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Romania has a rich hydrographic network, which permitted the construction of over 80 large dams on its water courses, estimating a number between 545 and 674 hydropower plants that were either built or were in a different construction stage on the rivers of Romania in 2021. These hydropower plants were often built outside specific legislation regarding ecological impacts, especially before 1990. Longitudinal fragmentation of rivers causes severe ecological impacts on biodiversity, food chains, and nutrient cycles. Someșul Cald River is the main tributary of Someșul Mic River, the most important water source for the northwestern region of Transylvania. On its course, several dams and reservoirs were built from 1968 to 1980 for electricity production and population freshwater supply. The present study aimed to analyze the length–weight relationships (LWRs) and condition factors occurring in the longitudinally fragmented Someșul Cald River. The LWRs, relative condition factor Kn, and Fulton condition factor K were determined based on total length and wet body weight. Comparisons of LWRs, Kn, and K across river sections constrained by dams showed that some fish species exhibited similar growth patterns and physiological conditions, while others differed significantly. Freshwater fish physiology is altered by longitudinal fragmentation, both natural and artificial. Barriers such as dams influence the energy gradient, limiting feed availability and, consequently, the life history of fish species. Long-term management plans regarding conservation should take into consideration existing fish species population dynamics, along with their physiological and somatic status. [ABSTRACT FROM AUTHOR]

The habitat of the European mudminnow, Umbra krameri Walbaum, 1792, is continuously decreasing due to human intervention. The species has a "vulnerable" status according to the IUCN Red List. Thus, new information about the species is needed for conservation efforts. Minnow traps were used for capturing Umbra krameri and other small fishes in the Jie River, Dolj County, southwestern Romania. Captured specimens of U. krameri were measured and weighed. Length-weight relations and relative condition factor were determined for the captured U. krameri specimens. A total of 94 fishes were captured using the minnow traps. They represented 7 species: European bitterling, Rhodeus amarus (Bloch, 1782), roach, Rutilus rutilus (Linnaeus, 1758), rudd, Scardinius erythrophthalmus (Linnaeus, 1758), Danubian spined loach, Cobitis elongatoides Băcescu et Mayer, 1969, weatherfish, Misgurnus fossilis (Linnaeus, 1758), tubenose goby, Proterorhinus marmoratus (Pallas, 1814), and U. krameri. The specimens of Umbra krameri represented 44% (41 specimens) of the total catch. The wet body weight (BW) of U. krameri ranged from 0.8 to 5.1 g, having a mean value of 2.102 g. The mean total length (TL) was 5.782 cm, ranging from 4.59 to 7.87 cm. According to the length-weight relation (LWR), the growth type of U. krameri was positive allometric based on the determined equation: BW = 0.0068TL3.277. The mean value determined for the relative condition factor (Kn) was 1.0056486. The growth condition of 46% of the specimens was poor (Kn < 1; n = 19), while the other 54% were in good condition (Kn = 1; n = 22). The presently reported study provides information about the presence of U. krameri in the Jie River (Dolj County, Romania), a location where the species has not been previously reported. The LWRs show an allometric positive growth. The relative condition factor shows that 46% of the specimens had poor growth, while the rest were in good condition. Minnow traps were an efficient tool for small fish capture. [ABSTRACT FROM AUTHOR]

In this study, we aimed to highlight the influence of anticoagulants on erythrocyte morphometry in different vertebrate species. Anticoagulants are a category of substances that inhibit blood clotting through various mechanisms. Due to this property, they are used to collect blood samples for a wide range of laboratory tests. The literature mentions that the use of anticoagulants produces morphological changes of erythrocytes, thus influencing results. Blood samples were collected from three warm-blooded vertebrate species (horse, rabbit, and chicken) and one lower vertebrate species with nucleated erythrocytes (fish) in vacutainers with Heparin and EDTA (ethylenediaminetetraacetic acid), in a normal concentration and a double concentration. At the time of harvesting, control smears were performed. In order to be able to compare the effects produced by anticoagulants on the morphology of erythrocytes, they were evaluated morphometrically at intervals of 3, 6, and 24 hrs. after harvest. The following features were evaluated using the Toup View software: length, width, surface and perimeter of erythrocytes for species with anucleated erythrocytes. The same characteristics were evaluated in the nucleus for species with nucleated erythrocytes. The data obtained were processed with statistical programs to highlight changes in erythrocyte morphology produced by anticoagulants. [ABSTRACT FROM AUTHOR]

Physiological stress response of Brown bullhead (Ameiurus nebulosus) was studied under laboratory conditions. This species is well known for the resistance and adaptability t°environmental factors. In this sense, metabolic and hematologic profiles were determined for low (6°C), medium (18°C) and high (31°C) water temperatures. An increase in blood cell numbers (RBC, WBC) and hematocrit (Ht) was determined under high temperature conditions, as a response t°low dissolved oxygen. Platelet count (PLT) remained relatively constant regardless of the water temperature. The metabolic profiles showed significant and very significant differences for most of the analyzed indices. The differences were due t°variations in temperature that influenced appetite and ingestion of feed, respectivelly the respiratory function by vasoconstriction or hypoxia. [ABSTRACT FROM AUTHOR]