Cyclomorphosis in Scenedesmus subspicatus (Chlorococcales, Chlorophyta): stimulation of colony development at low temperature

Trainor, Francis R.

doi:10.2216/i0031-8884-32-6-429.1

Cited by 24 publications

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“…Under in vivo conditions, Scenedesmus is usually a colonial alga forming colonies of between 2 and 16 cells. It also sometimes produces unicells resembling Chodatella at certain stages of its life cycle in nature (Egan and Trainor 1989;Trainor 1998). It has been postulated that the unicellular morph may be important in recolonization of waters in spring (Egan and Trainor 1989;Trainor 1998).…”

Section: Discussionmentioning

confidence: 99%

“…It also sometimes produces unicells resembling Chodatella at certain stages of its life cycle in nature (Egan and Trainor 1989;Trainor 1998). It has been postulated that the unicellular morph may be important in recolonization of waters in spring (Egan and Trainor 1989;Trainor 1998). In general it is the production of unicells from colonies (coenobia) that seems to be considered an important controlling step in the life-cycles of Scenedesmus (see for example Egan and Trainor 1989) and not the step from unicells to colonies that has been concentrated on by the zooplankton researchers, e.g., Hessen and van Donk (1993).…”

Section: Discussionmentioning

confidence: 99%

“…Unicells are dominant in young cultures (Swale 1967;Egan and Trainor 1989), at low cell numbers, and in dilute media (Egan and Trainor 1989). Temperatures over 20ЊC can also promote unicell production (Trainor 1993). Low temperatures are thought to result in coenobia (Trainor 1993).…”

Section: Discussionmentioning

confidence: 99%

“…Studies on the induction of different Scenedesmus ecomorphs (coenobia-unicell interactions) are actually made very difficult due to the extreme phenotypic plasticity evinced by this alga. Indeed, a very large body of literature exists on the effect of different growth conditions and nutrient levels on Scenedesmus morphology (for detailed review see Trainor [1998]). …”

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confidence: 99%

“…Thus, we chose to ignore phosphate as an induction candidate in the first instance. In addition, because Scenedesmus coenobia formation has been shown to be influenced by different N concentrations (see Trainor et al 1976), we looked first to nitrogen excretory products as potential can-didates. Textbook knowledge (Parry 1960) seems to be that crustaceans excrete almost all their nitrogen as ammonia.…”

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confidence: 99%

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Max Planck Institute for Limnology, P.O. Box 165, 24302 Plön, Germany

Wiltshire

Lampert

1999

Limnology & Oceanography

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It is known that the zooplankter Daphnia induces colonies in the alga Scenedesmus. As Daphnia grazes on Scenedesmus, it has been postulated that colony formation represents an algal defense mechanism. This induction of Scenedesmus coenobia/colonies by Daphnia could be associated with a substance exuded by the animals that acts as a specific infochemical (kairomone) for Scenedesmus. However, the chemical nature of such a substance is still unknown. Because coenobia can be formed in the absence of Daphnia kairomone, as a result of different N concentrations in the algae and media, we checked different nitrogen excretory products of Daphnia as potential candidates. In this paper we test the hypothesis that ammonia and urea excreted by zooplankters (Daphnia) may induce coenobia formation in Scenedesmus. Using experiments with dialysis separation of Daphnia and algae we show that one of the excretory products of zooplankters, urea, can induce colony formation in Scenesdesmus, whereas ammonia has no effect. Although the effect of urea on coenobia formation may simply be a nutrient effect, this does not exclude the possibility that it results in grazing protection of the algae. Hence, urea produced by zooplankton may serve as a colony inducer to algae.The induction of colonies in the alga Scenedesmus by the zooplankter Daphnia has been the subject of many studies. This is mainly due to the original work by Hessen and van Donk (1993), which that showed that when Daphnia magna and Daphnia water were introduced to single-celled cultures of Scenedesmus subspicatus, the algae formed coenobia (the term coenobium is often used for Scenedesmus colonies, although strictly speaking the definition of coenobium is ''a colony of unicellular organisms having a definite form and organisation, which behaves as an individual and reproduces to give daughter coenobia'' [Lawrence 1997]) and that spine formation was also enhanced. Lampert et al. (1994) followed up this work and showed that coenobia were induced by adding Daphnia water to single-celled cultures of Scenedesmus acutus (now known to be Scenedesmus obliquus, strain SAG 276-3a, Göttingen, Hegewald). Both sets of authors showed that Daphnia had to be fed in order for colony induction to occur.As Daphnia is a grazer on Scenedesmus, it has been postulated that colony formation represents an algal defense mechanism (Hessen and van Donk 1993). However, the extensive work of van showed that colony induction of Scenedesmus is not specific to Daphnia magna. Indeed most cladocerans, a copepod (Eudiaptomus gracilis), and some rotifers seem to induce colony formation in S. acutus/obliquus. In terms of the postulated algal defense mechanism, this is rather intriguing, as some of these organisms are not known to consume Scenedesmus. Other incongruities have been revealed by Lürling and others (Lür-ling andvan Donk 1996, 1997; Lürling et al. 1997) in studies on the differences between single-celled and multicelled Scenedesmus in terms of food quality for ingesting Daphnia. Acknowled...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Max Planck Institute for Limnology, P.O. Box 165, 24302 Plön, Germany

Wiltshire

Lampert

1999

Limnology & Oceanography

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Effects of UV‐A Radiation on Desmodesmus armatus: Changes in Growth Rate, Pigment Content and Morphological Appearance

Pálffy¹,

Vörös

2006

International Review of Hydrobiology

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Laboratory cultures of Desmodesmus armatus (R. CHOD.) HEGEW. were grown under different levels of photosynthetically active radiation (PAR) supplemented with 3.75 mW · cm -2 UV-A radiation. Growth rate was monitored daily, chlorophyl-a concentration, total carotenoid content, cell number and the relative abundance of different coenobial forms was determined at the end of each experiment. Exposure to UV-A radiation resulted in an increasing inhibition of growth towards higher PAR levels, reaching 100% at 400 µmol · m -2 · s -1 . Cellular carotenoid content was higher in the presence of UV-A radiation, on the other hand no differences were observed in cellular chlorophyll-a concentration. UV-A radiation also induced changes in coenobium formation with a decreasing proportion of 4-celled coenobia and an increase in the abundance of 2-celled and teratologic coenobia, suggesting that high intensity UV-A radiation may influence cell cycle events or morphology development.

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Zooplankton-induced unicell-colony transformation in Scenedesmus acutus and its effect on growth of herbivore Daphnia

Lürling

Donk

1996

Oecologia

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The effects of colonial ecomorphs of the green alga Scenedesmus acutus on growth of Daphnia cucullata and D. pulex were examined. In ecologically relevant densities (up to 200 animals l) the relatively small D. cucullata did not induce colony formation in Scenedesmus acutus, whereas the larger congener D. pulex significantly promoted colony formation. Both clearance rate and population growth rate (r) were significantly lower in D. cucullata when fed colonial Scenedesmus then when fed unicellular food. However, for D. pulex no effects of food type were observed. These results show that large Daphnia may influence its food in such a way that smaller congeners and competitors are negatively affected.

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Cyclomorphosis in Scenedesmus subspicatus (Chlorococcales, Chlorophyta): stimulation of colony development at low temperature

Cited by 24 publications

References 0 publications

Max Planck Institute for Limnology, P.O. Box 165, 24302 Plön, Germany

Max Planck Institute for Limnology, P.O. Box 165, 24302 Plön, Germany

Effects of UV‐A Radiation on Desmodesmus armatus: Changes in Growth Rate, Pigment Content and Morphological Appearance

Zooplankton-induced unicell-colony transformation in Scenedesmus acutus and its effect on growth of herbivore Daphnia

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