Measure Of Phytoplankton Biomass Research Articles

Temperature, Salinity, and Fluorescence in Southern North Sea: High-Resolution Data Sampled from a Ferry.

/ In 1991 and 1992, temperature, salinity, and fluorescence were measured by automatic continuous registration using instrumentation on a ferry crossing the southern North Sea daily along a transect between Zeebrugge, Belgium, and Hull, United Kingdom. The temperature ranged between 4 and 21 degrees C off the Belgian coast and between 6 and 17 degrees C in the middle of the transect. Salinity varied between 34 and 35.5 PSU in the offshore part of the transect, but showed much larger variation along the Belgian and UK estuarine coasts. Fluorescence, which was used as a measure of phytoplankton biomass, was highest at the continental coast and lowest near the English coast. Spring blooms of phytoplankton were found along the continental coast and in the channel-influenced water; in 1991 the blooms were denser than in 1992. Some summer blooms were also recorded. Water masses could be distinguished on the basis of salinity and fluorescence patterns. The general patterns in the data are compared with the literature and discussed in relation to river discharge, light penetration, and wind speed and direction. Finally, the value of automatic and frequent measurements of fluorescence for monitoring phytoplankton is compared with less frequent observations at selected stations. It is concluded that accurate information about phytoplankton biomass can only be established from the high-frequency data. KEY WORDS: Monitoring; Sampling; North Sea; Ferry; Fluorescence; Salinity; Temperature

Determination of the distribution of dissolved organic carbon in the Indian sector of the Southern Ocean

During France JGOFS campaign ANTARES 2 (R.V. Marion Dufresne), samples were taken along a section of the 62°E meridian from 49° to 66°S. The high temperature catalytic oxidation (HTCO) method was used to determine the concentration of dissolved organic carbon (DOC). The analyses were conducted both on-board ship and after the cruise in the laboratory. Collecting and storing acidified samples for post-cruise analysis induced no significant differences. The use of two separate but identical channels on the carbon analyzer increased the number of samples analysed per day and allowed independent monitoring of the instrument blank and the calibration of the detector response. The mixed layer concentrations of organic carbon varied from about 52 μM C in the Antarctic Divergence (64°S) to about 63 μM C in the Polar Frontal Zone (49°S). Vertical profiles showed a slight, but significant, decrease in organic carbon below the mixed layer, to about 42 μM C below 2000 m across the transect. The homogeneity and low concentration of organic carbon in deep water is consistent with values recently reported for the equatorial Atlantic and Pacific Ocean and supports the evidence for a constant deep water DOC concentration. In addition, this provides a verification of the instrument performance, thus validating observed DOC data trends and allowing a comparison with the `modern' DOC literature. In general, the organic carbon concentration in the mixed layer was lower than previously published data of the main ocean basins, which might -reflect the low chlorophyll a concentration (<0.5 μg/l) encountered in this region. Along the 62°E meridian section, organic carbon showed a trend with corresponding measurements of phytoplankton biomass and bacterial production, underlining the dependence of bacterial growth on a pool of `freshly' produced DOC. Organic carbon was found to exhibit a weak inverse trend versus apparent oxygen utilization (AOU). This suggests that only a small part of the oxygen consumption is due to the mineralisation of DOC.

Production of dimethylsulfonium propionate and dimethylsulfide by phytoplankton in estuarine and coastal waters

We determined the concentrations of dimethylsulfide (DMS) and its metabolic precursor, dimethylsulfonium propionate (DMSP), in water and particulate samples obtained along transects through Delaware Bay, Chesapeake Bay (including the Potomac River), and Ochlockonee Bay (Florida). The Delaware and Chesapeake Bay transects extended into the open ocean. In most cases, we observed positive correlations between the concentrations of the biogenic sulfur species and salinity, particularly when the concentrations of the sulfur compounds were normalized to chlorophyll a as a measure of phytoplankton biomass. The normalized concentrations of DMS, dissolved DMSP, and particulate (intracellular) DMSP increased nonlinearly with salinity from estuarine through shelf to oceanic environments. Within each environment, dissolved DMS and dissolved and particulate DMSP correlated more strongly with salinity than with phytoplankton species composition. On the other hand, the sharp increases in Chl a#x2010;normalized biogenic sulfur concentrations from the estuarine to the coastal and shelf environments were most strongly correlated with differences in the species composition of the phytoplankton community between environments and appear to reflect differences in DMSP production between oceanic, coccolithophore#x2010;dominated communities and estuarine, diatom#x2010;dominated communities.

Spatial and temporal patterns in pigment biomass in Gulf Stream warm‐core ring 82B and its environs

A chronology of the horizontal and vertical distribution of phytoplankton pigment biomass provides a biological life history of Gulf Stream warm‐core ring 82B. Development of ring 82B is followed through three distinct periods: a winter/early spring period of deep convective overturn with uniform and relatively high pigment concentrations to depths of 400 m, a late spring stratification period with subsurface (20–30 m) pigment maxima and relatively high ring center values compared to surrounding waters, and a Gulf Stream interaction period when ring characteristics are dominated by intrusions of low pigment concentration waters. While the ring maintains a unique identity throughout these periods of its life, prolonged deep vertical mixing as well as episodic interactions with its surroundings have a significant influence on pigment distributions within the ring. These interactions generally enhance pigment biomass compared to the water mass from which it is derived. A consistent feature of pigment distribution is the remarkable coherence between this measure of phytoplankton biomass and the corresponding physical hydrodynamic structure of the upper water column.

Physicochemical Typologies of South-Central Ontario Lakes

We present basic physicochemical data and principal component analyses (PCA) of both morphometric and chemical variables for 37 Ontario lakes. Multivariately derived composite variables were substituted for more conventional independent variables in several regression models. These composite variables always explained a greater percentage of variance than the standard morphometric variables. A typology derived in part from the PCA was useful in identifying groups of lakes for which the Ragotzkie model predicting maximum depth of the summer thermocline was appropriate and other groups of lakes that appear to be outliers on the basis of insufficient volume. In addition, variables important in defining the typology, particularly [Formula: see text] ratio and lake volume, were shown to be among the most important in a stepwise, multiple linear regression explaining 91% of the variance in nannoplankton to filter-feeding zooplankton ratios in the lakes. This represents a 47% improvement over previously reported results. Total phosphorus still explained more variance in several measures of phytoplankton biomass than did a multivariately derived composite chemical variable, but there were significant explanatory improvements in phosphorus–phytoplankton regressions within lake groups derived from a typology based on a speciated chemical matrix. There appears to be some overlap in biological patterns from morphometrically and chemically defined lake types. We suggest that these may represent ends of a continuum of differing density regulation responses by the biological communities.

Empirical Relationships Between Phytoplankton and Zooplankton Biomass in Lakes

Empirical models based on regression analysis were derived using published values of phytoplankton and crustacean zooplankton biomass from lakes. Equations presented predict crustacean zooplankton biomass from measures of phytoplankton biomass. Zooplankton biomass was shown to be positively related to phytoplankton biomass based on an inter-lake comparison. Analyses of functional regression equations suggest that the ratio of zooplankton to phytoplankton biomass decreases as phytoplankton biomass increases among lakes. It is hypothesized that variation in the biomass of nannoplankton, representing the principal food source for crustaceans present in the phytoplankton community, can account for the variation in the biomass of the crustacean zooplankton community.Key words: phytoplankton, zooplankton, biomass, nannoplankton