engleski

Benthic diatoms as a tool for water quality assessment of rivers and streams in Croatia - Implementation of Water Framework Directive

The purpose of this paper is to make an inventory of the diatom assemblages in Croatian rivers and streams, to access the relationship between diatom species composition and environmental variables and to choose among existing metrics the one that is the most appropriate for Croatian rivers and streams. Investigations were performed during spring and summer in 2006, 2007 and 2009. Altogether, samples were collected on 141 sampling points on 92 different rivers and streams in Croatia. Samples for water chemistry analysis were taken at the most of the sampling points. Altogether 182 diatom species were noted and used for the analysis. Canonical analysis of principal coordinates (CAP) revealed that main environmental factors describing the dataset were waterbed type, total N, NO3-, oxygen saturation, type of waterbed and stream type. It seems that nutrients, especially phosphorus, have more important role concerning diatom assemblages when we look into the data at regional scale. SOM analysis distinguished 10 stream types which indicate that existing typology is too detailed for diatom assemblages. Using OMNIDIA software, numerous water quality indices were calculated and with combination of different multivariate analyses, correlations with environmental factors and expert opinion, trophic index was chosen as a metric for estimation of water quality in running waters in Croatia. For every species, indication and sensitivity values were adopted for Croatian geomorphology using simple linear regression between diatom species abundance and total phosphorus concentration. Boundaries were set for different groups of stream types, streams water quality map was drawn and reference sites were selected for further consideration.

Diatoms; water quality; rivers; streams; Croatia

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