Common Carp (Cyprinus carpio) Blood Cells in Hayem's Solution – Stable or Not?

A haematological analysis is commonly used in studies concerning fish, e.g.to evaluate the influence of various environmental factors on the physiological state of a population. Furthermore, a manual haematology is still used for conducting fish blood analyses. The aim of the current study was to determine how long after the procedure of blood collection in common carp (Cyprinus carpio) the samples diluted with Hayem's solution would provide results for the red blood cell and white blood cell counts with no significant changes. The blood was taken from 15 healthy individuals and diluted with Hayem's solution immediately after the collection procedure. Next, an erythrocyte count and leukocyte count were performed. The counts were repeated after 1, 2, 3, 5, 9, 16 and 23 days. The results of the current study indicate that the erythrocyte count should be performed within a maximum of 16 days (or better within 9 days) after the sample preparation, while the leukocyte count should be conducted within 2 days.

Influence of Fish Ponds on the Benthic Invertebrate Composition in Hydrological Networks of Selected Fish Farms in Southern Poland

Fish production can generate high amounts of wastewater containing compounds such as suspended solids, nitrogen and phosphorus. On the other hand, fish ponds provide a range of ecological functions including biocenotic, physiocenotic, hydrological and microclimatic functions as well as landscape shaping. The aim of this study was to determine the taxonomic composition of the bottom invertebrate fauna in selected watercourses on chosen carp fish farms and to assess the influence of fish farming on the taxonomic composition of the zoobenthos of the watercourses associated with such ponds. The research was conducted in four channels on two semi-intensive aquaculture fish farms located in Zaborze and Kraków (Poland). Sampling of the benthic fauna was carried out once a month between May and September 2018. The results showed that the mean monthly number of zoobenthos families in the inflow canal in Zaborze was higher than those in the outflow canal. Moreover, a decrease of the BMWP-PL index in the aforementioned farm may indicate a deterioration of the water quality resulting from its flow through the ponds. It can therefore be concluded that semi-intensive carp farming may affect the diversity of benthic invertebrate fauna in the watercourses connected to these ponds.

The effect of Roundup on embryonic development, early foxr1 and hsp70 gene expression and hatching of common carp (Cyprinus carpio L.)

The effects of herbicide Roundup (based on glyphosate) on the embryonic development, survival and hatching of common carp (Cyprinus carpio L.) larvae and alteration in foxr1 and hsp70 gene expression were determined. The eggs (obtained from 6 females) were fertilised and incubated in water containing 0; 1 or 10 μl L^-1 of Roundup formulation. During early embryonic development (24 and 48 h post-fertilisation - hpf), Roundup caused a statistically important decrease in the embryonic survival rate of common carp. Moreover, retardation of the hatching rate was observed in the group treated with the higher concentration of Roundup at 81 to 99 hpf. At the end of the experiment (99 hpf), an important increase in number of deformed larvae was observed in both groups treated with Roundup in comparison to the control group (52.06; 16.02 and 5.08%, respectively). Significant differences in transcript of the gene foxr1 were found in Roundup-intoxicated groups in comparison to the controls. In the case of hsp70 transcripts, no important changes in exposed groups were observed. These results showed that even small, environmentally relevant amount of Roundup present in the aquatic environment is able to affect the early life stages of common carp and change the transcripts of foxr1, which may have an adverse effect on the later proper development of the reproductive system.