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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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Vliv přítomnosti či absence střevličky východní (Pseudorasbora parva) na produkci ryb a kvalitu vody v rybnících firmy Blatenská ryba
KOUKOLÍK, Pavel
Topmouth gudgeon (further TG) Pseudorasbora parva (Temminck & Schlegel, 1846) is a small cyprinid naturally occurring in East Asia. TG causes a lot of economic lossess on the pond culture worldwide including Czech Republic. The aim of the present B.Sc. thesis was to assess an effect of TG on fish production and water quality in the ponds of the Blatenská ryba company. The experiment was perfomed in six ponds. Three of them had a control function where two-years common carp was stocked and necessary preventive measures were taken to rule out presence of any pest species. The other three ponds were also stocked by carp, but TG was stocked as well. Water, zooplankton, zoobenthos samples collecting, water properties measurements, topmouth gudgeon sampling and morphometric-gravimetric analyses of caught carp were performed on monthly basis from March to September. From the end of September to the the first half of October all six ponds were harvested, when the overal final fish biomass, health and physical (TL, SL, W, Fulton) condition of the cultured carp were monitored. A remarkable negative influence of TG upon water quality and pond production parameters were found. The impact of TG on water quality is believed to be indirect, due to mass elimination of big size zooplankton species (Daphnia sp.). Zooplankton unavailability caused the carp's foraging shift to zoobenthos, and afterwards carp bioturbation activity when carp digged in the pond ground. This activity resulted in intensive phosphorus releasing from the sediment to the water collumn which in combination with zooplankton absence led to water quality worsening. Moreover, TG presence also had a negative impact on pond production parameters and the health status of the carp stock. Production in ponds with TG was on average 70 % lower compared to the control group. In addition, 29 % of carp suffered from tissue lesions as a consequence of facultative parasitism of TG. The conclusions of the thesis clearly proved that it is necessary to take effective measures to control TG occurrence in pond aquaculture to ensure better economic results and stability of the pond environment.
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Sezónní dynamika výskytu střevličky východní (Pseudorasbora parva) ve vybraných rybnících
HOŠEK, Vojtěch
The objective of this bachelor's thesis was to find out the amount of undesirable species especially topmouth dudgeon. Topmouth dudgeon is a small species relative to carp and it is an non-native species in the Czech republic. It comes from Asia and to the Czech Republic it came from Hungary with another carp. Topmouth dudgeon has negative influence on fishery production a quality of water. Whole experiment was done in pond system which is located in the nature reservation Postřekovské rybníky. During seven months (April - October) there were seven control catches with the cast net. Every time there was taken sample from every single pond. Samples were calculated by Catch per unit effort method. Caught fish were identified, measured, weighted individually and then Fultons fitness coefficient was calculated. From the amount of caught fish was also calculated abundance (pieces.ha-1 ) and biomass (kg.ha-1). From known biomass was also calculated fish stock index. Next was made size structure of observed populations thanks to size cohorts. Whole dynamics of mentioned parameters was observed during time on every pond separately. The ponds were compared with each other and average of every pond value was calculated. There were small differences between the pond results, however in every pond there was a massive growth of topmouth dudgeon. This data was compared to the data of authors who also made research about topmouth dudgeon. The values found in the Postřekovské rybníky area were higher than those of the other authors. However, the trend of growth and decline of biomass and abundance was identical. There was also a comparison between our data from control catches and data from fish harvest. This work demonstrates topmouth dudgeon's ability to grow, it can be enlarged several times during the year. That's the reason why we should start fixing the problem and use effective measures.
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Vnímavost kaprovitých a nekaprovitých druhů ryb k CyHV-3
POSPÍCHAL, Aleš
Cyprinid herpesvirus 3 (CyHV-3) also known as koi herpesvirus (KHV) is a causative agent of highly contagious disease (koi herpesvirus disease) and can cause significant losses in fish stocks. The disease is restricted to koi and common carp, but recent investigations have shown that other cyprinids as well as non-cyprinid species may be asymptomatically susceptible to this virus and might play roles as potential carriers or can contribute to biological conservation leading to persistence of this virus in environment. Therefore, it seems to be important to verify not only the susceptibility of other cyprinid and non-cyprinid species, but also their ability to transmit KHV infection to susceptible species. We investigated the susceptibility of stone loach (Barbatula barbatula) and sterbel - a hybrid between sterlet (Acipenser ruthenus) and beluga (Huso huso) to KHV. The investigation was performed by means of their cohabitation together with na?ve koi and intraperitoneally KHV-infected koi (primary challenge). This part of investigation is followed by secondary challenge, when a portion of the surviving stone loach and sterbel was cohabited with health na?ve koi (testing of ability to carry KHV). All samples of fish both from primary challenge and secondary challenge were tested for the presence of KHV DNA by nested PCR. In the primary challenge, results of PCR revealed the presence of KHV DNA in 95% of cohabited na?ve koi samples. Furthermore, PCR analysis of fish samples surviving primary challenge revealed the presence of viral DNA in 77.8% (7/9) of stone loach and in 22.2% (2/9) of sterbel. In case of samples of fish coming from secondary challenge, nested PCR did not reveal any of them to be positive for KHV DNA. Next investigation was focused on assessment of the susceptibility of topmouth gudgeon (Pseudorasbora parva). In this case, we performed cohabitation based on two different conditions. All experiments consisted of primary and secondary challenges as well as in all previous cases. Firstly, we tested topmouth gudgeon under standard conditions (no-stress experiment). After the primary challenge, nested PCR did not reveal the presence of KHV DNA in any specimen of cohabited topmouth gudgeon, but all specimens of dead koi were KHV DNA positive. Nested PCR of fish tissues subjected to the secondary challenge did not show the transfer of virus to naive fish. After that, we changed the experimental conditions and we applied two stress factors (scaring by net and removal of skin mucus) to imitate the stress most commonly encountered in the wild. In this case, all samples were tested for the presence of KHV DNA using real-time PCR. After exposure to stress (removal of skin mucus), real-time PCR revealed four out of five samples (80%) of topmouth gudgeon to be positive for KHV DNA. Two out of five samples (40%) of topmouth gudgeon treated by scaring were found to be positive for the presence of viral DNA. Real-time PCR after the secondary challenge did not reveal any viral DNA positivity in specimens of topmouth gudgeon from groups previously exposed to stress. The stress experiments showed that removal of skin mucus might potentially lead to susceptibility of topmouth gudgeon to CyHV-3 infection, but the transmission of the virus to koi carp was not observed. Even though PCRs positive findings of KHV DNA in tissues of fish were relatively low, the presented results of cohabitation assays of cyprinid and non-cyprinid fish species indicate other species showing slight asymptomatic susceptibility to CyHV-3. On the other hand, on the base of our results coming from "virus-carrier" assays, we could not prove that hybrids between sterlet and beluga, stone loach and topmouth gudgeon can transfer this virus to naive koi.
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Využití střevličky východní (Pseudorasbora parva) při produkci násadového materiálu candáta obecného (Sander lucioperca)
Kadlec, Lukáš
The subject of the Diploma Thesis was to summarize all the data published either from scientific papers or collected during the experiments, relating to the possibility of using topmouth gudgeon as fish food. The main part is composed of the results and conclusions obtained from the experiments conducted in the model recirculation system, under controlled conditions. The experiments were focused on the feed preferences of the pikeperch (Sander lucioperca), for the given size category of the topmouth gudgeon (Pseudorasbora parva), stimulation of the food intake of the pikeperch in the conditions with different amounts of topmouth gudgeon, and on the intraspecific competition for food in cases with different numbers of the stocked pikeperch. Bigger food preference was confirmed for the topmouth gudgeon, in the size category up to 7 cm (on average 29.8 % of the whole body length), than for the topmouth gudgeon bigger than 8.5 cm (on average 42 % of the whole body length). Results also show higher food intake in-tensity in case of continuous supply of topmouth gudgeon, while the intraspecific stimu-lation of the food intake has not been either proven, or disproved. Data obtained enables us to better understand the nutritional activity of the pikeperch, and can be used in working conditions, with the aim to dose the amount of the topmouth gudgeon as fish food.
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The Occurrence and Basic Aspects of the Biology of Pseudorasbora parva (Temminck et Schlegel, 1842) in a Model Pond System located in the region of Třeboňsko
ČECH, Miroslav
The stone moroco (Pseudorasbora parva) is a invasive little fish whose species origin is not from our waters. It is desirable to eradicate this species from the Czech environment or at least decrease its numbers as much as possible, using an environmental method. The data for the dissertation was found out on a model pond system in Třeboňsko. This complex consists of thirteen ponds 203.1-hectare. The ponds in this locality are highly productive and their average depth is about one meter. The aim of the dissertation was to determine the composition of feed of Pseudorasbora parva and according to this, to assess the potential importance of this species as a rival to the locally bred carp (Cyprinus carpio). The other submission was to map the migration of Pseudorasbora parva in the aforementioned pond system and to determine what part of the pond is the most coveted by this fish and estimate the total number of fish population in some ponds. The use of fingerling nets was one of the methods used to catch Pseudorasbora parva in the shallow water of the ponds. Furthermore fish-pots were used for catching fish in the deeper parts, and drop nets were used for catching in the effluents. The Pseudorasbora parva was present for a whole calendar year in all parts of the system i.e. in all ponds, drains and in their effluents. The stone moroco occurred predominantly at the banks of the pond. The occurrence of fish in the open water was recorded sporadically. The sampling of plankton was carried out with plankton net in different seasons. With exception of winter when plankton was not found, the composition of feed the same during the whole year. Only proportional representation of species of plankton was different. The catching of Pseudorasbora parva was performed in the ponds Pražský, Rod, Láska and Víra, the fish was necropsied for assessment the intestine content. At the same time four carps of age group K2 were necropsied. By the analysis of the intestine content the conformity in the feed consummation by both aforementioned fish species was confirmed.
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