Pikeperch (
Sander lucioperca
), European catfish (
Silurus glanis
), common carp (
Cyprinus carpio
), and gobies (
Neogobius gymnotrachelus
,
Neogobius melanostomus
) were collected from the Danube ...River (Belgrade section), and samples of liver, muscle, or whole-body composites (in the case of gobies) were analyzed for As, Cu, Fe, Hg, Mn, and Zn with inductively coupled plasma optical spectrometry to find out if there was a correlation between accumulation of these elements in predatory and prey species, as well as in pairs of species with overlapping diets. Concentrations of all analyzed elements were either higher (Cu, Fe, Mn, Zn) in liver than in muscle, or equal (As, Hg), except for Hg in carp, which was higher in muscle. Mercury concentration in liver and muscle of predators (catfish, pikeperch) was significantly (<10
−4
) higher than in prey fishes (carp and gobies). The results indicate that Hg concentration was biomagnified through the food chain. Concentrations of As, Fe, and Hg in carp liver and gobies whole-body composite were similar, but carp had significantly (<10
−4
) higher values of Zn and Cu in liver. The regression analysis and trendline equations indicate that the concentrations of all tested elements, except for As in liver, and Mn and Fe in muscle, were similar in predatory fish (pikeperch and catfish), on one hand, and in prey fish (carp and gobies), on the other hand. Distinctly high Zn concentration in carp is very common in this species due to its physiology. Concentrations of Hg and Zn were higher than the maximum acceptable concentration due to the high pollution level in this section of the Danube River, accordingly posing a risk for the human consumption of these fish species.
Seventy‐six individuals of the European mudminnow Umbra krameri from two recent populations from Serbia (Bakreni Batar and Lugomir) and one from Bosnia and Herzegovina (Gromiželj) were analysed for ...habitat preferences and population structure. The population from Lugomir is a newly recorded population in Serbia. Besides this new record, it is noteworthy that all three studied locations are outside the currently known species distribution range limits.
As a basis for future conservation activities, the genetic and external body morphology variability of the European mudminnow Umbra krameri, a highly endangered fish species in Serbia and in Bosnia ...and Herzegovina, was determined for existing populations with the use of molecular markers (mitochondrial and microsatellite DNA) and geometric morphometric methods. Mitochondrial DNA cytochrome b gene analysis revealed two previously undescribed haplotypes: Da1 (the Lugomir population from the Danube River basin) and Sa1 (the Bakreni Batar and the Gromiželj populations from the Sava River system), with a corresponding genetic distance of 0·7%. Paired values of FST and DAS distances for microsatellite marker data show that the difference between the Danube and the Sava populations is seven to nine times higher than the difference between the populations within the Sava River system. Geometric morphometric analyses also support a clear separation of the Lugomir population from the Bakreni Batar and the Gromiželj populations. The analysis of the body shape variation, however, indicates a significant difference between the two genetically indistinguishable Sava populations. The observed genetic and phenetic relationships of the analysed mudminnow populations most probably represent a consequence of historical, geographical and ecological factors. These results will offer guidelines for future protection, conservation and sustainable management of this species in the region.
A sample of 198 asp (Aspius aspius) was collected over a 28.5 km long section of the Danube River, upstream and downstream from the mouth of the Sava River, in order to provide information on ...population structure, diet, growth, and condition of this species. Total body lengths of sampled fish were 90-405 mm, and body weights 5-567 g. The sample was predominantly sub-adult fish aged 0+ to 4+ years. Sexually immature asp prevailed over the sexually mature asp. The sex ratio (1.4 : 1) was biased toward males. Male asps in the Danube become sexually mature only in their fifth year of life, and the females even later, as no sexually mature females were caught. The diet spectrum consists exclusively of fishes; of seven determined prey species, most important are bleak Alburnus alburnus, roach Rutilus rutilus, and goldfish Carassius auratus. Highest value of the seasonal vacuity index is in November (Iv = 94.1), and the smallest in July (Iv = 35.6). Trophic niche breadth is largest in May (H = 1.40), and smallest in November (H = 0.00). The largest average number of prey items is found in age class 4+ (2.33), the smallest in age class 0+ (1.00). Von Bertalanffy growth parameters are Linfinity = 526.46, K = 0.28, and t₀ = 0.22. The length-weight relationship is described as log W = -5.16 + 3.03 log L. Fulton's condition factor increases with fish length, from 0.70 to 0.83. Regarding seasonal fluctuations, this factor begins to increase in late spring, with the trend continuing until autumn, and then decreasing from autumn to spring.
The analysis of 18 elements in muscle, liver, gills, and gonads of sichel (
Pelecus cultratus
), ruffe (
Gymnocephalus cernua
), and European perch (
Perca fluviatilis
), caught at a polluted segment ...of the Danube River near Belgrade, was carried out with the aim to expand the knowledge about the ecotoxicology of these species for monitoring purposes and the possible impact on human health. Generally, the elemental concentration significantly differed between species and tissues (
p
< 0.0001), and a statistical interaction between these two factors was observed (
p
< 0.0001). In muscle and liver, concentrations of Hg and Se were statistically higher in ruffe than in sichel and European perch. In gills, statistically highest concentrations of Mn, Sr, and Zn were found in sichel, and of Fe in European perch. In gonads, statistically highest concentrations of As were detected in sichel, of Zn in ruffe, and of Mn and Mo in European perch. The highest number of coefficients of partial correlations between fish weight and element levels was found in sichel (11 in total). Of all analyzed elements, Al and B had the highest number of partial correlations in tissues. The levels of Hg exceeded the maximum acceptable concentration (0.5 mg kg
−1
) in all muscle samples, which can pose a risk for human consumption. Different diet preferences of the investigated fish species resulted in a different accumulation of elements in tissues, and ruffe (as a species that consume mainly benthic macroinvertebrates) accumulated the highest level of Hg, which makes it suitable for monitoring of this element in water bodies.
Monthly samples of caddisfly (Trichoptera) larvae were taken from ten localities along a 151 km long section of the Nišava River (eastern Serbia) during a one year study, with the aim to assessing ...the spatial composition of the caddisfly assemblage along the river gradient, to identify key environmental factors influencing its variability, to find out if caddisflies are suitable as biological indicators of water quality in this region, and to asses if the caddisfly assemblage in the river follows the river continuum concept. Twenty-three morphologically distinct taxa belonging to 14 genera were identified. The dominant family was Hydropsychidae with 70.34% of specimens examined, followed by Brachycentridae with 9.74% specimens. The longitudinal variability of the caddisfly assemblage has shown a clear dependence on physical and chemical parameters. The CCA analysis suggests that BOD5and concentration of total phosphorus are the most important factors in structuring the caddisfly assemblage. The species diversity was greatest at localities with the highest oxygen concentration and low nutrient levels. The caddisfly assemblage proved to be useful in identifying differences in environmental conditions in the Central Balkan region.
Des échantillons mensuels de larves de phryganes (trichoptères) ont été prélevés dans dix localités réparties dans un secteur long de 151 km de la rivière Nišava (Serbie orientale) au cours d’une étude d’un an, dans le but; d’évaluer la composition spatiale de l’assemblage de phryganes le long de la rivière, d’identifier les principaux facteurs environnementaux qui influent sur sa variabilité, pour savoir si les trichoptères sont appropriés comme indicateurs biologiques de la qualité de l’eau dans cette région, et d’évaluer si l’assemblage de phryganes dans la rivière suit le concept de continuum fluvial. Vingt-trois taxons morphologiquement distincts appartenant à 14 genres ont été identifiés. La famille dominante était les Hydropsychidae avec 70,34 % des spécimens examinés, suivis par les Brachycentridae avec 9,74 % des spécimens examinés. La variabilité longitudinale de l’assemblage de phryganes a montré une dépendance claire des paramètres physiques et chimiques. L’analyse CCA suggère que la DBO5 et la concentration de phosphore total sont les facteurs les plus importants dans la structuration de l’assemblage de phryganes. La diversité des espèces était la plus élevée dans des localités ayant la plus forte concentration d’oxygène et de faibles niveaux d’éléments nutritifs. L’assemblage de phryganes s’est avéré utile pour identifier les différences dans les conditions de l’environnement dans la région centrale des Balkans.
The sedentary nature of many members of the river macroinvertebrate community allows spatial and temporal analyses of disturbance effects. This characteristic also implicates their strong affinity ...towards certain types of microhabitats. The results of the mayfly (Ephemeroptera) community structure analysis in the Nisava River (Serbia) have shown a clear dependence of the mayfly community on habitat type (solid vs. loose bottoms), physical and chemical parameters (nutrient content), and season. Over a one-year period, on a monthly basis, 28 species of mayfly were identified at 12 localities along the 151 km long stretch of the Nišava River. The community structure changed longitudinally with the changes of physical and chemical parameters and habitat type. The lowest Shannon's diversity index was estimated for the localities with the lowest percentage of solid bottoms (rock, pebble). The highest diversity index was estimated for localities with the highest percentage of solid bottoms and the lowest average content of phosphorus and nitrogen.
The analysis of 18 elements in muscle, liver, gills, and gonads of sichel (Pelecus cultratus), ruffe (Gymnocephalus cernua), and European perch (Perca fluviatilis), caught at a polluted segment of ...the Danube River near Belgrade, was carried out with the aim to expand the knowledge about the ecotoxicology of these species for monitoring purposes and the possible impact on human health. Generally, the elemental concentration significantly differed between species and tissues (p < 0.0001), and a statistical interaction between these two factors was observed (p < 0.0001). In muscle and liver, concentrations of Hg and Se were statistically higher in ruffe than in sichel and European perch. In gills, statistically highest concentrations of Mn, Sr, and Zn were found in sichel, and of Fe in European perch. In gonads, statistically highest concentrations of As were detected in sichel, of Zn in ruffe, and of Mn and Mo in European perch. The highest number of coefficients of partial correlations between fish weight and element levels was found in sichel (11 in total). Of all analyzed elements, Al and B had the highest number of partial correlations in tissues. The levels of Hg exceeded the maximum acceptable concentration (0.5 mg kg.sup.-1) in all muscle samples, which can pose a risk for human consumption. Different diet preferences of the investigated fish species resulted in a different accumulation of elements in tissues, and ruffe (as a species that consume mainly benthic macroinvertebrates) accumulated the highest level of Hg, which makes it suitable for monitoring of this element in water bodies.
Planktonic cnidarians were investigated at six stations in the Boka Kotorska Bay from March 2009 to June 2010 by vertical hauls of plankton net from bottom to surface. In total, 12 species of ...hydromedusae and six species of siphonophores were found. With the exception of the instant blooms o/Obelia spp. (341 ind. m super(-3) in December), hydromedusae were generally less frequent and abundant: their average and median values rarely exceed 1 ind. m super(-3). On the contrary, siphonophores were both frequent and abundant. The most numerous were Muggiaea kochi, Muggiaea atlantica, and Sphaeronectes gracilis. Their total number was highest during the spring-summer period with a maximum of 38 ind. m super(-3) observed in May 2009 and April 2010. M. atlantica dominated in the more eutrophicated inner area, while M. kochi was more numerous in the outer area, highly influenced by open sea waters. This study confirms a shift of dominant species within the coastal calycophores in the Adriatic Sea observed from 1996: autochthonous M. kochi is progressively being replaced by allochthonous M. atlantica in the coastal waters, especially in the eutrophicated areas. This study provides a detailed report on the composition and abundance of the planktonic cnidarians community in this region, and should be considered as a baseline for future studies on gelatinous zooplankton.Original Abstract: Istrazivanje planktonskih zarnjaka obavljeno je na sest postaja Boka-Kotorskog zaljeva od ozujka 2009. do lipnja 2010. Uzorci su sakupljeni vertikalnim potezima planktonske mreze od dna do povrsine. Ukupno je nadeno 12 vrsta hidromeduza i 6 vrsta sifonofora. S izuzetkom velikih nakupina vrste roda Obelia u prosincu 2009. (341 jed. m super(-3)), prosjecne vrijednosti hidromeduza rijetko su prelazile vrijednost od 1 jed. m super(-3). Za razliku od hidromeduza, sifonofore su bile cesce i brojnije, osobito u proljece i ljeto. Najbrojnije su bile Muggiaea kochi, Muggiaea atlantica i Sphaeronectes gracilis. Najveca gustoca od 38 jed. m super(-3) utvrdena je u svibnju 2009 i ozujku 2010. godine. Vrsta M. atlantica je dominirala u eutroficiranom unutrasnjem dijelu zaljeva, dok je M. kochi bila brojnija u vanjskom dijelu zaljeva koji je pod jakim utjecajem otvorenog mora. Nasa istrazivanja su potvrdila dosadasnja saznanja za Jadransko more da u obalnim, osobito eutroficiranim podrucjima, novo pridosla sifonofora M. atlantica postaje dominatna u odnosu na autohtonu vrstu M. kochi. Ova istrazivanja donose prve detaljne podatke o sastavu i brojnosti planktonskih zarnjaka Boka-Kotorskog zaljeva i predstavljaju osnovu za buduca istrazivanja zelatinoznog zooplanktona.
Five anchovy (Engraulis encrasicolus, Linnaeus 1758) eggs were caught during an ichthyoplankton survey in Boka Kotorska Bay (south Adriatic Sea) with a PairOVET (modified CalVet) plankton net on ...December 5 super(th), 2006. Eggs were found at two sampling stations (42 degree 28'30.24" N, 18 degree 44'41.81" E and 42 degree 29'30.23" N, 18 degree 40'41.84" E). It is the third record of anchovy eggs in the winter months in the Adriatic Sea.Original Abstract: Pet jaja brgljuna (Engraulis encrasicolus, Linnaeus 1758) su uhvacena tijekom istrazivanja ihtioplanktona u Bokokotorskom zaljevu (juzni Jadran) s PairOVET (izmijenjeni CalVet) i planktonskom mrezom 5. prosinca 2006. godine. Jaja su pronadena na dva mjesta uzorkovanja (42 degree 28'30.24 "N, 18 degree 44'41 0,81" E i 42 degree 29'30 0,23 "N, 18 degree 40'41 0,84" E). Ovo je treci nalaz jaja brgljuna u zimskim mjesecima u Jadranu.
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