| Abstract |
Zebrafish is a small, colourful, tropical fish inhabiting small ponds and slow moving streams in Southeast Asia. For the past few decades, it has been a very important model-organism in research fields such as Neurobiology, Developmental Biology and Genetics. Even though, only recently did the researchers start to examine the basic aspects of its biology and ecology. It is widely known that swimming
performance is a very important characteristic for fish survival, as it can affect food capture, mating success and the escape from predators. Developmental temperature and sex are two well known factors that strongly affect swimming capacity of fish.
Therefore, in the present study, the effect of sex in the swimming performance of zebrafish reared in different temperatures was examined. For this purpose, 4 populations were reared in different water temperatures (22, 25, 28 and 31οC) and after being acclimatized in a common temperature (26.5οC) for over a month, they were subjected to swimming exercises in order to evaluate the
maximum relative critical velocity (RUcrit) in each case. Moreover, as the accumulation of the lactate in fish muscles defines at a great extend their exercise ability, the muscle lactate concentrations before and after exhaustive exercise were also measured.
Rearing temperature seems to affect swimming capacity only in the case of male zebrafish, as the fish that were reared in 22οC showed statistically significant lower performance than the ones reared in 31οC. Furthermore, the results showed statistically significant differences between males and females that were reared in
31οC, where the males turned out to be faster swimmers. This differentiation cannot be explained from a metabolic aspect, because as the measurements of the muscle lactate concentrations revealed, the females seem capable of higher performances.
Therefore, the observed difference in swimming capacity is probably due to the added mass of eggs and its associated drag (due to larger girth and/or lower muscle power to body mass ratio), or the changes in the contractile properties of the muscles.
In order to shed more light in this subject, future work could include
comparing swimming performances of female zebrafish before and right after spawning, studying the effect of pregnancy on quantity and size of muscle fibres and the relative distribution of muscle tissue in fish body and examining if the temperature affects differently the ontogeny of muscle in males and females.
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Επίδραση της θερμοκρασίας εκτροφής και του φύλου στην κολυμβητική ικανότητα του zebrafish (Danio rerio)
