Winter Carnivory and Diapause Counteract the Reliance on Ice Algae by Barents Sea Zooplankton

Kohlbach, Doreen; Schmidt, Katrin; Hop, Haakon; Wold, Anette; Al-Habahbeh, Amalia Keck; Belt, Simon T.; Woll, Matthias; Graeve, Martín; Smik, Lukas; Atkinson, Angus; Assmy, Philipp

doi:10.3389/fmars.2021.640050

Cited by 17 publications

(22 citation statements)

References 130 publications

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“…This pattern of intake is similar to what has been found in other areas, such as North Atlantic (Mayor et al, 2006;Castellani et al, 2008;Mayor et al, 2009a) and the English Channel (Djeghri et al, 2018), and supports the understanding that C. finmarchicus are less selective than other calanoid copepods (Teegarden et al, 2008). Diatoms dominated the diet of C. finmarchicus at most stations examined, as is often reported Søreide et al, 2008;Cleary et al, 2017;Kohlbach et al, 2021). This intake simply reflects the predominance of diatoms in the microplankton, rather than these cells being positively selected for.…”

Section: Ingestionsupporting

confidence: 88%

“…Diatoms are thought to be key in the diet of Calanus Kohlbach et al, 2021), positively correlating with both ingestion and production. Understanding patterns of prey selection by Arctic Calanus is a fundamental precursor to determining how the changing food environment will impact their ability to obtain the necessary resources to reproduce.…”

Section: Introductionmentioning

confidence: 99%

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Grazing, egg production and carbon budgets for Calanus finmarchicus across the Fram Strait

et al. 2022

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Calanoid copepods comprise around 90% of Arctic zooplankton biomass and are fundamental to the ecological and biogeochemical functioning of high-latitude pelagic ecosystems. They accumulate lipid reserves during the productive months and represent an energy-rich food source for higher trophic levels. Rapidly changing climate in the Arctic may alter the quantity and composition of the food environment for one of the key copepod species, Calanus finmarchicus, with as yet unquantified effects on its production. Here we present rates of feeding and egg production in female C. finmarchicus exposed to the range of feeding conditions encountered across the Fram Strait in May/June 2018. Carbon (C) budgets were constructed and used to examine the relationship between feeding and growth (= egg production) in these animals. C-specific ingestion rates (mean ± standard deviation) were highly variable, ranging from 0.015 ± 0.004 to 0.645 ± 0.017 day-1 (mean = 0.295 ± 0.223 day-1), and were positively correlated with food availability. C-specific egg production rates ranged from 0.00 to 0.049 day-1 (mean = 0.012 ± 0.011) and were not correlated with either food availability or ingestion rate. Calculated gross growth efficiencies (GGE: growth/ingestion) were low, 0.12 ± 0.13 (range = 0.01 to 0.39). The assembled C budgets indicate that the average fraction of ingested food that was surplus to the requirements for egg production, respiration and losses to faecal pellets was 0.17 ± 0.42. We suggest that this excess occurred, at least in part, because many of the incubated females were still undergoing the energetically (C-) expensive process of gonad maturation at the time of sampling, an assertion that is supported by the relatively high C:N (nitrogen) ratios of the incubated females, the typically low egg production rates, and gonad maturation status. Ontogenetic development may thus explain the large variability seen in the relationship between egg production and ingestion. The apparently excessive ingestion rates may additionally indicate that recently moulted females must acquire additional N via ingestion to complete the maturation process and begin spawning. Our results highlight the need for improved fundamental understanding of the physiology of high-latitude copepods and its response to environmental change.

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Section: Ingestionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Grazing, egg production and carbon budgets for Calanus finmarchicus across the Fram Strait

et al. 2022

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“…This may contribute to seasonal variations in δ 15 N values and computed trophic position for species and FGs (Hoondert et al, 2021). Some FGs (e.g., copepod FGs) are omnivorous and change diet seasonally from phytoplankton in spring and summer to protozoa and detritus during summer (De Laender et al, 2010;Kohlbach et al, 2021). Generally, high δ 15 N values of have been observed in several FGs during winter and spring when feeding at lower trophic levels are reduced (Olive et al, 2003;Hertz et al, 2015).…”

Section: Comparison Of Trophic Positions Estimated From Ecopath and L...mentioning

confidence: 99%

Comparison Between Trophic Positions in the Barents Sea Estimated From Stable Isotope Data and a Mass Balance Model

Pedersen

2022

Front. Mar. Sci.

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The trophic position concept is central in system ecology, and in this study, trophic position (TP) estimates from stable-isotopes and an Ecopath mass-balance food web model for the Barents Sea were compared. Two alternative models for estimating TP from stable isotopes, with fixed or scaled trophic fractionation were applied. The mass-balance model was parametrized and balanced for year 2000, was comprised of 108 functional groups (Gs), and was based on biomass and diet data largely based on predator stomach data. Literature search for the Barents Sea Large Marine Ecosystem revealed 93 sources with stable isotope data (δ15N values) for 83 FGs, and 25 of the publications had trophic position estimated from nitrogen stable isotopes. Trophic positions estimated from the mass-balance model ranged to 5.1 TP and were highly correlated with group mean δ15N values, and also highly correlated with the original literature estimates of trophic positions from stable isotopes. On average, TP from the mass-balance model was 0.1 TP higher than the original literature TP estimates (TPSIR) from stable isotopes. A trophic enrichment factor (TEF) was estimated assuming fixed fractionation and minimizing differences between trophic positions from Ecopath and TP predicted from δ15N values assuming a baseline value for δ15N calculated for pelagic particulate organic matter at a baseline TP of 1.0. The estimated TEF of 3.0‰ was lower than the most commonly used TEF of 3.4 and 3.8‰ in the literature. The pelagic whales and pelagic invertebrates functional groups tended to have higher trophic positions from Ecopath than from stable isotopes while benthic invertebrate functional groups tended to show an opposite pattern. Trophic positions calculated using the scaled trophic fractionation approach resulted in lower TP than from Ecopath for intermediate TPs and also a larger TP range in the BS. It is concluded that TPs estimated from δ15N values using a linear model compared better to the Ecopath model than the TPs from scaled fractionation approach.

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“…To enhance understanding and predictions of Earth System functioning and global change under the mounting pressures of the Anthropocene (IPCC, 2018(IPCC, , 2019, it is imperative that we understand the role of zooplankton within the world's oceans under present conditions, the potential impacts of future change and associated risks (Reid et al, 2003;Atkinson et al, 2012;Constable et al, 2014b;Pecuchet et al, 2020;Kohlbach et al, 2021), and adequately represent zooplankton dynamics in Earth System Models (ESMs) (Le Quéré et al, 2005Quéré et al, , 2016Buitenhuis et al, 2010). This requires specific knowledge of the complex interactions and mechanisms associated with zooplankton dynamics, their sensitivity to drivers of change, and the resultant effects on ecosystems and socioeconomics.…”

Section: Introductionmentioning

confidence: 99%

Status, Change, and Futures of Zooplankton in the Southern Ocean

et al. 2022

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In the Southern Ocean, several zooplankton taxonomic groups, euphausiids, copepods, salps and pteropods, are notable because of their biomass and abundance and their roles in maintaining food webs and ecosystem structure and function, including the provision of globally important ecosystem services. These groups are consumers of microbes, primary and secondary producers, and are prey for fishes, cephalopods, seabirds, and marine mammals. In providing the link between microbes, primary production, and higher trophic levels these taxa influence energy flows, biological production and biomass, biogeochemical cycles, carbon flux and food web interactions thereby modulating the structure and functioning of ecosystems. Additionally, Antarctic krill (Euphausia superba) and various fish species are harvested by international fisheries. Global and local drivers of change are expected to affect the dynamics of key zooplankton species, which may have potentially profound and wide-ranging implications for Southern Ocean ecosystems and the services they provide. Here we assess the current understanding of the dominant metazoan zooplankton within the Southern Ocean, including Antarctic krill and other key euphausiid, copepod, salp and pteropod species. We provide a systematic overview of observed and potential future responses of these taxa to a changing Southern Ocean and the functional relationships by which drivers may impact them. To support future ecosystem assessments and conservation and management strategies, we also identify priorities for Southern Ocean zooplankton research.

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Winter Carnivory and Diapause Counteract the Reliance on Ice Algae by Barents Sea Zooplankton

Cited by 17 publications

References 130 publications

Grazing, egg production and carbon budgets for Calanus finmarchicus across the Fram Strait

Grazing, egg production and carbon budgets for Calanus finmarchicus across the Fram Strait

Comparison Between Trophic Positions in the Barents Sea Estimated From Stable Isotope Data and a Mass Balance Model

Status, Change, and Futures of Zooplankton in the Southern Ocean

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