Phytoplankton observations in offshore Norwegian coastal waters between 62° N and 69° N. 2. Diatom societies from Möre to Vesterålen, March–April 1968–1971

Braarud, Trygve; Nygaard, Ingrid

doi:10.1080/00364827.1980.10431478

Cited by 20 publications

(17 citation statements)

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“…Thus, the importance of the heterotrophic components of the microbial loop became recognised (Williams 1981); however, the role of photosynthetic picophytoplankton in northern ecosystems still received little attention. This was due to the fact that sampling efforts traditionally have been focused on the spring bloom period because the new production of larger-celled species in this period has a strong link to mesozooplankton and fish production (Sverdrup 1953, Steele 1974, Braarud & Nygaard 1978. During the spring bloom, the relative abundance of picophytoplankton is low (Li et al 1993) when compared to oligotrophic subtropical waters (Agawin et al 2000).…”

Section: Open Pen Access Ccessmentioning

confidence: 99%

Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic spring bloom development

Paulsen¹,

Riisgaard²,

John³

et al. 2017

Aquat. Microb. Ecol.

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My study underpins that picophytoplankton are important contributors to primary production, especially during the winter-spring transition (Paper I and III) and autumn (Paper V). They boosted the growth of heterotrophic microorganisms before the onset of the diatom spring bloom in the Subarctic Atlantic (Paper I) and dominated the phytoplankton biomass in the high turbid parts of a NE Greenland fjord influenced by glacial meltwater (Paper V). Picophytoplankton were better adapted to low light conditions and demonstrated higher growth rates, than larger phytoplankton (Paper I, II, III, V). In the Polar-influenced water near Greenland, Synechococcus were negligible, while in the Atlantic influenced waters picoeukaryotes and Synechococcus were often equally abundant and the latter dominated on several occasions during autumn and winter (Paper I and III). Unexpectedly, abundances of Synechococcus were as high at 65°N as at 79°N, and molecular analysis suggests the presence of new clades specially adapted to Arctic conditions. Bacteria were generally rather carbon-than nutrient limited, and their abundance increased rapidly in response to the pre-bloom picophytoplankton production of labile carbon in both the Arctic and Subarctic (Paper I and V). In NE Greenland the terrestrial DOM supplied from the Greenland ice sheet proved to be highly bioavailable compared to the 7 autochthonous fjord DOM (Paper IV). The in situ changes in DOM, which were examined via fluorescence signal of different DOM components (FDOM), surprisingly demonstrated that the highest net-growth of bacteria was not coupled to the labile glacial runoff in the surface, but rather to sub-surface the humic-DOM, commonly considered to be refractory. This may be explained by the presence of specific dominating taxa of bacteria that had the ability to degrade humic-DOM (Paper V).Across regions, HNF exerted strong control of picophytoplankton and bacteria (Paper I, II, III, V). HNF grew significantly faster than microzooplankton and were therefore less affected by mixing and relatively more important grazers than their micro-sized counterparts in well-mixed water columns (Paper I and II). HNF larger than 5µm controlled picophytoplankton particularly in the early productive season, while small HNF (3-5µm) mainly kept bacteria in check in autumn (Paper III, V). In conclusion, the studies underline that pico-sized plankton play a fundamental part in the carbon transfer in high latitude ecosystems both as primary producers and via the microbial loop. Picophytoplankton appeared better adapted than larger phytoplankton to low light conditions, and bacteria were capable of degrading terrestrial derived DOM, however, these abilities are highly community specific. The data suggest that a change in mixing patters will affect the microbial food structure and that shifts in coastal microbial community composition should be anticipated with increased runoff. 8 List of publicationsThe thesis is based on preliminary data and the following fived papers referred to in the t...

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Section: Open Pen Access Ccessmentioning

confidence: 99%

Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic spring bloom development

Paulsen¹,

Riisgaard²,

John³

et al. 2017

Aquat. Microb. Ecol.

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“…Kamatani (1982) showed that dissolution of diatom frustules was strongly dependent on organic coating, surface texture, temperature, and &atom species. Skeletonema costatum, which typically dominates the spring bloom in Norwegian coastal waters (Lannergren & Skjoldal 1976, Braarud & Nygaard 1980, Hegseth 1982, Erga & Heimdal 1984, displayed the most rapid dissolution with a rate coefficient of 1.3 X ~O -~h -l at 10 "C. However, since shaking increased the dissolution rate by about an order of magnitude for 2 other species (Kamatani 1982), the rate coefficient could be as high as about 10-~h-' for sinking frustules of Skeletonema costatum. Rates in the range 1 0 -~ to 10-'h-' represent dissolution of 15 to 81 % of the Psi in 1 wk.…”

Section: Sedimentation In Springmentioning

confidence: 99%

Sedimentation of particulate organic matter and silicium during spring and summer in Lindaspollene, Western Norway

Skjoidal¹,

Wassmann²

1986

Mar. Ecol. Prog. Ser.

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Sedimentation of organic and inorganic matter was determined at 18, 38, 70 and 85 m between 17 March and 8 October 1982, m the land-locked flord Llndespollene Rates of sedimentation were highest dunng spnng with 2 peaks in sedmentation followmg the first spnng diatom bloonl and a second bloom not dominated by diatoms About half of the biomass (C and N) formed dunng these 2 blooms apparently sedimented out from the euphohc zone Based on the vertical structure of the plankton commumty it is concluded that sedimenting material dunng summer mainly originates from the deeper part of the euphotic zone containing a chlorophyll maxlmum layer Sedimentation of organic matter was correlated with sedimentahon of parhculate shcium both d u n n g spnng and summer, suggesting that s i n l n g of diatom frustules is a major transport mechanism for vertical flux of organic material Recovery of parhculate sihcium In sediment traps compared to seston content was lower than for organic matenal This indicates rapid dissoluhon of shcium most of which apparently occurred withln the sediment traps Decreasing sedimentahon flux of organic material with depth below the euphohc zone and concomrmtant decrease in the N/C raho and increase in the P/C raho are interpreted to reflect substanhal mineralization and associated microbial growth on the sinking matenal

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“…The onset of the spring bloom varies from year to year, but the causes of the variation have not yet been identified. It could well be that the complex hydrography of offshore coastal waters could play a major role (Braarud and Nygård, 1978). The spring bloom consists mainly of diatoms and generally it occurs with a delay of about three weeks from Møre (62 N) to Lofoten (69 N; Smayda, 1959).…”

Section: Discussionmentioning

confidence: 99%

A possible connection between hydrography and the distribution of Calanus finmarchicus on the Norwegian midshelf in 1997

Pedersen¹

2000

ICES Journal of Marine Science

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Phytoplankton observations in offshore Norwegian coastal waters between 62° N and 69° N. 2. Diatom societies from Möre to Vesterålen, March–April 1968–1971

Cited by 20 publications

References 0 publications

Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic spring bloom development

Heterotrophic nanoflagellate grazing facilitates subarctic Atlantic spring bloom development

Sedimentation of particulate organic matter and silicium during spring and summer in Lindaspollene, Western Norway

A possible connection between hydrography and the distribution of Calanus finmarchicus on the Norwegian midshelf in 1997

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