Vytautas Kesminas

Species Composition of Macroinvertebrates in Medium-Sized Lithuanian Rivers

The article is devoted to the analysis of the taxonomic composition of macroinvertebrates in 17 medium-sized Lithuanian rivers with different kinds of substrata. One hundred and sixty taxa of invertebrates were identified in the course of the study. The obtained results proved that in the same river the number of taxa and Shannon-Weavers index of diversity are substratum type dependent. The greatest number of taxa was established in the stone substratum while the smallest was recorded in the sand one. The richest biodiversity and the highest Shannon-Weaver.s index in the stone substratum were recorded in the Jiesia River. Rivers with increased organic contamination were dominated by Trichoptera of the genus Hydropsyche.

Changes in macrophytes and fish communities in the cooler of Ignalina nuclear power plant (1988–2008)

Abstract On the basis of long-term studies of the radionuclide and heavy metals accumulation and scatter in biotic and abiotic components of Drūksiai Lake as well as of water and bottom sediments toxicity and genotoxicity, radioactive, chemical and thermal pollution potential impacts on macrophytes and fish communities of Drūksiai Lake were evaluated. Before starting exploitation of Ignalina Nuclear Power Plant (INPP) 95 species of macrophytes were found in Drūksiai Lake. Since the start-up of the second nuclear reactor of INPP (1987), significant alternations in macrophytes species composition and biomass in Drūksiai Lake were especially observed to 1989. Resistant to the pollution macrophytes species began to dominate in the Lake. In 2007–2008 in the main part of the Lake, in which INPP sewage entered, only resistant to anthropogenic impacts macrophytes species were found. Fish species composition also has changed. The varietal diversity of the fish in the Lake significantly decreased from 23–26 (before...

Fish Diversity and Growth in Lakes of Aukštaitija National Park

The article presents data on fish community structure and distribution in lakes of Aukstaitija National Park as well as dynamics of quantitative and qualitative parameters of biological indices in those lakes. Investigations were performed in 20 different-sized lakes in 1993–2002. It was established that due to anthropogenic load trophicity of certain small lakes had significantly changed. A total of 26 species representing eight families was recorded in the investigated lakes. Fish communities of the majority of mesotrophic and eutrophic lakes were dominated by roach (Rutilus rutilus L.), on average making up 42% of the number and 30% of the weight of fish caught in a lake, and perch (Perca fluviatilis (L.)), constituting 16% and 4%, respectively. The most intense changes in fish diversity and community structure were recorded in the small lakes Joskutis, Baltys, and Juodenis, previously poisoned with polychlorpinen. In the other lakes, no changes in species diversity were observed in 1960–2002. As a res...

Accumulation of heavy metals (Cu, Zn, Ni, Cr, Pb, Cd) in tissues of perch (Perca fluviatilis L.) and roach Rutilus rutilus (L.) under experimental conditions

Santrauka Ivertintas sunkiuju metalu pasiskirstymas gelavandeniu žuvu audiniuose monitoringiniuose vandens telkiniuose, taip pat ir kuoju bei eseriu, paveiktu sunkiuju metalu didžiausiomis leidžiamosiomis koncentracijomis (DLK), audiniuose. Eksperimentiniai tyrimai atlikti su Cu, Zn, Ni, Cr, Pb, Cd, kuriu kiekvienas pasižymi kancerogeniniu mutageni‐niu poveikiu. Nustatyta, kad svino DLK (0,2 mg/kg) buvo virsyta eseriu raumenyse 1,6 karto, o kuoju ‐ 1,4 karto. Kadmio DLK (0,05 mg/kg) eseriu ir kuoju raumenyse buvo virsyta apie 1,2 karto. Taip pat nustatyta, kad eseriai sunkiuosius metalus kaupia intensyviau nei kuojos. Eksperimentiniai duomenys sutampa su sunkiuju metalu tyrimu monitoringiniuose vandens telkiniuose duomenimis. Žuvu audiniuose Pb ir Cd koncentracijos yra didžiausios ir dažnai virsija Lietuvos higienos normoje nurodytaja DLK. Tokie rezultatai ipareigoja nuolat kontroliuoti sunkiuju metalu kieki žuvyse. Rezultatai pateikiami sunkiuju metalu sklaidos pasiskirstymo grafikuose.

The Present State of Salmon (Salmo Salar L.) in Lithuania

According to historical data, salmon used to spawn in 16 rivers in Lithuania. At present wild salmon smolt production has been recorded in two rivers only, the Žeimena and Neris, both of them belonging to the Nemunas River basin. During the last decade the abundance of salmon migrating to the Nemunas River basin varied in the range of 3,400 to 7,800 individuals (on average – 4,818). The potential smolt production in Lithuanian rivers amounts to 180,000 ind. However, the actual annual wild salmon smolt production ranges from 4,500 to 20,200 ind, that makes only 2.5–11% of that potential. The average density of salmon parr in these rivers is low – 1.4 ind/100 m2. The maximum density of salmon parr in the Žeimena River amounts to 5.6–9.7 ind/100 m2 and the average density – to 4.56 ind/100 m2, 0+ age group predominating. Investigations of salmon smolt migration in the Mera River revealed, that migration usually starts in the beginning of April, and lasts till the beginning of May. Migration is the most inten...

Salmon (Salmo Salar) and Sea-Trout (Salmo Trutta) Restocking Efficiency in Potential Rivers of Lithuania. Initial Study

The article presents initial data on salmon (Salmo salar) and sea-trout (Salmo trutta) restocking efficiency in potential rivers of Lithuania. 0+ juveniles were released into rivers in spring with the abundance of surviving individuals evaluated in autumn. Restocking efficiency was found to be considerably higher in those river stretches where fish migration towards the lower river reaches was restricted to weirs. About 30–50% of the juveniles released in spring survived in these localities until autumn. The relative abundance of juveniles in the stretches open to migration fluctuated in the wide range: salmon relative abundance varied from 0.1 to 16.1% (5.0% on average) and that of sea-trout – from 1.2 to 76.4% (24.4% on average). Salmon juveniles were found to display a much stronger tendency to migrate downstream from their release site than the juveniles of sea-trout. Still stronger liability to migrate towards the lower river reaches is characteristic of salmon juveniles that were raised until autumn...

Experimental investigation of heavy metal accumulation in tissues of stone loach noemacheilus barbatulus (L.) and rainbow trout oncorhynchus mykiss (walbaum) exposed to a model mixture (Cu, Zn, Ni, Cr, Pb, Cd)

Abstract During experiment, fish were exposed to a heavy metal model mixture (Cu, Zn, Ni, Cr, Pb, Cd) for 14 days. Heavy metal concentrations corresponded to Maximum Permitted Concentrations (MPC) in surface waters. The amount of heavy metals in fish tissues was determined using atomic absorption spectrophotometry (AAS). Though both investigated fish species accumulated heavy metals with similar general intensity, the stone loach did it in the sequence gills > liver > muscle, and the rainbow trout ‐ conversely: muscle > liver > gills. Ni concentration in the stone loach muscle made 0.607 mg/kg and Pb concentration was 0.21 mg/kg, whereas Cd concentration in the rainbow trout muscle reached 0.45 mg/kg and exceeded the MPC indicated in the Lithuanian hygiene standard. These results coincide with the data of the heavy metal research into fish species from natural water bodies. Pb and Cd concentrations in fish tissues are the highest and frequently exceed the MPC. These findings urge for the constant control ...

Ichthyofauna of the Neris River: Diversity, Abundance, State

In the article, results of the research conducted in 1997-1999 into the ichthyofauna of the Neris River are described. Data on fish species diversity and distribution of various fish species in different biotopes are presented. Impact made by a river biotope structure and pollution on the fish community is analysed. Under decreased pollution, species diversity is increasingly influenced by biotope structure, the impact of pollution still being quite remarkable on community structure, however. In addition, distribution of fish species rare and endangered in Lithuania and Europe as well as their abundance and state are described in detail.

The Growth of Brown Trout (Salmo trutta fario L.) in Different Climatic Regions of Lithuania

The growth rate of brown trout (Salmo trutta fario L.) varies across its distribution range, as well as in the rivers of three different Lithuanian climatic regions. Interspecific and intraspecific competition that is closely related even to minor climatic differences is considered to be one of the major factors determining differences in trout growth. The highest significant (p < 0.05) growth rate was found in juvenile trout at the age 0+ and 1+ in the rivers with the lowest species richness, whereas the growth rate in trout at the age 2+ and over was highest in the rivers with the highest species richness. No statistically significant correlation between trout size and density in different age groups was found in the investigated climatic regions of Lithuania, spare environmental capacity probably plays the major role here. However, significant differences in different age groups were observed in trout size and species richness, which attests to the impact of interspecific competition on trout growth.

Fish Spring Migration in rhe Žeimena and Mera Rivers

Fish spring migration was investigated in the Žeimena River, in 1996 and its tributary, the Mera River, in 1998. It was established that the abundance of migrating fish species varies depending on water temperature, and this dependence is parabolic. Optimal temperatures for fish migration differed in the Žeimena and Mera rivers by 2-3°C due to different hydrological parameters of the rivers. The beginning of fish spring migration may change at the interval of 10-15 days. Fish migration in the investigated rivers was divided into several types according to the character of migration. These types are characteristic for fish species belonging to different ecological groups: 1) active spawning migration of non-migratory reophilous fish species; 2) active migration of migratory fish (salmon, sea-trout) and their smolts; 3) migration of limnophilous and reophilous fish juveniles from lakes. The mechanisms and reasons of the latter migration are not quite clear, but its course is determined by specific ecologica...