A. Hegediš

Non-native and translocated fish species in Serbia and their impact on the native ichthyofauna

A total of 22 fish species have been introduced into the inland waters of Serbia, either intentionally or accidentally. This paper provides a summary of data concerning time and reason of introduction, mode of expansion, degree of acclimatization, impact on native fish and estimated area of recent distribution. Four of the non-native fish species currently occupy more than 51% of Serbian territory while 5 of them occupy between 21–50% of territory. This paper reviews impacts of introduced freshwater fish in Serbia based on collected data.

Distribution and accumulation of elements (As, Cu, Fe, Hg, Mn, and Zn) in tissues of fish species from different trophic levels in the Danube River at the confluence with the Sava River (Serbia)

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.

A report of Eriocheir sinensis (H. Milne Edwards, 1854) [Crustacea: Brachyura: Grapsidae] from the Serbian part of the Danube River

Two specimens of the Chinese mitten crab, Eriocheir sinensis, were found in the Serbian part of the Danube River (1995, 1084

Spectral sensitivity of the dogfish shark (Scyliorhinus canicula)

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Past and present of and perspectives for the Danube huchen, Hucho hucho (L.), in the Danube basin

km of the watercourse and 2001, 1174

Feeding habits of huchen Hucho hucho (Salmonidae) fry in the River Tresnjica, Yugoslavia

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Spectral sensitivity of the electroretinogram b-wave in dark-adapted Prussian carp ( Carassius gibelio Bloch, 1782)

km). Description, biology, origin and distribution of this species, as well as potential impact to the aquatic ecosystems are discussed. These are first records of this invasive crab in Serbian part of the Danube River.

Radoslav K. Andjus (1926-2003): a brief summary of his life and work.

The action spectrum of the electroretinographic (ERG) b-wave and the unmasked late receptor potential (LRP) were measured under a variety of conditions (isolated eyecup, detached retina, b-wave recording in fresh preparations, LRP measurements after low-temperature aging, dark and light adaptation). It was shown that in the dogfish, Scyliorhinus canicula (L.), eyecup spectral sensitivity matched closely the pigment 502 spectral curve like other rhodopsin-possessing marine species. The ERG b-wave is as good an indicator of spectral sensitivity as the unmasked LRP that directly reflects the responsiveness of photoreceptors. Differences in spectral sensitivity were not revealed between dogfish preparations studied under a variety of conditions (isolated eyecup vs. detached retina; b-wave recording in fresh preparations vs. LRP measurements after low-temperature aging; dark vs. light adaptation). We developed a new model for spectral sensitivity data.

Effects of mine tailing and mixed contamination on metals, trace elements accumulation and histopathology of the chub ( Squalius cephalus ) tissues: Evidence from three differently contaminated sites in Serbia

Abstract Huchen, Hucho hucho (L.), also known as Danube salmon, is an iconic, endemic species inhabiting the Danube basin of Central Europe. Historically, the Danube huchen inhabited a significant portion of the Danube drainage basin stretching to the Iron Gate and the majority of large and medium-sized tributaries. Larger populations in the natural zoogeographical distribution of Danube huchen were once found in Austria, Bavaria, the former Yugoslavia, Slovakia, and western Ukraine. Currently, the species is severely fragmented within the Danube drainage, where most populations exclusively depend on stocking and natural reproduction is very limited due to habitat alterations and flow regime changes. In the Czech Republic and Poland, Danube huchen occurrence is the result of introducing the species to several rivers in the Baltic Sea and North Sea drainage basins. Danube huchen is a threatened species throughout is range of occurrence, and, according to IUCN criteria, it is classified as endangered (EN). Habitat degradation is the most serious negative factor impacting huchen populations. Dam construction, pollution, and river regulation have led to loss and degradation of spawning sites. Detailed research on population abundance and structure is greatly needed to help identify the populations which are most threatened and to help to develop the best protection systems.

Prediction of fish catch in the Danube River based on long-term variability in environmental parameters and catch statistics

Abstract About 10000 huchen larvae, obtained by artificial spawning, were introduced on 28 May 1995 into the River Tresnjica, a tributary to the River Drina, using procedures applied routinely by local fishing associations. During next two months, only 33 fry were caught in the river. Nevertheless, valuable information has been obtained for the first time on young huchens in the Drina basin. The fry apparently selected slower or almost stagnant water habitats outside the main river course. The variability of prey organisms found in fry stomachs decreased with fry length. Larger and particularly motile prey, especially mayfly larvae, gradually dominated the fry diet. Also for the first time, we document homing instinct in huchens with mark‐recapture information: one out of the nine adults, tagged after spawning, was recaptured the following year at the same spawning site.