SHORT COMMUNICATION Consumption of large, Chlorella-bearing ciliates (Stentor) by Mesocyclops araucanus in North Patagonian lakes NORBERT KAMJUNKE 1 *, MARCO KRAMPS 2 , SILVANA CHAVEZ 2 AND STEFAN WOELFL 2 1 DEPARTMENT RIVER ECOLOGY , HELMHOLTZ CENTRE FOR ENVIRONMENTAL RESEARCH UFZ, BRU ¨ CKSTR. 3A, MAGDEBURG 39114, GERMANY AND 2 INSTITUTO DE CIENCIAS MARINAS Y LIMNOLO ´ GICAS, UNIVERSIDAD AUSTRAL DE CHILE, CASILLA 567, VALDIVIA, CHILE *CORRESPONDING AUTHOR: norbert.kamjunke@ufz.de Received June 13, 2012; accepted in principle June 13, 2012; accepted for publication June 21, 2012 Corresponding editor: Beatrix E. Beisner Ingestion of the large pelagic ciliates Stentor araucanus and S. amethystinus by the cyclopoid copepod Mesocyclops araucanus was independent of light conditions and copepod sex, but rates were twice as high on S. araucanus as on S. amethystinus. Copepods consumed 44–183% of their biomass daily. Absorption efficiency was 5–40%, while 20–30% of the ingested food was found in the faeces. In field samples, 32–93% of Mesocyclops had ingested Stentor, indicating the importance of this food source. KEYWORDS: predation; cyclopoid copepods; mixotrophic ciliates; Stentor; North Patagonian lakes Ciliates are preyed upon by copepods in both marine (Pierce and Turner, 1992; Sanders and Wickham, 1993) and freshwater systems (Wiackowski et al., 1994). The vulnerability of ciliates to metazoan ingestion is highly variable and depends among other factors on size, escape behaviour and morphological or chemical defences of the ciliate (Wickham 1995a, b; Jack and Gilbert, 1997; Adrian and Schneider-Olt, 1999). Among ciliates, mixotrophs with endosymbiotic algae have been shown to be a substantial component of pelagic food webs in oceans and freshwaters (see reviews by Pierce and Turner, 1992; Dolan, 1992; Laybourn-Parry et al., 1997), particularly the genus Stentor in New Zealand, Australian and North Patagonian lakes (Laybourn-Parry et al., 1997; Modenutti et al., 1998; Woelfl and Geller, 2002; Woelfl, 2007). On an annual average, Stentor (cell diameter 200–300 mm) containing symbiotic green algae (Chlorella) contributed 39–69% to the total zooplankton biomass in 5 out of 14 deep North-Patagonian lakes in Chile (maximum densities: 190 – 646 ind L 21 ; Woelfl, 2007). Possible predators of large mixotrophic ciliates in North Patagonian lakes are fish larvae (Kamjunke et al., 2009) and cyclopoid copepods (Woelfl, 2007), whereas other ciliate predators common in northern hemisphere lakes, e.g. carnivorous cladocerans (Leptodora, Bythotrephes, Polyphemus) or insect larvae (e.g. Chaoborus), are absent from North Patagonian lakes (Modenutti et al., 1998; Woelfl, 2007). Stentor is potentially a suitable prey for carnivorous raptorial cyclopoid copepods, because it is large, doi:10.1093/plankt/fbs051, available online at www.plankt.oxfordjournals.org. Advance Access publication July 17, 2012 # The Author 2012. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com JOURNAL OF PLANKTON RESEARCH j VOLUME 34 j NUMBER 10 j PAGES 922 – 927 j 2012 Downloaded from https://academic.oup.com/plankt/article-abstract/34/10/922/1457123/Consumption-of-large-Chlorella-bearing-ciliates by guest on 16 September 2017