Zooplankton activity fueling the microbial loop: Differential growth response of bacteria from oligotrophic and eutrophic waters

Peduzzi, Peter; Herndl, Gerhard J.

doi:10.4319/lo.1992.37.5.1087

Cited by 81 publications

(60 citation statements)

References 10 publications

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“…These di¡erences may be related to the quantity and quality of the DOM produced by copepod activity and by the physiological condition of di¡erent bacterial assemblages found in each environment. Peduzzi & Herndl (1992) observed high monomeric carbohydrate concentration and bacterial activity in experiments where copepods were included. Furthermore, these authors observed that bacterial communities living in an oligotrophic environment were more e⁄cient to utilize the newly available substrate source, perhaps as an initial response of starved bacteria to the new introduced substrate (Morita, 1984).…”

Section: Implications For Coastal and Oceanic Areasmentioning

confidence: 96%

“…Zooplankton act not only as consumers of an important fraction of the primary production (PP) and as nutrient regenerators, but also play an active role in the cycling of prey carbon into DOM (Peduzzi & Herndl, 1992). Marine copepods may constitute up to 80% of the total zooplankton biomass (Verity & Smetacek, 1996), and they are a key group in the energy transfer through pelagic food webs.…”

Section: Introductionmentioning

confidence: 99%

“…Peduzzi & Herndl, 1992). In the present study we aimed to assess the e¡ect of the grazing activity of Acartia tonsa on the biomass response of oceanic and coastal natural bacterial communities.…”

Section: Introductionmentioning

confidence: 99%

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Bacterial growth response to copepod grazing in aquatic ecosystems

et al. 2007

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The growth rate response of bacterial communities to the potential increase of dissolved organic matter (DOM) produced by the copepod Acartia tonsa was assessed in experiments conducted in three stations representing three contrasting aquatic environments (coastal embayment, shelf and ocean). Bacterial assemblages were inoculated in filtered seawater where A. tonsa had previously grazed. Utilization of DOM over time was evaluated after the addition of bacterial inoculums as the biomass changes in both ‘control’ and ‘copepod’ treatments. In the embayment and ocean a high bacterial growth was observed in the treatments with seawater where copepod were feeding. Additional field measurements of bacterial, primary production and zooplankton biomass support the idea that bacterial communities living in oceanic environments can be efficient to utilize the newly available substrate. Copepods play a key role not only as conveyors of carbon up through the classical food-web, but also generated significant amounts of bacterial substrate in the microbial loop food-web.

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Section: Implications For Coastal and Oceanic Areasmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Bacterial growth response to copepod grazing in aquatic ecosystems

et al. 2007

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“…This readily utilizable DOC is mainly derived from phytoplankton extracellular release (Bell & Sakshaug 1980, Bell 1983, Lignell 1990, Williams 1990, Sundh 1992a,b, Obernosterer & Herndl 1995, Biddanda & Benner 1997 and from the grazing activity of zooplankton on phytoplankton (Riemann et al 1986, Peduzzi & Herndl 1992. Both phytoplankton primary production and zooplankton grazing activity exhibit distinct diel patterns.…”

Section: Introductionmentioning

confidence: 99%

Diel periodicity of bacterioplankton in the euphotic zone of the subtropical Atlantic Ocean

Kuipers¹,

Noort²,

Vosjan³

et al. 2000

Mar. Ecol. Prog. Ser.

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We tested the hypothesis that in the euphotic zone of oligotrophic oceanic waters, the growth-limiting nutrients for bacterioplankton vary over a diel cycle due to competition with phytoplankton, leading to distinct diel patterns in bacterioplankton. During a cruise across the subtropical Atlantic Ocean, a distinct diel periodicity in bacterioplankton was detectable, with highest bacterial abundance in the early morning and declining over the day. A peak in the frequency of dividing cells (FDC, 20 to 25% of the total bacterial community) was recorded at midnight; FDC rates were consistently low during the day and cell volume increased over the day until the early night period. No diel variations in these parameters were detectable in the layers below the deep chlorophyll maximum (DCM). Bio-assay experiments with freshly collected, N+P amended water were started in the early morning. No significant bacterial growth was detectable in the early morning while, in the bio-assays that started at noon, significant bacterial growth was detectable in the N+P treatments. P amendment alone also caused an increase in bacterial abundance although to a lesser extent. Thus, we have evidence that the bacterioplankton in the euphotic layer of the subtropical Atlantic are not limited by the availability of N+P in the morning (most likely limited in C) but at noon when they are competing with phytoplankton for the inorganic N+P sources. Based on the concomitantly measured decline in inorganic N+P in the bio-assays, we estimated the C:N:P ratio of newly produced bacteria. The mean atomic C:N:P ratio for the bacteria in the N+P amended bio-assay experiments started in the early morning was C:N:P = 15:13:1 while the corresponding ratio for bacteria in the bio-assays started at noon was C:N:P = 118:11:1. This diel variation in the C:N:P ratio was caused by the 1 order of magnitude higher bacterial C production at noon as compared to the early morning. Thus, excess uptake of N+P occurs during the morning and luxury C uptake during noon. This plasticity in the C:N:P ratio of bacterioplankton might be a strategy to overcome, at least partly, periods of shortage in a specific nutrient species in the oligotrophic subtropical Atlantic. MARINE ECOLOGY PROGRESS SERIES

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“…In turn, larger zooplankton grazing on microzooplankton further provide organic matter for bacterial growth through excretion of nutrient rich organic compounds (DOM) and fecal pellet production (POM) (Peduzzi and Herndl, 1992). From this point of view, the recycling of organic nutrients is facilitated by bacterial consumers rather than bacteria themselves, known as consumer-driven nutrient recycling (CNR) (Elser and Urabe, 1999).…”

Section: Role Of the Microbial Loop In Regulating Nutrient Flowsmentioning

confidence: 99%

Examination of the role of the microbial loop in regulating lake nutrient stoichiometry and phytoplankton dynamics

et al. 2014

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Abstract. The recycling of organic material through bacteria and microzooplankton to higher trophic levels, known as the "microbial loop", is an important process in aquatic ecosystems. Here the significance of the microbial loop in influencing nutrient supply to phytoplankton has been investigated in Lake Kinneret (Israel) using a coupled hydrodynamicecosystem model. The model was designed to simulate the dynamic cycling of carbon, nitrogen and phosphorus through bacteria, phytoplankton and zooplankton functional groups, with each pool having unique C : N : P dynamics. Three microbial loop sub-model configurations were used to isolate mechanisms by which the microbial loop could influence phytoplankton biomass, considering (i) the role of bacterial mineralisation, (ii) the effect of micrograzer excretion, and (iii) bacterial ability to compete for dissolved inorganic nutrients. The nutrient flux pathways between the abiotic pools and biotic groups and the patterns of biomass and nutrient limitation of the different phytoplankton groups were quantified for the different model configurations. Considerable variation in phytoplankton biomass and dissolved organic matter demonstrated the sensitivity of predictions to assumptions about microbial loop operation and the specific mechanisms by which phytoplankton growth was affected. Comparison of the simulations identified that the microbial loop most significantly altered phytoplankton growth by periodically amplifying internal phosphorus limitation due to bacterial competition for phosphate to satisfy their own stoichiometric requirements. Importantly, each configuration led to a unique prediction of the overall community composition, and we conclude that the microbial loop plays an important role in nutrient recycling by regulating not only the quantity, but also the stoichiometry of available N and P that is available to primary producers. The results demonstrate how commonly employed simplifying assumptions about model structure can lead to large uncertainty in phytoplankton community predictions and highlight the need for aquatic ecosystem models to carefully resolve the variable stoichiometry dynamics of microbial interactions.

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Zooplankton activity fueling the microbial loop: Differential growth response of bacteria from oligotrophic and eutrophic waters

Cited by 81 publications

References 10 publications

Bacterial growth response to copepod grazing in aquatic ecosystems

Bacterial growth response to copepod grazing in aquatic ecosystems

Diel periodicity of bacterioplankton in the euphotic zone of the subtropical Atlantic Ocean

Examination of the role of the microbial loop in regulating lake nutrient stoichiometry and phytoplankton dynamics

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