Abstract
The zooplankton communities often exhibit daily vertical migrations to avoid natural ultraviolet radiation and/or fish predation. However there is no information on this topic in Chilean North Patagonian lakes up to date. Therefore, this study deals with a first characterization of plankton crustacean daily vertical migration in two temperate, oligotrophic lakes (Villarrica and Panguipulli lakes, 39°S) in Southern Chile. Zooplankton were collected at different depths intervals (0-10m, 10-20 m, 20-30m, 30-40m) at early morning, middle day, evening and night in the studied site. The results revealed that zooplankton species (Daphnia pulex, Ceriodaphnia dubia, Neobosmina chilensis, Mesocyclops araucanus, and Tropocyclops prasinus) are abundant in surface zones at night, early morning and evening, whereas at middle day the zooplankton abundances are high at deep zones. The results agree with observations for Argentinean and North American lakes where these daily migration patterns in crustacean zooplankton species were reported due mainly natural ultraviolet radiation exposure, whereas for northern hemisphere lakes the vertical migration is due to combined effect of natural ultraviolet radiation and fish predation exposure.
Highlights
In southern Chile and Argentina there is an area called NordPatagonian lakes (39-41°S)
The results revealed the presence of seven species in studied lakes: three cladocerans: Daphnia pulex De Geer, 1877 (Panguipulli), Ceriodaphnia dubia Richard, 1894 (Caburgua and Panguipulli) and Neobosmina chilensis Daday, 1902 (Villarrica), and four copepods Tumeodiaptomus diabolicus Brehm 1935 (Panguipulli), Boeckella gracilipes Daday, 1901 (Panguipulli), Mesocyclops araucanus Löffler, 1962 and Tropocyclops prasinus (Fischer, 1860) (Tables 1 and 2)
T. prasinus was only present in lake Villarrica, whereas M. araucanus inhabited only lake Panguipulli
Summary
In southern Chile and Argentina there is an area called NordPatagonian lakes (39-41°S). They exhibit characteristics that are unique to these lakes in relation to temperate northern hemisphere lakes. They lack predators such as Chaoborus and Leptodora (Kamjunke et al, 2009, 2012). In these lakes Calanoid copepods dominate the mesozooplankton followed by cyclopoid copepods and Cladocera (Campos, 1984; Soto and Zúñiga, 1991; Modenutti et al, 2010; De los Ríos-Escalante et al, In press). The phytoplankton community is dominated by Diatoms (Campos, 1984)
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