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Spatial distribution of eastern ground beetles in the pond
KADLEC, Bohdan
Stone Moroko is one of the non-native fish species in our territory. It is a small carp fish whose origin is in Asia. In many places in the Czech Republic or in abroad, their presence cause damage. The aim of my Bachelor Thesis was to find out more about the behaviour of this weed fish. We were interested to know, how far from the shore it stay. Whether its activity is more intense during the day than at night. Whether the fish appear more at the surface or at the bottom. There were performed 5 measurements on the Kvítkovice pond, each took 24 hours. The measurements were carried out from June till October 2021. The pond was divided into 5 different parts A, B, C, D, E. Piles were used to obtain samples. These were located at the different distances from the shore. In some places, where the depth of the water allowed it, 2 piles were used. One was placed on the bottom and the other one on the surface. Samples were also collected by using a throwing net. At each of the localities A, B, C, D, a throwing net was thrown 5 times in the area of the littoral. Site E was located in the middle of the pond, so catching by the throwing net did not take place here. Water sampling was also monitored at 6 different locations for each sampling. We managed to catch in total 50 fish using a throwing net and 267 fish by using the piles. Four species were represented: Stone Moroko (Pseudorasbora parva), Pumpkinseed (Lepomis gibbosus), Brown Bullhead (Ameiurus nebulosus) and Common Carp (Cyprinus Carpio). Our results show that the activity of weed fish species is higher during the day than at night. We managed to catch 75% of the samples during the day, but only 25% during the night. The Stone Moroko remained more at the bottom, unlike the Pumpkinseed, which occurred mainly at the surface. There was a statistically significant decrease in the number and weight of Stone Moroko with increasing distance from the shore. However, this trend has not been statistically confirmed for variegated Pumpkinseed. The Stone Moroko preferred localities A and C. Pumpkinseed preferred localities D and E. Site B was equally preferred by both species. The most suitable months for obtaining samples are July, August and September. The calculated fish biomass in July was 2.07 kg.ha-1, in August 8,079 kg.ha-1 and in September 2,964 kg.ha-1.
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