Artikler, rapporter og annet (arktisk og marin biologi)

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Artikler, rapporter og annet (arktisk og marin biologi)

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• Bioaccumulation of phenanthrene and benzo[a]pyrene in Calanus finmarchicus

  Jensen, Louise Kiel; Jæger, Iris; Honkanen, Jani O.; Caroll, JoLynn (Journal article; Tidsskriftartikkel, 2011)

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  Abstract:	With petroleum exploration and development expanding in the Arctic (AMAP, 2007) there is a need to obtain additional information on the ecotoxicology of Arctic organisms. Here we perform 192 hr laboratory exposure experiments on the keystone Arctic zooplankton species, Calanus finmarchicus. We trace the accumulation and depuration of two polycyclic aromatic hydrocarbons (PAHs): phenanthrene and benzo[a]pyrene (B[a]P) using 14C labeled PAH compounds. Copepods were not fed during the experiment, limiting uptake to diffusion processes alone. The lighter PAH compound, phenanthrene, accumulated rapidly in C. finmarchicus, reaching steady state within 96 h. The heavier PAH compound, B[a]P, accumulated more slowly and steady state was not reached within the 192 h exposure period. As expected, the bioconcentration factor (BCF) for B[a]P was higher than for phenanthrene in accordance with a higher octanol/water partition coefficient for B[a]P (log Kow = 6.04) compared to phenanthrene (log Kow = 4.53). However, for both compounds, log BCF was lower than log Kow that may indicate active biotransformation and excretion of the selected PAH compounds. These findings on the bio-uptake kinetics for petroleum hydrocarbons are essential for evaluating the potential consequences of an oil spill in the Arctic.
  Description:	This is the submitted manuscript version of the paper. This paper is part of Louise Kiel Jensen's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3794
  URI:	http://hdl.handle.net/10037/3802

  File(s) in this item: 1

  article.pdf   (161.7Kb)
• Seasonal microbial processes in a high-latitude fjord (Kongsfjorden, Svalbard) : I. Heterotrophic bacteria, picoplankton and nanoflagellates

  Iversen, Kriss Wenche Rokkan; Seuthe, Lena (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)

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  Abstract:	Temporal dynamics of the microbial food web in the Barents Sea and adjacent water masses in the European Arctic are to a large extent unknown. Seasonal variation in stocks and production rates of heterotrophic bacteria and phototrophic and heterotrophic picoplankton and nanoflagellates was investigated in the upper 50 m of the highlatitude Kongsfjorden, Svalbard, during six field campaigns between March and December 2006. Heterotrophic bacteria, picoplankton and nanoflagellates contributed to ecosystem structure and function in all seasons. Activity within the microbial food web peaked during spring bloom in April, parallel to low abundances of mesozooplankton. In the nutrient-limited post-bloom scenario, an efficient microbial loop, fuelled by dissolved organic carbon from abundant mesozooplankton feeding on phytoplankton and protozooplankton, facilitated maximum integrated primary production rates. A tight microbial food web consisting of heterotrophic bacteria and phototrophic and heterotrophic picoplankton and nanoflagellates was found in the stratified water masses encountered in July and September. Microbial stocks and rates were low but persistent under winter conditions. Seasonal comparisons of microbial biomass and production revealed that structure and function of the microbial food web were fundamentally different during the spring bloom when compared with other seasons. While the microbial food web was in a regenerative mode most of the time, during the spring bloom, a microbial transfer mode represented a trophic link for organic carbon in time and space. The microbial food web’s ability to fill different functional roles in periods dominated by new and regenerated production may enhance the ecological flexibility of pelagic ecosystems in the present era of climate change.
  Description:	This article is part of Lena Seuthe's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3777
  URI:	http://hdl.handle.net/10037/3779

  File(s) in this item: 1

  article.pdf   (1.196Mb)
• Microbial processes in a high-latitude fjord (Kongsfjorden, Svalbard) : II. Ciliates and dinoflagellates

  Seuthe, Lena; Iversen, Kriss Wenche Rokkan (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)

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  Abstract:	The composition and ecological role of ciliates and dinoflagellates were investigated at one station in Kongsfjorden, Svalbard, during six consecutive field campaigns between March and December 2006. Total ciliate and dinoflagellate abundance mirrored the seasonal progression of phytoplankton, peaking with 5.8 9 104 cells l-1 in April at an average chlorophyll a concentration of 10 lg l-1. Dinoflagellates were more abundant than ciliates, dominated by small athecates. Among ciliates, aloricate oligotrichs dominated the assemblage. A large fraction ([60%) of ciliates and dinoflagellates contained chloroplasts in spring and summer. The biomass of the purely heterotrophic fraction of the ciliate and dinoflagellate community (protozooplankton) was with 14 lg C l-1 highest in conjunction with the phytoplankton spring bloom in April. Growth experiments revealed similar specific growth rates for heterotrophic ciliates and dinoflagellates (\0–0.8 d-1). Food availability may have controlled the protozooplankton assemblage in winter, while copepods may have exerted a strong control during the post-bloom period. Calculations of the potential grazing rates of the protozooplankton indicated its ability to control or heavily impact the phytoplankton stocks at most times. The results show that ciliates and dinoflagellates were an important component of the pelagic food web in Kongsfjorden and need to be taken into account when discussing the fate of phytoplankton and biogeochemical cycling in Arctic marine ecosystems.
  Description:	This paper is part of Lena Seuthe's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3777
  URI:	http://hdl.handle.net/10037/3778

  File(s) in this item: 1

  article.pdf   (991.8Kb)
• Early marine migration of European silver eel(Anguilla anguilla) in Northern Norway

  Davidsen, Jan Grimsrud; Rikardsen, Audun H.; Finstad, B; Økland, Finn; Thorstad, E.B.; Mo, TA (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)

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  Description:	This is the accepted manuscript version of the article. Published article available at http://dx.doi.org/10.1111/j.1095-8649.2011.02943.x
  URI:	http://hdl.handle.net/10037/3641

  File(s) in this item: 1

  article.pdf   (470.6Kb)
• Host range, symbiotic effectiveness and nodulation competitiveness of some indigenous cowpea bradyrhizobia isolates from the transitional savanna zone of Ghana

  Ampomah, Osei Yaw; Ofori-Ayeh, E; Solheim, Bjørn; Svenning, Mette M (Journal article; Tidsskriftartikkel; Peer reviewed, 2008)

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  URI:	http://hdl.handle.net/10037/3302

  File(s) in this item: 1

  article.pdf   (954.1Kb)

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