Invasive plant species can inhibit the growth of native plants by competing for resources as well as by secreting allelochemicals. Indigobush (Amorpha fruticosa L.), a deciduous shrub adaptable to a ...wide range of environmental conditions, was introduced into Europe as a decorative and valuable honey plant. In this study, we assayed the phytotoxic effect of aqueous leaf extracts (1, 3 and 5%) obtained from A. fruticosa leaves on seed germination and seedling growth of four important agricultural species (Trifolium pratense L. cultivar “VIVA”, Medicago sativa L. cultivar OS‐100, Helianthus annuus L. hybrid “Matej” and Triticum aestivum L. cultivar OS‐Olimpija). Five parameters were analyzed: germination percentage, mean germination time, germination index, fresh weight of seedling root and shoot. The phytotoxicity of A. fruticosa leaf extract was compared to that of juglone, a strong allelochemical that is known to inhibit growth of numerous plant species. The results demonstrate that A. fruticosa phytotoxicity is dependent on both the plant species tested and leaf extract concentration, with higher concentration extracts having stronger phytotoxicity. The highest concentration (5%) leaf extract caused similar inhibition of seed germination and seedling growth to that of juglone. The results of this study suggest that the rapid invasion of A. fruticosa in agricultural areas may have a negative impact on growth and yield of valuable forage and agricultural crops.
The phytotoxicity of Amorpha fruticosa is dependent on both the plant species tested and leaf extract concentration, with higher concentration extracts having stronger effect. The rapid invasion of A. fruticosa in agricultural areas may have a negative impact on growth and yield of valuable forage and agricultural crops.
Changes in the functional groups of zooplankton were studied in autumn in a temperate floodplain lake (Lake Sakadaš, Kopački Rit Nature Park, Croatia) and in the Drava River (in the Croatian part of ...the river). Various abiotic parameters as well as available food sources (phytoplankton and microphytes (algae and cyanobacteria) developing on epixylon, epilithon and artificially introduced microplastics called “plastisphere”) were also studied. The lake was hydrologically isolated from the main river during the study, while the water level of the Drava River fluctuated, resulting in larger variations in limnological parameters. Due to stable conditions in the lake, zooplankton abundance, biomass, and species richness were higher than in the Drava River. In both environments, zooplankton species feeding on bacteria, detrital suspensions, and small algae were most abundant, with predators and microfilter-feeders being more abundant in the lake. Microphytes were diverse and mostly small and medium-sized in phytoplankton and all substrate types. Stable lake conditions promoted higher abundance of the zooplankton group, which effectively uses larger algae as a food source. The lower abundance of zooplankton feeding on larger algae and predatory species in the river suggests that the epilithon and plastisphere community was a less mature community compared to the lake, and the heterotrophic component with ciliates and/or other small heterotrophs was not well developed. The importance of plastispheres was particularly evident under the turbid hydrologic conditions that prevailed in the river at the end of the study, when phytoplankton biomass decreased and zooplankton abundance steadily increased, suggesting that microphytes colonised on microplastics were an additional food source for higher trophic levels.
Croatia, having high plant species diversity, offers an important opportunity for studying the wild plant uses in an ethnobotanical context. Comprehensive investigations were undertaken in Croatian ...Mediterranean areas, but little is currently known about wild plants traditionally used by local populations in the north-eastern part of Croatia situated in the Pannonian sector of Pannonio-Carpathian province. An ethnobotanical survey was undertaken at the two study areas: in the six settlements around the town of Našice and seven settlements in the area of Đakovo. A study was performed using questionnaires with 54 informants. A total of 44 plant taxa belonging to 25 families were recorded. The highest number of taxa belongs to families Asteraceae, Lamiaceae and Rosaceae. Plants were mostly used for the treatment of various disorders, while only seven taxa were used as food. Urtica dioica, Rosa canina and Matricaria chamomilla were the most important plants used for the treatment of various diseases. Comparison with traditionally used plants in neighbouring regions indicated similarity concerning plants uses and the mode of applications. The study represents a baseline for further investigations of valuable wild plants and ethnobotanical knowledge in the investigated area.
The diversity of early spring vascular flora was studied in the Sub-Pannonic steppic grassland in the village of Bilje, north eastern Croatia. In all, 109 plant taxa within 35 families were found. ...The highest number of taxa belongs to the families Poaceae, Fabaceae, Asteraceae, Caryophyllaceae, Lamiaceae and Rosaceae. Specific habitat conditions, characterized by moderately wet and moderately acidic soil with intermediate fertility and the effects of the continental climate favour the development of different plant life forms. Out of the total recorded plant taxa, hemicryptophytes make up 59.6%, followed by therophytes (22.0%) and geophytes (13.8%). Chorological analysis shows that the most numerous are plants of Eurasian (33.9%), Pontic-Central-Asian (21.1%) and Central European (21.1%) floral elements. According to their status in the Red List, three critically endangered (CR), one vulnerable (VU) and three nearly threatened (NT) plant species were found. Altogether, the steppe-like grassland in Bilje is a unique habitat rich in valuable plants of the Croatian flora, including the critically endangered
, therefore it is of great importance to preserve it. Important management tools include mowing and controlling the spreading of cultivated and invasive plant species.
Lake Jošava (Croatia) is a shallow reservoir surrounded by agricultural land. In the present study, the trophic cascade was tested by examining the effects of stocking with common carp on plankton ...and periphytic microphytes. Before stocking, the phytoplankton community was dominated by the chrysophyte
Synura uvella
. In the epilithon and epiphyton, the predominant diatoms were prostrate, stalk-forming, and motile taxa representing an important food source for adult copepods. After stocking, phytoplankton biomass declined and the community shifted towards small centric diatoms, allowing the small-bodied zooplankton to exploit them. The lower biomass of adult copepods allowed rotifers to proliferate and exploit phytoplankton, while small cladocerans and nauplii fed primarily on epilithon. One month after stocking, phytoplankton was dominated by cryptophytes, small centric diatoms and chlorophytes, which were an important food for rotifers, while none of the zooplankton groups showed a significant relationship with the epilithic and epiphytic communities. By the end of the experiment, food was scarce due to reduced biomass of autotrophs, and zooplankton possibly began to feed on other sources. Our results add to the knowledge about the trophic cascade hypothesis in small shallow reservoirs.
To study the early colonization processes, polyethylene terephthalate (PET) microfragments were immersed in Lake Sakadaš and the Drava River and sampled weekly together with the surrounding biotic ...communities - phytoplankton, zooplankton, epixylon in the lake and epilithon in the river. At the end of the study, a rise in water level occurred in the river, which altered the environmental conditions and plankton communities. In studied environments, all of the sampled biotic communities were diverse and abundant. Plastispheres formed in both waters by the seventh day of incubation and developed rapidly, reaching a peak in abundance on the last day of the study. Initial colonization was supported equally by planktonic and periphytic taxa in both environments, but after initial settlement, plastisphere assemblages were affected differently in the river and lake. This study suggests that PET microfragments are a suitable substrate for microphyte settlement and may provide an important pathway for their transport in dynamic freshwater floodplains and river systems.
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•The PET fragments support the rapid development of three-dimensional plastispheres.•Initial colonization is supported by planktonic and periphytic taxa equally.•Following succession, the plastispheres in the lake resemble an epixylic community.•Progression of plastispheres in the river favours the settlement of planktonic taxa.
This paper presents the results of the research on the overall distribution of selenium (Se) in various aquatic compartments (water, sediment, plankton and macrophytes) at six selected sites of the ...Croatian part of the Drava and Danube rivers, the connected floodplain lake and the melioration channel system carried out in two sampling periods (flooding in June and the drought period in September). In addition, the physicochemical water properties, plankton composition and biomass were analysed. Our study revealed low mean Se contents in sediments and water, indicating Se deficiency in the studied freshwater systems. The physicochemical environment, including Se distribution, was primarily influenced by hydrology rather than site-specific biogeochemical and morphological characteristics. The flooding period was characterised by higher Se content in water and higher transparency, nitrate and total nitrogen concentrations than drought conditions. At the river sites, sediment Se content was the highest during the flood period, while at all other sites, higher concentrations were found during the drought, reaching the maximum in the lake. Although Se concentrations were below the threshold for aquatic ecotoxicity, they increased in the following order: water (0.021–0.187 μg Se L−1) < sediments (0.005–0.352 mg Se kg−1) < macrophytes (0.010–0.413 mg Se kg−1) < plankton (0.044–0.518 mg Se kg−1) indicating its possible biomagnification at the bottom of the food chain. Species known for high Se accumulation potential dominated the biomass of the main plankton groups and the composition of the macrophyte community, which may provide a more sensitive and accurate steady-state compartment monitor for Se assessment in freshwater biotopes.
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•Low Se content in sediments and water indicates Se deficiency in the studied area.•Se concentration increased in the order: water < sediments < macrophytes < plankton.•Hydrology influences the Se distribution in aquatic compartments.•Se potentially accumulates at the bottom of the food web.
Intensive human activities have resulted in a critical reduction of grasslands in Croatia, one of the richest Europian countries in terms of biodiversity. Sub-Pannonic steppic grasslands are very ...rare, only few occur in the continental part of Croatia and most of them are protected as NATURA 2000 sites. We studied vascular flora of the Sub-Pannonic stepic grassland with the aim to examine the changes in plant communities 15 years from the mowing application. Results showed that hand mowing once per year at the end of vegetation season increased the species diversity as well as the number of medium and low growth taxa. The critically endangered, nearly threatened and vulnerable species remained preserved. The occurrence of trees, shrubs and invasive species as a consequence of succession and anthropogenic influences could be important threat for steppe-like grassland flora. From a conservation point of view infrequent mowing regime could be an effective management tool, although it needs to be adapted to regional and local circumstances for maintaining high biodiversity of steppe-like grasslands and valuable plant species.
The estimation of the toxic influences of herbicide products on non-target aquatic organisms is essential for evaluation of environmental contamination. We assessed the effects of the herbicide ...S-metolachlor (S-MET) on unicellular green microalga Parachlorella kessleri during 4–72 in vitro exposure to concentrations in the range 2–200μg/L. The results have shown that S-MET had a significant effect on algae, even in doses 10 and 20 times lower than the EC50 values obtained for P. kessleri (EC50-72h=1090μg/L). It generates reactive oxygen species in algae, decreases their growth and photosynthetic pigment concentration, changes their ultrastructure and alters the cellular antioxidant defence capacities. The levels of protein adducts with the reactive aldehyde 4-hydroxy-2-nonenal (HNE), the end-product of lipid peroxidation, were significantly elevated in S-MET treated cells revealing the insufficient effectiveness of P. kessleri antioxidant mechanisms and persistent lipid peroxidation. Since algae are fundamental aquatic food component, the damaged algal cells, still capable of dividing while having persistently increased content of HNE upon S-MET contamination could represent an important environmental toxic factor that might further affect higher organisms in the food chain.
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•Oxidative stress response was assessed in P. kessleri following S-MET exposure.•S-MET alters algal growth and antioxidant mechanisms inducing lipid peroxidation.•HNE-protein adducts accumulate in P. kessleri during longer S-MET treatment.•Algae with increased HNE content could represent environmental toxic factor.
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