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The sperm collected from common and grass carp males was stored at 5oC, and activated with water of various temperatures (20, 26, and 30oC). Time of spermatozoa motility was measured. Motility decreased with time after milt collection. Common carp spermatozoa were active longer, up to 70–80 s. In most series their activity was reduced after 24 hours. Spermatozoa of grass carp were active up to 30–55 s, and their motility shortened already in 8 hours post collection. After 24 hours they were motile less than 10 s. The effect of temperature of activation was observed – the spermatozoa were active for the longest time at 20oC. Spermatozoa motility time was also affected by temperature of storage. Even short–term (15 min) keeping spermatozoa at 20oC shortened their motility time in both species, and after 2 hour storage common carp sperm motility was reduced by about 50%.
The study was conducted on common carp and grass carp embryos and larvae developed under laboratory conditions, at various temperatures and in the presence of heavy metals (Cu 0.20-0.27 mg dm⁻³ , Pb 2.0-4.0 mg dm⁻³ , Cd 0.2 mg dm⁻³ ). Heart rate was measured at various developmental stages and was observed to increase along with fish development in all experimental groups. This may be explained by the increase in the metabolic rate of developing embryos. Development was faster at higher temperatures, and the heart rate was usually higher. The results of the present study confirm that heart rate is a reliable indicator of the metabolic rate of developing fish embryos.The embryos and larvae which were exposed to heavy metals had higher heart rates in comparison to those of the control group. This indicates that metal-induced stress caused an increase in metabolic rate. A decrease in heart rate during hatching was observed at non-optimum temperatures and was particularly pronounced in metal-exposed embryos; this indicates that the disturbances were related to the high sensitivity of the fish at this stage.
This work proposes modifications to the existing system for identifying the steps of embryonic and larval development in fish. The term “compensatory phase of development” is proposed for the phase from hatching to the first intake of food. Both the new designations of these steps and the new name of this phase do not require a declaration of whether the hatched individual is considered to be an embryo or a larva, something that has been, to date, a matter of dispute. Unification will allow for the wider use of the new nomenclature, and make easier the comparison of results. This work examines the influence of the thermal history during the embryonic period (temperatures of 20, 24, 28, and 32°C) on later development, growth, and survival of common carp, Cyprinus carpio L., and grass carp, Ctenopharyngodon idella (Val.) larvae, at a constant temperature of 23°C. It was confirmed that the optimal temperature ranges for the embryonic development of common carp and grass carp are higher than those currently applied widely in practice of 18-22°C and 21-26°C, respectively. Based on the evaluation of the development, growth, and survival of the larvae, it was determined that the optimal temperature for embryonic development is 26-28°C for the common carp and 32°C for the grass carp. It was confirmed that even a short-term increase in temperature from 20°C to 24°C during the compensatory phase has a positive influence on subsequent common carp larvae growth.
The aim of the study was to estimate the effect of culture conditions and culture site on magnesium (Mg) and zinc (Zn) concentrations in freshwater fish. The study encompassed dorsal muscles in five fish species: common carp (Cyprinus carpio L.), rainbow trout (Oncorhynchus mykiss Walbaum) and Siberian sturgeon (Acipenser baeri Brandt), northern pike (Esox lucius L.) and grass carp (Ctenopharyngodon idella Valenciennes). A total of 125 fish comprised 25 individuals of each species, aged from 6, 9, and 12 months. The fish were cultured in privately owned fish breeding ponds (Western Pomerania, Poland). For chemical and biochemical assays, samples of dorsal muscles were taken from each fish. Tissue samples were wet mineralised in concentrated HNO3 in a CEM MDS 2000 microwave oven. Magnesium and zinc concentrations were determined by inductively coupled plasma atomic emission spectrometry (ICP-MS) in a Jobin Yvon type JY-24 apparatus. The pursuit of the research we had an approval of the Polish Local Ethics Committee nr 9/05. The magnesium concentration in the dorsal muscles ranged from 95.3÷347.6 mg kg–1 w.w. The highest Mg concentration was found in rainbow trout (347.6±32.2 mg kg–1 w.w.), and the lowest in grass carp (95.3±11.3 mg kg–1 w.w.). Zinc concentration varied from 6.7÷98.8 mg kg–1 w.w. The highest was found in the muscles of Siberian sturgeon (98.8±0.4 mg kg–1 w.w.), and the lowest in rainbow trout (6.7±0.7 mg kg–1 w.w.). It was found that the breeding place significantly affected the Zn and Mg concentrations in the muscle tissue among individual freshwater fish species. The magnesium and zinc concentrations were also significantly affected by the type of feed.
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