Krill of the northern Benguela Current and the Angola-Benguela frontal zone compared: physiological performance and short-term starvation in Euphausia hanseni

Huenerlage, Kim; Búchholz, Friedrich

doi:10.1093/plankt/fbs086

Cited by 16 publications

(18 citation statements)

References 62 publications

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“…As a first conclusion, we assume all species sampled in normal, i.e. good nutritional condition not having suffered starvation, which otherwise would have been indicated by lower lipid contents and reduced whole-animal performance (Boyd et al 1978;Huenerlage and Buchholz 2013;Huenerlage and Buchholz in rev. ).…”

Section: Discussionmentioning

confidence: 99%

Lipid composition and trophic relationships of krill species in a high Arctic fjord

2014

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Our study deals with the lipid biochemistry of the krill community in the ecosystem of the high Arctic Kongsfjord (Svalbard). During the last decades, Kongsfjord experienced a change in krill species composition due to recent increased advection of Atlantic water masses carrying characteristic boreal as well as subtropical-boreal euphausiids into the ecosystem. The lipid biochemistry and trophic relationships of the species recently inhabiting the Arctic water masses are scarcely known, although a change in a krill population may have a significant impact on the ecosystem. A comparison of nutrition and energy storage strategies, stable isotopes, lipid profiles and fatty acid compositions showed remarkable differences between the krill species. These reflected the diverse feeding behaviours and specific adaptations to the environments of their origin: the boreal Meganyctiphanes norvegica and subtropical Nematoscelis megalops appear more carnivorous and have significantly lower mean lipid contents (29 and 10 %, respectively) and a different energy storage pattern (triacylglycerols and polar lipids, respectively) than the arctoboreal Thysanoessa inermis, which consists of up to 54 % of lipids mainly stored as wax esters ([40 %). These differences may have significant implications for the rapidly changing marine food web of Kongsfjord-especially for higher trophic levels relying on the nutritional input of animal lipids.

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Section: Discussionmentioning

confidence: 99%

Lipid composition and trophic relationships of krill species in a high Arctic fjord

2014

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“…Knowledge of overwintering strategies of northern krill species is limited (Berkes ; Auerswald et al ; Huenerlage and Buchholz ; Huenerlage et al ). In response to winter conditions, krill reduce their metabolic costs or shrink (reviewed by Meyer ), use energy reserves (e.g., Huenerlage et al ), and can also alter their food selectivity (Berkes ).…”

Section: Discussionmentioning

confidence: 99%

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

Cabrol

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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“…Regional comparisons of metabolic rates were conducted at 10°C only. All experiments were performed within 24 h of capture in order to minimize confounding effects due to starvation (Huenerlage and Buchholz, 2013). E. hanseni adults were first acclimated for approximately 12 h at 8-10°C and then further acclimated to the experimental temperatures in the respiration chamber for 1 to 4 h. The oxygen uptake was monitored in the dark over a period of 3 to 6 h. Each temperature experiment was run in triplicate with an additional empty chamber to serve as the control.…”

Section: Metabolic Measurementsmentioning

confidence: 99%

“…Nevertheless, we cannot entirely reject the possibility that the animals just passed a spawning event, resulting in low SDS. Huenerlage and Buchholz (2013) have shown that under experimental food deprivation E. hanseni immediately down-regulates metabolic parameters such as respiration and excretion rates. This fits our findings only partly, as respiration rates at station RPt were reduced but excretion rates remained unchanged.…”

Section: Regional Comparisonmentioning

confidence: 99%

“…Upwelling events influence growth and reproduction which in turn affect metabolic rates. This species directly invests energy into reproduction and growth, without storing large lipid reserves (Huenerlage and Buchholz, 2013). E. hanseni in the NBUS can be considered as living from hand-to-mouth but well adapted to life in a 'Sea of Plenty'.…”

Section: Species Comparisonmentioning

confidence: 99%

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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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Krill of the northern Benguela Current and the Angola-Benguela frontal zone compared: physiological performance and short-term starvation in Euphausia hanseni

Cited by 16 publications

References 62 publications

Lipid composition and trophic relationships of krill species in a high Arctic fjord

Lipid composition and trophic relationships of krill species in a high Arctic fjord

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

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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