| 1. |
- Arendt, Kristine Engel, et al.
(författare)
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Differences in plankton community structure along the Godthåbsfjord, from the Greenland Ice sheet to offshore waters
- 2010
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Ingår i: Marine Ecology Progress Series. - 0171-8630. ; 401, s. 49-62
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Tidskriftsartikel (refereegranskat)abstract
- This study describes differences in plankton community structure and in chemical and physical gradients between the offshore West Greenland Current system and inland regions close to the Greenland Ice Sheet during the post-bloom in Godthåbsfjorden (64° N, 51° W). The offshore region had pronounced vertical mixing, with centric diatoms and Phaeocystis spp. dominating the phytoplankton, chlorophyll (chl) a (0.3 to 3.9 μg l–1) was evenly distributed and nutrients were depleted in the upper 50 m. Ciliates and heterotrophic dinoflagellates constituted equal parts of the protozooplankton biomass. Copepod biomass was dominated by Calanus spp. Primary production, copepod production and the vertical flux were high offshore. The water column was stratified in the fjord, causing chl a to be concentrated in a thin sub-surface layer. Nutrients were depleted above the pycnocline, and Thalassiosira spp. dominated the phytoplankton assemblage close to the ice sheet. Dinoflagellates dominated the protozooplankton biomass, whereas copepod biomass was low and was dominated by Pseudocalanus spp. and Metridia longa. Primary production was low in the outer part of the fjord but considerably higher in the inner parts of the fjord. Copepod production was exceeded by protozooplankton production in the fjord. The results of both physical/chemical factors and biological parameters suggest separation of offshore and fjord systems.
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| 2. |
- Friis Møller, Eva, et al.
(författare)
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Production and fate of copepod fecal pellets acrossthe Southern Indian Ocean
- 2011
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Ingår i: Marine Biology. - : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 158:3, s. 677-688
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Tidskriftsartikel (refereegranskat)abstract
- The vertical distribution of copepods, fecal pellets and the fecal pellet production of copepods were measured at seven stations across the Southern Indian Ocean from productive areas off South Africa to oligotrophic waters off Northern Australia during October/November 2006. We quantified export of copepod fecal pellet from surface waters and how much was retained. Furthermore, the potential impact of Oncaea spp. and harpacticoid copepods on fecal pellets degradation was evaluated and found to be regional substantial. The highest copepod abundance and fecal pellet production was found in the western nutrient-rich stations close to South Africa and the lowest at the central oligotrophic stations. The in situ copepod fecal pellet production varied between 1 and 1,000 mu g C m(-3) day(-1). At all stations, the retention of fecal pellets in the upper 400 m of the water column was more than 99% and the vertical export of fecal pellets was low (< 0.02 mg m(-2) day(-1)).
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| 3. |
- Jonasdottir, Sigrun Huld, et al.
(författare)
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Biological oceanography across the Southern Indian Ocean - basin scale trends in the zooplankton community
- 2013
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Ingår i: Deep Sea Research Part I. - : Elsevier BV. - 0967-0637 .- 1879-0119. ; 75, s. 16-27
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Tidskriftsartikel (refereegranskat)abstract
- We present a study on the protozooplankton > 5 mu m and copepods larger than 50 mu m at a series of contrasting stations across the Southern Indian Ocean (SIO). Numerically, over 80% of the copepod community across the transect was less than 650 mu m in size, dominated by nauplii, and smaller copepods, while 80% of the biomass (as mg C m(-3)) was larger than 1300 mu m in body length. Predation by the carnivorous copepod Corycaeus sp. was estimated to be able to remove up to 2% d(-1) of the copepods < 1000 mu m in size. By the help of grazing models we estimated that primary producers were mainly grazed upon by ciliates and heterotrophic dinoflagellates (40-80% d(-1) combined) in temperate waters but appendicularians became increasingly important in the tropical waters grazing about 40% of the biomass per day. Despite their high abundance and biomass, copepods contributed less than 20% of the grazing at most stations. Secondary production was low (carbon specific egg production < 0.14 d(-1)) but typical for food limited oligotrophic oceans.
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| 4. |
- Møller, Eva Friis, et al.
(författare)
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The effect of changes in temperature and food on the development of calanus finmarchicus and Calanus helgolandicus populations
- 2012
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590. ; 57, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- We studied the response in development times of Calanus finmarchicus and Calanus helgolandicus to changes in temperature and food conditions. Grazing experiments were performed at different temperatures for both species, and the results were implemented in a stage-resolved zooplankton population model that predicted development times from biomass increments controlled by ingestion and metabolic losses. Predictions were validated against development data from the literature, and show that C. finmarchicus develops faster than C. helgolandicus below 11 °C and slower above. The different relative development rates of the species are related to different temperature responses in ingestion rates. A temperature increase of 1 °C to 2 °C may have consequences for the relative contribution of C. helgolandicus and C. finmarchicus to the copepod community, and both seasonal and spatial displacements of the Calanus populations can be expected under climate change.
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