Physiological Characteristics of a Dinoflagellate Peridinium bipes f. occultatum Forming Freshwater Red Tides in the Reservoirs.

Ikeda, Tomoji; Ohnishi, Yutaka; Hatamochi, Kazuhiro; Ishida, Yūzaburō; Kawai, Aakira

doi:10.3739/rikusui.58.395

Cited by 3 publications

(2 citation statements)

References 4 publications

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“…Nishibori et al (2000) determined high half saturation constant (Ks) values for phosphate and a low optimum N:P ratio for Peridinium bipes f. occultatum. Ikeda et al (1997) showed that the optimum light intensity for P. bipes f. occultatum was relatively high among freshwater phytoplankton. Leitao et al (2001) commenting on two cases of freshwater red tides in France reported that solar radiance was high in both situations, that ammonia and nitrate concentrations were not low and, that phosphates were almost completely depleted by the blooms suggesting that it plays an important role in its metabolism.…”

Section: Discussionmentioning

confidence: 98%

Blooms of the dinoflagellate Glenodinium sanguineum obtained during enclosure experiments in Lake Tovel (N. Italy)

Cantonati¹,

Tardio²,

Tolotti³

et al. 2003

J Limnol

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Freshwater red tides due to dinoflagellates are less common than their marine analogues, which are usually a serious problem and can even be toxic. This was not the case for Lake Tovel in the Adamello-Brenta Natural Park (Southern Alps, Italy), where the dinoflagellate Glenodinium sanguineum Marchesoni accumulated carotenoids (astaxanthin-like compound) and caused a spectacular and regular "summer reddening", which suddenly ceased in 1964. Today Lake Tovel is a temperate, meromictic (with dimictic mixolimnion), oligotrophic mountain lake, characterised by marked water level fluctuations. G. sanguineum is still present in the lake, although with markedly lower densities in comparison to the pre-1965 period. Enclosure studies were carried out to identify the main factors regulating the blooms. In 1998, by means of phosphorus enrichments, it was possible to obtain a marked increase in numbers of G. sanguineum. Phosphorus additions in similar enclosures in 1999, when weather conditions during the summer were not optimal (mostly cloudy with frequent rainfalls), did not have the same effect, since species known to thrive in spring or under icecover developed. In summer 2000, by attenuating light in one of the enclosures, it was shown that irradiance conditions strongly interacted with phosphorus availability in determining the species that dominated the phytoplankton. In summer 2001, G. sanguineum increased again in the enclosure enriched with phosphorus. Nitrogen was observed to become a limiting factor only in conditions forced by phosphorus additions. From the first four years of in situ experiments, we concluded that phosphorus and light conditions were among the key factors controlling the proliferation and the dominance of G. sanguineum

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Section: Discussionmentioning

confidence: 98%

Blooms of the dinoflagellate Glenodinium sanguineum obtained during enclosure experiments in Lake Tovel (N. Italy)

Cantonati¹,

Tardio²,

Tolotti³

et al. 2003

J Limnol

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“…This result is reasonable, because Pollingher and Serruya (1976) observed specific growth rates of P. cinctum f. westii ranging from 0.017 to 0.040 day Ϫ1 in Lake Kinneret and Peridinium spp. generally have low growth rates (Watanabe 1983;Lindström 1991;Nishihori et al 1991;Ikeda et al 1997;Kishimoto et al 1998a). The calculated specific growth rates were generally higher than the apparent ones, because the apparent specific growth rates were influenced by some factors, such as death, decomposition, predation, hydraulic washout, and so on, other than multiplication of vegetative cells.…”

Section: Season For Excystment In the Asahi Reservoirmentioning

confidence: 99%

Behavior of Peridinium bipes (Dinophyceae) resting cysts in the Asahi Reservoir

et al. 2001

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The role of resting cysts includes short-and longterm survival under extreme conditions, bloom initiation, species dispersal, reproduction, and preservation of genetic variation. Accordingly, it is important to understand their behavior in a water environment, especially in lakes and reservoirs where dinoflagellate blooms are observed. In this study, we estimated the behavior of the Peridinium bipes cysts in the Asahi Reservoir using laboratory experiments and field surveys. It was observed that the amount of light strongly influenced excystment, and few cysts germinated under dark conditions in the laboratory experiment. The minimum temperature on excystment was inferred from the laboratory experiment and field surveys to be about 5°C. Although the frequency of excystment did not depend on the water temperature from 10° to 20°C, the average preparation period for excystment decreased with the increase of water temperature. In the Asahi Reservoir, the excystment was estimated to occur during the months of March and April. If excystment did not occur in spring, the dinoflagellate bloom was not be observed until about July, although the bloom often began to appear in about May in the Asahi Reservoir. Consequently, the blooming season in the Asahi Reservoir is affected by the biomass of the germinated cysts in spring.

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