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  • 1.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Biologisk inventering av havsbottnar kring Örefjärden, Snöan och Bonden: Marinbiologisk inventering och naturvärdesbedömning av planerat marint naturreservat2009Report (Other academic)
  • 2.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Inventering och naturvärdesbedömning av fyra kustnära havsområden i Västerbotten - Tavasten, Ostnäs, Juviken/Lillhavet och Kinnbäcksfjärden2017Report (Other academic)
    Abstract [sv]

    En inventering och naturvärdesbedömning av fyra kustnära havsområden i Västerbottens län har genomförts. Inventeringen fokuserade på undervattensvegetation och består huvudsakligen av en visuell transektinventering genom video och dykning utförd av Umeå marina forskningscentrum 2007-2008. Kunskapsunderlaget har utökats genom att inkludera flera andra undersökningar. Totalt spänner underlaget över tidsperioden 1997-2012.

  • 3.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Miljöövervakning i Gaviksfjärden, Västernorrlands län: sammanställning och resultatanalys2014Report (Other academic)
  • 4.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Trophic interactions involving mysid shrimps (Mysidacea) in the near-bottom habitat in the Baltic Sea2004In: Aquatic Ecology, ISSN 1386-2588, E-ISSN 1573-5125, Vol. 38, no 3, p. 457-469Article in journal (Refereed)
    Abstract [en]

    In a six month mesocosm tank experiment, hypotheses were tested concerning the role of benthopelagic mysid shrimps (Mysidacea) in the near-bottom food web of the Bothnian Sea, in the northern Baltic Sea. The first hypothesis tested was that the mysids interact, through predation, with benthic deposit-feeding Monoporeia affinis amphipods. A second hypothesis tested was that the sediment type is important for the overwintering success of the mysids. Changes in abundance and mass were recorded for M. affinis and mysids when separate and when coexisting, in two sediment types differing in organic content (food level); soft muddy clay (rich) and fine sand (poor). Despite the fact that newborn M. affinis offspring, a plausible target for predation by mysids, were present in substantial numbers in the tanks, no consistent evidence for any interaction between these taxa was found. The biomass of mysids was slightly higher in the muddy clay than in the sand tanks, and the mechanism behind this substrate effect is discussed. A third hypothesis, that the mysids interact with near-bottom zooplankton, was investigated. The tanks were continually supplied with in situ near-bottom sea-water containing a seminatural assemblage of near-bottom plankton. As a result of mysid predation, tanks with mysids had lower abundance and biomass of cyclopoid copepods than tanks without mysids. Thus, the major interaction found was predation on near-bottom zooplankton by mysids and it is suggested that this interaction could potentially be an important food link, especially during periods with low food availability in the pelagic system.

  • 5.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Undervattensvegetation i Holmöarnas naturreservat: Inventeringar och miljöövervakningar genomförda under åren 1997, 2004 och 20072008Report (Other academic)
  • 6.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Uppföljning av naturtypen 1140 blottade ler- och sandbottnar i Bottenviken och Södra Östersjön: En pilotstudie2016Report (Other (popular science, discussion, etc.))
  • 7.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Övervakning av makrovegetation i Bottniska viken: En utvärdering av pågående undersökningar och underlag för vidareutveckling2014Report (Other academic)
  • 8.
    Albertsson, Jan
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Leonardsson, K
    Deposit-feeding amphipods (Monoporeia affinis) reduce the recruitment of copepod nauplii from benthic resting eggs in the northern Baltic Sea2001In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 138, no 4, p. 793-801Article in journal (Refereed)
    Abstract [en]

    We experimentally investigated the effect of different densities of the burrowing, deposit-feeding amphipod Monoporeia affinis on the recruitment of zooplankton from benthic resting eggs. Intact sediment cores with in situ density and species composition of zooplankton resting eggs and benthic fauna were collected in the northern Bothnian Sea, part of the Baltic Sea. We removed as many M, affinis as possible from the cores and then added different numbers of ill. affinis to the cores to generate a range of densities. The cores were exposed to different densities of M. affinis for either 3 or 40 days, after which the hatched zooplankton was registered. One subset of the cores were initially incubated under low temperature (2-3 degreesC, to prevent hatching) for 37 days (the resting phase), to allow for effects of M. affinis on unhatched resting eggs. These cores were then incubated under higher temperature (13 degreesC) for 3 days (the hatching phase), to induce hatching and allow for effects on hatching or hatched specimens. In a second subset of cores with the same time and temperature schedule, the M. affinis density was experimentally reduced at the start of the hatching phase, to evaluate the effect of M. affinis during the hatching phase. To a third subset of cores, we immediately initiated the hatching phase, without an experimental resting phase, to evaluate the effects induced during the resting phase. The most common zooplankton species that hatched was Eurytemora affinis (Copepoda), followed by Bosmina longispina maritima (Cladocera). In all cores that were subjected to a resting phase, the numbers of hatched E. affinis were log-linearly negatively related to density of M. affinis. An increase of M. affinis density from 1,000 to 5,000 individuals m(-2), normal field densities, reduced the hatching by 60-70%. The negative impact was mainly exerted during the hatching phase, suggesting predation on, burial of or physical injury of hatching nauplii or eggs in a late development stage as likely mechanisms. Also, the number of B. longispina maritima that hatched was reduced by M. affinis during the hatching phase, but no clear relation to density of M. affinis could be identified. The results show that M. affinis can reduce recruitment to zooplankton from benthic resting eggs. Such impact by the benthos on resting stages of zooplankton is therefore a potentially significant link between the benthic and pelagic systems.

  • 9.
    Albertsson, Jan
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Leonardsson, K
    Impact of a borrowing deposit-feeder, Monoporeia affinis, on viable zooplankton resting eggs in the northern Baltic Sea2000In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 136, no 4, p. 611-619Article in journal (Refereed)
    Abstract [en]

    We investigated the effect of different densities of the burrowing deposit-feeding amphipod Monoporeia affinis on the potential for recruitment of zooplankton from benthic resting eggs. Hatching of resting eggs was induced in the laboratory on sliced and resuspended 1-cm depth-sections of sediment cores, collected at six stations ill an archipelago area of the Gulf of Bothnia, Baltic Sea. The uppermost 5 cm of the sediment was studied. The most common species that hatched was Eurytemor affinis (Copepoda). Individuals from another copepod genus, Acartia, hatched in significant numbers only in the cores from two stations with low amphipod abundance. Cores from stations with high amphipod densities showed a deeper distribution of emerging E. affinis nauplii compared with stations with few amphipods: the oxidised sediment layer was also deeper at high M. affinis densities than at low. Total (0 to 5 cm strata pooled) number of hatched E. affinis nauplii was independent of amphipod density. This indicates that the effect of M. affinis on E. affinis eggs involves deeper burial due to bioturbation, rather than predation. Decreased benthic recruitment of zooplankton at localities with high M. affinis density is suggested, since more deeply positioned eggs are less likely to hatch. When hatching was induced in intact, non-sliced cores from one station, the number of E. affinis nauplii that hatched was on average 43% of the number that hatched in the upper centimetre of the sliced cores from the same station. This fraction (43%), if applied to the other stations, implied a potential for benthic recruitment of up to 80000 ind m(-2) for E. affinis. Due to its high abundance, M. affinis is likely to greatly reduce benthic recruitment of zooplankton in this system.

  • 10. Aljetlawi, A A
    et al.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Leonardsson, K
    Effect of food and sediment pre-treatment in experiments with a deposit-feeding amphipod, Monoporeia affinis2000In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 249, no 2, p. 263-280Article in journal (Refereed)
    Abstract [en]

    We experimentally investigated the effects of different pre-treatments of the sediment, and the effect of daily addition of fresh phytoplankton, on the growth and survival of 1-year-old (1 +) individuals of the deposit feeder Monoporeia affinis (Amphipoda). We used three different types of sieved sediment: pre-frozen muddy clay, non-pre-frozen muddy clay, and fine sand. The muddy clay contained phytoplankton originating from the surface sediment sampled in the field during the late spring bloom. No phytoplankton was initially present in sand. The experiment lasted for 18 days. M. affinis responded to the daily phytoplankton addition by increasing growth. Phytoplankton addition had no significant effects on the survival of M. affinis. Upon phytoplankton addition, the sandy and non-frozen muddy clay gave similar growth and survival responses. In contrast, the pre-frozen sediment resulted in significantly lower growth and survival. The growth was negative in all treatments without phytoplankton. Thus, the high initial chlorophyll content in the muddy clay was not of sufficient quality or concentration to allow a positive growth response in M. affinis. The growth of M. affinis was significantly correlated with the reduction of the chlorophyll. Our results indicated that M. affinis is capable of assimilating settled phytoplankton with no, or only a few days' time delay. (C) 2000 Elsevier Science BN: All rights reserved.

  • 11. Andersson, Agneta
    et al.
    Samuelsson, Kristina
    Haecky, Pia
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Changes in the pelagic microbial food web due to artificial eutrophication2006In: Aquatic Ecology, ISSN 1386-2588, E-ISSN 1573-5125, Vol. 40, no 3, p. 299-313Article in journal (Refereed)
    Abstract [en]

    The effect of nutrient enrichment on the structure and carbon flow in the pelagic microbial food web was studied in mesocosm experiments using seawater from the northern Baltic Sea. The experiments included food webs of at least four trophic levels; (1) phytoplankton-bacteria, (2) flagellates, (3) ciliates and (4) mesozooplankton. In the enriched treatments high autotrophic growth rates were observed, followed by increased heterotrophic production. The largest growth increase was due to heterotrophic bacteria, indicating that the heterotrophic microbial food web was promoted. This was further supported by increased growth of heterotrophic flagellates and ciliates in the high nutrient treatments. The phytoplankton peak in the middle of the experiments was mainly due to an autotrophic nanoflagellate, Pyramimonas sp. At the end of the experiment, the proportion of heterotrophic organisms was higher in the nutrient enriched than in the nutrient-poor treatment, indicating increased predation control of primary producers. The proportion of potentially mixotrophic plankton, prymnesiophyceans, chrysophyceans and dinophyceans, were significantly higher in the nutrient-poor treatment. Furthermore, the results indicated that the food web efficiency, defined as mesozooplankton production per basal production (primary production + bacterial production - sedimentation), decreased with increasing nutrient status, possibly due to increasing loss processes in the food web. This could be explained by promotion of the heterotrophic microbial food web, causing more trophic levels and respiration steps in the food web.

  • 12. Bergström, Lena
    et al.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Undervattensvegetation i Kronörens naturreservat, Västerbottens län: Inventeringar genomförda under åren 1996, 1997 och 20012003Report (Other academic)
  • 13. Holopainen, Reetta
    et al.
    Lehtiniemi, Maiju
    Meier, H. E. Markus
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Gorokhova, Elena
    Kotta, Jonne
    Viitasalo, Markku
    Impacts of changing climate on the non-indigenous invertebrates in the northern Baltic Sea by end of the twenty-first century2016In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 18, no 10, p. 3015-3032Article in journal (Refereed)
    Abstract [en]

    Biological invasions coupled with climate change drive changes in marine biodiversity. Warming climate and changes in hydrology may either enable or hinder the spread of non-indigenous species (NIS) and little is known about how climate change modifies the richness and impacts of NIS in specific sea areas. We calculated from climate change simulations (RCO-SCOBI model) the changes in summer time conditions which northern Baltic Sea may to go through by the end of the twenty-first century, e.g., 2-5 A degrees C sea surface temperature rise and even up to 1.75 unit decrease in salinity. We reviewed the temperature and salinity tolerances (i.e., physiological tolerances and occurrence ranges in the field) of pelagic and benthic NIS established in-or with dispersal potential to-the northern Baltic Sea, and assessed how climate change will likely affect them. Our findings suggest a future decrease in barnacle larvae and an increase in Ponto-Caspian cladocerans in the pelagic community. In benthos, polychaetes, gastropods and decapods may become less abundant. By contrast, dreissenid bivalves, amphipods and mysids are expected to widen their distribution and increase in abundance in the coastal areas of the northern Baltic Sea. Potential salinity decrease acts as a major driver for NIS biogeography in the northern Baltic Sea, but temperature increase and extended summer season allow higher reproduction success in bivalves, zooplankton, amphipods and mysids. Successful NIS, i.e., coastal crustacean and bivalve species, pose a risk to native biota, as many of them have already demonstrated harmful effects in the Baltic Sea.

  • 14. Laine, A
    et al.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Katajisto, J
    Rissanen, H
    Luokkanen, E
    Kronholm, M
    Integrated management system for the Bothnian Bay2005In: International Association of Theoretical and Applied Limnology, Vol 29, Pt 2, Proceedings, N Ostrobothnia Reg Environm Ctr, Oulu 90101, Finland., 2005, p. 869-872Conference paper (Refereed)
  • 15.
    Moksnes, Per-Olav
    et al.
    Göteborgs universitet.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Elfwing, Tina
    Stockholms universitet.
    Hansen, Joakim
    Stockholms universitet.
    Lindegarth, Mats
    Göteborgs universitet.
    Nilsson, Jonas
    Linnéuniversitetet.
    Rolff, Carl
    Stockholms universitet.
    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).
    Sammanvägd bedömning av miljötillståndet i Havet2013Report (Other academic)
  • 16.
    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).
    Andersson, Agneta
    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.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Hajdu, Susanna
    Höglander, Helena
    Gorokhova, Elena
    Skjevik, Ann-Turi
    Johansen, Marie
    Plankton2010In: Havet: om miljötillståndet i svenska havsområden. 2010 / [ed] Kristina Viklund (huvudredaktör), Ulrika Brenner, Annika Tidlund, Marie Svärd, Stockholm: Naturvårdsverket, 2010, p. 30-30Chapter in book (Other academic)
  • 17.
    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).
    Andersson, Agneta
    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.
    Karlsson, Chatarina
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Hajdu, Susanna
    Stockholms universitet.
    Höglander, Helena
    Stockholms universitet.
    Mattsson, Lisa
    Stockholms universitet.
    Gorokhova, Helena
    Stockholms universitet.
    Skjevik, Ann-Turi
    SMHI.
    Johansen, Marie
    SMHI.
    Pelagial biologi: plankton2011In: Havet 2011: om miljötillståndet i svenska havsområden. 2011 / [ed] Maria Lewander, Malin Karlsson och Karin Lundberg, Stockholm: Naturvårdsverket, Havsmiljöinstitutet och Havs- och vattenmyndigheten , 2011, p. 30-30Chapter in book (Other academic)
  • 18.
    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).
    Karlsson, Chatarina
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Andersson, Agneta
    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.
    Albertsson, Jan
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Hajdu, Susanna
    Stockholms universitet.
    Höglander, Helena
    Stockholms universitet.
    Mattsson, Lisa
    Stockholms universitet.
    Gorokhova, Elena
    Stockholms universitet.
    Skjevik, Ann-Turi
    SMHI.
    Johansen, Marie
    SMHI.
    Pelagial biologi: plankton2012In: Havet 2012: om miljötillståndet i svenska havsområden / [ed] Marie Svärd, Tina Johansen och Maria Lewander, Stockholm / Göteborg: Havsmiljöinstitutet och Havs- och vattenmyndigheten , 2012, p. 46-46Chapter in book (Other academic)
1 - 18 of 18
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