Bacterioplankton and picophytoplankton abundance, biomass, and distribution in the Western Canada Basin during summer 2008

He, Jianfeng; Zhang, Fang; Lin, Ling; Ma, Yuxin; Chen, Jianfang

doi:10.1016/j.dsr2.2012.08.018

Cited by 27 publications

(19 citation statements)

References 53 publications

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“…Our observations of low POC:PON in the BS‐CB occurred in conjunction with low abundance of > 5 µm chl a , low bSiO 2 concentrations, reduced abundance of larger (>8 µm) cells (diatoms, dinoflagellates, and cryptomonads), and a greater relative contribution of small (<8 µm) flagellates. This evidence supports the concept of planktonic communities dominated by small phytoplankton, bacterioplankton, and other heterotrophs, as in other Arctic basins [ Sherr et al ., ; Kirchman et al ., ; He et al ., ]. If there has indeed been a recent shift in the Canada Basin toward a community dominated by picophytoplankton (<2 µm) and bacterioplankton [ Li et al ., ] in response to sea ice melt, freshening, and stabilization of the water column [ McLaughlin and Carmack , ], then our findings point to the intriguing possibility that decreasing POC:PON ratios may be a consequence of this shift.…”

Section: Discussionmentioning

confidence: 99%

Low particulate carbon to nitrogen ratios in marine surface waters of the Arctic

Crawford

Wyatt

Wrohan

et al. 2015

Global Biogeochemical Cycles

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During the Canada's Three Oceans and Joint Ocean Ice Study projects in the summers of 2007 and 2008, we measured particulate organic carbon to nitrogen ratios (POC:PON) throughout the euphotic zone in Subarctic and Arctic waters. Average depth‐integrated values (2.65 ± 0.19) in the Beaufort Sea and Canada Basin (BS‐CB domain) were much lower than both the Redfield ratio (6.6) and the average ratios (3.9 to 5.6) measured across other Arctic‐Subarctic domains. Average uptake ratios of C and N (ρC:ρN) were also lower (0.87 ± 0.14) in BS‐CB than in the other four domains (2.10 to 3.51). Decreasing POC:PON ratios were associated with low concentrations of phytoplankton C, reduced abundance of biogenic silica (bSiO2), a smaller relative contribution of the >5 µm fraction to total chlorophyll a and a larger relative contribution of small flagellates (<8 µm) to total phytoplankton C. In the subsurface chlorophyll a maximum (SCM) within the BS‐CB domain, phytoplankton C represented only ~13% of POC; and therefore, the presence of heterotrophic microbes may have decreased POC:PON. These ratios are supported by data obtained during other Arctic programs in 2006, 2008, and 2009. Previous work has suggested a link between freshening of surface waters and increasing dominance of picophytoplankton and bacterioplankton in the Canada Basin, and the low POC:PON ratios measured during this study may be a consequence of this shift. Our results have ramifications for the conversion between C‐ and N‐based estimates of primary productivity, and for biogeochemical modeling of marine Arctic waters.

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Section: Discussionmentioning

confidence: 99%

Low particulate carbon to nitrogen ratios in marine surface waters of the Arctic

Crawford

Wyatt

Wrohan

et al. 2015

Global Biogeochemical Cycles

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“…Several studies have been carried out on picophytoplankton (size range 2-0.2 lm) communities in the Arctic Ocean (Gradinger and Lenz 1995;Li 1998;Sherr et al 2003;Lovejoy et al 2006;Terrado et al 2008;Cottrell and Kirchman 2009;Li et al 2009;He et al 2012). Such studies in the central Arctic Ocean, however, are rare (Gradinger and Lenz 1995;Sherr et al 2003;Kilias et al 2014) because water in this region was formerly covered with sea ice (Booth and Horner 1997).…”

Section: Introductionmentioning

confidence: 97%

Dominance of picophytoplankton in the newly open surface water of the central Arctic Ocean

Zhang

Lin

et al. 2015

Polar Biol

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Picophytoplankton are the main primary producers in oligotrophic oceans. They account for more than 90 % of the phototrophic biomass. Investigations of picophytoplankton in the central Arctic Ocean region are rare because these waters used to be completely covered with sea ice. Large, newly exposed water areas, however, appeared in the sea ice zone during the summer of 2010. This provided the first opportunity to study the Arctic picophytoplankton community in these newly open surface waters. This study focuses on the picophytoplankton in the areas near the Alpha-Mendeleev Ridge and Makarov Basin. Here, HPLC pigment analysis with CHEMTAX was used to study community populations, and 454 pyrosequencing with bioinformatics analysis was used to identify the dominant genera (species). Both Pearson correlation analysis and canonical correlation analysis were used to study the relationships between the community and environmental factors. We found chlorophyll a concentrations were low (0.05-0.39 lg l -1 ), and picophytoplankton dominated these areas. The abundances of picophytoplankton were 1.58 9 10 6 -9.47 9 10 6 cells l -1 and made up 44-80 % of the total chlorophyll a. Prasinophytes made up 0-88 % of the picoplanktonic chlorophyll a with the following distributions: diatoms (2-80 %), cyanobacteria (0-20 %), haptophytes (4-14 %), and dinoflagellates (2-11 %). The dominant genera (species) in the picoeukaryotes were Pyramimonas (Pyramimonas gelidicola), Micromonas (Micromonas pusilla), and Phaeocystis. Salinity and latitude were the primary factors controlling the community structure of the picophytoplankton.

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“…Prior to the recent decline in summer S. R. Shah et al: Prominent bacterial heterotrophy and sources of 13 C-depleted fatty acids sea ice, ice-tethered sediment traps in the Canada Basin documented a much smaller POC flux through the upper 200 m than is observed in other oligotrophic regions (Honjo et al, 2010). Despite a vanishingly small, and likely decreasing supply of autochthonous organic carbon exported from the sea surface, prokaryotic abundance at mesopelagic and bathypelagic depths in the Canada Basin (> 100 m) were found to be comparable to subtropical and equatorial regions (He et al, 2012;Uchimiya et al, 2013). This imbalance between prokaryotic abundance and sinking POC flux suggests the importance of an alternate carbon and energy source supporting microbial productivity in the deep Canada Basin.…”

Section: Introductionmentioning

confidence: 86%

“…Previous work indicates that ice cover affects POC flux, bacterial abundance and bacterial productivity in the western Arctic Ocean, but these investigations often combine the influences of ice cover and seasonality (Honjo et al, 2010; or compare the shallower, nutrient-rich and more ice-free Chukchi Sea with the western Canada Basin (He et al, 2012;Honjo et al, 2010;Moran et al, 2005;Rich et al, 1998). We find supporting evidence that ice cover affects the concentration and composition of epipelagic organic carbon within Canada Basin by comparing stations CB4 and CB9.…”

Section: Semi-permanently Ice-covered Vs Seasonally Ice-free Surfacementioning

confidence: 99%

Prominent bacterial heterotrophy and sources of <sup>13</sup>C-depleted fatty acids to the interior Canada Basin

et al. 2013

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Abstract. In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to deeper waters, particularly as our baseline understanding of organic carbon cycling in the deep basin is quite limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated and 13C-enriched under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ13C values that are similar to suspended POC at all depths and are more 13C-enriched than even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. Below surface waters, there is also the suggestion of a source of saturated even-numbered fatty acids which could represent contributions from laterally advected organic carbon and/or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C20–24), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon. At these deep depths, two individual fatty acids (C12 and iso-C17) are significantly depleted in 13C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin.

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Bacterioplankton and picophytoplankton abundance, biomass, and distribution in the Western Canada Basin during summer 2008

Cited by 27 publications

References 53 publications

Low particulate carbon to nitrogen ratios in marine surface waters of the Arctic

Low particulate carbon to nitrogen ratios in marine surface waters of the Arctic

Dominance of picophytoplankton in the newly open surface water of the central Arctic Ocean

Prominent bacterial heterotrophy and sources of <sup>13</sup>C-depleted fatty acids to the interior Canada Basin

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Bacterioplankton and picophytoplankton abundance, biomass, and distribution in the Western Canada Basin during summer 2008

Cited by 27 publications

References 53 publications

Low particulate carbon to nitrogen ratios in marine surface waters of the Arctic

Low particulate carbon to nitrogen ratios in marine surface waters of the Arctic

Dominance of picophytoplankton in the newly open surface water of the central Arctic Ocean

Prominent bacterial heterotrophy and sources of &lt;sup&gt;13&lt;/sup&gt;C-depleted fatty acids to the interior Canada Basin

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Prominent bacterial heterotrophy and sources of <sup>13</sup>C-depleted fatty acids to the interior Canada Basin