A Freshwater Red Tide on a Water Reservoir

Nakamoto, Nobutada

doi:10.3739/rikusui.36.55

Cited by 25 publications

(14 citation statements)

References 5 publications

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“…Restrictive density gradients are often diurnally pronounced, especially in very productive and sheltered crater lakes like L. Aranguadi (Talling et al, 1973;Wood et al, 1976) and the Kenyan lakes Simbi (Melack, 1979;Finlay et al, 1986, and personal observations) and Sonachi (Melack, 1981). They will be enhanced by the localized power consumption in very dense and absorptive algal populations, as noted by Nakamoto (1975) for dense populations of a dinoflagellate elsewhere.…”

Section: Discussionmentioning

confidence: 99%

Chemical and algal relationships in a salinity series of Ethiopian inland waters

1988

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Most Ethiopian lakes are parts of closed drainage systems and collectively form an extensive salinity series, here treated comparatively for geographical, chemical and algal characteristics. Chemical data are presented for 28 lakes and numerous inflows, including original analyses for 15 lakes, in which total ionic concentration and electrical conductivity vary over 4 orders of magnitude. The principal determinant of a lake's position in the series is the open or closed nature of its individual drainage. At present there are three major closed systems (Awash R. -Afar drainage, northern rift lakes, southern rift lakes), numerous crater lakes with seepage -in and -out, and two cryptodepressions with marine inputs. Salinity is primarily determined by evaporative concentration, enhanced in lakes associated with past marine influence or recent volcanic activity by readily soluble materials in the catchment, and by some thermal-reflux pathways. However, anomalously dilute closed lakes exist, indicative of other processes of solute loss (e.g. past basin overflow, 'reverse weathering', seepageout).There are strong positive correlations between increasing salinity and the concentrations of Na + , alkalinity and Cl-. The last is used, in conjunction with other analyses of atmospheric precipitation, to estimate the marine and denudative contributions and the evaporative concentration factor, and to distinguish trends of ionic species during evaporative concentration. With several exceptions, affected by past penetration of sea water into the Danakil and L. Assal cryptodepressions, the most saline lakes are soda lakes with HCO + CO]-and Na + predominant and Ca 2+ and Mg 2 + largely eliminated. Soluble reactive silicate and phosphate tend to increase in concentration along the salinity series, but the unknown dynamics of algal growth are likely to introduce variance. Concentrations in some lakes are extremely high, e.g. > 40 mg SiO 2 1 -1 and > I mg PO 4 -P 1-'.Phytoplankters recorded from individual lakes are tabulated and where available the community biomass concentration as chlorophyll a is given. Lakes of high salinity-alkalinity are typically very productive in terms of phytoplankton biomass and photosynthetic rates (exceptions: the very deep L. Shala and the very saline L. Abhe), supported in part by relatively high concentrations of phosphorus and inorganic carbon. Many species are of restricted salinity-alkalinity range, being characteristic of waters where levels are low (e.g. desmids, Melosira spp.), intermediate (e.g. Planctonema lauterborn), or high (e.g. Spirulinaplatensis). Phytoflagellates are most strongly represented in waters with higher concentrations of the bivalent cations Ca 2 + and Mg 2 + . The common cyanophyte Microcystis aeruginosa can tolerate a wide salinity range, here as elsewhere.

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Section: Discussionmentioning

confidence: 99%

Chemical and algal relationships in a salinity series of Ethiopian inland waters

1988

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“…A third approach has been to study a lake over a number of years (Yan, 1983; Mazumder & Taylor, 1994; Snucins & Gunn, 2000), avoiding the above difficulties but attracting the problem of inter‐annual variability in surface fluxes. Yet another approach has been to investigate localised increases in surface temperatures induced by plankton patchiness in individual lakes (Nakamoto, 1975; Sibley, Herrgesell & Knight, 1975), but this approach is also fraught with uncertainty over whether any changes are solely induced by the presence of the phytoplankton or whether some other cause might be responsible.…”

Section: Introductionmentioning

confidence: 99%

Quantifying effects of phytoplankton on the heat budgets of two large limnetic enclosures

Jones¹,

George²,

Reynolds³

2005

Freshwater Biology

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1. The aestival heat budgets of two large limnetic enclosures within a small lake in the English Lake District were studied. During summer, these enclosures had different nutrient supplies and consequently different phytoplankton populations. 2. As initial temperature profiles were similar and the incoming surface heat and momentum fluxes for the two enclosures were identical, subsequent changes in the heat budget were assumed to be induced by the biological differences between the enclosures. The proposed mechanism is an increased surface absorption of solar radiation leading to extra surface warming and a consequent excess loss of heat to the atmosphere through long-wave emittance and sensible and latent heat fluxes, conservatively estimated to be of the order of 10-30 W m )2 . 3. Theoretical calculations show that potential effects on a heat budget could be considerably larger than those observed here. The inherent non-linearity of the heat fluxes implies that such effects will be more important in warmer lakes than in colder ones. 4. Thermocline depth and strength were also altered by the response to differences in phytoplankton. 5. Any changes in climate or in nutrient loading from the catchment which substantially affect abundance or timing of phytoplankton populations in a lake will consequently also change the thermal structure of the lake.

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“…In recent years large-scale blooms, so called freshwater red tides, of dinoflagellates belonging to the genus Peridinium have often occurred in manmade lakes (Nakamoto, 1975;Ito, 1979;Hata, 1982) and rarely in natural lakes (Home et al, 1971;Pollingher and Serruya, 1976). For examples, P. cinctum in Lake Kinneret (Eren, 1969), P. cunningtonii and P. penardii in Nagase Reservoir (Hata, 1982), and P. bipes in Kazaya Reservoir (Watanabe, 1982) and in Ananai Reservoir (Hata, 1982).…”

Section: Introductionmentioning

confidence: 99%

Life Cycle of <i>Peridinium</i> sp. B3 (Dinophyceae) Isolated from Lake Begnas, Nepal

Sako

Nakanishi

Konda

et al. 1986

Bulletin of Japanese Society of Microbial Ecology

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Abstract:Encystment and excystment in the life cycle of a dinoflagellate Peridinium sp. B3, which was isolated from Lake Begnas in the Pokhara Valley, Nepal, were investigated by use of a clonal population.The maximum cell concentration was 3103 vegetative cellsml-1 in BL medium after about 4 weeks at 30C.Sexual reproduction of the cells was induced after the cells in late logarithmic phase were inoculated into nitrogen and phosphorous deficient medium, and also was spontaneously induced in BL medium.Sexual reproduction was isogamous and homothallic. The cycle was initiated by gamete formation, rn which gametes were produced by binary asexual divisions of the vegetative cells. Fusing pairs were formed by the mid-ventral union of gametes. The planozygote retained two red bodies and remained motile for about 2 weeks. Two weeks after the planozygote lost motility, the zygotes enlarged and became dark in color. The theca of the planozygote split around the girdle region and the hypnozygote (cyst) was produced.The matured cysts were dormant and remained viable for at least 1 month at 10C in darkness following maturation for 3 months at 30C. The dark-cold treated cysts excysted synchronously when the incubation temperature was raised to 30C. The protoplast emerged from the cyst wall by amoeboid movement. The excysted cell had two red bodies. This cell divided within 24-48h into 2 daughter cells each with a red body.

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A Freshwater Red Tide on a Water Reservoir

Cited by 25 publications

References 5 publications

Chemical and algal relationships in a salinity series of Ethiopian inland waters

Chemical and algal relationships in a salinity series of Ethiopian inland waters

Quantifying effects of phytoplankton on the heat budgets of two large limnetic enclosures

Life Cycle of <i>Peridinium</i> sp. B3 (Dinophyceae) Isolated from Lake Begnas, Nepal

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