Collection of dinoflagellates and other marine microalgae by centrifugation in density gradients of a modified silica sol 1

Price, Colin; Reardon, Ellen M.; Guillard, Robert R. L.

doi:10.4319/lo.1978.23.3.0548

Cited by 48 publications

(26 citation statements)

References 10 publications

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“…While Percoll may be satisfactory for stabilizing the sedimentation columns over short periods, it appears to be less satisfactory for determining the density of marine phytoplankton, as the density of some phytoplankton cells exceeds the maximum density of Percoll. Price et al (1978) added sorbitol, which permitted isopycnic banding of the cells, but the osmotic effects of the sorbitol would cause changes in cell volume and density. Price et al (1978) also drew attention to the possibility that the densities of cells might be altered in the presence of polymers and by changes in pH, so that the banding density might not correspond to their true density.…”

Section: Discussionmentioning

confidence: 99%

Sinking velocities of phytoplankton measured on a stable density gradient by laser scanning

Walsby

Holland

2005

J. R. Soc. Interface.

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Two particular difficulties in measuring the sinking velocities of phytoplankton cells are preventing convection within the sedimenting medium and determining the changing depth of the cells. These problems are overcome by using a density-stabilized sedimentation column scanned by a laser. For freshwater species, a suspension of phytoplankton is layered over a vertical density gradient of Percoll solution; as the cells sink down the column their relative concentration is measured by the forward scattering of light from a laser beam that repeatedly scans up and down the column. The Percoll gradient stabilizes the column, preventing vertical mixing by convection, radiation or perturbation of density by the descending cells. Measurements were made on suspensions of 15 mm polystyrene microspheres with a density of 1050 kg m K3 ; the mean velocity was 6.28 mm s K1 , within 1.5% of that calculated by the Stokes equation, 6.36 mm s K1 . Measurements made on the filamentous cyanobacterium Planktothrix rubescens gave mean velocities within the theoretical range of values based on the range of size, shape, orientation and density of the particles in a modified Stokes equation. Measurements on marine phytoplankton may require density gradients prepared with other substances.

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Section: Discussionmentioning

confidence: 99%

Sinking velocities of phytoplankton measured on a stable density gradient by laser scanning

Walsby

Holland

2005

J. R. Soc. Interface.

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“…Middle pump samples were processed using density stratification (as adapted from Price et al 1978) in an exploratory effort to speed up presorting. This procedure streamlined sorting of mollusks, but was not effective for soft-bodied taxa.…”

Section: Methodsmentioning

confidence: 99%

Larval distributions in inner‐shelf waters: The roles of wind‐driven cross‐shelf currents and diel vertical migrations

Garland

Zimmer

Lentz

2002

Limnology & Oceanography

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To determine how physical processes and biological behaviors influence larval dispersal on the inner shelf, time series of larval concentrations were quantified during August 1994, on the Outer Banks of North Carolina, U.S.A. Zooplankton pumps, moored in 21 m of water at 3.2, 8.7, and 12.2 m above bottom, collected larvae every 3 h for 3 weeks. Physical variables and larvae were sampled at similar time and space scales. Larval concentrations were typically 10 2 -10 4 m Ϫ3 for polychaetes, bivalves, and gastropods and 10-10 2 m Ϫ3 for brachyuran crab zoeae. There were two dominant scales of variability, 3-6 h and 2-10 d. The high-frequency signal is partially explained by diel vertical migrations-nocturnal ascent and daytime descent. This pattern would allow larvae to feed in subthermocline waters while avoiding visual predators. Low-frequency variations tracked with water temperature. Highest concentrations of worm larvae occurred in cool (upwelled) water and of crab zoeae in warm (downwelled) water. At least two larval groups comprised the clam and snail time series, one with fairly high abundances in cool water and the other with peak concentrations in warm water. Wind-driven cross-shelf transport is the most plausible explanation for these low-frequency fluctuations. For example, dense patches of worm larvae overlying parental habitat (offshore muds) would be carried shoreward in cool, upwelling flows. In contrast, brachyuran zoeae in nearsurface waters would descend at the coast during downwelling and, together with larvae aloft nearshore sediments, be transported seaward below the thermocline. Thus advected by strong along-shore and weaker cross-shelf currents, larvae zigzag up and down the coast. Vertically traversing the water column while they feed and grow, larvae ultimately seek a suitable habitat in which to settle.The inner portion of the continental shelf (roughly 5-30 m depth) is a dispersal corridor between intertidal and offshore habitats. Replete with planktonic larvae, it also provides soft sediments for benthic adults. Physical processes, such as wind-driven upwelling and downwelling, thermal fronts, eddies, tides, internal waves, tidal bores, surface waves, and storms, operate over spatial scales of 1 m to 10 3 km and temporal scales of hours to weeks (Mann and Lazier 1991). In this high-energy environment, physics should play 1 Previously published as Cheryl Ann Butman. To whom correspondence should be addressed. Present address: Department of Biology, University of California, 621 Charles E. Young Drive South, Los Angeles, California, 90095-1606. AcknowledgmentsWe thank D. Simoneau, W. Ostrom, J. Bouthillette, L. Costello, C. Marquette, J. D. Sisson, V. Starczak, and the captains and crews of the R/V Endeavor and R/V Cape Hatteras for deploying and recovering the moorings. K. Doherty, K. Fairhurst, S. Longworth, and J.D. Sisson engineered and constructed the plankton pumps and moorings, for which we are grateful. We are indebted to numerous divers who battled the wicked Outer-Banks ...

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“…In Expts I1 and 111, the Mesodinium were concentrated prior to isolation using Percoll (Price et al 1978). Seawater samples (30 ml) were layered over chilled 90 % Percoll-sorbitol seawater and centrifuged at 110 X g for 10 min at 10 "C in a swinging bucket rotor.…”

Section: Methodsmentioning

confidence: 99%

Photosynthesis in Mesodinium rubrum: species-specific measurements and comparison to community rates

Dk¹,

Putt²,

Lh³

et al. 1991

Mar. Ecol. Prog. Ser.

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ABSTRACT. The photosynthetic c h a t e Mesodinium rubrum is a common component of the plankton in estuarine, coastal and offshore areas. Unusually high photosynthetic rates [ 2 10 pghave been measured during vlsible blooms (red-waters) of this species, but llttle data were available on photosynthesis by Mesodmium during more routine conditions. We used single cell techniques to measure chlorophyll content and rates of photosynthesis in Mesodinium (16 to 18 X 21 to 22 pm in size) that were part of mixed-species phytoplankton assemblages in small estuaries and salt ponds. The carbon:chlorophyll a (wt:wt) ratio for Mesodinium ranged from 47 to 78. Light-saturated rates of photosynthesis ranged from 13 to 88 pg C cell-' h-' 11.8 to 8.6 pg C (pg chl a)-' h-']. These speciesspecific assimilation ratios were within the mid-range reported for community measurements made during Mesodinium red-waters and within the range reported for phytoplankton. Ik values for Mesodiniurn were 2-275 pE m-' S-' in all experiments. At saturating irradiance, carbon fixation ranged up to ca 14 % of body C h-' In our incubations, Mesodinium accounted for from < 1 to 2-70 % of the community primary production in surface water samples although at no time during our studies did it cause red-waters.

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Collection of dinoflagellates and other marine microalgae by centrifugation in density gradients of a modified silica sol 1

Cited by 48 publications

References 10 publications

Sinking velocities of phytoplankton measured on a stable density gradient by laser scanning

Sinking velocities of phytoplankton measured on a stable density gradient by laser scanning

Larval distributions in inner‐shelf waters: The roles of wind‐driven cross‐shelf currents and diel vertical migrations

Photosynthesis in Mesodinium rubrum: species-specific measurements and comparison to community rates

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