ZOOPLANKTON IN ANCIENT AND OLIGOTROPHIC LAKE OHRID (EUROPE) IN ASSOCIATION WITH ENVIRONMENTAL VARIABLES

ZOOPLANKTON IN ANCIENT AND OLIGOTROPHIC LAKE OHRID (EUROPE) IN ASSOCIATION WITH ENVIRONMENTAL VARIABLESDownload fileoriginal scientific paper
ZOOPLANKTON IN ANCIENT AND OLIGOTROPHIC LAKE OHRID (EUROPE) IN ASSOCIATION WITH ENVIRONMENTAL VARIABLESTasevska, O., Špoljar, M., Gušeska, D., Kostoski, G., Patcheva, S., Veljanoska Sarafiloska, E.Keywords:
copepodsrotifersmicrophgousraptorialsmetalimnionoligomictic lake

DOI number: http://dx.doi.org/10.1515/cjf-2017-0013

Volume: 75
Issue: 3
Pages: 128 - 141

Summary

Zooplankton is studied in the ancient, tectonic, oligomictic and oligotrophic Lake Ohrid (Macedonia, South Eastern Europe). The main aim of this study was to assess the seasonal and spatial patterns of the zooplankton functional feeding guilds in relation to the environmental conditions. Metalimnion of the lake was detected as the most productive environment, where biomass of the phytoplankton and abundance of the zooplankton reached their maxima. Pelagial zooplankton of low abundance (25 ± 22 ind. L-1) consisted of 16 species including two endemic copepods, Arctodiaptomus steindachneri (Richard, 1897) and Cyclops ochridanus (Kiefer, 1932). Calanoid copepods obtained remarkable share (60%) in the zooplankton assemblage. Microphagous zooplankton was mainly comprised of the most abundant rotifer Kellicottia longispina (Kellicott, 1879) in summer, nauplii of the calanoid Eudiaptomus gracilis (Sars, 1862) in spring and nauplii of the cyclopoid C. ochridanus in autumn. Due to their requirements for the bacterio-detritus suspension, this microphagous zooplankton occupied aphotic hypolimnion during the entire study period. Raptorials were typically represented by calanoid copepodites and adult copepods in the metalimnion, and were significantly and positively affected by temperature (r = 0.417, p = 0.001), dissolved oxygen (r = 0.463, p = 0.0001) and, particularly, phytoplankton biomass (r = 0.708, p < 0.00001). This is the first study in which the link between the lower and higher trophic levels is investigated in Lake Ohrid.