<i>Pyrosoma atlanticum</i> (Tunicata, Thaliacea): grazing impact on phytoplankton standing stock and role in organic carbon flux

Drits, A. V.; Арашкевич, Е. Г.; Semenova, T. N.

doi:10.1093/plankt/14.6.799

Cited by 35 publications

(80 citation statements)

References 23 publications

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“…Within this viscous regime, all mucous-mesh grazers exhibit mechanical, size-dependent selection (figure 1) with a lower limit of particle retention (set in part by the dimensions of the filter pores), and an upper limit that is set by the diameter of the mucous mesh or the animal's mouth (electronic supplementary material, table S2). The upper and lower limits of particle retention vary considerably by species (figure 1), but all appear to capture submicron particles with imperfect (less than 100%) efficiency [9,27,36,[72][73][74][75][76]. Despite this, cells in the picoplankton size range (0.2-2 mm) can still constitute an important contribution to the energetic demands of these organisms [36].…”

Section: Physical Selection Mechanisms (A) Sizementioning

confidence: 99%

Mammoth grazers on the ocean's minuteness: a review of selective feeding using mucous meshes

2018

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Mucous-mesh grazers (pelagic tunicates and thecosome pteropods) are common in oceanic waters and efficiently capture, consume and repackage particles many orders of magnitude smaller than themselves. They feed using an adhesive mucous mesh to capture prey particles from ambient seawater. Historically, their grazing process has been characterized as non-selective, depending only on the size of the prey particle and the pore dimensions of the mesh. The purpose of this review is to reverse this assumption by reviewing recent evidence that shows mucous-mesh feeding can be selective. We focus on large planktonic microphages as a model of selective mucus feeding because of their important roles in the ocean food web: as bacterivores, prey for higher trophic levels, and exporters of carbon via mucous aggregates, faecal pellets and jelly-falls. We identify important functional variations in the filter mechanics and hydrodynamics of different taxa. We review evidence that shows this feeding strategy depends not only on the particle size and dimensions of the mesh pores, but also on particle shape and surface properties, filter mechanics, hydrodynamics and grazer behaviour. As many of these organisms remain critically understudied, we conclude by suggesting priorities for future research.

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Section: Physical Selection Mechanisms (A) Sizementioning

confidence: 99%

Mammoth grazers on the ocean's minuteness: a review of selective feeding using mucous meshes

2018

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“…Pyrosomas are important tunicates that play a major role in food webs of many oceanic areas [19]. Yet, they are among the least investigated of all invertebrates, with very little information on their lipid structure.…”

Section: Discussionmentioning

confidence: 99%

Polar and Neutral Lipid Composition in the Pelagic TunicatePyrosoma atlanticum

Mayzaud

Boutoute

Perissinotto

et al. 2007

Lipids

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Structure and functioning of colonial pyrosomes are largely undescribed and their lipid characteristics have received limited attention. The aim of this paper is to fill this gap on one of the dominant species Pyrosoma atlanticum. Lipid content is tightly coupled to size and weight. Lipid composition shows a large dominance of structural polar lipids. Neutral lipids were dominated by sterols with low levels of acylglycerols and free fatty acids. Phospholipids show a dominance of PC with intermediate percentages of PE and DPG. Other constituents (PS, PI, LPC, sphingolipids) were present at lower levels. Fatty acid composition of DAG and TAG showed a dominance of saturated acids (16:0, 14:0), DHA and intermediate levels of MUFA. Phospholipids were dominated by DHA with values exceeding 30% of total FA in all categories except for PI, where lower percentages occurred. Saturated acids were second in abundance with MUFA showing intermediate concentrations. Sterols were dominated by 24-methylcholesta-5,22E-dien-3beta-ol with more than 22% of the total sterol. Cholesterol (cholest-5-en-3beta-ol) represented only 12 % of the total while 24-methylcholesta-5,24(28)E-dien-3beta-ol accounted for 11% of the total sterols. The low levels of triacylglycerols and free fatty acids, coupled with high concentrations of glycolipids and phytoplankton-derived degraded chloropigments, is evidence of a direct link with the digestive activity and substantiate the idea of a high physiological turnover as an alternative to large lipid accumulation. The fatty acid and sterol profiles are consistent with a diverse phytoplankton diet, and a strong contribution of phospholipid classes to energy needs, including locomotion.

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“…Further, zeaxanthin, which is a marker pigment of cyanobacteria, also contributed greatly to the total pigment pool (7 ng/L) at station 20. All tunicates are suspension feeders and have the ability to take-up very small particles, including bacteria (Drits et al 1992, Jørgensen and Goldberg 1953, Harbison and Gilmer 1976, Harbison and McAlister 1979. According to Drits et al (1992), the minimum size of particles for the pyrosomes to feed should be of considerably <3 μm.…”

Section: Rhizosolenia Styliformis 521mentioning

confidence: 99%

“…Thus, we favor the hypothesis that the pyrosome biomass was sustained by high densities of Synechococcus and flagellates that are of the right size (1 to 3 μm) to be retailed by tunicates and still not large enough to choke their filtration system. The high clearance (Harbison and Gilmer 1976, Deibel 1988, Madin and Cetta 1984 and consumption rates make tunicates an important consumer of phytoplankton crop under swarm condition (Drits et al 1992), due to which these colonial organisms produce very large quantities of faecal pellets and thus play an important role in the flux of organic carbon in the marine ecosystem (Esnal 1999). However, information available on their ingestion and particle clearance rate, particles/prey, and impact rates on planktonic biomass and production is sparse from the Arabian Sea.…”

Section: Rhizosolenia Styliformis 521mentioning

confidence: 99%

“…Here, we attempted to estimate carbon processing by P. spinosum in the Arabian Sea based on the work of Drits et al (1992) on P. atlanticum from off the Congo River mouth, even though these two tunicates are not very similar morphologically. We used the following values: filtration efficiency = 3 to 7.2 L ind −1 h −1 ); ingestion = 4% to 53% of the phytoplankton standing stock; rate of fecal pellet production = 1.4 to 2.2 pellets h −1 zooid −1 (this rate is similar to that for salps; Ramaswamy et al 2005); dry weight of each pellet = 2 μg; carbon content = 22% of the dry weight, and sinking rate of pellets = 70 m d −1 (this is 6 to 12 times slower than that of salps; Ramaswamy et al 2005).…”

Section: Rhizosolenia Styliformis 521mentioning

confidence: 99%

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Biogeochemistry and ecology of Pyrosoma spinosum from the Central Arabian Sea

et al. 2015

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Background: A swarm of pelagic tunicate (Pyrosoma spinosum) was found in the surface open waters of the Arabian Sea during late southwest monsoon (September 2007). The swarm site was characterized by moderate southwesterly wind (approximately 7 m s −1 ), relatively low sea-surface temperature (approximately 26°C), shallow mixed layer (approximately 50 m), and substantial macro-nutrient concentrations (surface values: 2.5 μM nitrate, 0.3 μM phosphate, 0.9 μM silicate, and 5.0 μM ammonium). Despite adequate macronutrient availability, the swarm site was characterized by low diversity of phytoplankton (>5 μm) and mesozooplankton in the upper 200 m. Low chlorophyll a concentration (27.3 mg/m 2 in the upper 120 m) at the swarm site was dominated (90% to 95% in the upper 40 m) by the Synechococcus (20 × 10 6 /ml).

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Pyrosoma atlanticum (Tunicata, Thaliacea): grazing impact on phytoplankton standing stock and role in organic carbon flux

Cited by 35 publications

References 23 publications

Mammoth grazers on the ocean's minuteness: a review of selective feeding using mucous meshes

Mammoth grazers on the ocean's minuteness: a review of selective feeding using mucous meshes

Polar and Neutral Lipid Composition in the Pelagic TunicatePyrosoma atlanticum

Biogeochemistry and ecology of Pyrosoma spinosum from the Central Arabian Sea

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