Dissolved organic matter and heterotrophic microneuston in the surface microlayers of the north atlantic.
24 Dec 1976-Science (American Association for the Advancement of Science)-Vol. 194, Iss: 4272, pp 1415-1418
TL;DR: The observations indicate that the surface microlayers are largely heterotrophic microcosms, which can be as rich as laboratory cultures, and that an appreciable part of the dissolved organic carbon is carbohydrate of phytoplankton origin, released and brought to the surface by migrating and excreting phagotrophic protists.
Abstract: Dissolved organic carbon, carbohydrates, and adenosine triphosphate in the size fractions 0.2 to 3 micrometers and 3 to 1000 micrometers are significantly enriched in the upper 150-micrometer surface layer compared to subsurface water, mean enrichment factors being 1.6, 2.0, 2.5, and 3.1, respectively. When calculated as a 0.1-micrometer microlayer of wet surfactants, the mean concentration of organic matter was 2.9 grams per liter, of which carbohydrates accounted for 28 percent. The data for plant pigments and particulate adenosine triphosphate indicated that bacterioneuston was enriched at seven of nine stations while phagotrophic protists were enriched at five stations. Instances of enrichment and inhibition were verified by cultural data for bacteria and amoebas. The observations indicate that the surface microlayers are largely heterotrophic microcosms, which can be as rich as laboratory cultures, and that an appreciable part of the dissolved organic carbon is carbohydrate of phytoplankton origin, released and brought to the surface by migrating and excreting phagotrophic protists.
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TL;DR: In this article, a regional generalisation of the vertical relations of the main components of the photic pump is proposed, which relates to the role of heterotrophs in excreting metabolic wastes (especially ammonia), which may fuel a significant component of integrated algal production.
590 citations
TL;DR: The bacterioplankton community of confined seawater at 25 degrees C changed significantly within 16 hours of collection as discussed by the authors and increased the turnover rate of amino acids in seawater sampled at Frying Pan Shoals, N.C.
Abstract: The bacterioplankton community of confined seawater at 25 degrees C changed significantly within 16 h of collection. Confinement increased CFU, total cell number (by epifluorescence microscopy), and average cell volume of bacterioplankton and increased the turnover rate of amino acids in seawater sampled at Frying Pan Shoals, N.C. The bacterioplankton community was characterized by two components: differential doubling times during confinement shifted dominance from bacteria which were nonculturable to bacteria which were culturable on a complex nutrient medium. Culturable cells (especially those of the genera Pseudomonas, Alcaligenes, and Acinetobacter) increased from 0.08% of the total cell number in the seawater immediately after collection to 13% at 16 h and 41% at 32 h of confinement. Differential filtration before confinement indicated that particles passing through a 3.9-microns-, but retained by a 0.2-micron-, pore-size Nuclepore filter may be a major source of primary amines to the confined population. The 3.0-microns filtration increased growth rate and ultimate numbers of culturable cells through the removal of bacterial predators or the release of primary amines from cells damaged during filtration or both.
420 citations
TL;DR: The sea-surface microlayer provides a habitat for a biota, including the larvae of many commercial fishery species, which are often highly enriched in density compared to subsurface water only a few cm below as mentioned in this paper.
348 citations
TL;DR: In this paper, the authors evaluated concentrations of marine bacteria and viruses in natural aerosols and in those simulated by bubbling sea sprays and compared them to the concentrations in SML (200- 400 μ m thick) and in subsurface waters.
338 citations
TL;DR: The finding of a highly surface-active, deoxysugar-rich polysaccharide material that can be rapidly (<0.5 h) and selectively extracted by bubble adsorption is significant, as it is apparent that this material played important roles in particle stickiness and TEP formation in the tank, and thus it may, at times, play similar roles in particles aggregation in the sea.
Abstract: A study was undertaken to evaluate the role of exocellular polysaccharides in the flocculation of a marine diatom bloom in a large tank mesocosm. Surface-active organic matter was extracted from 1.0 μ-filtered tank water by bubble adsorption each day for 7 days of the experiment. In agreement with past studies, particles (3–51 urn equivalent spherical diameter) were readily formed by bubbling and became concentrated in the foam. At the beginning of the bubbling (0–0.5 h), both particles and surface-active carbohydrates were extracted at high rates; however, these rates dropped off steeply after about 0.5 h of bubbling. The rate of particle formation by bubbling could be modeled fairly well by second order kinetics. The extracted, surface-active material was enriched in deoxysugars and galactose, while the residual material was enriched in glucose. Extracted surface-active carbohydrates reached a maximum of 33% of the total dissolved sugars ( 0.99) with particle stickiness (alpha). In addition, the concentration of surface-active carbohydrates was well correlated (2 = 0.91) with the concentration of transparent exopolymer particles (TEP) in the tank, and it was demonstrated that TEP could be copiously formed by bubbling of 1.0 μm-filered seawater. The finding of a highly surface-active, deoxysugar-rich polysaccharide material that can be rapidly (<0.5 h) and selectively extracted by bubble adsorption is significant, as it is apparent that this material played important roles in particle stickiness and TEP formation in the tank, and thus it may, at times, play similar roles in particle aggregation in the sea.
289 citations
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2,364 citations
TL;DR: In this paper, a method for the rapid determination of dissolved organic carbon in seawater in concentrations between 0.1 and 20 mg/liter was described, which was carried out in sealed glass ampoules using K 2 S 2 O 8 as an oxidizing agent after the sample has been freed of inorganic carbon.
Abstract: A method is described for the rapid determination of dissolved organic carbon in seawater in concentrations between 0.1 and 20 mg/liter. The oxidation is carried out in sealed glass ampoules using K 2 S 2 O 8 as an oxidizing agent after the sample has been freed of inorganic carbon. The resulting CO 2 is passed through a nondispersive infrared analyzer using nitrogen as a carrier and the signal output of the analyzer recorded. Using appropriate calibration curves, the carbon content is determined from the height of the peak. Approximately 100 samples can be analyzed in a single day with a precision of ± 0.1 mg/liter using a sample volume of 5 ml. A companion method is described for the determination of particulate carbon by high-temperature combustion after concentration of the sample on a glass-fiber filter. The precision of this method is ± 10 mug C in a range of 0-500 mug C. Approximately six samples can be analyzed in an hour.
857 citations
TL;DR: The excretion of photoassimilated carbon was determined for 22 species of unicellular marine algae in culture during periods of log-phase growth and for some natural marine phytoplankton populations from Vineyard Sound and the Gulf of Maine.
Abstract: The excretion of photoassimilated carbon was determined for 22 species of unicellular marine algae in culture during periods of log-phase growth and for some natural marine phytoplankton populations from Vineyard Sound and the Gulf of Maine. Carbon 14 tracers gave some information about the composition of the excreted material. Most of the algae excreted 3-6s of their photoassimilated carbon during logarithmic growth. A few species excreted as much as 10-25s under the same conditions. Algae subjected to two different light intensities, 3,000 lux and 25,000 Iux, varied less than 30% in their relative rates of excretion. However, algae exposed to direct sunlight (lOO,OOO120,000 lux) had very high excretion rates, possibly resulting from damage to the cells by photooxidation. Glycolic acid formed 938% of the total carbon excretion in Olisthodiscus sp., Chaetoceros pelagicus, Chlorococcum sp. and Skeletonema costatum. Lower relative amounts were excreted by most of the species studied. Skeletonema costatum excreted considerably more glycolic acid at light intensities below 15,000 lux than above. This is contrary to the findings of other investigators using the freshwater alga Chlorella pyrenoidosa. The amount of carbon excreted as protein ranged from 0.2 to 5.9%, and that excreted as chloroform-soluble material ranged from 2.8 to 10.3% of the total. After electrodialysis, 12-340/O of the compounds were recovered in the anion fraction. Considerable quantities of amino acids and peptides were also detected as excretory products of many of the algae. A few species excreted a single substance almost exclusively. Thus, Chlorella sp. excreted mainly proline, Dunaliellu tertiolectu mainly glycerol, and Olisthodiscus sp. mainly mannitol. Apparently healthy populations of natural phytoplankton excreted 4-16s of their photoassimilated carbon. However, 17-38s was excreted by a sample taken at the end of a diatom bloom, when a large number of empty frustules was present.
544 citations
349 citations
TL;DR: The chemical composition of cells of Chaetoceros affinis var.
319 citations