Feeding by Calanus glacialis in a high arctic fjord: potential seasonal importance of alternative prey

Cleary, Alison C.; Søreide, Janne E.; Freese, Daniela; Niehoff, Barbara; Gabrielsen, Tove M.

doi:10.1093/icesjms/fsx106

Cited by 50 publications

(51 citation statements)

References 62 publications

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“…the signal, of which there is an overlap with ciliates that would be consumed as prey (Cleary et al, 2017). Second, winter studies regarding the abundance of likely prey sources have been infrequent across the Arctic.…”

Section: Discussionmentioning

confidence: 99%

“…Second, winter studies regarding the abundance of likely prey sources have been infrequent across the Arctic. In the lead up to the spring bloom (March), a relatively high proportion of chaetognaths have been observed in the gut contents of C. glacialis (Cleary et al, 2017). Chaetognaths are primarily predators of Calanus, but it is suggested that at this time of year, Calanus will predate upon eggs and juvenile stages of chaetognaths.…”

Section: Discussionmentioning

confidence: 99%

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Eat or Sleep: Availability of Winter Prey Explains Mid-Winter and Spring Activity in an Arctic Calanus Population

et al. 2020

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Copepods of the genus Calanus have adapted to high levels of seasonality in prey availability by entering a period of hibernation during winter known as diapause, but repeated observations of active Calanus spp. have been made in January in high latitude fjords which suggests plasticity in over-wintering strategies. During the last decade, the period of Polar Night has been studied intensively in the Arctic. A continuous presence of an active microbial food web suggests the prevalence of low-level alternative copepod prey (such as microzooplankton) throughout this period of darkness. Here we provide further evidence of midwinter zooplankton activity using a decadal record of moored acoustics from Kongsfjorden, Svalbard. We apply an individual based life-history model to investigate the fitness consequences of a range of over-wintering strategies (in terms of diapause timing and duration) under a variety of prey availability scenarios. In scenarios of no winter prey availability (P win = 0 µg C L −1), the optimal time to exit diapause is in March. However, as P win increases (up to 40 µg C L −1), there is little fitness difference in copepods exiting diapause in January compared to March. From this, we suggest that Calanus are able (in energetic terms) to either i) exit diapause early to deal with uncertainty in spring bloom timing, or ii) remain active throughout winter if diapause is not possible (i.e., environment not deep enough, or not enough lipid reserves built up over the previous summer). The range of viable overwintering strategies increases with increasing P win , suggesting that there is more flexibility for Calanus spp. in a scenario of non-zero P win .

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Eat or Sleep: Availability of Winter Prey Explains Mid-Winter and Spring Activity in an Arctic Calanus Population

et al. 2020

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“…This trophic dynamic, termed the "mycoloop" (Kagami et al 2014), likely contributes to organic matter recycling and biological turnover within the euphotic zone, which confers a potential reduction of particulate organic matter export. The relevance of the Chytridiomycota to higher trophic levels appears to be seasonal, generally peaking during the spring phytoplankton bloom in high-latitude marine environments (Cleary et al 2017). Other zoosporic fungi include the Aphelida, Cryptomycota, Neocallimastigomycota, Olpidiomycota, and select members formerly within the Zygomycota, whose relative abundance in marine environments appears to be generally low, according to the limited number of DNA studies (e.g.…”

Section: Introductionmentioning

confidence: 99%

Global diversity and geography of planktonic marine fungi

et al. 2019

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Growing interest in understanding the relevance of marine fungi to food webs, biogeochemical cycling, and biological patterns necessitates establishing a context for interpreting future findings. To help establish this context, we summarize the diversity of cultured and observed marine planktonic fungi from across the world. While exploring this diversity, we discovered that only half of the known marine fungal species have a publicly available DNA locus, which we hypothesize will likely hinder accurate highthroughput sequencing classification in the future, as it does currently. Still, we reprocessed >600 high-throughput datasets and analyzed 4.9 × 10 9 sequences (4.8 × 10 9 shotgun metagenomic reads and 1.0 × 10 8 amplicon sequences) and found that every fungal phylum is represented in the global marine planktonic mycobiome; however, this mycobiome is generally predominated by three phyla: the Ascomycota, Basidiomycota, and Chytridiomycota. We hypothesize that these three clades are the most abundant due to a combination of evolutionary histories, as well as physical processes that aid in their dispersal. We found that environments with atypical salinity regimes (>5 standard deviations from the global mean: Red Sea, Baltic Sea, sea ice) hosted higher proportions of the Chytridiomycota, relative to open oceans that are dominated by Dikarya. The Baltic Sea and Mediterranean Sea had the highest fungal richness of all areas explored. An analysis of similarity identified significant differences between oceanographic regions. There were no latitudinal gradients of marine fungal richness and diversity observed. As more high-throughput sequencing data become available, expanding the collection of reference loci and genomes will be essential to understanding the ecology of marine fungi.

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“…Screening of rRNA molecular barcodes and clone data has detected fungal communities comprised of an uncharacterized phylogenetic branch of Chytridiomycota (18) that appear to be important prey for Arctic zooplankton (19). These Arctic Chytridiomycota communities are primarily found with members of the Dikarya in sea ice, sediment (8,20) and in association with driftwood (21).…”

Section: Introductionmentioning

confidence: 99%

Arctic marine fungi: biomass, functional genes, and putative ecological roles

Hassett¹,

Borrego

Vonnahme³

et al. 2019

The ISME Journal

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Recent molecular evidence suggests a global-distribution of marine fungi; however, the ecological relevance and corresponding biological contributions of fungi to marine ecosystems remains largely unknown. We assessed fungal biomass from the open Arctic Ocean by applying novel biomass conversion factors from cultured-isolates to environmental sterol and CARD-FISH data. We found an average of 16.54 nmol m -3 of ergosterol in sea ice and seawater, which corresponds to 1.74 mg C m -3 (444.56 mg C m -2 in seawater). Using Chytridiomycota-specific probes, we observed freeliving and particulate-attached cells that averaged 34.07 µg C m -3 in sea ice and seawater (11.66 mg C m -2 in seawater). Summed CARD-FISH and ergosterol values approximate 1.77 mg C m -3 in sea ice and seawater (456.23 mg C m -2 in seawater), which is similar to biomass estimates of other marine taxa generally considered integral to marine food webs and ecosystem processes. Using the GeoChip microarray, we detected evidence for fungal viruses within the Partitiviridae in sediment, as well as fungal genes involved in the degradation of biomass and the assimilation of nitrate. To bridge our observations of fungi on particulate and the detection of degradative genes, we germinated fungal conidia in zooplankton fecal pellets and grew fungal conidia after eight months incubation in sterile seawater. Ultimately, these data suggest that fungi could be as important in oceanic ecosystems as they are in freshwater environments. Significance Statement:The oceans cover 71% of the world's surface; however, the contributions of marine fungi to these environments remain a gap to understanding marine ecosystem processes and associated biogeochemical cycling. Here we provide the first biomass estimates of fungi from the Arctic Ocean, supplemented with a functional gene inventory, and experiment-based ecological data demonstrating putative niches occupied by fungi in the marine environment. We provide evidence that marine fungi comprise a comparable quantity of biomass relative to other taxonomic groups that are generally considered to be essential ecosystem components.

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Feeding by Calanus glacialis in a high arctic fjord: potential seasonal importance of alternative prey

Cited by 50 publications

References 62 publications

Eat or Sleep: Availability of Winter Prey Explains Mid-Winter and Spring Activity in an Arctic Calanus Population

Eat or Sleep: Availability of Winter Prey Explains Mid-Winter and Spring Activity in an Arctic Calanus Population

Global diversity and geography of planktonic marine fungi

Arctic marine fungi: biomass, functional genes, and putative ecological roles

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