engleski

Taxonomic composition of benthic diatoms (Bacillariophyta) from two marine lakes on the Island of Mljet (Adriatic Sea, Croatia)

The marine lakes, “Malo” and “Veliko Jezero” (Little and Big Lake), are one of the first established marine reserves in the world. They are, in fact, two karstic basins on the island of Mljet which are filled by the holocene ingression of the Adriatic Sea. The lakes with the surrounding area are protected under the category of the National Park since 1960. The aim of the study was to determine the species composition and abundance of benthic diatoms in two marine lakes. Samples were taken from two stations (“Malo jezero” N 42° 46' 58, 35" E 17° 20' 56, 95" at 1 m depth ; “Veliko jezero” N 42° 46' 57, 46" E 17° 21' 06, 28" at 8 m depth ) during spring 2011. Samples were fixed in a 4% formalin solution and prepared for investigation by cleaning frustules using the method described by Hustedt (1930). Examination and identification of benthic diatoms were carried out using the oil immersion lens (100 x) of the Microstar binocular microscope, AO Scientific Instruments. Samples were also studied by means of scanning electron microscopy. Photomicrographs were taken for the majority of taxa. Altogether, 96 taxa included in 33 genera were determined. The largest number of taxa were found within the genera Mastogloia (11), Amphora (10), Diploneis (10) and Nitzschia (7). In the “Veliko jezero” altogether 60 taxa were found. While, in the “Malo jezero”, which is very isolated from open Adriatic waters and presents a unique ecosystem, altogether 59 taxa were found of which only 22 are the same as in the “Veliko jezero”. Sörensen similarity index between two samples was 37%. The presented findings contribute to an essential base-line information of littoral marine diatom for future studies. Knowledge of the diatom community structure in the marine protected areas is important for marine ecology and conservation biology.

benthic diatoms; marine lakes; Mljet

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