The cyprinids embryo development biology is well-known in many countries of the world, but in Romanian speciality literature there are relatively few references to this. Also there is little information regarding the embryo development environment and especially the way in which certain environment factors influence the embryogenesis of the cyprinids. Several studies considered the water hardness as a factor that would limit the spread of certain species. The aim of this paper is to emphasize the most important aspects of the ways in which water hardness influences development of carp (Cyprinus carpio) embryos. During the experiment 5 variants with different hardness degrees of water were used to monitor the development of carp embryos in 80x15 mm Petri dishes at an optimal density (1 embryo/ 3 ml) and at a 24 o C temperature. We wanted to observe the morphological aspect of the embryos and to establish the embryonic stage in which they are at one point and finally to determine the hatching rate. In the hard water variant (V5=20 o dH) the embryos started to die 10 hours after the beginning of the experiment and 36 hours after the fertilization the mortality was 100%. In the moderate hard water variant (V4=15 o dH), after 76 hours of  incubation the hatching was at a 100% rate, but all newly hatched carps died when in direct contact with the environment. In the medium hard water variant (V3=10 o dH) after 144 hours of monitoring the one embryo to be in the hatching period for over 60 hour,  died inside the corion resulting in a final mortality of 13,3%. In the first two variants of water of low (V2=5 o dH) and very low hardness (control variant, V1=0 o dH) the hatching was of 100%. Statistically between V1 and V4, respectively V5 there are very significant differences.  Between V1 and V2, respectively V3 there is no differences. The research on the influence of water hardness on Cyprinus carpio embryos development emphasized that an incubation environment in which such a factor is present, can induce a different embryo development rate.

carp; embryo development; water hardness

Presentation: oral