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Potravní chování nepůvodních druhů hlaváčovitých ryb
GEBAUER, Radek
Global homogenisation of biota is observed at an ever-increasing rate, causing environmental and economic losses as well as emerging health risks. Ecological and economic consequences of biological invasions fuel the need for an urgent targeted and cost-effective management given the amount of invaders, vectors and pathways. We examined the effects of environmental and human-related factors on distribution of alien animal species richness in the Czech Republic (Central Europe). We compiled a set of maps showing the level of invasion of six categories of alien animal species in each of 628 grid cells (ca. 12.0 × 11.1 km) covering the Czech Republic. Relationships between alien species richness and 12 variables characterizing climatic conditions, topography, land cover, and human population size were calculated using the generalized least squares method. Species richness of all aliens, of invertebrates, and of terrestrial species showed the strongest positive relationship with mean annual temperature, while the number of black and grey (proposed prominent invaders) and aquatic species was most closely related to the presence of large rivers. Alien vertebrates showed a strong negative relationship with annual precipitation. The highest alien animal species richness was found in and near large population centres and in agricultural landscapes in warm and dry lowlands. The gateways for alien aquatic species are rather large rivers over sport fishing and aquaculture import. Two benthic fish species, round goby Neogobius melanostomus and western tubenose goby Proterorhinus semilunaris have recently expanded beyond their native ranges. Both species exert a detrimental effect on fish communities' structure directly via predation on fish eggs and indirectly via alterations of food webs. We quantified and compared the foraging behavior and efficiency of invasive N. melanostomus and alien P. semilunaris upon common carp Cyprinus carpio larvae at two temperature levels (20 and 25 °C) and in three different habitat structures (sand, cobbles, cobbles with artificial plant) using the functional response approach. Both alien predators showed type II FR in all temperature and habitat treatments. Intra-specific comparison showed no significant temperature dependency on assessed FR parameters, attack rate and handling time, suggesting broad temperature tolerance of both tested predators. The handling time did not differ between predators suggesting similar per capita ecological impact at high prey densities. Proterorhinus semilunaris showed a lower maximum feeding rate at 25 °C compared to the rest of treatments suggesting a lower temperature optima compared to N. melanostomus. Interspecific comparison showed similar values of handling time in cobble substrate and cobbles with artificial plant suggesting similar per capita ecological impacts of both aliens. Intraspecific comparison showed significantly lower values of handling time in both predators in habitat with cobbles reflecting higher maximum feeding rate. Therefore, impact of both invaders in such environment could elevate. Neogobius melanostomus showed higher attack rate in sandy habitat compared to P. semilunaris, while no significant differences were observed in other habitat treatments.
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Monitoring of 0+ juvenile fish communities in selected Moravian rivers
GEBAUER, Radek
Monitoring of 0+ juvenile fish communities was realized in years 2012 and 2013 in 39 localities in 25 selected Moravian rivers. It was realized in collaboration with Povodí Moravy SOE research workers. The aim of this diploma thesis was to conduct a survey of 0+ juvenile fish communities and evaluate basic attributes of these ichthyocenosis (species richness, biodiversity, equitability, abundance and domiance). Secondary aim was the evalutation od hydromorphological conditions and water quality based on data provided by Povodí Moravy SOE. This monitoring was realized using the mobile FEG 1500 electrofishing device. The electrofishing crew moved upstream using continuous fishing strategy. Each locality was selected by highly experienced research workers of Povodí Moravy SOE. Caught fish were determined immediately and carefully retruned to the stream. In total there was present 28 0+ juvenile fish species. The most frequent was chub (Leuciscus cephalus, 23 localities), gudgeon (Gobio gobio, 19 localities) and roach (Rutilus rutilus, 19 localities). In 13 localities occured the fish fry of barbel (Barbus barbus) wich is positive surprise due to its sensitivity to water pollution. In contrast the massive presence of round goby (Neogobius melanostomus) in some localities was an unpleasant finding. 4 localities were without fish fry. This survey has observed increasing trend of biodiversity depending on improving of hydromorphological status while the abundance showed almost no diference. Saprobic index of 0+ juvenilie fish community increased with deteriorating of water quality which could mean that the fish fry is relatively reliable indicator of water quality. The results of this diploma thesis could be used in documenting of Moravian streams and in comparisson with another monitorings in these localities.
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Fish Population in Tributaries of Tepla Vltava River
GEBAUER, Radek
Monitoring of fish populations in tributaries of Tepla Vltava River was performed in 2010. This survey was held in pre-selected localities. The aim was to detect the status of local ichthyofauna in terms of biodiversity, equitability, abundance, dominance and size variation. The results can be used for comparison with future researches at these localities. To catching fish was used the electrofishing. Each section was 200 m long and the electrofishing crew went upstream in entire width of the flow. Caught fish were determined, measured and carefully returned back to the stream. Based on acquired information was evaluated the status of fish populations. All together we have caught 7 fish species and 1 cyclostomes species ? brook lamprey. In terms of dominance took the first place brook trout (average 79 %) followed by the bullhead (12.9 %). Other protected and endangered species were: brook lamprey, fathead minnow and burbot. In terms of biodiversity was on the first place Olšinka (1.07), lowest biodiversity was on the brooks Jedlový, Houženský and Kubohuťský stream, the value of biodiversity was here 0. Highest equitability was calculated on the middle section of the Kaplický stream (0.95). The worst stream was the Jedlový stream. On 200 m long section of this stream occured only 9 pieces of brook trout.
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