Predrag Simonović

Morphology, Feeding, and Reproduction of the Round Goby, Neogobius melanostomus (Pallas), in the Danube River Basin, Yugoslavia

The round goby Neogobius melanostomus was the last Ponto-Caspian goby species to enter in the Danube River bordered by Serbia and Yugoslavia. There are five Ponto-Caspian goby species in the waters of Serbia including the sand goby Neogobius fluviatilis, the round goby Neogobius melanostomus, the racer goby Neogobius gymnotrachelus, the bighead goby Neogobius kessleri, and the tubenose goby Proterorhinus marmoratus. The sand, bighead, and tubenose gobies occur along the Yugoslav Danube and in the lower reach of the Danubes tributaries; the racer goby is found both upstream and downstream of the Djerdap II dam; and, the round goby has been collected only downstream of the Djerdap II dam. Investigations on the continuous morphological characters of the round goby revealed neither sexual dimorphism, nor significant differences in adult size-classes, although some suggestions of sexual dimorphism were found in cranial skeletal analyses. Analysis of external continuous characters revealed a west-east cline along the distribution range of the round goby in the Black Sea basin. Molluscivory for the round goby was corroborated along the Danube. Standard length of each age class for the round goby in the Danube was less than populations in the Caspian and Azov seas.

Correspondence between ontogenetic shifts in morphology and habitat use in minnow Phoxinus phoxinus

The morphology of minnows Phoxinus phoxinus from two rivers at the south-east of England was analysed on mensural characters and qualitative traits (occurrence of appendages, pattern of pigmentation and scalation). Eight developmental intervals were identified from the qualitative traits, and bivariate and multivariate analysis revealed that allometric growth occurs occasionally during ontogeny, mainly in earlier developmental periods. Body shape is under the influence of rapid increase during development, mainly due to the quick growth in early developmental intervals. The exclusion of ‘general size’, remarkable in early developmental intervals, revealed several ‘shape’ characters that mainly determine minnow morphology by changing the mode of variability during development (e.g. caudal characters, maximum body height, belly length and ventral head length). The tail certainly undergoes the most consistent and most durable change, its characters being the most variable and the most discriminative for developmental periods from larvae to adults. The most prominent alteration in the overall shape development occurs at the transition from larva to juvenile, both regarding the number of characters involved into the change and their variability. This transition takes place at about 28 mm SL, which corresponds to a significant change in microhabitat use in both the rivers Lee and Frome, characterized by shifts by 0+ juveniles to significantly deeper waters than those occupied by larvae, with increased amounts of either submerged filamentous algae (Lee) or vegetation (Frome).

Around or across the Carpathians: colonization model of the Danube basin inferred from genetic diversification of stone loach (Barbatula barbatula) populations

Despite increasing information about postglacial recolonization of European freshwater systems, very little is known about pre‐Pleistocene history. We used data on the recent distribution and phylogenetic relationships of stone loach mitochondrial lineages to reconstruct the initial colonization pattern of the Danube river system, one of the most important refuges for European freshwater ichthyofauna. Fine‐scale phylogeography of the Danubian populations revealed five highly divergent lineages of pre‐Pleistocene age and suggested the multiple origin of the Danubian stone loach. The mean sequence divergence among lineages extended from 7.0% to 13.4%, which is the highest intraspecific divergence observed so far within this river system. Based on the phylogeographical patterns, we propose the following hypothesis to relate the evolution and dispersal of the studied species with the evolution of the Danube river system and the Carpathian Mountains: (i) during the warmer period in the Miocene, the areas surrounding the uplifting Alps and Carpathians served as mountainous refuges for cold‐water adapted fish and promoted the diversification of its populations, and (ii) from these refuges, colonization of the emerging Danube river system may have taken place following the retreat of the Central Paratethys. Co‐existence of highly divergent mtDNA lineages in a single river system shows that range shifts in response to climatic changes during the Quaternary did not cause extensive genetic homogenization in the stone loach populations. However, the wide distribution of some mtDNA lineages indicates that the Pleistocene glaciations promoted the dispersal and mixing of populations through the lowlands.

Bioaccumulation of Heavy Metals and Microelements in Silver Bream (Brama brama L.), Northern Pike (Esox lucius L.), Sterlet (Acipenser ruthenus L.), and Common Carp (Cyprinus carpio L.) From Tisza River, Serbia

The aim of this study was to determine the concentrations of Al, As, B, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr, and Zn in liver, gills, gonads, and brain of four ecologically different fish species in Serbia: piscivorous northern pike, benthivorous sterlet and silver bream, and omnivorous common carp. Fish were caught at four sites along the stretch of the River Tisza in the Pannonian part of Serbia during October 2010. Results revealed that heavy metals and microelements with the highest values in fish samples were Fe, Al, and Zn. The highest concentration of heavy metals and microelements was recorded in omnivorous common carp, and organs that most intensively accumulated the greatest number of metals were liver and gills, whereas the locality did not exert a marked impact on level of bioaccumulation.

Evaluation of genotoxic potential throughout the upper and middle stretches of Adige river basin

In this study a comprehensive genotoxicological survey throughout the upper and middle stretches of Adige river basin is presented. The study was carried out at 7 sites located along the Adige main course and one the most significant tributaries, the Noce creek, both presenting different levels of pollution pressure. To give an insight into the nature of the genotoxic activity we employed the battery of prokaryotic and eukaryotic assays. Mutagenicity in water samples was evaluated by SOS/umuC test in Salmonella typhimurium TA1535/pSK1002. The level of DNA damage as a biomarker of exposure (comet assay) and biomarker of effect (micronucleus assay) and the level of oxidative stress as well (Fpg - modified comet assay) were studied in blood cells of Salmo cenerinus Nardo, 1847 and Salmo marmoratus Cuvier, 1829. Within the applied bioassays, comet assay showed the highest potential for discriminating the sampling sites which are under lesser extent of pressure (sampling sites 1-Barnes at Bresimo and 4-Noce downstream S. Giustina) from the sites under high pressure (sampling sites 5-Noce at Mezzolombardo and 6/7-Adige upstream and downstream municipality of Trento). Significant correlation between the standard and Fpg - modified comet assay indicated that oxidative stress could be a major contributor to observed DNA damage in collected specimens.

Re‐evaluation of Salmo data by Gridelli (1936)—description of stocking, hybridization and repopulation in the River Soča basin

History of stocking in Salmo marmoratus habitat in the Adriatic region and its effects are poorly known due to data deficiency. Well‐documented research from 1936 based on trout external morphological characters was compared with research of extant trout populations based on genetic markers in an attempt to clarify the impact of stocking in the River Soča basin. Application of multivariate statistical methods reveals a similar pattern of native and non‐native trout distribution in 1936 and after a recently started S. marmoratus repopulation project. Remnants of initial stocking from 1906 were detected in one stream in the upper Soča basin. Gridellis samples of S. dentex, one of the least researched trout species of the Adriatic region, were also re‐analysed and were found to differ from all other trout populations used in the study.

Metals in the sediment and liver of four fish species from different trophic levels in Tisza River, Serbia

In aquatic environments metals originate from various natural and anthropogenic sources. The degree of contamination in fish tissues depends on the pollutant, fish species, their mode of feeding, sampling site and trophic level. This study presents concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr and Zn in sediment and liver of four ecologically different fish species: piscivorous northern pike (Esox lucius L.), benthivorous sterlet (Acipenser ruthenus L.) and silver bream (Brama brama L.), and omnivorous common carp (Cyprinus carpio L.). Fish were caught at four sites along the stretch of the River Tisza in Serbia during October 2010. The concentrations of metals have been assessed using the inductively coupled plasma – optical emission spectrometry. Results revealed that metals with the highest values in sediment and fish samples were Al and Fe, respectively and sometimes concentrations of Zn are in the same order of magnitude as Fe concentrations. The highest concentration of metals was recorded in omnivorous common carp.

RISKS TO STOCKS OF NATIVE TROUT OF THE GENUS SALMO (ACTINOPTERYGII: SALMONIFORMES: SALMONIDAE) OF SERBIA AND MANAGEMENT FOR THEIR RECOVERY

Background. Insuffi ciently controlled stocking compromises the high diversity of wild trout stocks of Serbia. Native brown trout, Salmo cf. trutta Linnaeus, 1758, and Macedonian trout, Salmo macedonicus (Karaman, 1924), reveal remarkable diversity assessed using the mtDNA molecular markers, with the eight exclusive and several more widely spread haplotypes found in them. Four alien trout species and strains and one strain of Macedonian trout were introduced into the home areas of the native wild trout stocks in Serbia. In addition to them, wild trout stocks were also affected by farmed rainbow trout, Oncorhynchus mykiss (Walbaum, 1792), and brook trout Salvelinus fontinalis (Mitchill, 1815), that regularly escape to streams, and from Ohrid trout, Salmo letnica (Karaman, 1924), and Arctic charr, Salvelinus alpinus (Linnaeus, 1758), stocked into streams and reservoirs. Risk of invasiveness that wild trout stocks are exposed to and their restoration were driving forces for this study. Materials and methods. Trout specimens from the Jerma River sampled in 2013 were additionally analysed for their mtDNA haplotype. The invasiveness potential of eleven alien trout species and strains introduced by stocking into wild brown- and Macedonian trout stocks in Serbia were assessed with the Fish Invasiveness Screening Kit (FISK). Results. Five of introduced trout species and strains were classifi ed as having a high risk (sensu lato) and two of them as having a high risk (sensu stricto) of being (or becoming) invasive. Conclusion. Progressively rising and insuffi ciently controlled fi shing and management with stocking of non-indigenous trout in wild brown trout stocks are the main current threats to the original diversity. Alien brown trout strains cross breed with native brown trout and incorporate into their stocks. Currently, feral rainbow-, brook-, and Ohrid trout reveal great invasive potential by naturalization in waters heavily stocked with them. The fi sheries measures aiming to control and/or to eradicate alien strains of brown trout involve the restriction of stocking, landing of trout suspected as of alien strain or species, as well as the stringent control of stocking material used for the restorative stocking. They are mandatory, regarding the conservational dependence of wild brown trout stocks.

Molecular and ecological features of the soft-muzzled trout Salmo obtusirostris (Heckel, 1852) in the Zeta River, Montenegro

This paper reports about the occurrence of soft-muzzled trout in Montenegro. It was found only in the Zeta River, at three localities, always in low abundance. Results of genetic investigation on twelve microsatellite loci (i.e., high Fst and high heterozygozity values) as well as lack of hybridization with the putative brown trout unequivocally confirm that the soft-muzzled trout from the Zeta River is a species distinct from the putative brown (Salmo cf. farioides) and marble (Salmo marmoratus) trout that live in sympatry with it. This paper also confirms high genetic diversity of Zeta River soft - muzzled trout population. Habitat and feeding analyses revealed that soft-muzzled trout reduce the competition with syntopic putative brown trout by displacing as the bottom-dweller in their common type of habitat, as well as by narrowing its feeding niche and feeding dominantly with the benthic macroinvertebrates, the Gammarus shrimps as their far dominant feeding item. Results also revealed that they did not share the same habitat with marble trout. Due to this population low abundance and their importance on species level, Zeta River soft-muzzled trout conservation needs are urgent in terms of in situ protection and repopulation measures.

Evaluation of Genotoxic Pressure along the Sava River.

In this study we have performed a comprehensive genotoxicological survey along the 900 rkm of the Sava River. In total, 12 sites were chosen in compliance with the goals of GLOBAQUA project dealing with the effects of multiple stressors on biodiversity and functioning of aquatic ecosystems. The genotoxic potential was assessed using a complex battery of bioassays performed in prokaryotes and aquatic eukaryotes (freshwater fish). Battery comprised evaluation of mutagenicity by SOS/umuC test in Salmonella typhimurium TA1535/pSK1002. The level of DNA damage as a biomarker of exposure (comet assay) and biomarker of effect (micronucleus assay) and the level of oxidative stress as well (Fpg—modified comet assay) was studied in blood cells of bleak and spirlin (Alburnus alburnus/Alburnoides bipunctatus respectively). Result indicated differential sensitivity of applied bioassays in detection of genotoxic pressure. The standard and Fpg—modified comet assay showed higher potential in differentiation of the sites based on genotoxic potential in comparison with micronucleus assay and SOS/umuC test. Our data represent snapshot of the current status of the river which indicates the presence of genotoxic potential along the river which can be traced to the deterioration of quality of the Sava River by communal and industrial wastewaters. The major highlight of the study is that we have provided complex set of data obtained from a single source (homogeneity of analyses for all samples).