First observations of crustacean zooplankton abundance in nothrm Patagonian rivers
Rios Escalante, Patricio De Los
Habit, Evelyn M.
Manosalva, Aliro J.
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The zooplankton assemblages present in Chilean lakes are characterized by ahigh abundance of calanoid copepods, but at low species numbers, with maximumabundance and species diversity found at latitudes between 39 and 41°S (De losRíos-Escalante, 2010). From a hydrological perspective, the northern and centralpart of Chilean Patagonia can be characterized as comprising three distinct regions.North of 39°S there are mixed rivers fed by summer snow melting and winter rains.Between latitudes 39 and 41°S, many rivers originate from large Andean lakes,whereas river systems from 41 to 49°S originate from glaciers and melting snowand are characterized by variable flow (Niemeyer & Cereceda, 1984; De los Ríos-Escalante, 2010). Some of these rivers thus originate in lakes and it is possible thatthe zooplankton is transported downstream from the lake, with the effluent, overlarge distances, as has been shown for rivers in North America and Western Europe(Havel & Shurin, 2004; Walks & Cyr, 2004).The aim of this study was to describe the zooplankton assemblages in Patago-nian rivers at latitudes between 39 and 45°S (table I; fig. 1). Zooplankton sampleswere collected by filtering, through a 45μm mesh net, 60 litres of water collectedjust below the surface using a 10-litre bucket. Material retained on the net was pre-served in 60-70% ethanol (final concentration). Specimens were identified in thelaboratory with the works of Araya & Zúñiga (1985) and Bayly (1992).