Sea-ice decline makes zooplankton stay deeper for longer

Flores, Hauke; Veyssière, Gaëlle; Castellani, Giulia; Wilkinson, Jeremy; Hoppmann, Mario; Kärcher, Michael; Valcic, Lovro; Cornils, Astrid; Geoffroy, Maxime; Nicolaus, Marcel; Niehoff, Barbara; Priou, Pierre; Schmidt, Katrin; Stroeve, Julienne

doi:10.21203/rs.3.rs-2436026/v1

Cited by 3 publications

(3 citation statements)

References 53 publications

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“…Changes in their abundance, distribution, and genetic health may greatly impact marine wildlife and local communities. The projected loss of sea ice due to climate change will affect populations through habitat loss [12,13], changes in prey distribution [14,15], increased predation pressure from killer whales ( Orcinus orca ) [16], and increased ship traffic [17]. As ice-adapted animals, narwhals and bowhead whales will need to adjust quickly to changing environments, which may be limited by potential genetic consequences carried over from commercial whaling.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the genetic legacy of commercial whaling in bowhead whales and narwhals

de Greef,

Müller,

Thorstensen

et al. 2024

Preprint

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Commercial whaling decimated many whale populations over several centuries. Bowhead whales (Balaena mysticetus) and narwhal (Monodon monoceros) have similar habitat requirements and are often seen together in the Canadian Arctic. Although their ranges overlap extensively, bowhead whales experienced significantly greater whaling pressure than narwhals. The different harvest histories but similar habitat requirements of these two species provide an opportunity to examine the demographic and genetic consequences of commercial whaling. We whole-genome resequenced Canadian Arctic bowhead whales and narwhals to delineate population structure and reconstruct demographic history. Bowhead whale effective population size sharply declined contemporaneously with the intense commercial whaling period. Narwhals instead exhibited recent growth in effective population size, reflecting limited opportunistic commercial harvest. Although the genetic diversity of bowhead whales and narwhals was similar, bowhead whales had more genetic diversity prior to commercial whaling and will likely continue to experience significant genetic drift in the future. In contrast, narwhals appear to have had long-term low genetic diversity and may not be at imminent risk of the consequences of the erosion of genetic diversity. This work highlights the importance of considering population trajectories in addition to genetic diversity when assessing the genetics of populations for conservation and management purposes.

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Section: Introductionmentioning

confidence: 99%

Unraveling the genetic legacy of commercial whaling in bowhead whales and narwhals

de Greef,

Müller,

Thorstensen

et al. 2024

Preprint

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show abstract

“…Our results, showing positive correlations between DHA proportions and temperature (Figure S5), suggest that flagellates can benefit from warmer, more stratified, surface waters. Such late summer pulses of DHA‐rich food can benefit zooplankton recruitment by lengthening their growing and reproductive season and by providing a depot of nutrition for the winter‐active part of the populations (Flores et al., 2023; Hobbs et al., 2020; Tremblay et al., 2011). Without doubt, the spring diatom bloom will remain the major annual primary production event in the Arctic (Ardyna et al., 2013) and this study shows that EPA and DHA proportions are high, irrespective of their production in sea ice or the upper water column, as long as the nutrient supply is sufficient.…”

Section: Discussionmentioning

confidence: 99%

Essential omega‐3 fatty acids are depleted in sea ice and pelagic algae of the Central Arctic Ocean

Schmidt,

Graeve,

Hoppe

et al. 2023

Global Change Biology

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Microalgae are the main source of the omega‐3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), essential for the healthy development of most marine and terrestrial fauna including humans. Inverse correlations of algal EPA and DHA proportions (% of total fatty acids) with temperature have led to suggestions of a warming‐induced decline in the global production of these biomolecules and an enhanced importance of high latitude organisms for their provision. The cold Arctic Ocean is a potential hotspot of EPA and DHA production, but consequences of global warming are unknown. Here, we combine a full‐seasonal EPA and DHA dataset from the Central Arctic Ocean (CAO), with results from 13 previous field studies and 32 cultured algal strains to examine five potential climate change effects; ice algae loss, community shifts, increase in light, nutrients, and temperature. The algal EPA and DHA proportions were lower in the ice‐covered CAO than in warmer peripheral shelf seas, which indicates that the paradigm of an inverse correlation of EPA and DHA proportions with temperature may not hold in the Arctic. We found no systematic differences in the summed EPA and DHA proportions of sea ice versus pelagic algae, and in diatoms versus non‐diatoms. Overall, the algal EPA and DHA proportions varied up to four‐fold seasonally and 10‐fold regionally, pointing to strong light and nutrient limitations in the CAO. Where these limitations ease in a warming Arctic, EPA and DHA proportions are likely to increase alongside increasing primary production, with nutritional benefits for a non‐ice‐associated food web.

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“…Light is one of the critical drivers of marine primary production, acting as a trigger for sea ice algae and phytoplankton blooms (Ardyna et al., 2020; Leu et al., 2015). Changes in the seasonality of the under‐ice light regime also influence the vertical migration of zooplankton (Brierley, 2014; Flores et al., 2023), an active biological carbon pump that accounts for 85–132\% of sinking organic carbon (Darnis & Fortier, 2012). While in situ}studies have improved understanding of the partitioning of incoming light and its relationship to ice and snow properties (Mundy et al., 2007; Veyssiere et al., 2022), quantifying how the bottom‐ice light regime is changing on a pan‐Arctic scale over long time‐periods requires the use of satellite observations or output from climate models.…”

Section: Introductionmentioning

confidence: 99%

Mapping Potential Timing of Ice Algal Blooms From Satellite

Stroeve,

Veyssiere,

Nab

et al. 2024

Geophysical Research Letters

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As Arctic sea ice and its overlying snow cover thin, more light penetrates into the ice and upper ocean, shifting the phenology of algal growth within the bottom of sea ice, with cascading impacts on higher trophic levels of the Arctic marine ecosystem. While field data or autonomous observatories provide direct measurements of the coupled sea ice‐algal system, they are limited in space and time. Satellite observations of key sea ice variables that control the amount of light penetrating through sea ice offer the possibility to map the under‐ice light field across the entire Arctic basin. This study provides the first satellite‐based estimates of potential sea ice‐associated algal bloom onset dates since the launch of CryoSat‐2 and explores how a changing snowpack may have shifted bloom onset timings over the last four decades.

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Sea-ice decline makes zooplankton stay deeper for longer

Cited by 3 publications

References 53 publications

Unraveling the genetic legacy of commercial whaling in bowhead whales and narwhals

Unraveling the genetic legacy of commercial whaling in bowhead whales and narwhals

Essential omega‐3 fatty acids are depleted in sea ice and pelagic algae of the Central Arctic Ocean

Mapping Potential Timing of Ice Algal Blooms From Satellite

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