Carbon intake by zooplankton. Importance and role of zooplankton grazing in the Indian sector of the Southern Ocean

Mayzaud, Patrick; Tirelli, Valentina; Errhif, Ahmed; Labat, Jean‐Philippe; Razouls, Suzanne; Perissinotto, Renzo

doi:10.1016/s0967-0645(02)00077-2

Cited by 42 publications

(15 citation statements)

References 54 publications

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“…in the absence of significant iron inputs to surface waters) the POOZ pelagic ecosystem shows low primary production, with small phytoplankton fueling a weak biological pump that is characterized by high protistan grazing, and efficient remineralization of fixed carbon and nutrients (Landry et al, 2002). Consequently, the mesozooplankton, even when present, play a weak role in phytoplankton grazing although salps or appendicularians can sometimes have a much more significant impact than copepods (Mayzaud et al, 2002). At times, occasional salp swarms, often represented by Salpa thompsoni, can be efficient grazers able to remove an amount of organic carbon almost equivalent to all of the primary production (Pakhomov et al, 2002;Atkinson et al, 2004).…”

Section: Plankton Community Structures In the Southern Oceanmentioning

confidence: 99%

Iron fertilization and the structure of planktonic communities in high nutrient regions of the Southern Ocean

Quéguiner

2013

Deep Sea Research Part II: Topical Studies in Oceanography

128

140

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In this review article, plankton community structure observations are analyzed both for artificial iron fertilization experiments and also for experiments dedicated to the study of naturally iron-fertilized systems in the Atlantic, Indian and Pacific sectors of the Southern Ocean in the POOZ (Permanently Open Ocean Zone) and the PFZ (Polar Frontal Zone). Observations made in natural systems are combined with those from artificially perturbed systems, in order to evaluate the seasonal evolution of pelagic communities, taking into account controlling factors related to the life cycles and the ecophysiology of dominant organisms. The analysis considers several types of planktonic communities, including both autotrophs and heterotrophs. These communities are spatially segregated owing to different life strategies. A conceptual general scheme is proposed to account for these observations and their variability, regardless of experiment type. Diatoms can be separated into 2 groups: Group 1 has slightly silicified fast growing cells that are homogeneously distributed in the surface mixed layer, and Group 2 has strongly silicified slowly growing cells within discrete layers. During the growth season, Group 1 diatoms show a typical seasonal succession of dominant species, within time windows of development that are conditioned by physical factors (light and temperature) as well as endogenous specific rhythms (internal clock), and biomass accumulation is controlled by the availability of nutrients. Group 1 diatoms are not directly grazed by mesozooplankton which is fed by protozooplankton, linking the microbial food web to higher trophic levels. Instead, successive dominant species of Group 1 are degraded via bacterial activity at the end of their growth season. Organic detritus fragments feed protozooplankton and mesozooplankton. The effective silicon pump leads to the progressive disappearance of silicic acid in surface waters. In contrast, Group 2 is resistant to grazing due to its strong silicification, and its biomass accumulates continuously but relatively slowly throughout the productive period. Group 2 diatoms are concentrated at or near the seasonal pycnocline and thus benefit from upward nutrient fluxes by diapycnal mixing. The decrease in light and the deep convective mixing in the fall produce both light and nutrient limitation leading to a massive carbon export of Group 2 diatoms, a major annual event of the biological pump. This scheme describes the seasonal evolution of plankton communities in surface waters of the Southern Ocean. The scheme could probably be extended to ecosystems that are characterized by a seasonal bloom under influence of iron or other nutrients.

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Section: Plankton Community Structures In the Southern Oceanmentioning

confidence: 99%

Iron fertilization and the structure of planktonic communities in high nutrient regions of the Southern Ocean

Quéguiner

2013

Deep Sea Research Part II: Topical Studies in Oceanography

128

140

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“…Copepod ingestion rates were compared to estimates of basic respiratory requirements for copepods based on empirical relationships published in the literature (Mayzaud et al, 2002).…”

Section: Copepods and Grazing Measurementsmentioning

confidence: 99%

The fate of biogenic iron during a phytoplankton bloom induced by natural fertilisation: Impact of copepod grazing

Sarthou

Vincent

Christaki

et al. 2008

Deep Sea Research Part II: Topical Studies in Oceanography

116

130

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International audienceThe impact of copepod grazing on Fe regeneration was investigated in a naturally iron fertilised area during KEOPS (Kerguelen Ocean and Plateau compared Study, Jan.-Feb. 2005). 55Fe labelled natural plankton assemblages (< 200 μm) were offered as food to copepod predators sampled in the field (Calanus propinquus, Rhincalanus gigas, Metridia lucens and Oithona frigida). Diatoms (Eucampia antarctica, Corethron inerme and Navicula spp.) constituted the bulk of the protists whereas microzooplankton (i.e. ciliates and dinoflagellates) were in very low abundance. Copepod grazing on phytoplankton ranged from 0.3 to 2.6 µgC ind-1 d-1 and reflected low utilisation of the food stocks (1-10% of total Chlorophyll a d-1) and low daily rations (0.2-3.3 % body C d-1). Copepod grazing resulted in a 1.7-2.3-fold increase in Fe regeneration. Fe speciation determined by extraction onto C18 columns showed that less than 1% of the regenerated Fe was complexed with hydrophobic organic ligands. This suggests that Fe was regenerated as inorganic species and/or bound to freely soluble organic ligands. The biogenic Fe budget established from our study and literature based data indicates that most of the primary production is recycled through the detrital pool, which represents the largest Fe pool (49% of total Fe). Our iron budget further indicates that mesozooplankton and diatoms represent the dominant Fe biomasses above the Kerguelen plateau. The rate of Fe regeneration accounts for half of the Fe demand, strengthening the need for new Fe sources to sustain the massive phytoplankton bloom above the Kerguelen plateau

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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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Carbon intake by zooplankton. Importance and role of zooplankton grazing in the Indian sector of the Southern Ocean

Cited by 42 publications

References 54 publications

Iron fertilization and the structure of planktonic communities in high nutrient regions of the Southern Ocean

Iron fertilization and the structure of planktonic communities in high nutrient regions of the Southern Ocean

The fate of biogenic iron during a phytoplankton bloom induced by natural fertilisation: Impact of copepod grazing

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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