Seasonal and large-scale spatial variability of the energy reserves and the feeding selectivity of Meganyctiphanes norvegica and Thysanoessa inermis in a Subarctic environment

Cabrol, Jory; Nadalini, Jean-Bruno; Tremblay, Réjean; Galbraith, Peter S.; Nozais, Christian; Starr, Michel; Plourde, Stéphane; Winkler, Gesche

doi:10.1016/j.pocean.2019.102203

Cited by 6 publications

(1 citation statement)

References 43 publications

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“…The diversification of fin whale diets after 2001 likely occurred in response to a decrease in Arctic krill abundance or availability during this period of warming oceanographic conditions 20 and community changes 45 . Krill species in the EGSL are composed of two genera exhibiting distinct thermal niches 50 and ecology 51 , 52 . While total krill biomass changed little over our study period, krill composition shifted progressively toward a dominance of the more temperate species, the northern krill 49 .…”

Section: Discussionmentioning

confidence: 99%

Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

Cabrol

Lesage

Leclerc

et al. 2021

Sci Rep

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This study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale (Balaenoptera physalus). We examined skin biopsies from 99 fin whales sampled in the St. Lawrence Estuary (Canada) over a nine year period (1998–2006) during which environmental change was documented. We analyzed stable isotope ratios in skin and fatty acid signatures in blubber samples of whales, as well as in seven potential prey species, and diet was quantitatively assessed using Bayesian isotopic models. An abrupt change in fin whale dietary niche coincided with a decrease in biomass of their predominant prey, Arctic krill (Thysanoessa spp.). This dietary niche widening toward generalist diets occurred in nearly 60% of sampled individuals. The fin whale population, typically composed of specialists of either krill or lipid-rich pelagic fishes, shifted toward one composed either of krill specialists or true generalists feeding on various zooplankton and fish prey. This change likely reduced intraspecific competition. In the context of the current “Atlantification” of northern water masses, our findings emphasize the importance of considering individual-specific foraging tactics and not only population or group average responses when assessing population resilience or when implementing conservation measures.

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Section: Discussionmentioning

confidence: 99%

Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

Cabrol

Lesage

Leclerc

et al. 2021

Sci Rep

Self Cite

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Energy content of krill and amphipods in the Barents Sea from summer to winter: variation across species and size

Nowicki¹,

Borgå

Gabrielsen

et al. 2023

Polar Biol

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Arctic zooplankton develop large energy reserves, as an adaptation to strong seasonality, making them valuable prey items. We quantified the energy content (kJ g−1 dry weight) of abundant krill (arcto-boreal, Thysanoessa inermis and boreal, Meganyctiphanes norvegica) and amphipods (Arctic, Themisto libellula and sub-Arctic-boreal, Themisto abyssorum) in the Barents Sea in late summer (August) and early winter (December). Variation in energy content was attributed to species-specific traits and body size categories, the latter in part as a proxy for ontogeny. T. inermis had the highest energy content, (Aug: 26.8 ± 1.5 (SD) kJ g−1) and remained similar from summer to winter. Energy content increased in M. norvegica and decreased in both amphipod species, with the lowest energy content being in T. abyssorum (Dec: 17.8 ± 0.8 kJ g−1). The effect of body size varied between species, with energy content increasing with size in T. inermis and T. libellula, and no change with size in M. norvegica and T. abyssorum. The reproductive stages of T. libellula differed in energy content, being highest in gravid females. Energy content varied with species’ dependence on energy storage. Our findings highlight how phylogenetically and morphologically similar prey items cannot necessarily be considered equal from a predator´s perspective. Energetically, the northern T. inermis was higher quality compared to the more southern M. norvegica, and mostly so during summer. Ecological models and management strategies should consider such variation in prey quality, especially as Arctic borealization is expected to change species composition and the energetic landscape for predators.

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Seasonal changes in sediment erodibility associated with biostabilization in a subarctic intertidal environment, St. Lawrence Estuary, Canada

Waqas

Neumeier

Rochon

2020

Estuarine, Coastal and Shelf Science

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Seasonal and large-scale spatial variability of the energy reserves and the feeding selectivity of Meganyctiphanes norvegica and Thysanoessa inermis in a Subarctic environment

Cited by 6 publications

References 43 publications

Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

Energy content of krill and amphipods in the Barents Sea from summer to winter: variation across species and size

Seasonal changes in sediment erodibility associated with biostabilization in a subarctic intertidal environment, St. Lawrence Estuary, Canada

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