Do high Arctic coastal food webs rely on a terrestrial carbon subsidy?

Harris, Carolynn; McTigue, Nathan D.; McClelland, J. W.; Dunton, Kenneth H.

doi:10.1016/j.fooweb.2018.e00081

Cited by 49 publications

(41 citation statements)

References 75 publications

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“…Thus, small decreases in underwater PAR can lead to net heterotrophy. This supports the sediment "food bank" hypothesis as continuous primary production is not needed to sustain heterotrophic activity, since stored, labile, benthic OM can accumulate in shallow environments fueling respiration (Harris et al, 2018;Mincks et al, 2005). A "bank" of OM could explain why high levels of PAR led to a sustained pHT, and any instantaneous drop in PAR was immediately followed a decrease in daily average pHT.…”

Section: Par and Phsupporting

confidence: 67%

“…Arctic lagoons have relatively high diversity and abundance of benthic community invertebrates, ranging from 654 to 5,353 individuals m -2 with trophic linkages to birds and marine mammals (Griffiths et al, 1977Dunton et al, 2012). The benthic food web relies on both autochthonous microalgal production and allochthonous terrestrial organic matter (OM) inputs as carbon subsidies (Harris et al, 2018 (Dunton and Schonberg, 2006;Kinney et al, 1971;Mathews and Stringer, 1984;Robards, 2014). To our knowledge, only a single high-frequency year-round measurement of Beaufort Sea lagoon temperature and salinity exists (Harris et al, 2017), which is insufficient for understanding how these factors including biological metabolism may impact carbonate system dynamics.…”

Section: Introductionmentioning

confidence: 99%

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The Seasonal Phases of an Arctic Lagoon Reveal Non-linear pH Extremes

Miller¹,

Bonsell²,

McTigue³

et al. 2020

Preprint

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Abstract. The western Arctic Ocean, including its shelves and coastal habitats, has become a focus in ocean acidification research over the past decade as the colder waters of the region and the reduction of sea ice appear to promote the uptake of excess atmospheric CO2. Due to seasonal sea ice coverage, high-frequency monitoring of pH or other carbonate chemistry parameters is typically limited to infrequent ship-based transects during ice-free summers. This approach has failed to capture year-round nearshore carbonate chemistry dynamics which is modulated by biological metabolism in response to abundant allochthonous organic matter to the narrow shelf of the Beaufort Sea and adjacent regions. The coastline of the Beaufort Sea comprises a series of lagoons that account for > 50 % of the land-sea interface. The lagoon ecosystems are novel features that cycle between open and closed phases (i.e., ice-free, and ice covered, respectively). In this study, we collected high-frequency pH, salinity, temperature, and PAR measurements in association with the Beaufort Lagoon Ecosystem LTER for an entire calendar year in Kaktovik Lagoon, Alaska, USA, capturing two open water phases and one closed phase. Hourly pH variability during the open water phases are some of the fastest rates reported, exceeding 0.4 units. Baseline pH varied substantially between open phase 2018 and open phase 2019 with a difference of ~ 0.2 units despite similar hourly rates of change. Salinity-pH relationships were mixed during all three phases displaying no correlation in open 2018, a negative correlation in closed 2018–2019, and positive correlation during open 2019. The high-frequency of pH variability could partially be explained by photosynthesis-respiration cycles as correlation coefficients between daily average pH and PAR were 0.46 and 0.64 for open 2018 and open 2019 phases, respectively. The estimated annual daily average CO2 efflux was 5.9 ± 19.3 mmol m−2 d−1, which is converse to the negative influx of CO2 estimated for the coastal Beaufort Sea despite exhibiting extreme variability. Considering the geomorphic differences in Beaufort Sea lagoons, further investigation is needed to assess if there are periods of the open phase in which all lagoons are sources of carbon to the atmosphere, potentially offsetting the predicted sink capacity of the greater Beaufort Sea.

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Section: Par and Phsupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

The Seasonal Phases of an Arctic Lagoon Reveal Non-linear pH Extremes

Miller¹,

Bonsell²,

McTigue³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…In contrast, sediments on the broader Chukchi Sea shelf tend to be more uniform over larger regions in accordance with larger current systems (Grebmeier et al 2015). Also, the Beaufort Sea shelf contains a diverse range of carbon sources as possible food sources for the benthos, including large amounts of terrestrial organic material from massive river discharge, marine phytoplankton, microphytobenthos, ice algal production, and macroalgal stands in the coastal Beaufort Sea (Bell et al 2016, Harris et al 2018. In contrast, there are fewer sources of macroalgae and terrestrial material on the Chukchi shelf.…”

Section: Functional Diversity Metricsmentioning

confidence: 99%

Comparison of functional diversity of two Alaskan Arctic shelf epibenthic communities

Sutton

Iken

Bluhm

et al. 2020

Mar. Ecol. Prog. Ser.

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Alaskan Arctic shelf communities are currently experiencing dramatic changes that will likely affect ecosystem functioning of Arctic marine benthic communities. Here, functional diversity based on biological traits was used to assess differences and similarities in ecosystem functioning between 2 shelf systems that are geographically close but vary in many environmental influences: the Arctic Beaufort and Chukchi Sea epibenthic communities. We hypothesized that (1) patterns of functional composition and diversity metrics reflect patterns in taxonomic composition and diversity metrics in these 2 shelf communities; and (2) patterns in functional diversity metrics are distinct between the 2 shelves. We evaluated 9 biological traits (body form, body size, feeding habit, fragility, larval development, living habit, movement, reproductive strategy, sociability) for 327 taxa in 2014 and 2015. For each trait, multiple modalities (specific expressions within a trait) were considered. Patterns in functional diversity metrics on both shelves reflected those in taxonomic diversity metrics. However, shelf communities were more similar in functional- than in taxonomic composition. Beaufort Sea communities had higher functional dissimilarity and functional evenness driven by differences in the modalities within body form, body size, larval development, and reproductive strategy. These traits primarily affect nutrient cycling, energy turnover, and recovery from disturbances, suggesting a stronger potential for future maintenance of ecosystem function, and indicating a more even use of resources in the Beaufort Sea. The combination of functional and taxonomic diversity metrics enabled a comprehensive understanding of how ecological niche space is used and how epibenthic communities function in Alaskan Arctic shelf systems.

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“…The fate of terrestrial materials in the marine system is linked to physical and biological processes in the water column. Flocculation and sedimentation at the land-ocean interface (Meslard et al, 2018), and photodegradation and mineralization can act to remove OM from the water column while uptake by coastal biota can integrate terrestrial OM into the marine food-web (Parsons et al, 1989;Harris et al, 2018). Turbid freshwater plumes can also stratify the water column and inhibit nutrient-rich deep water renewal (Torsvik et al, 2019), while also rapidly attenuating light critical for photosynthesis (Murray et al, 2015;Holinde and Zielinski, 2016;Pavlov et al, 2019), with implications for the autotrophic: heterotrophic balance in nearshore areas (Wikner and Andersson, 2012).…”

Section: Introductionmentioning

confidence: 99%

Terrestrial Inputs Drive Seasonality in Organic Matter and Nutrient Biogeochemistry in a High Arctic Fjord System (Isfjorden, Svalbard)

et al. 2020

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Climate-change driven increases in temperature and precipitation are leading to increased discharge of freshwater and terrestrial material to Arctic coastal ecosystems. These inputs bring sediments, nutrients and organic matter (OM) across the landocean interface with a range of implications for coastal ecosystems and biogeochemical cycling. To investigate responses to terrestrial inputs, physicochemical conditions were characterized in a river-and glacier-influenced Arctic fjord system (Isfjorden, Svalbard) from May to August in 2018 and 2019. Our observations revealed a pervasive freshwater footprint in the inner fjord arms, the geochemical properties of which varied spatially and seasonally as the melt season progressed. In June, during the spring freshet, rivers were a source of dissolved organic carbon (DOC; with concentrations up to 1410 µmol L −1). In August, permafrost and glacial-fed meltwater was a source of inorganic nutrients including NO 2 + NO 3 , with concentrations 12-fold higher in the rivers than in the fjord. While marine OM dominated in May following the spring phytoplankton bloom, terrestrial OM was present throughout Isfjorden in June and August. Results suggest that enhanced land-ocean connectivity could lead to profound changes in the biogeochemistry and ecology of Svalbard fjords. Given the anticipated warming and associated increases in precipitation, permafrost thaw and freshwater discharge, our results highlight the need for more detailed seasonal field sampling in small Arctic catchments and receiving aquatic systems.

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Do high Arctic coastal food webs rely on a terrestrial carbon subsidy?

Cited by 49 publications

References 75 publications

The Seasonal Phases of an Arctic Lagoon Reveal Non-linear pH Extremes

The Seasonal Phases of an Arctic Lagoon Reveal Non-linear pH Extremes

Comparison of functional diversity of two Alaskan Arctic shelf epibenthic communities

Terrestrial Inputs Drive Seasonality in Organic Matter and Nutrient Biogeochemistry in a High Arctic Fjord System (Isfjorden, Svalbard)

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