Author/Editor		Brancelj, Anton
Title		The extinction of Arctodiaptomus alpinus (Copepoda) following the introduction of charr into a small alpine lake Dvojno Jezero (NW Slovenia)
Type		članek
Source		Aquat Ecol
Vol. and No.		Letnik 33
Publication year		1999
Volume		str. 355-61
Language		eng
Abstract		In 1991 about twenty-five age 2+ specimens of the Arctic charr (Salvelinus ulpinus (L.) (length between 100 and 130 mm) were introduced into the fishless small mountain lake Dvojno Jezero (= Twin Lake) (area 0.5 + 0.4 ha; max. depth 8 m, altitude 1670 m) in NW Slovenia. The first spawning of the Arctic charr was observed in autumn 1994 and regularly each year thereafter. Fish of different sizes were observed from 1995 onward each year but a fish census was never carried out. Autumn zooplankton samples, collected before the introduction of Arctic charr, contained adults (including ovigerous females) of two copepod species: Cyclops abyssorum tatricus and Arctodiaptomus alpinus. No planktonic Cladocera were found. Seven years after the introduction of fish standing crop of zooplankton declined 100-fold. The zooplankton contained only a few copepodites (IV and V) of C. a. tarricus. Simultaneously, water transparency declined and the concentration of chlorophyll a increased and filamentous green algae and picoplankton became abundant in the littoral zone of both lakes.
Descriptors		FISHES ZOOPLANKTON CRUSTACEA FRESH WATER WATER POLLUTANTS CHLOROPHYLL PHYTOPLANKTON BIOMASS NITROGEN PHOSPHORUS OXYGEN