Petar Žutinić

Defining centric diatoms of most relevant phytoplankton functional groups in deep karst lakes

Phytoplankton in karst lakes is characterized by co-occurrence of chrysophytes (Chrysophyceae), dinoflagellates (Dinophyceae), and diatoms (Bacillariophyta) as the most diverse and abundant group. Using Reynolds functional approach in ecological phytoplankton investigations makes karstic lakes comparable and facilitates interpretation of their responses to changing environmental conditions. Accurate taxonomic identification to species level, based on precise resolution of specific characteristics by electron microscopy, is essential in order to correctly associate species into coda. This paper defines the most abundant centric diatoms and coexisting species in the phytoplankton of karst lakes in Croatia as a contribution to better description of phytoplankton functional groups dominated by centric diatoms. Several representatives for diatom-based Reynolds functional groups of four lakes in Croatia were described in this paper: Pantocsekiella costei and Stephanocostis chantaica for group A, Pantocsekiella ocellata and Cyclotella distinguenda for group B, and Stephanodiscus neoastraea for group C, together with their ecological preferences which clearly correspond to pertaining functional classification. Selected and coexisting functional groups define natural, oligo- to mesotrophic karst deep lake systems.

Distribution of endangered Italian gudgeon Romanogobio benacensis (Cypriniformes, Cyprinidae, Gobioninae) with remarks on distinguishing morphological characters

Abstract Distribution data on many freshwater fish species in Croatia are scarce and species identifications are difficult, requiring further detailed studies. This paper presents a report of the Italian gudgeon Romanogobio benacensis from the Mirna River in the Istra Peninsula in Croatia, in the south-east from its previously known distribution range. The identification of R. benacensis in Croatia was supported by a morphological comparison with R. benacensis from Italy and Slovenia, the common gudgeon Gobio gobio, and the Danubian gudgeon Gobio obtusirostris from geographically close locations. A combination of character states (number of scales between anus and anal-fin origin, branched pectoral-fin rays, lateral-line scales, total, abdominal, and caudal vertebrae, and the size and number of lateral blotches) distinguishes R. benacensis from both G. gobio and G. obtusirostris. The phylogenetic analyses using mitochondrial sequences of cytochrome b gene confirmed that specimens from the Mirna River belong to R. benacensis. Also, Reka River system (Adriatic Sea basin) in Slovenia is inhabited by a possibly introduced Danubian gudgeon, G. obtusirostris, and not by R. benacensis.

Do benthic diatom assemblages reflect abiotic typology: a case study of Croatian streams and rivers

Abstract Benthic diatoms are widely used in Europe and worldwide to access ecological status of running waters. One of key goals of Water Framework Directive is to classify rivers and streams using biological quality elements and type specific reference conditions. According to system B which incorporates additional abiotic descriptors, there are 24 water types in Croatia. For biological analyses 92 rivers and streams with 140 sampling points were chosen and sampled for benthic diatoms and water chemistry simultaneously. Self organizing map (SOM) analysis was used to define biotypes from species composition and abundance of benthic diatoms. Grouping of samples in SOM resulted in 10 distinctive groups. Based on their geographical position and site characteristics, groups represent sites with similar properties (as waterbed, catchment size, altitude, size of stream) belonging to different ecoregions in Croatia. Analysis of variance revealed statistically significant differences (p<0.05) among SOM groups concerning ammonia, nitrates and total phosphorus. Indicator species analysis (IndVal) singled out species that were significantly characteristic (p<0.05) for SOM and abiotic types. Compared to abiotic groups, in which 7 out of 24 have no indicator species, all SOM groups have one or several characteristic diatom species, thus indicating diatom assemblages as valuable site descriptors. Canonical analysis of principal coordinates analysis also indicated that SOM grouping of samples is statistically reliable. Grouping of similar sites, although placed into different abiotic types, makes SOM groups with its corresponding representative species an easy tool for water quality assessment and description of reference assemblage.

Erratum to: Morpho-functional classifications of phytoplankton assemblages of two deep karstic lakes

Due to an unfortunate turn of events, the first-and surnames of all authors were transposed in the original publication. The correct representation of the authors and their affiliations are listed above and below and should be treated as definitive by the reader.