Survey of algal picoplankton from lakes in five continents

Hawley, Graham R. W.; Whitton, Brian A.

doi:10.1080/03680770.1989.11898948

Cited by 6 publications

(5 citation statements)

References 8 publications

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“…Pico plankton cyanobacteria appear to be almost ubiquitous in lakes and ponds (Stockner and Antia, 1986;Stockner, 1988;Stockner and Shortreed, 1988;Hawley and Whitton, 1991b), though critical studies are still required on waters at lower pH values and in saline environments. Surveys do not always distinguish between prokaryotic and eukaryotic picophytoplankton, but it seems clear that in general pico plankton cyanobacteria increase in importance in deep, nutrient-poor lakes (Hawley and Whitton, 1991a).…”

Section: Ecowgical Distributionmentioning

confidence: 99%

Diversity, Ecology, and Taxonomy of the Cyanobacteria

Whitton

1992

Photosynthetic Prokaryotes

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114

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Section: Ecowgical Distributionmentioning

confidence: 99%

Diversity, Ecology, and Taxonomy of the Cyanobacteria

Whitton

1992

Photosynthetic Prokaryotes

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144

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“…Algal biovolumes were calculated according to Sun and Liu (2003). The picophytoplankton fraction was counted by taking advantage of the autofluorescence of photosynthetic pigments (Caron 1983, Hawley andWhitton 1991). Samples were collected on 0.2-lm black polycarbonate filters (Isopore GTPB 02500; Isopore, Billerica, Massachusetts, USA) then mounted on a microscope slide with a drop of immersion oil (Immersol Zeiss 518 F; Zeiss, Jena Germany).…”

Section: Enumeration Of Phytoplanktonic Organismsmentioning

confidence: 99%

Effects of the Herbicide Roundup on Freshwater Microbial Communities: A Mesocosm Study

Pérez

Torremorell

Mugni

et al. 2007

Ecological Applications

152

102

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The impact of the widely used herbicide glyphosate has been mainly studied in terrestrial weed control, laboratory bioassays, and field studies focusing on invertebrates, amphibians, and fishes. Despite the importance of phytoplankton and periphyton communities at the base of the aquatic food webs, fewer studies have investigated the effects of glyphosate on freshwater microbial assemblages. We assessed the effect of the commercial formulation Roundup using artificial earthen mesocosms. The herbicide was added at three doses: a control (without Roundup) and two treatments of 6 and 12 mg/L of the active ingredient (glyphosate). Estimates of the dissipation rate (k) were similar in the two treatments (half-lives of 5.77 and 7.37 d, respectively). The only two physicochemical parameters showing statistically significant differences between treatments and controls were the downward vertical spectral attenuation coefficient kd(lambda), where lambda is wavelength, and total phosphorus concentration (TP). At the end of the experiment, the treated mesocosms showed a significant increase in the ratio kd(490 nm)/k(d)(550 nm) and an eightfold increase in TP. Roundup affected the structure of phytoplankton and periphyton assemblages. Total micro- and nano-phytoplankton decreased in abundance in treated mesocosms. In contrast, the abundance of picocyanobacteria increased by a factor of about 40. Primary production also increased in treated mesocosms (roughly by a factor of two). Similar patterns were observed in the periphytic assemblages, which showed an increased proportion of dead: live individuals and increased abundances of cyanobacteria (about 4.5-fold). Interestingly, the observed changes in the microbial assemblages were captured by the analysis of the pigment composition of the phytoplankton, the phytoplankton absorption spectra, and the analysis of the optical properties of the water. The observed changes in the structure of the microbial assemblages are more consistent with a direct toxicological effect of glyphosate rather than an indirect effect mediated by phosphorus enrichment.

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“…Picoplanktonic cells have been found in freshwater and marine environments of different trophic conditions. Their average densities are higher in mesotrophic and eutrophic areas (STOCKNER, 1991 a;ANDREOLI et al, 1989) where, on the other hand, their contribution to the total primary production appears relatively lower than in oligotrophic lakes (PETERSEN, 1991, STOCKNER, 1991HAWLEY and WHITTON, 1991). The departures from this general rule encountered in some highly eutrophic environments (VOROS et.…”

Section: Introductionmentioning

confidence: 99%

Fluorometric Characterization of Two Picocyanobacteria Strains from Lakes of Different Underwater Light Quality

Callieri

Amicucci

Bertoni

et al. 1996

Intl Review of Hydrobiology

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Unicellular autofluorescent picoplankton ranging from 0.6 to 0.9 ym in diameter were isolated from Lake Maggiore and from Lake Balaton. The cyanobacterial isolates contain two accessory pigments: phycoerythrin (PE) and phycocyanin (PC) respectively. The in vivo spectral properties of the two clones were compared to identify characteristics of the pigments. In vivo fluorescence excitation and emission spectra revealed that clones with PE are composed only of phycoerythrobilin chromophores and lack phycourbbilin. Glycerol treatment enhances the fluorescence yield up to 3 times and improves the detection sensitivity of PE particularly at 436 and 520 nm and of PC at 600 nm. The vertical profiles of the underwater irradiance at different wavelengths were measured in both lakes to study the light quality of the natural environment of the two strains. Growth rates of both clones growing at different light intensities and wavelengths, selected by the same filters used for vertical profiles, were estimated. The results showed a difference in growth rate of phycoerythrin and phycocyanin containing cells exposed to an equal quantum tlux of preferential illumination. In particular the maximum growth rate was reached by PE cells exposed to green light and by PC cells exposed to red light.

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Survey of algal picoplankton from lakes in five continents

Cited by 6 publications

References 8 publications

Diversity, Ecology, and Taxonomy of the Cyanobacteria

Diversity, Ecology, and Taxonomy of the Cyanobacteria

Effects of the Herbicide Roundup on Freshwater Microbial Communities: A Mesocosm Study

Fluorometric Characterization of Two Picocyanobacteria Strains from Lakes of Different Underwater Light Quality

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