when compared with measurements made with the Winkler titration method (3% deviation), followed the expected temperature response (Q(10) = 3.0), were correlated with chlorophyll a and were congruent with earlier reported values in the literature. The main source of uncertainty was a necessary correction for system drift during the incubation period, due to oxygen release from the plastic components. Additionally, less stringent temperature control on board research vessels during rough seas reduced the precision. We conclude that the developed Optode system can be used to measure respiration in productive coastal waters. Samples from cold or deep waters were, however, often below the detection limit.

  • 37. Winder, Monika
    et al.
    Bouquet, Jean-Marie
    Bermudez, J. Rafael
    Berger, Stella A.
    Hansen, Thomas
    Brandes, Jay
    Sazhin, Andrey F.
    Nejstgaard, Jens C.
    Båmstedt, Ulf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Jakobsen, Hans H.
    Dutz, Joerg
    Frischer, Marc E.
    Troedsson, Christofer
    Thompson, Eric M.
    Increased appendicularian zooplankton alter carbon cycling under warmer more acidified ocean conditions2017In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 62, no 4, p. 1541-1551Article in journal (Refereed)
    Abstract [en]

    Anthropogenic atmospheric loading of CO2 raises concerns about combined effects of increasing ocean temperature and acidification, on biological processes. In particular, the response of appendicularian zooplankton to climate change may have significant ecosystem implications as they can alter biogeochemical cycling compared to classical copepod dominated food webs. However, the response of appendicularians to multiple climate drivers and effect on carbon cycling are still not well understood. Here, we investigated how gelatinous zooplankton (appendicularians) affect carbon cycling of marine food webs under conditions predicted by future climate scenarios. Appendicularians performed well in warmer conditions and benefited from low pH levels, which in turn altered the direction of carbon flow. Increased appendicularians removed particles from the water column that might otherwise nourish copepods by increasing carbon transport to depth from continuous discarding of filtration houses and fecal pellets. This helps to remove CO2 from the atmosphere, and may also have fisheries implications.

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