Growth and Moulting in Northern Krill (Meganyctiphanes norvegica Sars)

Búchholz, Friedrich; Buchholz, Cornelia

doi:10.1016/b978-0-12-381308-4.00006-6

Cited by 17 publications

(6 citation statements)

References 42 publications

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“…Krill species all have a complex life cycle that does not terminate with a single imaginal molt followed by a unique reproductive event (or season), like most crustacean zooplankton species (e.g., copepod species). Instead, reproductively active adults can thrive for several years and actively modulate their size between periods of active growth and reproduction and periods of rest and shrinking, depending on the environmental conditions (Buchholz and Buchholz ). From a modeling point‐of‐view, these complex dynamics presents substantial challenges since they cannot be efficiently abstracted by common age‐class or size‐class approaches.…”

Section: Discussionmentioning

confidence: 99%

“…In general, the duration of the post-molt phase is about 30-40% of the IMP, while the duration of the pre-molt phase varies between 60% and 70% of the IMP (Nicol and Stolp 1990;Buchholz 1991;Buchholz and Buchholz 2010). The duration of the IMP itself is variable in time and is strongly associated with the environmental temperature (Sameoto 1976;Cuzin-Roudy and Buchholz 1999), although some studies suggest a secondary role for food availability (Nicol and Stolp 1991;Siegel and Nicol 2000) and light (Buchholz and Buchholz 2010). In our model, we only considered the dominant role of temperature and we did not take into account the potential impact of food availability, due to the lack of knowledge of its contribution in development.…”

Section: Modeling Physiological Processes Moltingmentioning

confidence: 99%

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Individual‐based modeling explains the contrasted seasonality in size, growth, and reproduction of the sympatric Arctic (Thysanoessa raschii) and Nordic krill (Meganyctiphanes norvegica) in the St. Lawrence Estuary, eastern Canada

Benkort

Plourde

Winkler

et al. 2018

Limnology & Oceanography

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The Nordic krill Meganyctiphanes norvegica and Arctic krill Thysanoessa raschii both dominate the krill community within the Estuary and Gulf of St. Lawrence system where they are central forage species for its pelagic ecosystem. We developed a species‐specific physiological individual based model that implements the critical physiological processes of growth, molting, and reproduction of female adults as responses to environmental forcing. Key innovations of our approach were the decoupling between the molting schedule and growth, as well as considering two distinct sources of prey (phytoplankton and mesozooplankton). Our simulation results revealed that the details of the feeding process were critical for an accurate representation of the production dynamics of adult individuals from both species. Their specific feeding preferences on phytoplankton and mesozooplankton resulted in distinct species‐specific phenological patterns that reproduced observations. The present study highlights the importance of detailed knowledge of diet and feeding behavior of krill species to improve our understanding of population responses in a rapidly changing environment.

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Section: Discussionmentioning

confidence: 99%

Section: Modeling Physiological Processes Moltingmentioning

confidence: 99%

Individual‐based modeling explains the contrasted seasonality in size, growth, and reproduction of the sympatric Arctic (Thysanoessa raschii) and Nordic krill (Meganyctiphanes norvegica) in the St. Lawrence Estuary, eastern Canada

Benkort

Plourde

Winkler

et al. 2018

Limnology & Oceanography

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“…In addition to these temperate fish species, the temperate−boreal northern krill Meganycti phanes nor vegica, first observed in polar cod stomachs in 2015 in the northern Barents Sea (Eriksen et al 2020), was observed in 3 stomachs. The northern krill, increasingly observed in the Arctic Ocean with the enhanced Atlantic water inflow, has previously already been suggested as a useful indicator of change (Buchholz & Buchholz 2010). As rising sea temperatures and changes in circulation patterns in the Barents Sea allow boreal and sub-Arctic species to expand northward into areas previously occupied by Arctic species (Fossheim et al 2015, Dalpadado et al 2020, a shift in the prey composition of polar cod is expected.…”

Section: Extending the Prey Spectrum Of Polar Codmentioning

confidence: 99%

Comparative visual and DNA-based diet assessment extends the prey spectrum of polar cod Boreogadus saida

Maes

Schaafsma²,

Christiansen

et al. 2022

Mar. Ecol. Prog. Ser.

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The Arctic marine ecosystem is changing fast due to climate change, emphasizing the need for solid ecological baselines and monitoring. The polar cod Boreogadus saida functions as a key species in the Arctic marine food web. We investigated the stomach contents of polar cod from the northern Barents Sea using DNA metabarcoding with the mitochondrial cytochrome c oxidase I gene in parallel with classical visual analysis. Arctic amphipods and krill dominated the diet in both methods. Yet, metabarcoding allowed for the identification of digested and unidentifiable prey and provided higher taxonomic resolution, revealing new and undiscovered prey items of polar cod in the area. Furthermore, molecular results suggest a higher importance of barnacles and fish (presumably eggs and pelagic larvae) in the diet than previously recorded. Parasites and, in 6 cases, other prey items were only visually identified, demonstrating the complementary nature of both approaches. The presence of temperate and boreal prey species such as northern krill and (early life stages of) European flounder and European plaice illustrates the advection of boreal taxa into the polar region or may be indicative of ongoing borealisation in the Barents Sea. We show that a combination of visual analysis and metabarcoding provides complementary and semi-quantitative dietary information and integrative insights to monitor changing marine food webs.

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“…The hydrographic conditions during the sampling periods are described in Buchholz et al (2010; report of cruise D356) and Lahajnar et al (2011; report of cruise MSM17/3).…”

Section: Hydrographic and Trophic Conditionsmentioning

confidence: 99%

Life in the sea of plenty: Seasonal and regional comparison of physiological performance of Euphausia hanseni in the northern Benguela upwelling system

Werner

Buchholz

Búchholz

2015

Journal of Sea Research

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Variability in upwelling events may lead to periods of constrained food availability in the northern Benguela upwelling system (NBUS), thereby affecting the physiological state and metabolic activity of euphausiids. Most attention has so far been paid to seasonal effects but little is known about regional variability. Metabolic activity (expressed by respiration and excretion rates) and physiological state (expressed by reproductive effort and moult activity) in Euphausia hanseni were examined at different stations during austral summer (minimum upwelling) and austral winter (maximum upwelling). Overall, regional differences in physiological state, influencing metabolic activity, were greater than seasonal ones, indicating favourable conditions for growth and reproduction year-round. Higher respiration rates were found for females in more advanced stages of sexual development. Moult stage did not affect oxygen consumption rates, however. The physiological state of E. hanseni at the time of capture may serve as a meaningful indicator of the associated hydrographic conditions in the NBUS, to be further used in eco-system analysis on seasonal or long-term time scales. A latitudinal comparison of species highlights the extraordinary physiological plasticity of euphausiids.

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Growth and Moulting in Northern Krill (Meganyctiphanes norvegica Sars)

Cited by 17 publications

References 42 publications

Individual‐based modeling explains the contrasted seasonality in size, growth, and reproduction of the sympatric Arctic (Thysanoessa raschii) and Nordic krill (Meganyctiphanes norvegica) in the St. Lawrence Estuary, eastern Canada

Individual‐based modeling explains the contrasted seasonality in size, growth, and reproduction of the sympatric Arctic (Thysanoessa raschii) and Nordic krill (Meganyctiphanes norvegica) in the St. Lawrence Estuary, eastern Canada

Comparative visual and DNA-based diet assessment extends the prey spectrum of polar cod Boreogadus saida

Life in the sea of plenty: Seasonal and regional comparison of physiological performance of Euphausia hanseni in the northern Benguela upwelling system

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