Showing papers by "Hongbin Liu published in 2000"
University of California, Santa Cruz1, Texas A&M University2, University of South Carolina3, Woods Hole Oceanographic Institution4, University of Hawaii5, University of Texas at Austin6, University of California, San Diego7, Monterey Bay Aquarium Research Institute8, College of William & Mary9, University of Rhode Island10
TL;DR: In this article, the biomass of planktonic organisms, ranging from heterotrophic bacteria through microplankton-sized organisms, was estimated using a variety of methods including #ow cytometry and microscopy.
Abstract: One of the main objectives of the Joint Global Ocean Flux Studies (JGOFS) program is to develop an understanding of the factors controlling organic carbon production in the ocean and the time-varying vertical #ux of carbon from surface waters (US JGOFS (1990) US JGOFS Planning Report Number 11; Sarmiento and Armstrong (1997) US JGOFS Synthesis and Modeling Project Implementation Plan). A considerable amount of evidence suggests that carbon cycling and the potential for exporting carbon from ocean systems is a function of food web structure. As part of the US JGOFS Arabian Sea Studies, the biomass of planktonic organisms, ranging from heterotrophic bacteria through microplankton-sized organisms, was estimated using a variety of methods including #ow cytometry and microscopy. This is a "rst attempt to combine biomass data from a number of sources, evaluate the structure of the food
216 citations
TL;DR: The thicker EPS mucus layer surrounding A. lagunensis cells under hypersaline conditions might be a protective adaptation that permits it to bloom under hypersarial conditions that most other phytoplankton cannot survive.
Abstract: Laboratory experiments with batch cultures showed that the Texas brown tide alga, Aureoumbra lagunensis Stockwell, DeYoe, Hargraves et Johnson, produced a large amount of extracellular polymeric substance (EPS) that formed an extracellular polysaccharide mucus layer. Both dissolved and particulate carbohydrate and EPS concentrations increased as A. lagunensis cultures progressed from exponential growth phase, through stationary phase, to declining phase. Particulate carbohydrate and EPS concentrations per cell were more than three times higher during the declining phase than that in exponential growth phase, reflecting a large increase in the EPS mucus layer. The amounts of carbohydrate and EPS produced by A. lagunensis were significantly higher under hypersaline conditions. The thicker EPS mucus layer surrounding A. lagunensis cells under hypersaline conditions might be a protective adaptation that permits it to bloom under hypersaline conditions that most other phytoplankton cannot survive. This could be one of the reasons why the Texas brown tide persisted in the Laguna Madre, an often hypersaline coastal lagoon, for 7 years.
83 citations
TL;DR: It is hypothesized that, in addition to other factors, the presence of a mucus layer of exopolymer secretions outside its cell wall may have played a role in reducing microzooplankton grazing on A. lagunensis, and therefore contributing to the persistence of the brown tide bloom.
Abstract: “Texas brown tide”, a nuisance algal bloom formed by the marine pelagophyte Aureoumbra lagunensis, persisted without interruption from 1990–1997 in Laguna Madre, Texas. We hypothesize that, in addition to other factors, the presence of a mucus layer of exopolymer secretions (EPS) outside its cell wall may have played a role in reducing microzooplankton grazing on A. lagunensis, and therefore contributing to the persistence of the brown tide bloom. Three protozoan species common to the bloom waters fed A. lagunensis with low or high EPS showed significantly reduced growth rates with a high EPS diet. An additional experiment with the ciliate Aspidisca sp. revealed that the lower growth rate was caused by a reduced grazing rate on A. lagunensis with high EPS. A. lagunensis cells with high EPS might be unpalatable to Aspidisca, hence forced it to feed on bacteria as an alternate food source. Also, the EPS mucus might have affected the feeding mechanics of ciliates by adhering to their cilia and clogging their feeding apparatus. Motion analysis of swimming behavior of Aspidisca fed high and low EPS A. lagunensis revealed altered behavior in the presence of high EPS that could affect their grazing efficiency.
77 citations
TL;DR: In this paper, a pulsed filtered vacuum are deposition system was used to prepare thin and granular Co-C films and the results confirmed that these films exhibit high sp3 fraction of over 80%.
Abstract: A pulsed filtered vacuum are deposition system was used to prepare ta-C thin films and granular Co-C films. The ta-C films prepared at various substrate bias voltages were characterized using Raman spectroscopy and spectroscopic ellipsometry of which the results confirmed that these ta-C films exhibit high sp3 fraction of over 80%. The composition of the granular Co-C films prepared by the same system was determined by non-Rutherford backscattering spectrometry. The properties of these Co-C Films, as deposited and after vacuum annealing at various temperatures, were studied using Raman spectroscopy, electrical measurements, magnetic measurements by a SQUID magnetometer, atomic force microscopy and magnetic force microscopy. It was found that the dependence of the Raman spectra of these films on annealing temperature was associated with the formation and dissociation of a cobalt carbide phase and the graphitization of amorphous carbon. The magnetic properties showed complicated composition and annealing te...
13 citations