Thermal performance of planktonic ciliates differs between marine and freshwaters: A case study providing guidance for climate change studies

Predicting the performance of aquatic organisms in a future warmer climate depends critically on understanding how current temperature regimes affect the organisms’ growth rates. Using a meta-analysis for published experimental data, we calculated the activation energy (Ea) to parameterize the thermal sensitivity of marine and freshwater ciliates, major players in marine and freshwater food webs. We hypothesized that their growth rates increase with temperature but that ciliates dwelling in the immense, thermally stable ocean are closely adapted to their ambient temperature and have lower Ea than ciliates living in smaller, thermally more variable freshwater environments. The Ea was in the range known from other taxa but significantly lower for marine ciliates (0.390 ± 0.105 eV) than for freshwater ciliates (0.633 ± 0.060 eV), supporting our hypothesis. Accordingly, models aiming to predict the ciliate response to increasing water temperature should apply the environment-specific activation energies provided in this study

Life-history omnivory in the fairy shrimp Branchinecta orientalis (Branchiopoda: Anostraca)

Very little is known about the feeding of naupliar and juvenile life stages of omnivorous fairy shrimps (Crustacea: Anostraca). Here, we aim to reveal whether the fairy shrimp Branchinecta orientalis is an ontogenetic omnivore and at which age and ontogenetic stage they gain the ability to feed on zooplankton. We assess how food uptake rates change with age until reaching maturity by providing algae (pico- and nanoplanktonic unicellular algae) and zooplankton (rotifers and copepod nauplii) as food in individual experiments. We found that the fairy shrimp B. orientalis started to feed on both types of algal prey immediately after hatching. Nanoplanktonic algae likely represented the most important food source until reaching maturity. Moreover, fairy shrimps started to feed on zooplankton already when they were 7 days old. Slow-moving rotifers gradually gained importance in the fairy shrimp diet with time. Our results reveal an ontogenetic change in the prey spectrum of fairy shrimp. The systematic shift towards omnivory likely affects both phyto- and zooplankton community composition, possibly contributing to temporal changes in food web dynamics in fairy shrimp habitats, and temporary ponds, which may warrant more detailed investigations in future studies

How Can Tufa Deposits Contribute to the Geotourism Offer? The Outcomes from the First UNESCO Global Geopark in Serbia

The study focuses on the present state and the assessments of geotourism development of the two most representative tufa deposits in the Djerdap National Park—the first UNESCO Global Geopark in Serbia. The findings were designated through implementing the freshly upgraded methodology—M-GAM-1-2 based on an early modified geosites assessment model (M-GAM). To overcome the limitations of the previous model, the authors implemented additional enhancements and involved members of the local community (residents and authorities) in the study to comprehensively evaluate the observed sites. The outcomes revealed that the attitudes of all stakeholders should be taken into consideration in order to develop geotourism properly, additionally attract visitors, and preserve tufa deposits for future generations of locals and visitors. Moreover, geotourism at the observed sites can be one of the vital activities of the population, as well as a type of compensation for various limitations in the development, which are imposed by the regimes of natural and cultural heritage protection within the recently established UNESCO Global Geopark

Pleistocene allopatric differentiation followed by recent range expansion explains the distribution and molecular diversity of two congeneric crustacean species in the Palaearctic

Pleistocene glaciations had a tremendous impact on the biota across the Palaearctic, resulting in strong phylogeographic signals of range contraction and rapid postglacial recolonization of the deglaciated areas. Here, we explore the diversity patterns and history of two sibling species of passively dispersing taxa typical of temporary ponds, fairy shrimps (Anostraca). We combine mitochondrial (COI) and nuclear (ITS2 and 18S) markers to conduct a range-wide phylogeographic study including 56 populations of Branchinecta ferox and Branchinecta orientalis in the Palaearctic. Specifically, we investigate whether their largely overlapping ranges in Europe resulted from allopatric differentiation in separate glacial refugia followed by a secondary contact and reconstruct their postglacial recolonization from the inhabited refugia. Our results suggest the existence of distinct refugia for the two species, with genetic divergence among intraspecific lineages consistent with late Pleistocene glacial cycles. While B. ferox lineages originated from Mediterranean refugia, the origin of B. orientalis lineages was possibly located on the Pannonian Plain. We showed that most dispersal events predominantly happened within 100 km, coupled with several recent long-distance events (> 1000 km). Hence the regional habitat density of suitable habitats in Central Europe is possibly a key to the co-existence of the two species. Overall, our study illustrates how isolation in combination with stochastic effects linked to glacial periods are important drivers of the allopatric differentiation of Palaearctic taxa

Microbial stowaways: Waterbirds as dispersal vectors of aquatic pro‐ and microeukaryotic communities

Aim: Waterbirds are important dispersal vectors of multicellular organisms; however, no study to date has focused on their potential role in dispersing aquatic microbial communities. We explicitly studied endozoochory of prokaryotes and unicellular mi- croeukaryotes by waterbirds using DNA metabarcoding. By directly comparing the dispersed set of organisms to the source pool of a natural metacommunity, we aimed at a realistic estimate of the importance of waterbird zoochory for natural microbial communities. Location: Temporary saline soda pans in Austria and Hungary. Taxon: Prokaryotes and unicellular microeukaryotes. Methods: In 2017 and 2018, water samples were collected from a network of 25 tem- porary ponds along with fresh droppings of five waterbird species including the domi- nant greylag goose (Anser anser). Prokaryotic and microeukaryotic communities were identified via 16S and 18S rRNA gene amplicon sequencing. After quality filtering of sequence reads, pro- and microeukaryotic amplicon sequence variant (ASV) composi- tions were compared between the aquatic and dropping samples, across years and waterbird species. Results: 28% of the dominant aquatic prokaryotic and 19% of the microeukaryotic ASVs were transported by A. anser. ASV richness was lower, but compositional varia- tion was higher in A. anser droppings than in aquatic communities, probably resulting from stochastic pick-up from multiple aquatic habitats. The composition of prokary- otic ASVs in bird droppings differed among the 2 years and reflected the actual aquatic communities. The dispersed set of microbes were largely similar among the waterbird species except for the planktivore filter- feeder northern shoveler (Spatula clypeata), which dispersed more microeukaryotes than the other waterbirds. Main conclusions: Using an amplicon sequencing approach to characterize aquatic microorganisms in waterbird droppings and in the associated environment, our study provides strong evidence for endozoochory of natural communities. These results imply that waterbirds may be crucial in maintaining ecological connectivity between aquatic habitats at the level of microbial communities

Risky Travel? Subjective vs. Objective Perceived Risks in Travel Behaviour—Influence of Hydro-Meteorological Hazards in South-Eastern Europe on Serbian Tourists

In terms of climate related security risks, the region of South-Eastern Europe (SEE) can be identified as one of the world’s hot spots. As weather-related hazards continue to increase in num-bers and spatial distribution, risk perception in the tourism industry becomes even more important. Additionally, people’s perception of natural hazards is one of the key elements in their decision-making process when choosing a travel destination. Although a vast number of studies have exam-ined aspects of risk perception, an integrated approach which considers both objective and subjec-tive factors related to the tourism industry and hydro-meteorological hazards remains relatively scarce. This pioneering study inspects the causality between objective perceived risks, as well as subjective risk factors. A methodological approach and the obtained results present a certain nov-elty since the previous conceptualized Psychological Preparedness for Disaster Threat Scale (PPDTS) was applied for the first time in the tourism industry. The obtained results reveal the pres-ence of a statistically significant relationship between objective risks and certain subjective risk fac-tors (gender, age, education, prior experience, anticipation, and awareness). Therefore, this study may offer a conceptual platform for both theoretical and practical implications for enhanced ap-proaches oriented toward more qualitative risk management at a given travel destination, in regions prone to hydro-meteorological hazards

Thermal performance of planktonic ciliates differs between marine and freshwaters: A case study providing guidance for climate change studies

Abstract Predicting the performance of aquatic organisms in a future warmer climate depends critically on understanding how current temperature regimes affect the organisms' growth rates. Using a meta‐analysis for the published experimental data, we calculated the activation energy (Ea) to parameterize the thermal sensitivity of marine and freshwater ciliates, major players in marine and freshwater food webs. We hypothesized that their growth rates increase with temperature but that ciliates dwelling in the immense, thermally stable ocean are closely adapted to their ambient temperature and have lower Ea than ciliates living in smaller, thermally more variable freshwater environments. The Ea was in the range known from other taxa but significantly lower for marine ciliates (0.390 ± 0.105 eV) than for freshwater ciliates (0.633 ± 0.060 eV), supporting our hypothesis. Accordingly, models aiming to predict the ciliate response to increasing water temperature should apply the environment‐specific activation energies provided in this study

How Can Tufa Deposits Contribute to the Geotourism Offer? The Outcomes from the First UNESCO Global Geopark in Serbia

The study focuses on the present state and the assessments of geotourism development of the two most representative tufa deposits in the Djerdap National Park—the first UNESCO Global Geopark in Serbia. The findings were designated through implementing the freshly upgraded methodology—M-GAM-1-2 based on an early modified geosites assessment model (M-GAM). To overcome the limitations of the previous model, the authors implemented additional enhancements and involved members of the local community (residents and authorities) in the study to comprehensively evaluate the observed sites. The outcomes revealed that the attitudes of all stakeholders should be taken into consideration in order to develop geotourism properly, additionally attract visitors, and preserve tufa deposits for future generations of locals and visitors. Moreover, geotourism at the observed sites can be one of the vital activities of the population, as well as a type of compensation for various limitations in the development, which are imposed by the regimes of natural and cultural heritage protection within the recently established UNESCO Global Geopark

Risky Travel? Subjective vs. Objective Perceived Risks in Travel Behaviour—Influence of Hydro-Meteorological Hazards in South-Eastern Europe on Serbian Tourists

In terms of climate related security risks, the region of South-Eastern Europe (SEE) can be identified as one of the world’s hot spots. As weather-related hazards continue to increase in numbers and spatial distribution, risk perception in the tourism industry becomes even more important. Additionally, people’s perception of natural hazards is one of the key elements in their decision-making process when choosing a travel destination. Although a vast number of studies have examined aspects of risk perception, an integrated approach which considers both objective and subjective factors related to the tourism industry and hydro-meteorological hazards remains relatively scarce. This pioneering study inspects the causality between objective perceived risks, as well as subjective risk factors. A methodological approach and the obtained results present a certain novelty since the previous conceptualized Psychological Preparedness for Disaster Threat Scale (PPDTS) was applied for the first time in the tourism industry. The obtained results reveal the presence of a statistically significant relationship between objective risks and certain subjective risk factors (gender, age, education, prior experience, anticipation, and awareness). Therefore, this study may offer a conceptual platform for both theoretical and practical implications for enhanced approaches oriented toward more qualitative risk management at a given travel destination, in regions prone to hydro-meteorological hazards