As a part of an exposure and effect monitoring conducted along the river Mureş, Western Romania in 2004, the health status of two indigenous fish species, sneep (Chondrostoma nasus) and European chub (Leuciscus cephalus) was investigated upstream and downstream the city of Arad. In fish, histopathology was assessed in liver and gills, and heavy metals (cadmium, copper, lead and zinc) were analyzed in liver samples. In both fish species, histopathological reactions in the gills (epithelial lifting, focal proliferation of epithelial cells of primary and secondary lamellae and resulting fusion of secondary lamellae, hyperplasia and hypertrophy of mucous cells, focal inflammation and necrosis of epithelial cells) were most severe at the two sampling sites upstream Arad city, which were shown to be polluted by copper, cadmium, faecal coliforms and streptococci in a parallel study. At these two sites, also histopathology in the liver of L. cephalus was more prominent than at the two downstream sites. In C. nasus, symptoms in the liver (focal inflammation with lymphocytic infiltrations, macrophage aggregates and single cell necrosis) were also highly pronounced at the sampling site located directly downstream the municipal sewage treatment plant of Arad. With the exception of copper accumulation in L. cephalus caught at the most upstream sampling site, in both fish species cadmium and copper accumulation were exceptionally high and did not differ significantly between the four sampling sites.

Along a downstream stretch of River Mureş, Romania, adult males of two feral fish species, European chub (Leuciscus cephalus) and sneep (Chondrostoma nasus) were sampled at four sites with different levels of contamination. Fish were analysed for the biochemical markers hsp70 (in liver and gills) and hepatic EROD activity, as well as several biometrical parameters (age, length, wet weight, condition factor). None of the biochemical markers correlated with any biometrical parameter, thus biomarker reactions were related to site-specific criteria. While the hepatic hsp70 level did not differ among the sites, significant elevation of the hsp70 level in the gills revealed proteotoxic damage in chub at the most upstream site, where we recorded the highest heavy metal contamination of the investigated stretch, and in both chub and sneep at the site right downstream of the city of Arad. In both species, significantly elevated hepatic EROD activity downstream of Arad indicated that fish from these sites are also exposed to organic chemicals. The results were indicative of impaired fish health at least at three of the four investigated sites. The approach to relate biomarker responses to analytical data on pollution was shown to fit well the recent EU demands on further enhanced efforts in the monitoring of Romanian water quality.

Two new populations of the European mudminnow, Umbra krameri Walbaum, 1792, were encountered in Banat and Oltenia regions, southwestern Romania, within 2014-2017. The mudminnows were captured with a hand net used normally for frogs. This is the first record of this species for Banat. In Oltenia U. krameri was encountered in a region where it was considered extinct. In both areas U. krameri was present in its characteristic habitats, i.e., small water bodies with dense aquatic vegetation. Umbra krameri is subject to human pressure in both areas, but this pressure is more severe in Banat, where the agriculture is more intensive. The rare findings of the species in southern Romania are probably due to unsuitable searching methods often used in surveys, i.e., conducted only in large, but unsuitable aquatic habitats, and using classical ichthyological methods, such as electrofishing.

No abstract

The Crişul Repede River is belonging at Cris (Körös) Rivers system which is a tributary on the left shore of Tisa River. In the last decades the fishfaunaofthenaturalwatershasundergoingadeclineinthespeciesnumber.Theothersuccessiveprocessisthefishspeciesreplacement due by the immigration of some exotically fishesandtheretirementofsomeofthenativespecies.The Crişul Repede fishfaunahasregisteredadeclinecausedmainlybytheriverdamming,waterpollutionandeutrophisation.Ondespite of that negative factors the fishesfromtheupperriverwasmaintainlessaffectedunliketotheotherrivers.Thereaftertheeconomical transition and the industries reorganization process were redounded to diminishing the impact of these harmful factors. The former studies about the Cris fishfaunacitedanumberof48nativespeciesand12exoticones.Duringtheresearchtripscarriedoutsince10yearsago (beginning in 1995) was identifiedanumberof40fishspeciesandthepresenceoftheother8 speciesarestilluncertain.Thesturgeonspecies Acipenser ruthenus and the migratory fishAnguillaanguillahaveascarcepresenceandtheycannotbefoundinthelastdecade.A number of 5 exotically fishesarebehavedasremarkableintrudersinnaturalwaters:Pseudorasboraparva,Carassiusauratusgibelio,Ictalurus nebulosus, Ictalurus melas, and Lepomis gibbosus. Some of the exotically fishesalreadyrecordedintheHungarianstretchesofthe Crisuri (Körös) was not recorded in the Romanian section of the river (Mylopharyngodon piceus, Ictiobus bubalus, Ictalurus punctatus, Clarias gariepinus, Micropterus salmoides, Oreochromis niloticus, Perccottus glenii). The pervading of these species is expecting also in the Romanian section of the rivers.The present major threatening factors concerning the fishfaunaarerepresentedbythehabitatchanges.Theriverdammingandtheriverside levees have a negative influenceonthefishfauna.Theformerphenomenonofwaterpollutionitseemsthatisreplacedbythehabitat changes. The dam lakes caused unregulated fluctuationsonthewaterlevelandtemperaturedownstreamofit.Theembankmentforpreventing the floodingwasperformedthroughshorteningtherivermeander.Thelostmeandersoftheriversarerepresentinganoptimalhabitat for fishspawning.