Nutrient cycling in a microflagellate food chain: II. Population dynamics and carbon cycling

Caron, DA; Goldman, JC; Andersen, OK; Dennett,

doi:10.3354/meps024243

Cited by 154 publications

(100 citation statements)

References 6 publications

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“…These low ingestion rates were, in large part, due to the relatively low phosphorus cell quotas of the Plimited prey (Table l ) . As reported earlier, microflagellate clearance (m1 cell-' d-') and specific growth rates (d-') were not greatly affected by prey nutritional state (Table 1 and Caron et al 1985). Phosphorus excretion under these conditions did not begin until the transition phase, and then at a very low rate (0.1 to 0.2 pg P cell-' d-l); even lower excretion rates occurred during the stationary period (Table 3).…”

Section: Phosphorus Excretion By Microflagellatessupporting

confidence: 78%

“…In fact, in the current experiments the average gross growth efficiency of Paraphysomonas jmperforata was 44 + 11 %, based on cell volume . Caron et al (1985) also found that respiration and, to a lesser extent, release of dissolved organic carbon by P. imperforata was tightly coupled to nutrient regeneration. Thus, as discussed previously , the marine microbial food web must be exceedingly complex with, at least, several grazing steps to achieve the high (90+ O/O) regeneration efficiencies attributed to microzooplankton by Eppley & Peterson (1979) and Jackson (1979).…”

Section: Dark Lncubat/o/v P€r/od (Days)mentioning

confidence: 85%

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Nutrient cycling in a microflagellate food chain: III. Phosphorus dynamics

Andersen¹,

Goldman²,

Caron³

et al. 1986

Mar. Ecol. Prog. Ser.

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100

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As part of a series of grazing experiments in batch cultures, we found that the phagotrophlc microflagellate Paraphysomonas imperforata, while grazing on the diatom Phaeodactylum tn'cornutum or bacteria, was responsible for the bulk of phosphorus regeneration. Regeneration of soluble reactive phosphorus (SRP) and dissolved organic phosphorus (DOP) was negligible in control cultures of the diatom alone, bacteria alone, or the 2 microbes together. When the m~croflagellate grazed on prey organisms that had been precultured with excess nutrients or under nitrogen limitation there was considerable regeneration of total dissolved phosphorus (TDP = SRP + DOP). Rates of TDP regeneration were greatest during exponential growth of the microflagellate and then decreased through the transition and stationary phases. Overall, up to 70 % of the phosphorus initially incorporated into prey biomass was regenerated through the stationary phase. Total excretion of DOP was about 15 to 20% of TDP, although DOP excretion made up a larger fraction of total phosphorus excretion for short periods during the exponential phase of growth. When the prey were phosphoruslimited virtually no TDP was excreted throughout the entire growth cycle of the microflagellate. Our results indicate that Protozoa have higher weight-specific rates of phosphorus excretion than do Metazoa. Although metabolic activity is not the sole indicator of the role Protozoa play in the nutrient regeneration process, our results, together with those from size-fractionation studies on nutrient regeneration, point toward a major role for Protozoa in pelagic waters where they constitute a large fraction of the zooplankton biomass.

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Section: Phosphorus Excretion By Microflagellatessupporting

confidence: 78%

Section: Dark Lncubat/o/v P€r/od (Days)mentioning

confidence: 85%

Nutrient cycling in a microflagellate food chain: III. Phosphorus dynamics

Andersen¹,

Goldman²,

Caron³

et al. 1986

Mar. Ecol. Prog. Ser.

Self Cite

100

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“…this range, or higher, are frequently used in food-web models, resulting in considerable potential for ciliate production. However, reported values of K, for planktonic oligotrich ciliates actually range between 8 and 76% (Caron et al 1990, extracted from table 2). Because inferences about food-web structure are highly sensitive to this coefficient, it bears further experimental attention.…”

mentioning

confidence: 99%

“…Given the natural variability of ciliate biovolume (Hamilton and Preslan 1969;Fenchel and Jonsson 1988) and that of some prey items of ciliates (Ammerman et al 1984;Caron et al 1985), biovolume can be an uncertain currency for such calculations. In addition to natural variations in cell size, fixatives and preservatives can cause shrinkage of ciliates (Choi and Stoecker 1989), microflagellates (Klein Breteler 1985), and bacteria, further calling into question volume-specific estimates of K,.…”

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confidence: 99%

Growth kinetics of the omnivorous oligotrich ciliate Strombidium sp

Ohman

Snyder

1991

Limnology & Oceanography

120

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The marine ciliate Strombidium sp. can bc raised through multiple generations on a monoxenic diet of the bacterium Vibrio natriegens, but Strombidium specific growth rates and yields are 3-4 times higher when a heterotrophic microllagellate is included as prey. In contrast to earlier studies we found that Strombidium grew inefficiently when feeding as a bacterivore, with gross growth efficiencies (K,) of 1 l-20% (determined on a nitrogen-, carbon-, and protein-specific basis). On the same bacterial diet K, of the scuticociliate Uronema sp. was 49-70%. Bacterivorous Uronema attained a 9-fold higher specific growth rate and 30-fold higher cell yield than Strombidium. Thus, the species composition of a ciliate assemblage can markedly influence the fate of microbial loop production.Cell volume of live Strombidium sp. varied > 3-fold during a growth cycle. Cell organic composition also varied: the C: N (mass) ratio decreased from 7.7 in stationary phase cells to 4.5 in exponentially growing cells, reflecting the ingestion of N-rich prey. In addition to these natural variations in cell volume, preservatives can shrink cells to half of their live volume, resulting in spurious values of ciliate growth efficiency if computed on a volume-specific basis.

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“…Heterotrophic bacteria in aquatic ecosystems depend on nutrients and dissolved organic matter as resources, and bacteria are in turn preyed upon by protozoan and metazoan plankton Caron et al 1985;Azam 1998). As such, bacteria channel dissolved inorganic and organic matter into higher trophic levels.…”

mentioning

confidence: 99%

Seasonal and vertical difference in negative and positive effects of grazers on heterotrophic bacteria in Lake Biwa

Gurung

Nakanishi

Urabe

2000

Limnology & Oceanography

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Grazers affect prey abundance negatively through grazing and positively through releasing nutrients and substrates. In the present study, the relative importance of these positive and negative effects of grazers on bacterial abundance was examined seasonally at 2.5 m and 30 m depths in Lake Biwa. We used a method by Elser and Goldman to estimate in situ growth rate, grazing rate, and the fraction of growth rate that was stimulated by grazers smaller than 100 m. At 2.5 m, the bacterial grazing rate showed clear seasonal changes with higher values in summer. At 30 m, bacterial grazing was significant but consistently low throughout the year. The fraction of the growth rate stimulated by grazers was changed with season and depth. At 2.5 m, bacteria compensated 30-40% of grazing loss by using deficient nutrients released by the grazers from May to October. During that period, bacterial growth rate was severely limited by phosphorus, and it is most likely that phosphorus release by grazers was stimulating bacteria. At 30 m, however, the bacterial growth rate was not stimulated by the grazers in the majority of the cases. Bacterial growth rate was limited by low temperature at this depth, so nutrient return from grazers does not have a beneficial effect on bacterial growth. These results indicate that the relative importance of positive and negative effects of grazers on bacterial abundance differs seasonally and vertically, and that positive effect becomes important when bacterial growth is limited by nutrients. In a given habitat, bacterial abundance changes less than one order of magnitude in spite of high growth rates. The present study suggests that grazers contribute to numerical stability of bacterial assemblages not only through grazing but also by regenerating deficient nutrients.

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Nutrient cycling in a microflagellate food chain: II. Population dynamics and carbon cycling

Cited by 154 publications

References 6 publications

Nutrient cycling in a microflagellate food chain: III. Phosphorus dynamics

Nutrient cycling in a microflagellate food chain: III. Phosphorus dynamics

Growth kinetics of the omnivorous oligotrich ciliate Strombidium sp

Seasonal and vertical difference in negative and positive effects of grazers on heterotrophic bacteria in Lake Biwa

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