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59 results on '"Bjerring, Rikke"'

52. A community-based framework for aquatic ecosystem models

Author

Trolle, Dennis, primary, Hamilton, David P., additional, Hipsey, Matthew R., additional, Bolding, Karsten, additional, Bruggeman, Jorn, additional, Mooij, Wolf M., additional, Janse, Jan H., additional, Nielsen, Anders, additional, Jeppesen, Erik, additional, Elliott, J. Alex, additional, Makler-Pick, Vardit, additional, Petzoldt, Thomas, additional, Rinke, Karsten, additional, Flindt, Mogens R., additional, Arhonditsis, George B., additional, Gal, Gideon, additional, Bjerring, Rikke, additional, Tominaga, Koji, additional, Hoen, Jochem’t, additional, Downing, Andrea S., additional, Marques, David M., additional, Fragoso, Carlos R., additional, Søndergaard, Martin, additional, and Hanson, Paul C., additional

Published
2011
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53. Short-and long term niche segregation and individual specialization of brown trout (Salmo trutta) in species poor Faroese lakes

Author

Brodersen, Jakob, primary, Malmquist, Hilmar J., additional, Landkildehus, Frank, additional, Lauridsen, Torben L., additional, Amsinck, Susanne L., additional, Bjerring, Rikke, additional, Søndergaard, Martin, additional, Johansson, Liselotte S., additional, Christoffersen, Kirsten S., additional, and Jeppesen, Erik, additional

Published
2011
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54. Subfossil Cladocera in relation to contemporary environmental variables in 54 Pan-European lakes

Author

BJERRING, RIKKE, primary, BECARES, ELOY, additional, DECLERCK, STEVEN, additional, GROSS, ELISABETH M., additional, HANSSON, LARS-ANDERS, additional, KAIRESALO, TIMO, additional, NYKÄNEN, MIRVA, additional, HALKIEWICZ, ANNA, additional, KORNIJÓW, RYSZARD, additional, CONDE-PORCUNA, JOSÉ M., additional, SEFERLIS, MILTIADIS, additional, NÕGES, TIINA, additional, MOSS, BRIAN, additional, AMSINCK, SUSANNE LILDAL, additional, ODGAARD, BENT VAD, additional, and JEPPESEN, ERIK, additional

Published
2009
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57. Trophic structure inferred from cladoceran subfossils.

Author

Johansson, Liselotte Sander, Amsinck, Susanne Lildal, Bjerring, Rikke, and Jeppesen, Erik

Subjects
SPECIES diversity, FISHES, LAKES, PREDATION, BIODIVERSITY, CHLOROPHYLL, FISHERY management, AQUATIC biodiversity, ECOLOGY
Abstract

Analyses of cladoceran remains were conducted on an 11-m sediment core from Dallund Sø, Denmark, covering approximately the last 7000 years. The densities of planktivorous fish and macrophyte coverage were inferred from previously established transfer functions for Danish lakes using pelagic and plant-associated cladocerans, respectively, as palaeoenvironmental indicators. This is the first reconstruction of the abundance of fish and macrophytes covering millennial timescales. The cladoceran assemblages indicated an early period (4830 BC to c. 750 BC) with low species diversity, being dominated mainly by small-sized pelagic taxa. An intervening period (750 BC–AD 1100) followed, dominated by macrophyte-associated taxa and large-sized pelagic species. A marked increase in the abundance of remains occurred at c. AD 1200 coincident with the introduction of the mouldboard plough to Denmark and major forest clearance in the lake catchment. Further upcore (AD 1300–1700) mud-dwelling taxa increased in importance. Finally (AD 1700–1998), a shift occurred towards taxa characterizing eutrophic conditions. Redundancy analyses and cladoceran-inferred submerged macrophyte coverage and planktivorous fish density indicated overall low levels of nutrients and chlorophyll a, moderate macrophyte coverage (10–24%) and moderate to high fish predation prior to the Roman Iron Age (AD 0–400) followed by higher levels of nutrients and chlorophyll a and lower macrophyte coverage (< 10%) and moderate fish predation in recent times. The results suggest that the lake became increasingly eutrophic through time, not least after forest clearance and intensification of agriculture in Mediaeval times. [ABSTRACT FROM AUTHOR]

Published
2005
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59. Short-and long term niche segregation and individual specialization of brown trout ( Salmo trutta ) in species poor Faroese lakes

Author

Brodersen, Jakob, Malmquist, Hilmar, Landkildehus, Frank, Lauridsen, Torben, Amsinck, Susanne, Bjerring, Rikke, Søndergaard, Martin, Johansson, Liselotte, Christoffersen, Kirsten, Jeppesen, Erik, Brodersen, Jakob, Malmquist, Hilmar, Landkildehus, Frank, Lauridsen, Torben, Amsinck, Susanne, Bjerring, Rikke, Søndergaard, Martin, Johansson, Liselotte, Christoffersen, Kirsten, and Jeppesen, Erik

Abstract

Trophic niche divergence is considered to be a major process by which species coexistence is facilitated. When studying niche segregation in lake ecosystems, we tend to view the niche on a one-dimensional pelagic-littoral axis. In reality, however, the niche use may be more complex and individual fidelity to a niche may be variable both between and within populations. In order to study this complexity, relative simple systems with few species are needed. In this paper, we study how competitor presence affects the resource use of brown trout (Salmo trutta) in 11 species-poor Faroese lakes by comparing relative abundance, stable isotope ratios and diet in multiple habitats. In the presence of three-spined sticklebacks (Gasterosteus aculeatus), a higher proportion of the trout population was found in the pelagic habitat, and trout in general relied on a more pelagic diet base as compared to trout living in allopatry or in sympatry with Arctic charr (Salvelinus alpinus). Diet analyses revealed, however, that niche-segregation may be more complex than described on a one-dimensional pelagic-littoral axis. Trout from both littoral and offshore benthic habitats had in the presence of sticklebacks a less benthic diet as compared to trout living in allopatry or in sympatry with charr. Furthermore, we found individual habitat specialization between littoral/benthic and pelagic trout in deep lakes. Hence, our findings indicate that for trout populations interspecific competition can drive shifts in both habitat and niche use, but at the same time they illustrate the complexity of the ecological niche in freshwater ecosystems

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