Comparison of sinking and sedimentation rate measurements in a diatom winter/spring bloom

Riebesell, Ulf

doi:10.3354/meps054109

Cited by 95 publications

(49 citation statements)

References 39 publications

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“…Aggregate formation and relevance of mixing Sedimentation was significantly enhanced by aggregation of (living) particles at the peak of the bloom, and a phenomenon already observed in previous laboratory and field experiments (e.g., Riebesell 1989;Kiørboe et al 1994). Relative loss rates due to aggregate formation reached values up to 0.5 day -1 (Fig.…”

Section: Size-mediated Indirect Interactionsmentioning

confidence: 57%

Mechanistic origins of variability in phytoplankton dynamics. Part II: analysis of mesocosm blooms under climate change scenarios

Wirtz

Sommer²

2013

Mar Biol

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Driving factors of phytoplankton spring blooms have been discussed since long, but rarely analyzed quantitatively. Here, we use a mechanistic size-based ecosystem model to reconstruct observations made during the Kiel mesocosm experiments (2005)(2006). The model accurately hindcasts highly variable bloom developments including community shifts in cell size. Under low light, phytoplankton dynamics was mostly controlled by selective mesozooplankton grazing. Selective grazing also explains initial dominance of large diatoms under high light conditions. All blooms were mainly terminated by aggregation and sedimentation. Allometries in nutrient uptake capabilities led to a delayed, post-bloom dominance of small species. In general, biomass and trait dynamics revealed many mutual dependencies, while growth factors decoupled from the respective selective forces. A size shift induced by one factor often changed the growth dependency on other factors. Within climate change scenarios, these indirect effects produced large sensitivities of ecosystem fluxes to the size distribution of winter phytoplankton. These sensitivities exceeded those found for changes in vertical mixing, whereas temperature changes only had minimal impacts.

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Section: Size-mediated Indirect Interactionsmentioning

confidence: 57%

Mechanistic origins of variability in phytoplankton dynamics. Part II: analysis of mesocosm blooms under climate change scenarios

Wirtz

Sommer²

2013

Mar Biol

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“…High sedimentation of diatoms during spring blooms has been reported by Smetacek (1985) and Peinert et al (1982). In general, diatom sinking rates increase dramatically upon nutrient depletion (Bienfang 1981, Riebesell 1989. During our study the diatom bloom, dominated by Skeletonema costatum, became silicate depleted.…”

Section: Diatom Spring Bloommentioning

confidence: 58%

“…Assilrning daiiy losses of 5 O/b due to cell lysis and assuming no growth of diatoms after the peak in cell number (Day 92), daily sedimentation losses varied between 4 and 15% of diatom standing stock per day. This is low compared to valaes (up to 50% d-l) reported by Riebesell (1989) and Passow (1991). In their studies the mixing of the water column was considerably reduced, probably resulting in enhanced sedimentation of the diatom population.…”

Section: Diatom Spring Bloommentioning

confidence: 72%

“…Grazing and cell lysis could account for all of the phytoplankton losses (mainly from the >8 pm size fraction), so sedimentation apparently was of no importance. Riebesell (1989) also found that sedimentation was not a significant loss factor for Chaetoceros spp. and Leptocylindrus minimus.…”

Section: Transition Periodmentioning

confidence: 77%

“…During our study the diatom bloom, dominated by Skeletonema costatum, became silicate depleted. Riebesell (1989) found enhanced sinking of ungrazed Skeletonema costatum and Thalassiosira spp, cells during the diatom spring bloom. These high sinking rates (max.…”

Section: Diatom Spring Bloommentioning

confidence: 99%

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Effects of grazing, sedimentation and phytoplankton cell lysis on the structure of a coastal pelagic food web

Brussaard¹,

Riegman²,

Noordeloos³

et al. 1995

Mar. Ecol. Prog. Ser.

211

146

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The influence of grazing, sedimentation and phytoplankton cell lysis on the dynamics of a coastal pelagic ecosystem in the Southern Bight of the North Sea was studied during spring/summer 1992. Diatoms in the > 8 pm size fraction dominated during early spring, due to size-differential control by microzooplankton. This diatom spring bloom became silicate depleted and declined by sedimentation. A Phaeocystis bloom developed in early summer. Phytoplankton cell lysis was the major loss factor for Phaeocystjs, accounting for 75% of the decline of the bloom. Bacterial production was positively correlated with phytoplankton cell lysis, and bacterial carbon demand could be supplied by cell lysis. This illustrates the importance of phytoplankton cell lysis in providing energy for the microbial loop. A new method (nicotine addit~on technique) was used to estimate mesozooplankton grazing on microzooplankton. h4esozooplankton appeared to prefer microzooplankton as a food source, though there occasionally was substantial grazing on phytoplankton. We conclude that grazing and sedimentation, as well as call lysis, are structuring mechanisms for algal bloom dynamics.

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Sedimentation - the main Loss Factor in Waters Dominated by Diatoms. Results of Long-Term Investigations

Horn

Hörn

2000

Internat. Rev. Hydrobiol.

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In the mesotrophic reservoir Saidenbach, diatoms are dominating the phytoplankton. The long‐term mean percentage (1989 to 1996) was 77% of the total phytoplankton biovolume. Sedimentation is the major loss process for these mainly microplanktic algae. In the sediment trap they contribute, on average, 95% to the biovolume, i.e. they are overrepresented because all other phytoplankton taxa reach the bottom in a non‐recognizable state or do not arrive there at all. The mean phytoplankton biovolume sedimenting during the period 1989 to 1996 was 3.5 cm3 m–2 d–1. With a time delay of two weeks the flux showed the same high variations (about 0.2 to 20 cm3 m–2 d–1) as the abundance in the pelagic. The diatom concentration in the open water has the highest influence on dynamics and amount of the phytoplankton flux, thus explaining 82% of its variance. In the annual average the calculated sedimentation rates for selected diatoms are always 2 to 2.5 times higher than the positive rates of change, whereas the grazing rates are about 10% of these positive rates only. The comparison of yearly biomass yields and losses shows similar results: The sedimentation of diatoms amounts to 1217 cm3 m–2 a–1 (mean of 8 years), i.e. 2.5 times higher than the positive yearly diatom net production of 494 cm3 m–2 a–1 observedin the reservoir for the same period. Provided there are no further essential loss components and the yearly gross production can be assumed to be the sum of annual sedimentation and grazing losses, some 13% only of the phytoplankton gross production (or 9% of diatom production) are grazed in one year, while 87% (or 91% of the diatoms) sediment. The long‐term measurements show the great significance of the diatom sedimentation and confirm their function as a so‐called lake internal tertiary treatment step (Grim, 1967). Under the prerequisites of a diatom water (i.e. P limitation with sufficient Si supply and adequate turbulence) high sedimentation losses guarantee the maintenance of a low trophic state. Moreover, they are the cause for the high buffering capacity, even for unusually high nutrient loads within restricted periods.

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Comparison of sinking and sedimentation rate measurements in a diatom winter/spring bloom

Cited by 95 publications

References 39 publications

Mechanistic origins of variability in phytoplankton dynamics. Part II: analysis of mesocosm blooms under climate change scenarios

Mechanistic origins of variability in phytoplankton dynamics. Part II: analysis of mesocosm blooms under climate change scenarios

Effects of grazing, sedimentation and phytoplankton cell lysis on the structure of a coastal pelagic food web

Sedimentation - the main Loss Factor in Waters Dominated by Diatoms. Results of Long-Term Investigations

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