Symbiotic association of the ciliate Ophrydium naumanni with Chlorella causing a deep chlorophyll a maximum in an oligotrophic South Andes lake

• Published in: Journal of plankton research Vol. 21; no. 1; pp. 167 - 178
• Main Authors: QUEIMALINOS, C. P, MODENUTTI, B. E, BALSEIRO, E. G
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 1999; Oxford Publishing Limited (England)
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Chlorella; Chlorophyll; Chlorophylls; Ciliates; Enumeration; Euphotic zone; Exploitation; Fresh water ecosystems; Fundamental and applied biological sciences. Psychology; Inland waters; Lakes; Light; Metalimnion; Ophrydium; Ophrydium naumanni; Phytoplankton; Profiles; Symbionts; Synecology; Thermal stratification; Vertical profiles; Water column; South America; Argentina; America; Argentina, Moreno Oeste L; Protozoa; Chlorella; Temperature; Symbiotic relation; Algae; Bathymetry; Chlorophyceae; Chlorophyll a; Freshwater environment; Luminous intensity; Chlorophyta; Animal plant relation; Seasonal variation; Content; Vertical profile; Lakes; Phytoplankton; Ciliata; Zooplankton; Population density; Thallophyta
• ISSN: 0142-7873; 1464-3774; 1464-3774
• DOI: 10.1093/plankt/21.1.167

Vertical profiles of temperature, light and chlorophyll a concentration were examined in Lake Moreno Oeste, an oligotrophic South Andean lake (Argentina), during the warmest period of the year (November-April), when thermal stratification is characteristic. Concurrent samples for the enumeration of phytoplankton and green ciliates were taken, and the different contribution of these fractions to total chlorophyll a concentration was analysed. The development of a distinctive deep chlorophyll maximum was observed during summer months. The deep chlorophyll maximum was situated near the limit of the euphotic zone and just below the upper limit of the metalimnion. The results showed that the green ciliate Ophrydium naumanni with endosymbiotic Chlorella dominated the metalimnion causing the deep chlorophyll maximum. Additional laboratory experiments revealed a strong dependence of O.naumanni on light. Therefore, the symbiotic association appears to be an effective exploitation of the water column in poor-nutrient-high-light ecosystems like large Andean lakes.