| 1. |
- Dahlgren, Kristin, et al.
(author)
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Seasonal variation in wax ester concentration and gut content in a Baltic Sea copepod [Limnocalanus macrurus (Sars 1863)]
- 2012
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In: Journal of Plankton Research. - Oxford : Oxford University Press. - 0142-7873 .- 1464-3774. ; 34:4, s. 286-297
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Journal article (peer-reviewed)abstract
- 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.
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| 2. |
- Olsen, Bernt Rydland, et al.
(author)
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PCR-DHPLC assay for the identification of predator-prey interactions
- 2012
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In: Journal of Plankton Research. - Oxford : Oxford University Press. - 0142-7873 .- 1464-3774. ; 34:4, s. 277-285
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Journal article (peer-reviewed)abstract
- 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.
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| 3. |
- Troedsson, Christofer, et al.
(author)
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Effects of ocean acidification, temperature and nutrient regimes on the appendicularian Oikopleura dioica: A mesocosm study
- 2013
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In: Marine Biology. - 0025-3162. ; 160:8, s. 2175-2187
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Journal article (peer-reviewed)abstract
- ncreasing pCO2 is hypothesized to induce shifts in plankton communities toward smaller cells, reduced carbon export rates and increased roles of gelatinous zooplankton. Appendicularians, among the most numerous pan-global “gelatinous” zooplankton, continuously produce filter-feeding houses, shortcutting marine food webs by ingesting submicron particles, and their discarded houses contribute significantly to carbon fluxes. We present a first mesocosm-scale study on the effects of temperature, pCO2 and bloom structures on the appendicularian, Oikopleura dioica. There were effects of temperature and nutrients on phytoplankton communities. No shifts in functional phytoplankton groups, nor changes in particle sizes/morphotypes, known to impact appendicularian feeding, were observed under manipulated pCO2 conditions. However, appendicularian abundance was positively correlated with increased pCO2, temperature and nutrient levels, consistent with hypotheses concerning gelatinous zooplankton in future oceans. This suggests appendicularians will play more important roles in marine pelagic communities and vertical carbon transport under projected ocean acidification and elevated temperature scenarios.
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