Population dynamics and trophic coupling in pelagic microorganisms in eutrophic coastal waters

Andersen, Per; Sørensen, H. B.

doi:10.3354/meps033099

Cited by 120 publications

(53 citation statements)

References 15 publications

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“…To examine this possibility, specific clearance rates were calculated by dividing grazing rates by bacterial densities (Table 4). Results showed that specific clearance rates of HNF in Uranouchi-Wan were 1 to 3 nl HNF -1 h -1 and those were exactly similar range to those previously reported (Andersen and Sørensen, 1986;Fukami et al, 1991a) but that HNF clearance rates in the 5 and 10 m depths were generally higher than those in surface layer (Table 4). This suggests that HNF in deeper layers were more active than the surface ones.…”

Section: Discussionsupporting

confidence: 76%

“…From many recent studies, it is generally accepted that HNF is one of the most important bacterial consumers (Andersen and Sørensen, 1986;Fenchel, 1986;Rassoulzadegan and Seldon, 1986;Pace, 1988;Wikner and Hagström, 1988;Nakamura et al, 1994). Previous studies have clarified the distribution of bacteria and HNF in various aquatic environments.…”

Section: Introductionmentioning

confidence: 99%

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Distribution of heterotrophic nanoflagellates and their importance as the bacterial consumer in a eutrophic coastal seawater

et al. 1996

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Seasonal and vertical changes in abundances of bacteria and heterotrophic nanoflagellates (HNF), and HNF grazing on bacteria were investigated in a small eutrophic inlet of Uranouchi-Wan throughout the years. Bacterial densities in the surface water ranged from 1.2 to 11 (average 4.3) × 10 6 cells ml -1 with a couple of maxima following the algal blooming. Densities of HNF ranged from 0.54 to 73 (average 16.4) × 10 3 cells ml -1 in the surface, and showed almost similar fluctuation pattern to that of bacteria with a time lag of about 1 to 2 weeks. Grazing rates of HNF on bacteria obtained by FLB method were 4.78 to 16.9 (average 10.3 ± SD 4.8) cells HNF -1 h -1 in the surface layer in summer, and consequent total bacterial consumption rates by HNF fluctuated from 4 to 99 × 10 4 cells ml -1 h -1 . In deeper layers, however, as HNF densities and grazing rates on bacteria were low, the grazing pressure of HNF on bacteria was small. Turnover times of bacteria by HNF grazing in the surface layer were calculated as relatively constant values of 40 to 60 h, however, it decreased to as low as 6 to 7 h when the HNF activity was highest. These results indicate that bacteria grew so actively by consuming organic matter in seawater as to compensate high HNF grazing pressure, and that bacteria and HNF in the microbial loop play important roles on the turnover of substrates in coastal ecosystems.

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Section: Discussionsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Distribution of heterotrophic nanoflagellates and their importance as the bacterial consumer in a eutrophic coastal seawater

et al. 1996

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“…Our values for flagellate abundances were close to those obtained in the St. Lawrence estuary, 1.9 X 106 to 6 X 106 cells 1-' (Lovejoy et al 1993), and in the marine shallow-water Lirnfjorden in Denmark, 2 X 106 cells 1-' (Andersen & Sarensen 1986).…”

Section: 126038supporting

confidence: 62%

Retention of ciliates and flagellates by the oyster Crassostrea gigas in French Atlantic coastal ponds:protists as a trophic link between bacterioplankton and benthic suspension-feeders

Dupuy¹,

Gall²,

Hartmann³

et al. 1999

Mar. Ecol. Prog. Ser.

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Retention of ciliates and flagellates by the oyster. In order to evaluate the importance of the 'protozoan trophic link' for energy transfer from the 'microbial food web' to large benthic suspension feeders, we offered a coastal pond comn~unity of ciliates and flagellates as potential prey to the oyster Crassostrea gigas. Clearance rate, filtered particles and relative retention efficiency were evaluated. In the grazing experiment, 94 % of ciliates and 86% of flagellates (size between 4 and 72 pm), were retained by the oyster. Whatever their size, protists were similarly retained by the oyster gills. In terms of carbon, oysters retain on average 126 pg C h-' g-' dry weight, a value over 4 times h~g h e r than reported for phytoplankton. These results indicate that a field community of protists can contribute in coastal oyster rearing ponds to the energy requirements of the oyster C. gigas. We report here the first experimental ev~dence of a significant retention of a protist community by oysters, supporting the role of protists as a trophic link between picoplankton and benthic filter-feeding bivalves. The importance of phytoplankton in the nutrition of oysters is well documented , Pastoureaud et al. 1996. However, in oyster rearing environments, such as the particularly light-limited turbid estuary of Marennes-Oleron, or in coastal ponds of the Charente where nutrients are quickly exhausted, phytoplankton cannot entirely account for the energy requirements of oysters .In the oceans, more than 50% of the primary production is due to unicellular organisms less than 3 pm in size (Li et al. 1983, Glover et al. 1986), which constitutes a nutrient source of particulate and dissolved organic matter for heterotrophic organisms. Dissolved organic matter (DOM) present in coastal waters (Pomeroy & Wiebe 1993) provides a potential for high bacterial production. Thus, in the 0 Inter-Research 1999Resale of full artrcle not perrnltted

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“…In marine pelagic environments, heterotrophic nanoflagellates are the most probable consumers of bacterial cell production (Fenchel 1984(Fenchel , 1986. Laboratory experiments with cultured flagellates have demonstrated that they are adapted to predation on bacteria-sized particles (Fenchel 1982a), and they occur in seawater in concentrations sufficient to control bacterial biomass (see Sherr and Sherr 1984).…”

mentioning

confidence: 99%

Trophic interactions between heterotrophic nanoflagellates and bacterioplankton in manipulated seawater enclosures1

Bjørnsen

Riemann

Horsted

et al. 1988

Limnology & Oceanography

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Biomasses of bacterioplankton and heterotrophic flagellates and bacterial net production rates were measured intensively during three periods of 16-25 d in estuarine experimental enclosures manipulated by additions of inorganic nutrients, fish, and mussels. Tightly coupled oscillations in biomasses of bacteria and flagellates were found, particularly during summer. The amplitude of the oscillations increased in response to artificial eutrophication with inorganic nutrients and decreased in response to predation control from added mussels. Losses of bacterioplankton by grazing were assessed indirectly with carbon balances for each enclosure and directly with procaryotic inhibitors and with 3H-labelcd bacteria. Estimates obtained by these three independent approaches showed clearance rates averaging 1.5-2.5 nl h-l flagellate-l.Comparison of grazing rates to increases in flagellate biomass revealed minimum estimates of flagellate carbon yield averaging 33%. High minimum yields were found in some enclosures during summer. Carbon sources other than bacteria may have been used by heterotrophic flagellates in these situations.

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Population dynamics and trophic coupling in pelagic microorganisms in eutrophic coastal waters

Cited by 120 publications

References 15 publications

Distribution of heterotrophic nanoflagellates and their importance as the bacterial consumer in a eutrophic coastal seawater

Distribution of heterotrophic nanoflagellates and their importance as the bacterial consumer in a eutrophic coastal seawater

Retention of ciliates and flagellates by the oyster Crassostrea gigas in French Atlantic coastal ponds:protists as a trophic link between bacterioplankton and benthic suspension-feeders

Trophic interactions between heterotrophic nanoflagellates and bacterioplankton in manipulated seawater enclosures1

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