Phytoplankton Surveys in the Arctic Fram Strait Demonstrate the Tiny Eukaryotic Alga Micromonas and Other Picoprasinophytes Contribute to Deep Sea Export

Bachy, Charles; Sudek, Lisa; Choi, Chang Jae; Eckmann, Charlotte; Nöthig, Eva‐Maria; Metfies, Katja; Worden, Alexandra Z.

doi:10.3390/microorganisms10050961

Cited by 14 publications

(17 citation statements)

References 62 publications

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“…This suggestion is supported by the lack of a relationship between available food and chlorophyll a (add details of correlation (or lack thereof) here). This disparity is also potentially attributable to the high abundances of picoplankton (≤2 µm cell diameter) that have been reported to occur in the Fram Strait, in particular the Micromonas genus of prasinophytes (Bachy et al, 2022), that were not enumerated in our study.…”

Section: Ingestionmentioning

confidence: 71%

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: Ingestionmentioning

confidence: 71%

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

et al. 2022

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“…Though our dataset is limited, it suggests that Micromonas could become increasingly important in coastal regions as tidewater submarine discharge and its associated nutrient delivery to surface water declines in the future. However, though smaller phytoplankton species, like Micromonas , have not traditionally been considered major players in carbon export from the surface ocean, new evidence shows this could change when Micromonas makes up the majority of the phytoplankton community (Bachy et al 2022). Data from Fram Strait reveals Micromonas spp.…”

Section: Discussionmentioning

confidence: 99%

Rubisco in high Arctic tidewater glacier‐marine systems: A new window into phytoplankton dynamics

Roberts,

Bhatia,

Rowland

et al. 2024

Limnology & Oceanography

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The hundreds of tidewater glaciers found in the Canadian Arctic Archipelago have the potential to enhance delivery of nutrients and other material to the surface ocean. Despite this, their influence on marine ecosystems, specifically phytoplankton, is poorly characterized. Here we developed and applied a quantitative mass spectrometry‐based approach to measure phytoplankton ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) concentrations to examine differences in productivity in glacierized and non‐glacierized marine systems in Jones Sound, Nunavut, within Inuit Nunangat. Comparisons to chloroplast 16S rRNA gene amplicon sequencing data suggested that these measurements detect the majority of Rubisco produced in Jones Sound. Because Rubisco catalyzes carbon fixation, we used these measurements to estimate total and group‐specific primary production potential, which were within the range of historical primary production measurements made using classical methods in this region. Our measurements also revealed that up to 2% of total protein in the water column is Rubisco, and that Rubisco concentrations are correlated with chlorophyll fluorescence, with maxima near the nitracline. Rubisco produced by diatom genera Chaetoceros and Thalassiosira were higher in marine regions influenced by glaciers, while Rubisco from Micromonas (Chlorophyta) was greater in non‐glacierized regions. This suggests that future climate scenarios may favor smaller phytoplankton groups, like Micromonas, with consequences for food webs and carbon cycling. This study broadens our understanding of how tidewater glaciers will impact phytoplankton communities, now and in a warmer future, and lays the foundation for using this mass spectrometry‐based approach to quantify phytoplankton group‐specific carbon fixation potential in other marine regions.

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“…Even though it appears to be growing well at 6 °C [ 91 ] and has shown a high adaptation potential to warming [ 92 ], its population may crash rapidly if temperatures exceed this upper limit. Studies have shown the importance of this genus to overwintering standing stocks and deep-sea export [ 93 , 94 , 95 ], indicating consequences for the ecosystem if temperatures rise to 9 °C.…”

Section: Discussionmentioning

confidence: 99%

Winners and Losers of Atlantification: The Degree of Ocean Warming Affects the Structure of Arctic Microbial Communities

Ahme

Jackowski

Wolf

et al. 2023

Genes

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Arctic microbial communities (i.e., protists and bacteria) are increasingly subjected to an intrusion of new species via Atlantification and an uncertain degree of ocean warming. As species differ in adaptive traits, these oceanic conditions may lead to compositional changes with functional implications for the ecosystem. In June 2021, we incubated water from the western Fram Strait at three temperatures (2 °C, 6 °C, and 9 °C), mimicking the current and potential future properties of the Arctic Ocean. Our results show that increasing the temperature to 6 °C only minorly affects the community, while an increase to 9 °C significantly lowers the diversity and shifts the composition. A higher relative abundance of large hetero- and mixotrophic protists was observed at 2 °C and 6 °C compared to a higher abundance of intermediate-sized temperate diatoms at 9 °C. The compositional differences at 9 °C led to a higher chlorophyll a:POC ratio, but the C:N ratio remained similar. Our results contradict the common assumption that smaller organisms and heterotrophs are favored under warming and strongly indicate a thermal limit between 6 °C and 9 °C for many Arctic species. Consequently, the magnitude of temperature increase is a crucial factor for microbial community reorganization and the ensuing ecological consequences in the future Arctic Ocean.

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Phytoplankton Surveys in the Arctic Fram Strait Demonstrate the Tiny Eukaryotic Alga Micromonas and Other Picoprasinophytes Contribute to Deep Sea Export

Cited by 14 publications

References 62 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

Rubisco in high Arctic tidewater glacier‐marine systems: A new window into phytoplankton dynamics

Winners and Losers of Atlantification: The Degree of Ocean Warming Affects the Structure of Arctic Microbial Communities

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