Grazing by protists and seasonal changes in the size structure of protozooplankton and phytoplankton in a temperate nearshore environment (western Gulf of St. Lawrence, Canada)

Tamigneaux, Éric; Mingelbier, Marc; Klein, Bert; Legendre, Louis

doi:10.3354/meps146231

Cited by 50 publications

(28 citation statements)

References 22 publications

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“…Aquat Microb Ecol 34: [165][166][167][168][169][170][171][172][173][174][175][176][177][178][179][180]2004 Our results show that microprotozoans can remove a significant percentage of PP (26 to 45% d -1 ), and have a much higher impact than small zooplankton (1 to 6% d -1 ). Our estimates of microprotozoan impacts are within the range found in coastal waters off Washington, USA (17 to 52%: Landry & Hassett 1982), the Baltic Sea (23%: Uitto et al 1997); and Gulf of St Lawrence (40 to 100%: Tamigneaux et al 1997). Therefore, the microheterotrophic pathway may also be an important link in highly productive upwelling areas.…”

Section: Planktonic Production and Carbon Flowsupporting

confidence: 52%

“…Carbon fixed by primary producers is transferred along upwelling food webs through both 'microbial' and 'classical' pathways, and the proportion directed along each route probably depends largely on the size of the primary producers (Walker & Peterson 1991, Mann 1992. There is increasing evidence that the microbial food web is a fundamental and almost permanent feature of not only oligotrophic but also eutrophic marine systems (Neuer & Cowles 1994, Tamigneaux et al 1997. The significance of bacteria and microprotozoans as components of the biomass, and their role in biogeochemical cycles in upwelling systems have been widely recognized (Newel & Turley 1987, Painting et al 1992, Ducklow et al 2001.…”

Section: Introductionmentioning

confidence: 99%

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Plankton community structure and carbon cycling in a coastal upwelling system. II. Microheterotrophic pathway

Vargas¹,

González²

2004

Aquat. Microb. Ecol.

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Planktonic food-web structure and carbon dynamics were studied in Mejillones Bay (23°S, off northern Chile) on 3 occasions: February, August and October 2001. Mejillones Bay was influenced by moderate upwelling events during February and October and presented a shallow (30 to 40 m depth) oxygen minimum layer (OML). On all sampling occasions, chain-forming diatoms that were grazed by small zooplankton and heterotrophic (h-)dinoflagellates comprised most of the autotrophic biomass. Heterotrophic (h-)nanoflagellates were largely bacterivorous, and responsible for a substantial removal of bacterial biomass, mostly associated with productive surface waters and the OML. Ciliate biomass was relatively low during all periods, but ciliates removed a large fraction of h-nanoflagellate production (12 to 22 % d -1). Thus, in the microbial food web bacterial carbon can be transferred to ciliates and then subsequently to zooplankton. The impact of small zooplankton on primary production (PP) was relatively low on all sampling occasions. Small copepods and appendicularians removed from 0.6 to 5%, and from 0.08 to 0.6% PP d -1 respectively. Appendicularians were the only zooplankton able to graze on bacteria, but grazing impact was not sufficient to regulate bacterial biomass. The microheterotrophic pathway could be an important link in this highly productive upwelling embayment. Our results showed that a large part of the photosynthetically fixed carbon was channeled through the microbial food web, with only a small part allocated to copepods and appendicularians. The food-web structure of Mejillones Bay can be classified as multivorous, with herbivorous and microbial grazing playing an important role in carbon export.

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Section: Planktonic Production and Carbon Flowsupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Plankton community structure and carbon cycling in a coastal upwelling system. II. Microheterotrophic pathway

Vargas¹,

González²

2004

Aquat. Microb. Ecol.

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“…These results suggest that at this time, small ciliates around 15 to 30 µm in size contributed significantly to grazing loss rates on the < 5 µm size class. This result is consistent with previous studies , Tamigneaux et al 1997) that report both HNF and ciliates as significant grazers of small eukaryotes. The results overall suggest that HNF and, to a lesser extent small ciliates, play an important role by repackaging the smaller phytoplankton biomass into a size that is more accessible for larger predators and, hence, form an important link in the food web.…”

Section: Grazing On Autotrophic Components Of the Food Websupporting

confidence: 83%

“…Anderson & Fenchel (1985) and McManus & Fuhman (1986) reported HNF as the primary consumers of bacteria, while and Tamigneaux et al (1997) report ciliates < 20 µm as the dominant grazers of prey < 5 µm. suggested that elevated levels of bacterial production may selectively stimulate the growth of small (bacterivorous) ciliates.…”

Section: Importance Of Phytoplankton (Autotrophs) Versus Heterotrophsmentioning

confidence: 99%

Growth and grazing within the microbial food web of a large coastal embayment

Safi

Vant²,

Hall³

2002

Aquat. Microb. Ecol.

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“…Intensive feeding of copepods on protozoa is found in different marine ecosystems (Tamigneaux et al 1997, Mayzaud et al 2002, Calbet & Saiz 2005 although the intensity of this feeding process differs between systems. For example, the grazing of copepods on protozoa was only half of the grazing of copepods on phytoplankton in all seasons and for different regions in the Greenland Sea (Moller et al 2006).…”

Section: Feeding On Microbial Carbon By Copepodsmentioning

confidence: 99%

Carbon transfer in a herbivore- and microbial loop-dominated pelagic food webs in the southern Barents Sea during spring and summer

Laender¹,

Oevelen²,

Soetaert³

et al. 2010

Mar. Ecol. Prog. Ser.

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We compared carbon budgets between a herbivore-dominated and a microbial loopdominated food web and examined the implications of food web structure for fish production. We used the southern Barents Sea as a case study and inverse modelling as an analysis method. In spring, when the system was dominated by the herbivorous web, the diet of protozoa consisted of similar amounts of bacteria and phytoplankton. Copepods showed no clear preference for protozoa. Cod Gadus morhua, a predatory fish preying on copepods and on copepod-feeding capelin Mallotus villosus in spring, moderately depended on the microbial loop in spring, as only 20 to 60% of its food passed through the microbial loop. In summer, when the food web was dominated by the microbial loop, protozoa ingested 4 times more bacteria than phytoplankton and protozoa formed 80 to 90% of the copepod diet. Because of this strong link between the microbial loop and copepods (the young cod's main prey item) young cod (< 3 yr) depended more on the microbial loop than on any other food web compartment, as > 60% of its food passed through the microbial loop in summer. Adult cod (≤3 yr) relied far less on the microbial loop than young cod as it preyed on strictly herbivorous krill in summer. Food web efficiency for fish production was comparable between seasons (~5 × 10 -4 ) and 2 times higher in summer (5 × 10 -2 ) than in spring for copepod production. KEY WORDS: Food web · Microbial loop · Protozoa · Copepods · Gadus morhua Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 398: [93][94][95][96][97][98][99][100][101][102][103][104][105][106][107] 2010 (PAL-LTER) Program (Ross et al. 1996). Apart from abiotic quantities (e.g. nutrient levels), sampling campaigns typically include measurements of primary and bacterial (secondary) production and of standing stocks of the main phytoplankton species, bacteria and mesozooplankton. Because of the focus on the microbial components of the pelagic food web, mesozooplankton are often the highest trophic level considered. Relationships between (bacterial and/or primary) production and consumption (by [proto]zooplankton) tend to be estimated by grazing experiments (as in Vargas et al. 2007) or by numerical modelling (Fasham et al. 1999).Whereas the microbial components of the pelagic food web play a crucial role in biogeochemical cycles (Sabine et al. 2004), they also provide the necessary resources for higher trophic levels such as fish, marine mammals and humans. The differences between phytoplankton food webs and microbial food webs in terms of the efficiency of elemental cycling may thus lead to differences in terms of production rates of higher trophic levels. This concern is being included in emerging end-to-end approaches that amalgamate the food web's different trophic levels next to physical drivers to investigate the effect of environmental perturbations on marine ecosystems (e.g. Cury et al. 2008, Pedersen et al. 2008. Although relationships between lower and h...

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Grazing by protists and seasonal changes in the size structure of protozooplankton and phytoplankton in a temperate nearshore environment (western Gulf of St. Lawrence, Canada)

Cited by 50 publications

References 22 publications

Plankton community structure and carbon cycling in a coastal upwelling system. II. Microheterotrophic pathway

Plankton community structure and carbon cycling in a coastal upwelling system. II. Microheterotrophic pathway

Growth and grazing within the microbial food web of a large coastal embayment

Carbon transfer in a herbivore- and microbial loop-dominated pelagic food webs in the southern Barents Sea during spring and summer

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