Biologie, rizika ohrožení a ochrana ryb rodu hrouzek Gobio

Jacob Tetzeli

Bachelor's thesis

Biology, risk assessment, and conservation of species in genus Gobio

Abstract:

Hrouzci jsou malé, bentické a hejnové druhy ryb, rozmnožující se nad písečným substrátem dna. Hrouzci se vyskytují se v řadě typů říčního prostředí a jejich biologie je relativně dobře popsána. Avšak do současnosti chybí ucelené informace o jejich pohybové aktivitě, migracích a sociálním chování. Některé druhy hrouzků jsou uváděny jako ohrožené nebo kriticky ohrožené. Avšak kromě obecných popisů degradace vodního prostředí nejsou známé konkrétní příčiny úbytku hrouzků v určitých typech prostředí. Cílem bakalářské práce je rešerše publikovaných údajů o biologii hrouzků, jejichž sumarizace by mohla zpřesnit příčiny jejich úbytku a možnosti ochrany. Paralelním cílem rešerše je nastínit možné indikace sledovaným druhem kontaminace životního prostředí.

Abstract:

The bachelor's thesis is focused on literature search, summary and evaluation of knowledge about the biology, ecological requirements, distribution changes and conservation of European gudgeon species of the genus Gobio sensu lato (Gobio sensu lato, i.e. including species that have been recently transferred to the genus Romanogobio). The main focus is on the most widespread, euryvalent and most studied species Gobio gobio, as well as on G. (Romanogobio) albipinnatus, G. (Romanogobio) kesslerii and G. uranoscopus, which have the status of species of European importance. The reliability of the distribution data for these species is significantly affected by their considerable morphological similarity, the unresolved taxonomic status of some subspecies and forms and the existence of interspecific hybrids. Over the last decades, the overall distribution and population abundance of gudgeons seems to rather decrease, though there are some exceptions. Published data on habitat preference show a significant effect of water flow velocity (species rheophily decreases in the G. uranoscopus > G. (Romanogobio) kessleri >G. (Romanogobio) albipinnatus > G. gobio series). Furthermore, the status of populations is affected by habitat fragmentation and the presence of physical (antropogenic) migration barriers and the resulting limited availability of food and spawning sites that might lead to the negative effects of inbreeding or interspecific hybridisation. In addition, the distribution and abundance of populations are significantly affected by water temperature (through direct effects on gametogenesis, development of fertilised eggs and the youngest developmental stages, number of egg batches and overall fecundity) and chemistry (pollution by heavy metals and other persistent chemicals, steroid hormones that have adverse effects on reproduction, etc.). 10 Based on the above mentioned, it is recommended to study the distribution, abundance and population status of individual species in more detail. The proposed conservation measures are, in particular, the removal of migration barriers, the maintenance of maximum habitat diversity, the protection of water quality and the prevention of unwanted introductions of alien populations of the same or other closely related species

Keywords

rod Gobio, behaviorální ekologie, prefernece a vliv prostředí

Keywords

genus Gobio, behavioral ecology, environmental preferences

Language used: Czech

Date on which the thesis was submitted / produced: 24. 4. 2023

Thesis defence

• Date of defence: 25. 5. 2023
• Supervisor: prof. Mgr. Ondřej Slavík, Ph.D.
• Reader: Tereza Valchářová, Ing.

Czech University of Life Sciences Prague

Faculty of Agrobiology, Food and Natural Resources

Bachelor programme:
Landscape Conservation and Use of Natural Resources