Krill diversity and population structure along the sub-Arctic Godthåbsfjord, SW Greenland

Agersted, Mette Dalgaard; Nielsen, Torkel Gissel

doi:10.1093/plankt/fbt139

Cited by 17 publications

(18 citation statements)

References 35 publications

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“…Chl a values were converted to carbon using a C:Chl a ratio of 43.3 (Sejr et al 2007), and krill weight (W, mg C) was estimated from the length-weight regression in Agersted & Nielsen (2014):…”

Section: Grazing Rates -Gut Fluorescence Techniquementioning

confidence: 99%

“…In the Godthåbsfjord system (Nuup Kangerlua) SW Greenland, krill is dominated by Thysanoessa raschii. Other resident species include T. inermis, T. longicaudata and Meganyctiphanes norvegica (Agersted & Nielsen 2014). The fjord is draining the Greenland Ice Sheet to the open sea, and the run-off from the Ice Sheet has a strong influence on the fjord (Mortensen et al 2011) and plankton composition (Calbet et al 2011;Arendt et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…However, knowledge about larger zooplankton organisms in the fjord is limited (e.g. Agersted et al 2011;Agersted and Nielsen 2014).…”

Section: Introductionmentioning

confidence: 99%

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Gut evacuation rate and grazing impact of the krill Thysanoessa raschii and T. inermis

et al. 2014

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Gut evacuation rates and ingestion rates were measured for the krill Thysanoessa raschii and T. inermis in Godthåbsfjord, SW Greenland. Combined with biomass of the krill community, the grazing potential on phytoplankton along the fjord was estimated. Gut evacuation rates were 3.9 and 2.3 h −1 for T. raschii and T. inermis, respectively. Ingestion rates were 12.2 ± 7.5 µg C mg C −1 day −1 (n = 4) for T. inermis and 4.9 ± 3.2 µg C mg C −1 day −1 (n = 4) for T. raschii, corresponding to daily rations of 1.2 and 0.5 % body carbon day −1. Clearance experiments conducted in parallel to the gut evacuation experiment gave similar results for ingestion rates and daily rations. Krill biomass was highest in the central part of the fjord's length, with T. raschii dominating. Community grazing rates from krill and copepods were comparable; however, their combined impact was low, estimated as <1 % of phytoplankton standing stock being removed per day during this late spring study.

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Section: Grazing Rates -Gut Fluorescence Techniquementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gut evacuation rate and grazing impact of the krill Thysanoessa raschii and T. inermis

et al. 2014

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“…Krill are keystone species of marine pelagic food webs, allowing the transfer of energy and essential nutritional elements from lower to upper trophic levels (TLs) by serving as prey for numerous ecosystem relevant species (e.g., Mauchline ; Savenkoff et al ; Agersted and Nielsen ). In northern Atlantic regions, krill communities are dominated by three species, the temperate/boreal Meganyctiphanes norvegica , the Arctic species T. inermis, and the boreal/arctic T. raschii (Berkes ; Mauchline ; Agersted and Nielsen ). The biogeographic distribution of these species follows a latitudinal gradient, because of their specific thermal preferences, which also lead to differential vertical distribution patterns within the water column.…”

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confidence: 99%

“…The biogeographic distribution of these species follows a latitudinal gradient, because of their specific thermal preferences, which also lead to differential vertical distribution patterns within the water column. Both distribution patterns result in spatial habitat overlap and sympatric coexistence (Barange ; Agersted and Nielsen ; Plourde et al ). Knowledge of the ecology of these three species and the mechanisms allowing for coexistence is relatively limited, but needed to predict how potential interspecific competition affects the trophic structure and the energy flow throughout food webs.…”

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Trophic niche partitioning of dominant North‐Atlantic krill species, Meganyctiphanes norvegica, Thysanoessa inermis, and T. raschii

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Trombetta

Amaudrut

et al. 2018

Limnology & Oceanography

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Different krill species have a pivotal position in many marine food webs by both preying upon several trophic levels and being forage species for consumers. Within these food webs, different krill species coexist, though it remains unclear what mechanisms allow for the coexistence, for instance, of northern krill species in subarctic environments. Here, we hypothesize that the stable coexistence of sympatric krill species is based on trophic niche partitioning related to seasonal trade‐offs between their respective food preferences, their energy needs, and prey availability. To test our hypothesis, we analyzed the diets, feeding selectivity, and lipid composition of three coexisting northern krill species (Meganyctiphanes norvegica, Thysanoessa inermis, and Thysanoessa raschii) throughout 1 yr using a multimarker approach. We assessed lipid classes, fatty acids, and stable isotope signatures of krill and potential food sources (27 groups, from phytoplankton to lipid‐rich copepods) to elucidate seasonal variation of niche utilization. Results revealed strong trophic niche separation occurring at a very fine trophic scale (species level) throughout the year. The three krill species showed different degrees of food specialization rather than being purely opportunistic as classically proposed. Feeding on copepod prey was important to accumulate energy reserves for overwintering and subsequent rebuilding of energy reserves. Energy reserve utilization might reduce potential competition for the limited available resources, especially under low food conditions.

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Feeding ecology of capelin (Mallotus villosus) in a fjord impacted by glacial meltwater (Godthåbsfjord, Greenland)

et al. 2018

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Krill diversity and population structure along the sub-Arctic Godthåbsfjord, SW Greenland

Cited by 17 publications

References 35 publications

Gut evacuation rate and grazing impact of the krill Thysanoessa raschii and T. inermis

Gut evacuation rate and grazing impact of the krill Thysanoessa raschii and T. inermis

Trophic niche partitioning of dominant North‐Atlantic krill species, Meganyctiphanes norvegica, Thysanoessa inermis, and T. raschii

Feeding ecology of capelin (Mallotus villosus) in a fjord impacted by glacial meltwater (Godthåbsfjord, Greenland)

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