Regular high contribution of Gonyostomum semen to phytoplankton biomass in a small humic lake

The in vivo fluorescence of chlorophyll a was measured in samples of natural phytoplankton taken from the Římov Reservoir (Czech Republic) during the years 1987 and 1988. The fluorescence intensities of samples either with or without addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron, DCMU) were found reliable for calculating the concentration of chlorophyll a during periods when cyanobacteria were not abundant. The correction for background non-chlorophyll fluorescence appeared to be essential. No distinct correlation between a DCMU-induced increase of the fluorescence and primary production of phytoplankton was found.

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Evaluating ozone dose for AOC removal in two-step GAC filters

Water Science & Technology ◽

10.2166/wst.1998.0347 ◽

1998 ◽

Vol 37 (9) ◽

pp. 113-120 ◽

Cited By ~ 6

Author(s):

R. Vahala ◽

T. Ala-Peijari ◽

J. Rintala ◽

R. Laukkanen

Keyword(s):

Activated Carbon ◽

Organic Carbon ◽

Second Step ◽

Humic Lake ◽

Short Term ◽

Feasible Method ◽

Assimilable Organic Carbon ◽

Water Treatment Plants ◽

Ozone Dose ◽

Ozonated Water

Upgrading an existing post-ozonation plant with two-step granular activated carbon (GAC) filtration for assimilable organic carbon (AOC) removal was studied. The effects of ozone dose on AOC formation and its removal in the subsequent two-step GAC filtration was studied using chemically pretreated 2 to 14° C humic lake water. Two parallel pilot-plant trains with different ozone doses (0 to 1.2 mgO3/mgTOC) and a short-term ozonation study were performed. The optimum ozone dose for maximum AOC formation was 0.4–0.5 mgO3/mgTOC. The AOC-P17 of ozonated water was three-fold higher and AOC-NOX over ten-fold higher than in non-ozonated water, while the following biofiltration (first step) removed 51% and 72% of AOC-P17 and AOC-NOX, respectively. The adsorber (second step) contributed to less than 10% of the overall AOC reduction. It appeared that biofiltration is a feasible method in upgrading water treatment plants for AOC removal even when treating cold humic waters, while the subsequent adsorber seems to have less significance for AOC removal.

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Air-water interface: dynamics of nutrients and picoplankton in the surface microlayer of a humic lake

SIL Proceedings 1922-2010 ◽

10.1080/03680770.1995.11900726 ◽

1997 ◽

Vol 26 (2) ◽

pp. 319-322 ◽

Cited By ~ 2

Author(s):

Anna Hillbricht-Ilkowska ◽

Iwona Jasser ◽

Iwona Kostrzewska-Szlakowska

Keyword(s):

Surface Microlayer ◽

Water Interface ◽

Humic Lake ◽

Interface Dynamics ◽

Air Water Interface

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Differences between Nearshore and Offshore Phytoplankton Communities in Lake Ontario

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f87-264 ◽

1987 ◽

Vol 44 (12) ◽

pp. 2155-2163 ◽

Cited By ~ 33

Author(s):

I. M. Gray

Keyword(s):

Chlorophyll A ◽

Phytoplankton Biomass ◽

Algal Biomass ◽

Phytoplankton Community ◽

Seasonal Pattern ◽

Principal Component ◽

Lake Ontario ◽

Dominant Group ◽

Phytoplankton Communities ◽

Eutrophic Species

Differences between nearshore and offshore phytoplankton biomass and composition were evident in Lake Ontario in 1982. Phytoplankton biomass was characterized by multiple peaks which ranged over three orders of magnitude. Perhaps as a consequence of the three times higher current velocities at the northshore station, phytoplankton biomass ranged from 0.09 to 9.00 g∙m−3 compared with 0.10 to 2.40 g∙m−3 for the midlake station. Bacillariophyceae was the dominant group at the northshore station until September when Cyanophyta contributed most to the biomass (83%). Although Bacillariophyceae was the principal component of the spring phytoplankton community at the midlake station, phytoflagellates (49%) and Chlorophyceae (25%) were responsible for summer biomass, with the Chlorophyceae expanding to 80% in the fall. The seasonal pattern of epilimnetic chlorophyll a correlated with temperature. While chlorophyll a concentrations were similar to values from 1970 and 1972, algal biomass had declined and a number of eutrophic species (Melosira binderana, Stephanodiscus tenuis, S. hantzschii var. pusilla, and S. alpinus) previously found were absent in 1982.

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Spatiotemporal Variability of Surface Phytoplankton Carbon and Carbon-to-Chlorophyll a Ratio in the South China Sea Based on Satellite Data

Remote Sensing ◽

10.3390/rs13010030 ◽

2020 ◽

Vol 13 (1) ◽

pp. 30

Author(s):

Wenlong Xu ◽

Guifen Wang ◽

Long Jiang ◽

Xuhua Cheng ◽

Wen Zhou ◽

...

Keyword(s):

South China Sea ◽

Chlorophyll A ◽

South China ◽

Satellite Data ◽

Phytoplankton Biomass ◽

The South China Sea ◽

Spatiotemporal Variability ◽

The South ◽

Chl A ◽

China Sea

The spatiotemporal variability of phytoplankton biomass has been widely studied because of its importance in biogeochemical cycles. Chlorophyll a (Chl-a)—an essential pigment present in photoautotrophic organisms—is widely used as an indicator for oceanic phytoplankton biomass because it could be easily measured with calibrated optical sensors. However, the intracellular Chl-a content varies with light, nutrient levels, and temperature and could misrepresent phytoplankton biomass. In this study, we estimated the concentration of phytoplankton carbon—a more suitable indicator for phytoplankton biomass—using a regionally adjusted bio-optical algorithm with satellite data in the South China Sea (SCS). Phytoplankton carbon and the carbon-to-Chl-a ratio (θ) exhibited considerable variability spatially and seasonally. Generally, phytoplankton carbon in the northern SCS was higher than that in the western and central parts. The regional monthly mean phytoplankton carbon in the northern SCS showed a prominent peak during December and January. A similar pattern was shown in the central part of SCS, but its peak was weaker. Besides the winter peak, the western part of SCS had a secondary maximum of phytoplankton carbon during summer. θ exhibited significant seasonal variability in the northern SCS, but a relatively weak seasonal change in the western and central parts. θ had a peak in September and a trough in January in the northern and central parts of SCS, whereas in the western SCS the minimum and maximum θ was found in August and during October–April of the following year, respectively. Overall, θ ranged from 26.06 to 123.99 in the SCS, which implies that the carbon content could vary up to four times given a specific Chl-a value. The variations in θ were found to be related to changing phytoplankton community composition, as well as dynamic phytoplankton physiological activities in response to environmental influences; which also exhibit much spatial differences in the SCS. Our results imply that the spatiotemporal variability of θ should be considered, rather than simply used a single value when converting Chl-a to phytoplankton carbon biomass in the SCS, especially, when verifying the simulation results of biogeochemical models.

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Response of ocean phytoplankton community structure to climate change over the 21st century: partitioning the effects of nutrients, temperature and light

Biogeosciences ◽

10.5194/bg-7-3941-2010 ◽

2010 ◽

Vol 7 (12) ◽

pp. 3941-3959 ◽

Cited By ~ 96

Author(s):

I. Marinov ◽

S. C. Doney ◽

I. D. Lima

Keyword(s):

Climate Change ◽

Community Structure ◽

Sea Ice ◽

Phytoplankton Biomass ◽

Phytoplankton Community ◽

Vertical Mixing ◽

Phytoplankton Community Structure ◽

Marginal Sea ◽

Small Phytoplankton ◽

The Impact

Abstract. The response of ocean phytoplankton community structure to climate change depends, among other factors, upon species competition for nutrients and light, as well as the increase in surface ocean temperature. We propose an analytical framework linking changes in nutrients, temperature and light with changes in phytoplankton growth rates, and we assess our theoretical considerations against model projections (1980–2100) from a global Earth System model. Our proposed "critical nutrient hypothesis" stipulates the existence of a critical nutrient threshold below (above) which a nutrient change will affect small phytoplankton biomass more (less) than diatom biomass, i.e. the phytoplankton with lower half-saturation coefficient K are influenced more strongly in low nutrient environments. This nutrient threshold broadly corresponds to 45° S and 45° N, poleward of which high vertical mixing and inefficient biology maintain higher surface nutrient concentrations and equatorward of which reduced vertical mixing and more efficient biology maintain lower surface nutrients. In the 45° S–45° N low nutrient region, decreases in limiting nutrients – associated with increased stratification under climate change – are predicted analytically to decrease more strongly the specific growth of small phytoplankton than the growth of diatoms. In high latitudes, the impact of nutrient decrease on phytoplankton biomass is more significant for diatoms than small phytoplankton, and contributes to diatom declines in the northern marginal sea ice and subpolar biomes. In the context of our model, climate driven increases in surface temperature and changes in light are predicted to have a stronger impact on small phytoplankton than on diatom biomass in all ocean domains. Our analytical predictions explain reasonably well the shifts in community structure under a modeled climate-warming scenario. Climate driven changes in nutrients, temperature and light have regionally varying and sometimes counterbalancing impacts on phytoplankton biomass and structure, with nutrients and temperature dominant in the 45° S–45° N band and light-temperature effects dominant in the marginal sea-ice and subpolar regions. As predicted, decreases in nutrients inside the 45° S–45° N "critical nutrient" band result in diatom biomass decreasing more than small phytoplankton biomass. Further stratification from global warming could result in geographical shifts in the "critical nutrient" threshold and additional changes in ecology.

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