Filtration of colloidal melanin from sea water by planktonic tunicates

Flood, Per R.; Deibel, Don; Morris, Claude C.

doi:10.1038/355630a0

Cited by 106 publications

(82 citation statements)

References 22 publications

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“…The appendicularian was then removed, placed in a second petri dish filled with filtered sea water, oriented in profile view, and photographed. Both body size and house diameter were measured, and house volume was calculated assuming a spherical shape (Flood and Deibel 1998;Alldredge 2004). The relationship between appendicularian size and house volume was used to estimate the house volume for the rest of the chemostat experiment and then to determine the enrichment factor (EF) of ciliates inside houses, calculated as the ratio of ciliate concentration inside the house relative to ciliate concentration in the water.…”

Section: Methodsmentioning

confidence: 99%

“…These houses, once discarded, sink through the water column and can be a major component of the marine snow (Hansen et al 1996;Alldredge 2004;Robison et al 2005). With this extremely efficient filtration structure, appendicularians can consume particles from 0.2 to 30 mm (Flood and Deibel 1998) and therefore are usually considered to be both bacterivorous and herbivorous, although ciliates have been observed inside appendicularian houses (Davoll and Silver 1986;Vargas and Gonzá lez 2004;Tö nnesson et al 2005), which suggested a possible interaction.…”

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Experimental and modeling evidence of appendicularian‐ciliate interactions

Lombard

Eloire

Gobet

et al. 2009

Limnology & Oceanography

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Interactions between appendicularians and ciliates were observed over the life span of Oikopleura dioica in laboratory cultures and clarified with the use of mathematical modeling and microscopic observations. Complex interactions including competition, parasitism, predation, and histophagy occurred simultaneously, resulting in apparent mutualism. The large ciliate Strombidium sp. entered the inlet filters of appendicularian houses (larger than 500 mm body size) by distorting the mesh. Once inside, Strombidium fed on particles concentrated on the filters. When appendicularians were larger than 900 mm, both the high flow rate in the buccal tube and their esophagus width allowed the ''host'' appendicularian to capture and ingest ciliates. Thus, ciliates seem to be sequentially competitors, then parasites or commensal in appendicularian houses, and finally prey for appendicularians. Appendicularian rates of somatic growth and reproduction were enhanced when ciliates were ingested. This additional food supply could be essential in oligotrophic environments. Reciprocally, appendicularians support higher ciliate growth rates, allowing ciliates to survive and grow in food-limited environments. Appendicularians thus modify the size spectrum of the microbial food web both by removing small organisms (0.2-30 mm) and enhancing the growth of mid-sized and large ciliates.

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Experimental and modeling evidence of appendicularian‐ciliate interactions

Lombard

Eloire

Gobet

et al. 2009

Limnology & Oceanography

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“…The staiemeru that colloidal mailer is biol ogicall y labile co uld be supporte d indirec tly or directly by the following facts: they have sho rt residence times and rap id turnover rate s (Moran & Bucsseter. 1992: Sautschl el at., 1994 ; they ca n be utili zed ind irectly o r direc tly by bacte ria or microzoop lankton (Flood et al, 1992) ; bacterial respiration and cell number both increase when cae a nd bacteria came into close co ntact through surface coag ulatio n (Johnson et ai., 1986 : Kepkay and Johnson , 19 88, 198 9;and Kepkey. t990a, b).…”

Section: J2 Characteristics Of Mari Ne Colloidsmentioning

confidence: 99%

Lipid class and carbohydrate concentrations in marine colloids

1998

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“…The primary mechanisms are direct interception of particles traveling on streamlines that come within one particle radius of the filter element, and diffusional deposition caused by Brownian effects or random motility, which deflect particles from streamlines and cause contact with the filter. Theoretical models of caddisfly larvae (12,13) and experiments on marine appendicularians (14)(15)(16) showed encounter of particles much smaller than the mesh size via diffusional deposition and direct interception, and theory suggests that other encounter mechanisms (inertial impaction and gravitational deposition) are negligible for most marine filter-feeders (13,17,18). The transition from encounter to capture depends on the sticking coefficient α, which represents the fraction of encountered particles that is captured.…”

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confidence: 99%

Filtration of submicrometer particles by pelagic tunicates

Sutherland

Madin

Stocker

2010

Proc. Natl. Acad. Sci. U.S.A.

143

135

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Salps are common in oceanic waters and have higher per-individual filtration rates than any other zooplankton filter feeder. Although salps are centimeters in length, feeding via particle capture occurs on a fine, mucous mesh (fiber diameter d ∼0.1 μm) at low velocity (U = 1.6 ± 0.6 cm·s −1 , mean ± SD) and is thus a low Reynoldsnumber (Re ∼10 −3 ) process. In contrast to the current view that particle encounter is dictated by simple sieving of particles larger than the mesh spacing, a low-Re mathematical model of encounter rates by the salp feeding apparatus for realistic oceanic particle-size distributions shows that submicron particles, due to their higher abundances, are encountered at higher rates (particles per time) than larger particles. Data from feeding experiments with 0.5-, 1-, and 3-μm diameter polystyrene spheres corroborate these findings. Although particles larger than 1 μm (e.g., flagellates, small diatoms) represent a larger carbon pool, smaller particles in the 0.1-to 1-μm range (e.g., bacteria, Prochlorococcus) may be more quickly digestible because they present more surface area, and we find that particles smaller than the mesh size (1.4 μm) can fully satisfy salp energetic needs. Furthermore, by packaging submicrometer particles into rapidly sinking fecal pellets, pelagic tunicates can substantially change particle-size spectra and increase downward fluxes in the ocean.biofiltration | low Reynolds number | salps | colloids | carbon cycle F ilter feeding is a common strategy among marine plankton for collecting small food particles from a suspension. Pelagic tunicates in the class Thaliacea, order Salpida, have the highest perindividual filtration rates of all marine zooplankton filter feeders (1). Weight-specific clearance rates (70-4,153 mL·mg C −1 ·h −1 ) (2) are higher than most copepod and krill species. Salps filter feed by rhythmically pumping water into the oral siphon, through the pharyngeal chamber, and out the atrial siphon (Fig. 1A). This pumping action, generated by circular muscle bands, also creates a propulsive jet for locomotion. Food particles entering the pharyngeal chamber are strained through a mucous net that is continuously secreted and rolled into a food strand that moves posteriorly toward the esophagus. The bag-like net is secreted by the endostyle and fills much of the pharyngeal chamber (Fig. 1A). This feeding mechanism results in ingestion of any particles that enter the atrial siphon and adhere to the filtering mesh.After digestion, particles are packaged into dense fecal pellets, which often contain undigested or partially digested plankton (3, 4). These pellets remain intact for days (4) and have sinking speeds (200-3,646 m·d −1 ) (5, 6) that are higher than most copepod or krill pellets (3). Furthermore, diurnal vertical migration by some species may accelerate vertical export (7,8). The combination of high filtration rates, small mesh size, and rapid pellet sinking implies that salps have the potential to shift particle distributions toward larger sizes, con...

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Filtration of colloidal melanin from sea water by planktonic tunicates

Cited by 106 publications

References 22 publications

Experimental and modeling evidence of appendicularian‐ciliate interactions

Experimental and modeling evidence of appendicularian‐ciliate interactions

Lipid class and carbohydrate concentrations in marine colloids

Filtration of submicrometer particles by pelagic tunicates

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