Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 23

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  Leuciscus cephalus
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Background. Fish are often used as indicators of pollution levels in water environments. The omnivorous chub inhabiting rivers of Europe, including their more polluted parts, is a potentially suitable indicator. The information published, however, on the metal accumulation in the tissues of chub living in varyingly polluted waters (both polluted and unpolluted environments) is scarce. The presently reported study was conducted to examine the metal concentrations in selected tissues of chub living in a natural submontane river. Materials and Methods. Sediment samples (0–5 cm layer) and chub, Leuciscus cephalus (L.), were collected from the upper (stations 1–4) and lower (stations 5–8) sections of the Biała Tarnowska River in summer 2003. Fish age was determined from the otoliths. The AAS method was used to determine metal concentrations (Cd, Pb, Cu, and Zn) in sediment and chub tissues (spleen, liver, and muscle). Results. According to the values of the geochemical index (Igeo), the river sediments were not polluted by Pb, Cu, and Zn, while in various degrees polluted by Cd. Despite the low metal concentrations, the mean Cd and Cu concentrations were higher (c. 2× and 4×, respectively) in the upper part of the river compared to the lower section, while concentration of Pb and Zn were similar in the two areas. Chub accumulated the greatest amount of Cu in the liver, while the bulk of Cd, Pb, and Zn was found in the spleen. In the upper part of the river, elevated concentrations of trace elements in selected tissues of chub were found: Cu (spleen, muscle), Cd (spleen), Zn (muscle). The pollution status of the river, on the basis of trace element contents in the sediment, was also determined. Conclusion. The obtained results indicated tissue-specific metal accumulation in chub. Selected chub tissues are sensitive to Cd and Cu contents in the river sediment.
We analysed the effects of [(D-Ala⁶, Pro⁹NEt)-mGnRH+metoclopramide] i.e. Ovopel at the dose of 0.5 granule kg⁻¹ of body weight (b.w.), [(D-Arg⁶, Pro⁹NEt)-sGnRH+domperidone] i.e. Ovaprim at the dose of 0.25 ml kg⁻¹ b.w., luteinizing hormone releasing hormone (LHRHa) at the dose of 50 μg kg⁻¹ b.w. and carp pituitary extract (CPE) at the dose of 2 mg kg⁻¹ b.w. on the total volume of milt (TVM, ml), volume of milt per kg of body weight (VOM, kg⁻¹ b.w.), spermatozoa motility [%], osmolality of seminal plasma (mOsm kg⁻¹), spermatozoa concentration (×10⁹ ml⁻¹), total sperm produced (TSP, ×10⁹) and total number of spermatozoa per kg of b.w. (TNS, ×10⁹ kg⁻¹ b.w.) in the chub Leuciscus cephalus (L.). Milt was collected 24 hours after injection from individuals (n=9) belonging to each group. The control group (control, n=9) consisted of the males which were given 0.9% NaCl at 0.5 ml kg⁻¹ b.w. The highest values of TVM and VOM were observed after Ovaprim (5.88±1.62 ml and 19.24±3.56 ml kg⁻¹ b.w. respectively) and CPE stimulation (5.39±1.19 ml and 19.61±3.32 ml kg⁻¹ b.w. respectively). The lowest TVM and VOM values were observed after LHRHa injection (2.46±0.89 ml and 8.95±3.13 ml kg⁻¹ b.w. respectively) and those values were statistically different from values recorded after Ovopel (P<0.05), Ovaprim (P<0.001) and CPE (P<0.001). A significant increase in spermatozoa motility (P<0.05) was observed following hormonal stimulation as compared to the control, regardless of the type of hormonal agent applied. The values of osmolality were similar in all the groups with no significant differences between them (288–300 mOsm kg⁻¹, P>0.05). The highest spermatozoa concentrations in the control were 10.26±1.70 · 10⁹ ml⁻¹, and the lowest values were 5.47±0.99 · 10⁹ ml⁻¹, P<0.001, observed after Ovaprim stimulation. The highest TSP and TNS values were recorded after CPE injection (42.84±11.72 · 10⁹ and 160.4±65.67 · 10⁹ kg⁻¹ b.w. respectively), while the lowest were obtained following stimulation with LHRHa (23.57±8.56 · 10⁹ and 85.72±30.56 · 10⁹ kg⁻¹ b.w. respectively). Those differences were statistically significant (P<0.05). Considering the large volume of milt (TVM and VOM) and the large number of spermatozoa (TSP and TNS), chub spermation can be successfully stimulated with Ovaprim or CPE injections.
Bryozoans are widely distributed benthic invertebrates which form colonies both in running and stagnant waters. There are 19 freshwater species of Bryozoa in Europe, and only three have been recorded in Serbia so far. Statoblasts (the dormant stages of these colonial animals) are relatively frequently found in the gut contents of fish, but those of the Hyalinella punctata species (Phylactolaemata) have not been registered. Statoblasts of H. punctata were determined for the first time in the gut content of chub Leuciscus cephalus sampled from the Zapadna Morava River (West Serbia, Danube River basin) in late summer and autumn. The intactness in form supports their viability after the passage through intestines, implying that the fish may be a vector of the dispersal of H. punctata in new aquatic habitats, as well as a risk factor in the transmission of certain salmonid fish disease agents into fish farms and natural habitats.
Distribution of fish communities along the submountain river (upper Coruh River, Northeastern of Turkey) was assessed to evaluate course of the longitudinal pattern in fish species diversity. The watershed area of Coruh Basin is 21.000 km², river length 376 km and it flows into Black Sea in northeastern Turkey at average discharge of 149 m³ s⁻¹ (range: 45.2–1215 m³ s⁻¹). Fixed-site electrofishing sampling at five sites located 15–210 km from river source at 2100–950 m a.s.l (Q values ranged 5–200 m³ s⁻¹) was conducted from March 2001 to March 2002. A total of 12 species were collected. Number of species (8–10) did not differ among sites suggesting no longitudinal changes, but Shannon-Wiener biodiversity index (H`) increased downstream from 1.23 to 1.82. Two distinct fish assemblages were identified. Most abundant species were Leuciscus cephalus and Alburnoides bipunctatus. Both Oncorhynchus mykiss and Cyprinus carpio collected rarely are exotic fishes for Coruh River.
To assess the current ecosystem status of Montedoglio Reservoir and surrounding waters, the fish fauna has been analysed in 1993, about five years after the first experimental impoundment. Total number of 898 fishes of fifteen species have been collected of the total biomass of 117 kg. The most abundant species were pumpkinseed (Lepomis gibbosus), goldfish (Carassius auratus L.), bleak (Alburnus alburnus alborella De Fil.), largemouth bass (Micropterus salmoides Lac.), rudd (Scardinius erythrophthalmus L.), and chub (Leuciscus cephalus L.), while the three: Carp (Cyprinus carpio L.), goldfish, and largemouth bass accounted for the most biomass. Of the most common species, carp, chub, largemouth bass and rudd provided insight into population structure and growth. In 1992, a year of heavy spring rains and a rapid water exchange, a year-class abundance across all species was particularly poor. The results of water levels and outflows between 1992-1994 showed a high degree of instability of the system. It appeared to favour fish species depositing their eggs inshore (i.e. chub) and predators (i.e. largemouth bass), while species with life stages feeding on plankton or benthos were not favoured.
According to heterozygosity, allele number, and Correspondence Analysis, the chub populations of the lentic Saone River were genetically homogeneous while those of the lotic Rhone River (including flowing sections and standing backwaters) were diverse. These two groups of populations were distant by 150 km.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.