|
|
Comparison of different ways of breeding, nutrition and controlled reproduction of Lota lota
ZÁVORKA, Milan
Based on the results reached after 216 days of experimentation with various breeding types, it can be said that the type of feed is not of paramount importance. This fact is based on the previous adaptation of submitted food, this is especially important for artificial feed. From our point of view, the more important factor is temperature, intensity and method of breeding. Prey selections choices involving 11 species of fish were performed on age groups of different burbot. All groups of burbot preferred the following species: grass carp, pikeperch, tench and stone moroko. The non-preferred species was ruffe. And different preferences were set for common carp, silver carp, burbot, sunfish and also for roach. The study evaluated reproductive parameters in burbot (Lota lota ) and focused on incubation time in two localities. Burbot spawning was observed from January to early February at an average temperature of 1.55 +- 0.9 °C in Borova Lada and 4.78 +- 0.11 °C in Mydlovary. For burbot at the age of 2+, at an average 1166 +- 100 were determined number of swollen eggs per gram. Relative fecundity was at 257260 +- 70678 eggs per kilogram of female. The absolute fecundity was at 24232 +- 6753 eggs.The last parameter evaluated was the incubation period. The average incubation period in the years 2020-2022 was 202 +- 24.55 °D in Mydlovary and 75.8 +- 16.67 °D in Borova Lada. In connection with artificial spawning, in this study, we further point out the possibility of peeling artificially spawn eggs with NaClO, in which we did not observe a negative effect.
|
|
|
Vliv metazachloru a jeho metabolitu metazachloru OA na raná vývojová stádia raka mramorovaného
ZÁVORKA, Milan
Metazachlor is a selective herbicide used for controlling monocotyledonous and dicotyledonous weeds in oilseed rape and other cruciferous plants. It is mainly used as a pre-emergence herbicide. Metazachlor OA is one of the major degradation products of metazachlor. The aim of this study was to evaluate the effect of metazachlor and its major metabolite metazachlor OA on the early live stages of marbled crayfish (Procambarus virginalis). The effect of metazachlor and metazachlor OA was evaluated on the basis of behaviour, growth, biomarker of oxidative stress, antioxidant biomarkers, ontogenetic development and occurrence of morphological anomalies. The toxicity test was performed at five concentrations, two concentrations of metazachlor (3.2 micrograms/l and 22 micrograms/l) and two concentrations of metazachlor OA (3.2 micrograms/l and 22 micrograms/l) and one control (C). The test exposure was 40 days under defined laboratory conditions. The exposure of metazachlor and metazachlor OA at all tested concentrations caused statistically significantly higher mortality, delayed ontogenetic development and slower growth of crayfish. Metazachlor exposure in concentration 22 micrograms/l and metazachlor OA in concentrations 3.2 micrograms/l and 22 micrograms/l caused statistically significant reduction of antioxidant enzymes (SOD, CAT, GR, GST and GSH) levels in whole-body crayfish homogenate. Metazachlor OA showed a more pronounced adverse effect on the early live stages of marbled crayfish than its parent compound, metazachlor. Based on the results of this study we can point out the suitability of crayfish, especially their early live stages for toxicity tests and the possibilities of their use for biomonitoring of aquatic environment herbicides and their metabolites.
|
guest ::
RSS feed.