Biology subjects

Vrba, J.

Publications and source records attributed to Vrba, J..

3 recordsLinked to original sources

bioRxiv2025

A fresh perspective on carp feeding behavior in an aquaculture pond and its consequences for individual growth

The common carp (Cyprinus carpio) is an important species in global aquaculture. To optimize its production, it is necessary to understand its behaviour in relation to environmental and management factors. This study investigated the spatial and temporal dynamics of carp behaviour in a semi-intensive aquaculture pond under controlled feeding regimes over two growing seasons (2022-2023). Using telemetry and stable isotope analysis, we investigated activity, depth utilisation and feeding behaviour in relation to growth and aquaculture practices. The activity of carp and their spatial use changed over time, influenced by temperature, food availability and stocking density. Activity peaked in spring and early summer and was highest at night and twilight. In the warmer months, shallow areas (<0.5 m) were favoured, probably due to thermoregulation, oxygen levels or access to prey. Individual variability in foraging site use and food composition correlated with growth, highlighting the importance of behavioural traits in resource acquisition. A flood-induced rise in stocking density in 2022 increased competition for food, resulting in higher activity and lower growth compared to 2023. Stable isotope analysis showed that benthic invertebrates were the main food source, supplemented by cereals, emphasising the importance of a balanced natural and artificial diet. Our results emphasise the value of telemetry and isotope analysis for improving aquaculture practises. Recommendations include adapting feeding to seasonal and individual behaviour, mitigating density effects and promoting sustainable practises to optimise carp production.

animal behavior and cognition↗

bioRxiv2021

Habitat deterioration despite protection: long-term declines of littoral area of fishponds in Czech nature reserves

Fishponds play a key role in current pondscapes in many developed countries. Their littoral areas, supporting multiple ecosystem functions including the maintenance of aquatic and riparian biodiversity, have been adversely affected by the move shift towards more intensive aquaculture and widespread eutrophication in the middle 20th century. To counteract these changes, many fishponds received some protection, but its long-term efficiency has not been studied. Here we focus on the role of conservation status in protecting the area of littoral areas of fishponds in Czechia between the years 1950 and 2019. We found that the conservation status of these fishponds did not prevent habitat deterioration in most of the fishponds, especially during the second half of the 20th century. Moreover, we detected no significant effects of the reserve establishment year, fishpond area and conservation target on the littoral areas. This suggests that the conservation measures are insufficient across fishpond reserve types. We attribute the negative trends to persisting high fish stocks, especially of common carp, and eutrophication resulting from additional feeding, pond manuring, and ongoing nutrient inputs from the pond catchments. Sediment dredging and high grazing pressure by waterfowl in some reserves can further aggravate the situation. We conclude that effective protection of the littoral areas requires a paradigm shift towards less intensive fish stock management, more frequent summer drainage, and effective reduction of all nutrient inputs to increase the water quality. Such measures can help recover the littoral areas and the associated biota. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=54 SRC="FIGDIR/small/473897v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@8e9b31org.highwire.dtl.DTLVardef@6ecaf9org.highwire.dtl.DTLVardef@1cfaefdorg.highwire.dtl.DTLVardef@1e9952f_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LILittoral vegetation in ponds supports high biodiversity but often lacks protection. C_LIO_LIWe evaluated long-term changes in the littoral areas of fishponds in Czechia. C_LIO_LIThe areas decreased markedly in both protected and unprotected ponds since 1950. C_LIO_LIReserve duration, fishpond area and conservation target did not affect the trends. C_LIO_LIChanges in fishpond management are recommended for littoral area recovery. C_LI

ecology↗

bioRxiv2017

Hunters or gardeners?Linking community structure and function of trap-associated microbes to the nutrient acquisition strategy of a carnivorous plant

All higher eukaryotes live in a relationship with diverse microorganisms which colonize their bodily surfaces; plants are no exception. However, we still lack a satisfactory understanding of how these loosely associated microbiomes with immense diversity and functional potential interact with their hosts or how these interactions shape processes within populations and ecosystems. There is considerable similarity between microbial communities colonizing plant surfaces such as roots, and those of the animal gut. This often overlooked parallel allows us to look at microbial as well as host ecophysiology from a fresh perspective. The traps of carnivorous plants are sophisticated digestive organs and interface environments between the supply and the demand for nutrients. We selected the miniature ecosystem in the traps of aquatic carnivorous Utricularia plants as our model system. By assessing the trap-associated microbial community structure, diversity, function, as well as the nutrient recycling potential of bacterivory, we gained insight into the nutrient acquisition strategies of the Utricularia hosts. We conclude that trap ecophysiological function is in many aspects highly analogous to that of the herbivore gut and centers around complex microbial consortia, which act synergistically to covert complex organic matter, often of algal origin, into a source of nutrients for the plants.

microbiology↗