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Taxonomic composition and seasonality of marine benthic diatoms in Bosnia and Herzegovina (NW Mediterranean)

The aim of the study was to determine the taxonomic composition and seasonality of benthic marine diatoms in Bosnia and Herzegovina. Samples were taken from one station (coordinates: 42° 54' 58.7" N 17° 36' 17.6" E) at 1 and 8 m depths during all seasons in 2011. Samples were fixed in a 4% formalin solution and prepared for investigation by cleaning frustules using the method described by Hustedt (1933). In total, 400 valves per sample were counted. Examination, identification and counting of benthic diatoms were carried out using the oil immersion lens (100x) of the Microstar binocular microscope, AO Scientific Instruments. Diatoms were also studied by means of scanning electron microscopy (SEM). Photomicrographs were taken for the majority of taxa. Altogether, 270 taxa (species and infraspecific taxa) included in 75 genera were determined. The highest number of taxa was in spring (177) and the lowest in autumn (91). The largest number of taxa was found within the genera Mastogloia (27), Diploneis and Nitzschia (20), Amphora (19), Navicula (15), Halamphora and Cocconeis (10). Regarding depths, higher number of taxa was identified at 8 m depth in the most samples. According to Simpson and Shannon-Wiener indicies, the highest differences between surface and bottom samples were recorded in winter. Taxa Cocconeis scutellum Ehrenberg, Grammatophora oceanica Ehrenberg, Halamphora coffeaeformis (Agardh) Levkov, Licmophora remulus Grunow, Trachyneis aspera (Ehrenberg) Cleve were presented in all samples. In all seasons, the most abundant taxa were Cocconeis scutellum Ehrenberg (4-22.5%) at 1 m, and Halamphora coffeaeformis (Agardh) Levkov (6.25-13.25%) at 8 m depth.

benthic diatoms; marine environments; Bosnia and Herzegovina

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