Emergence and Composition of Trichoptera from Karst Habitats,Plitvice Lakes Region,Croatia

Adult Trichoptera were observed at the Plitvice Lakes, Croatia during two years (2000 and 2001) using pyramid‐type emergence traps. A total of 1350 individuals and 37 species were collected. Throughout the study, the emergence patterns showed only minor variations regarding differences in particular habitats. During 2000 most species emerged in June, and in 2001 in May. The complete emergence period is shown for all collected species and studied in detail for abundant species. Excluding Allogamus uncatus, all abundant species emerged in summer, with most exhibiting a long emergence period. Rhyacophila fasciata had the longest emergence period in both years of the study and also showed winter activity. Trichopteran diversity and equitability were calculated and trophic relationships of the collected species were identified for each sampling site in order to obtain better insight into trichopteran community structure. Results indicated that the trichopteran community could be grouped according to travertine barriers and stream habitat types. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crustacean plankton community (Crustacea: Copepoda and Cladocera) in gypsum karst lakes and their relation to abiotic parameters

Two gypsum karst lakes and one non-gypsum karst lake were studied for copepod and cladoceran species composition in relation to specific habitat characteristics. The investigation was conducted from March to June 2007. Four copepod and six cladoceran species were recorded. Gypsum karst lakes are characterized as sulphate lakes and they show significant differences from non-gypsum karst lakes in conductivity, TDS, alkalinity, calcium and sulphates. Data on environmental variables and zooplankton were analyzed using redundancy analysis (RDA). The model explained 65.73% of the variance of the crustacean zooplankton and environmental data by the first two axes. The analysis confirmed that the major environmental variables influencing zooplankton in gypsum karst lakes are conductivity, TDS, calcium and sulphates. In the non-gypsum karst lake, on the contrary, the major variables were oxygen concentration and alkalinity. Specific habitat characteristics of gypsum karst lakes influence the zooplankton community by reducing the number of species and leading to the dominance of one of them.     

A cave leech (Hirudinea, Erpobdellidae) from Croatia with unique morphological features

Croatobranchus mestrovi is a troglobitic leech from deep shaft-like caves in the Velebit Mountain, Dinaric karst, Croatia, living in cold (4–6 °C) water. Its oral sucker extends to form four pairs of triangular tentacles, each with about five finger-like papillae, but widening into a marginally crenulated disc when attached to a substrate. Pairs of stiff, finger-like lateral projections, probably gills, occur along the body behind the clitellum. Somites are simple five-annulate. Despite the unique head morphology and the presence of lateral outgrowths, the anatomy and 18S rRNA gene sequence of this species indicate that it is a member of the Erpobdellidae, closely related to Dina .     

Copepod communities in karstic mediterranean lakes along the eastern Adriatic coast

The copepod communities of karstic lakes along the eastern Adriatic coast were studied. Lakes were divided in several groups according to their morphology (deep, shallow, barrage and reservoirs), production (oligotrophic, mesotophic and eutrophic), and salinity of water: freshwater and brackish. Copidodiaptomus steueri, Eucyclops serrulatusand Macrocyclops albidus belong to the group that inhabited most of the lakes under the study, regardless of lake type. The shallow karstic lakes are usually inhabited by Thermocyclops dybowskii, T. oithonoides, Cyclops vicinus and Eudiaptomus padanus etruscus in freshwater biotopes, and Calanipedia aquaedulcis and Copidodiaptomus steueri in brackish biotopes. The last two species can also be found in deep karstic lakes with brackish water (Bacina lakes in the Neretva River delta). Species like Cyclops abyssorumcan be found in most deep freshwater lakes. Some Calanoida were recorded in only one lake, like Eudiaptomus transsylvanicusin the deep Lake Vrana on the island of Cres, or Eudiaptomus hadzici in the barrage Lake Visovac. Production of the lakes, expressed as copepod biomass, depends on lake trophy, and in some lakes also on hydrology and salinity. Most of the meso-eutrophic lakes in the study area had Calanoida dominating, while Cyclopoida dominated in some oligotrophic and eutrophic lakes as well.