Relationships between bacteria and heterotrophic nanoplankton in marine and fresh waters: an inter-ecosystem comparison

Sanders, Robert W.; Caron, David A.; Berninger, Ulrike-Gabriele

doi:10.3354/meps086001

Cited by 442 publications

(384 citation statements)

References 39 publications

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“…Some have argued that the observed decrease in bacterial biomass and activity with increasing trophic state is a result of increases in the consumption of bacterial biomass by protozoan grazers (e.g., Sanders et al 1992). It has also been proposed that bacterial mortality increases with trophic state as a result of increased viral lysis (Weinbauer and Peduzzi 1995).…”

Section: Resultsmentioning

confidence: 99%

Nutrient and light availability regulate the relative contribution of autotrophs and heterotrophs to respiration in freshwater pelagic ecosystems

Roberts

Howarth

2006

Limnol. Oceanogr.

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In this study, two main hypotheses were addressed. (1) Bacteria contribute proportionally less than autotrophs to ecosystem respiration as trophic status increases. This hypothesis was examined in a pond phosphorus-fertilization experiment and two microcosm nutrient-fertilization experiments. (2) The relative contribution of autotrophs to ecosystem respiration, at a given nutrient availability, increases as light availability increases. This hypothesis was tested in three light by nutrient factorial microcosm experiments. Rates of total plankton community, bacterial (Ͻ1 m fraction), and phytoplankton (total Ϫ bacterial) respiration all increased as nutrient availability increased. The contribution of bacteria to community respiration ranged between ϳ10 and 90%, with the highest contribution occurring under the most oligotrophic conditions. As light availability increased within each nutrient availability treatment, there was a similar decline in the contribution of bacteria to community respiration. Under oligotrophic conditions bacteria are better competitors for nutrients that limit both autotrophs and heterotrophs, but as nutrient availability increases, conditions become increasingly favorable for larger celled phytoplankton that have higher maximal nutrient uptake rates. As light availability increases, the relative contribution of phytoplankton to ecosystem respiration also increases. Light and nutrient availability are important regulators of the relative contributions of autotrophs and heterotrophs to ecosystem respiration, but the observed patterns are primarily driven by changes in phytoplankton production rates.

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Section: Resultsmentioning

confidence: 99%

Nutrient and light availability regulate the relative contribution of autotrophs and heterotrophs to respiration in freshwater pelagic ecosystems

Roberts

Howarth

2006

Limnol. Oceanogr.

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“…4b). Nevertheless, there was no proportional increases in HNF with respect to bacteria, suggesting that relationships between bacteria and flagellates may not be as widespread as suggested by Sanders et al (1992). They found this ratio was constant at about 1000:1 across a wide variety of ecosystems, and they examined the implications of this ratio by developing a model of bacterial dynamics as a function of substrate supply and flagellate predation.…”

Section: Bacterial Productionmentioning

confidence: 99%

“…Algae then obtain greater portions of P, and algal abundance begins to increase more rapidly than bacte~ rial abundance. Alternatively, it is possible that bacteria were more heavily grazed on in eutrophic than in oligotrophic systems (Beaver & Crisman, 1982;Sanders et al, 1992). Dortch & Packard (1989), as well, pointed out that the food webs in oligntrophic and eutrophic waters must be fundamentally different.…”

Section: Bacterial Productionmentioning

confidence: 99%

“…On the other hand, comparisons of the quantities of heterotrophic nanoflagellates (HNF) and bacteria imply that, in some 9 Addressee for all correspondence. D Blologische Anstalt t telgoland, Hamburg cases, predatory control (top-down regulation) of bacteria may be of major importance in eutrophic environments (Berninger et al, 1991;Sanders et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

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Relationship between bacteria, phytoplankton and heterotrophic nanoflagellates along the trophic gradient

Krstulović

Šolić

Marasović

1998

Helgoländer Meeresunters.

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Bacterial and heterotrophic ndnoflagellates (HNF) abundance, as well as bacterial production and chlorophyll a levels, were measured at live sites extending from the coastal zone toward the open Adriatic in the period from March to October "i995. The investigated areas were grouped into trophic categories according to concentrations of chlorophyll u. All the biotic-parrsmeters increased along the trophic gradient, ledding to eutrophy, but they did not increase at the same rate. The bacterial biomass : phytoplankton biomass {BB : chl u) ratio decreased from about 10 in the very oligntrophic area to 0.8 at the eutrophw site. In contrast, the bacterial abundance : HNF abundance ratio iB : HNF) increased from 1000 bacteria per 1 tlagellate in the oligotrophlc system to .1700 bacteria flagellate' in the eutrophic area. Decreasing BB : chl a and :ncreasing B : HNF ratios along the trophic gradient might rellect the dflterent structures of the microbial food web. Relationships between bacterial abur~danc:e and production, and chl a and t-{NF showed that bacterial abundance along the trophic grddient was regulated by the interplay between nutrient supply and grazing pressure. But in the oligotrophic system, bacterial abundance was more closely related to bacteriaL production and chl u than m the eutrophic system, suggesting stronger control of bacteridl abundance by substrate supply C)n the other hand, the coupling between bacteria and HNF, and uncoupling between bacterial dbundance and production in the eutrophic system, showed that the importance ot bactenovorv increased in richer systems.

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“…The cell numbers of HNF we encountered were in general in the lower end of those observed globally (Sanders et al 1992) but very similar to those found in Arctic marine systems during the period of winter− spring transition (Vaqué et al 2008, Iversen & Seuthe 2011. Peak abundances of 300 cells ml −1 were observed during our study period.…”

Section: Heterotrophic Protist: Top-down Control On Picophytoplankton?mentioning

confidence: 60%

Winter-spring transition in the subarctic Atlantic: microbial response to deep mixing and pre-bloom production

Paulsen¹,

Riisgaard²,

Thingstad³

et al. 2015

Aquat. Microb. Ecol.

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In temperate, subpolar and polar marine systems, the classical perception is that diatoms initiate the spring bloom and thereby mark the beginning of the productive season. Contrary to this view, we document an active microbial food web dominated by pico-and nanoplankton prior to the diatom bloom, a period with excess nutrients and deep convection of the water column. During repeated visits to stations in the deep Iceland and Norwegian basins and the shallow Shetland Shelf (26 March to 29 April 2012), we investigated the succession and dynamics of photosynthetic and heterotrophic microorganisms. We observed that the early phytoplankton production was followed by a decrease in the carbon:nitrogen ratio of the dissolved organic matter in the deep mixed stations, an increase in heterotrophic prokaryote (bacteria) abundance and activity (indicated by the high nucleic acid:low nucleic acid bacteria ratio), and an increase in abundance and size of heterotrophic protists. The major chl a contribution in the early winter−spring transition was found in the fraction <10 µm, i.e. dominated by pico-and small nanophytoplankton. The relative abundance of picophytoplankton decreased towards the end of the cruise at all stations despite nutrient-replete conditions and increasing day length. This decrease is hypothesised to be the result of top-down control by the fast-growing population of heterotrophic protists. As a result, the subsequent succession and nutrient depletion can be left to larger phytoplankton resistant to small grazers. Further, we observed that large phytoplankton (chl a > 50 µm) were stimulated by deep mixing later in the period, while picophytoplankton were unaffected by mixing; both physical and biological reasons for this development are discussed herein.

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Relationships between bacteria and heterotrophic nanoplankton in marine and fresh waters: an inter-ecosystem comparison

Cited by 442 publications

References 39 publications

Nutrient and light availability regulate the relative contribution of autotrophs and heterotrophs to respiration in freshwater pelagic ecosystems

Nutrient and light availability regulate the relative contribution of autotrophs and heterotrophs to respiration in freshwater pelagic ecosystems

Relationship between bacteria, phytoplankton and heterotrophic nanoflagellates along the trophic gradient

Winter-spring transition in the subarctic Atlantic: microbial response to deep mixing and pre-bloom production

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