| 1. |
- Dinasquet, Julie, et al.
(författare)
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Cascading effects of the ctenophore Mnemiopsis leidyi on the planktonic food web in a nutrient-limited estuarine system
- 2012
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Ingår i: Marine Ecology Progress Serie. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 460, s. 49-61
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Granhag, Lena, 1974, et al.
(författare)
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First recordings of the ctenophore Euplokamis sp. (Ctenophora, Cydippida) in Swedish coastal waters and molecular identification of this genus
- 2012
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Ingår i: Aquatic Invasions. - : Regional Euro-Asian Biological Invasions Centre Oy (REABIC). - 1818-5487 .- 1798-6540. ; 7:4, s. 455-463
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Tidskriftsartikel (refereegranskat)abstract
- The ctenophore Euplokamis sp. was observed and collected in the Gullmar fjord on the west coast of Sweden in April-August 2011 during regular jellyfish and zooplankton monitoring. In April-May 2011, both larval and adult Euplokamis sp. were collected in the surface water of the fjord and in June-August in the deep part of the fjord at 110-100 m. The typical morphological and behavioral characters of Euplokamis sp. were observed (i.e. coiled tentacle side branches and rapid swimming both in forward and reverse). With no published sequence data from the ctenophore family Euplokamidae, molecular identification using the nuclear 18S rRNA gene and internal transcribed spacer region I region (ITS1) revealed that Euplokamis sp. individuals were closely related to the morphologically similar ctenophore family Mertensiidae. Therefore, morphological and molecular data support the identification as Euplokamis. Euplokamis sp. densities in the deep water of the Gullmar fjord in June 2011 reached similar densities as the local ctenophore Beroe spp. The presence of Euplokamis sp. and other ctenophores in the area is discussed together with the importance of continuous monitoring of gelatinous forms to include detection of less frequent and more fragile ctenophore species. We also discuss the importance of molecular identification for ctenophore larvae and adult ctenophores of small size.
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| 3. |
- Granhag, Lena, 1974, et al.
(författare)
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Size-specific clearance rates of the ctenophore Mnemiopsis leidyi based on in situ gut content analyses
- 2011
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Ingår i: Journal of Plankton Research. - : Oxford University Press (OUP). - 0142-7873 .- 1464-3774. ; 33:7, s. 1043-1052
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Tidskriftsartikel (refereegranskat)abstract
- The ctenophore Mnemiopsis leidyi can consume large amounts of zooplankton prey.However, quantitative measurements of feeding rates, based on field data, arescarce. We measured the time required by the invasive M. leidyi to digest naturallyoccurring prey species in the Gullmar fjord, Sweden. Digestion times were relatedto prey size and type, number of prey in the gut and size of the predator. Largeprey species or many prey in the gut resulted in longer digestion times comparedwith small or few prey, but digestion time also varied with the size of M. leidyi. Theprey- and predator-specific digestion times were used together with in situ preyconcentrations and gut contents of M. leidyi to calculate the clearance rates.Clearance rate as a function of ctenophore size is presented for the most abundantmesozooplankton: Acartia sp., Oithona sp., Oikopleura dioica and Penilia avirostris. Onthe basis of the relation between digestion time and the carbon content ratiobetween prey and predator, we discuss the possible effects of mixed prey assemblageson the estimates of clearance rates.
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| 4. |
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| 5. |
- Møller, Lene Friis
(författare)
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Amerikansk kammanet
- 2010
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Ingår i: Havsutsikt. ; :3
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 6. |
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| 7. |
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| 8. |
- Selander, Erik, 1973, et al.
(författare)
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Parasitic anemone infects the invasive ctenophore Mnemiopsis leidyi in the North East Atlantic
- 2010
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Ingår i: Biological invasions. - : Springer Science and Business Media LLC. - 1387-3547 .- 1573-1464. ; 12:5, s. 1003-1009
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Tidskriftsartikel (refereegranskat)abstract
- We report of the first finding of parasitic sea anemone larvae infecting the invasive ctenophore Mnemiopsis leidyi in the North East Atlantic. Parasitic anemone larvae are common in the native habitat of Mnemiopsis, but have not previously been reported from any of the locations where Mnemiopsis has been introduced. General morphology and 18S rRNA sequences support the identification of the larvae as Edwardsiella sp. Excised anemone larvae were reared through metamorphosis and confirmed the identification of the parasite. Both Mnemiopsis and Edwardsiella larvae were monitored weekly during 2007 and 2008 and parasitic larvae were recorded from September to November both years. The highest density was observed in September 2008 when Edwardsiidae larvae reached 2.3 ind m(-3). In 2008 total density of the parasite occasionally exceeded 40% of the host density and the potential consequences for Mnemiopsis population dynamics are discussed.
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