High overlap of zoonotic helminths between wild mammalian predators and rural dogs - an emerging One Health concern?

The concept of One Health emphasizes the interdependence of human, animal and environmental health and is of growing significance, in part owing to the problems related to emerging infectious diseases of wildlife origin. Wild mammalian predators are a potential risk factor for transmission of zoonotic pathogens to domesticated animals and humans. This is especially relevant in rural areas, where transmission of zoonotic pathogens can occur particularly efficiently when free-ranging dogs are present. The main aim of this study was to determine helminth infections among wild mammalian predators and evaluate the overlap between helminth faunas of wild mammals and dogs. Scat samples of predators were collected in coastal areas of Western Estonia and genetic methodology applied for the correct identification of predator species from their scat. Parasitic helminths of mammalian predators in the scat samples were analysed and compared with dog data from a previous study. High helminth prevalence (~90%) was found in dominant predator species in the area, namely the red fox (Vulpes vulpes) and golden jackal (Canis aureus). Moreover, the helminth fauna of both wild species, including potentially zoonotic helminths, overlapped largely with that of rural dogs in the same area. The results, together with the ones from earlier parasitological studies among humans in Estonia, emphasize the potential risk of pathogen transmission from wild mammalian predators to dogs and from dogs to humans, making parasitic diseases of wildlife a One Health concern.

Free-ranging rural dogs are highly infected with helminths, contaminating environment nine times more than urban dogs.

Regardless of the highly efficient anthelmintics available and the control measures taken by dog owners and veterinarians, gastrointestinal parasites, especially zoonotic helminths, are still abundant in dogs and pose a health risk to humans. Free-ranging dogs in rural areas can be an important source of helminth infection. The aims of the present work were to collect scats of rural dogs, determine the environmental contamination caused by helminth infections among rural dogs of Western Estonia, analyse how diet affects helminth infection rate and compare the findings to a previous study focusing on dog helminths in urban areas of Estonia. To differentiate the scats of dogs from other sympatric canids, a genetic method was applied. Of 328 samples, genetic analysis identified 84 scats belonging to dogs, of which 87.0% were infected with helminths. A high proportion of rural dog scats harboured eggs of Taeniidae (65.5%), followed by Trichuris spp./Eucoleus spp. (15.5%), Uncinaria stenocephala (14.7%) and Toxocara canis (4.3%). Coinfections occurred in 34.5% of the samples, being the most common between Taeniidae and U. stenocephala (41.4%). The intensity model indicated higher helminth infection rate in rural dogs preying on rodents and game. In comparison to urban dogs, rural dogs were nine times more likely to be infected with intestinal parasites. These results emphasize the need to implement measures to reduce helminth infections in dogs living in rural areas of Western Estonia. Among a complex of measures to be taken, we suggest that it is also important to diagnose which gastrointestinal parasite species infect dogs to determine specific anthelmintic treatment against these parasites.

Surveying for Batrachochytrium dendrobatidis and B. salamandrivorans in wild and captive amphibian populations in Estonia and Latvia.

The pathogenic chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) cause infections that have become primary drivers of amphibian biodiversity loss. While globally widespread, the distribution margins of Bd and Bsal have not been determined, and the presence of these pathogens has probably gone unnoticed in many areas, especially in northern Eurasia. To better understand the presence and distribution of both pathogens in the northern temperate and boreal forest biomes, 243 individuals were sampled from 8 native amphibian species across Estonia. Additionally, 68 amphibians were sampled from captive collections in Estonia and Latvia. Pathogen infection was assessed using metabarcoding of the ITS2 marker. No positive matches for Bsal infection were found. Bd was detected in 13 specimens, 3 of which were sampled at the Riga Zoo (with a prevalence of 5.2%) and 10 in natural environments in Estonia (3.3%). The infected wild individuals belonged to 6 amphibian species and were detected throughout the mainland of Estonia, but not on islands. Prevalence of infection with Bd ranged between 3.1 and 12.5% among native species. In addition, we found molecular evidence for a potentially new sister species to Bd in nature. Although outbreaks of chytridiomycosis have never been observed in Estonia, it cannot be excluded that the dynamics of local amphibian populations are affected by Bd infections. Therefore, further work, including capture-mark-recapture studies and long-term monitoring, are required to clarify the impact of Bd on amphibians in Northern Europe.

Forest ditch maintenance impoverishes the fauna of aquatic invertebrates: Opportunities for mitigation.

One of the main factors causing biodiversity loss in wetlands is drainage, nevertheless, even drained areas may provide habitat for aquatic fauna in the form of drainage ditches. Assemblages in ditches are regularly disturbed by ditch maintenance, but the extent of these disturbances and mitigation possibilities are poorly documented. We conducted an experimental study in three commercially managed forest plots in eastern Estonia, aiming to find out how ditch network maintenance (DNM) affects the diversity and assemblages of aquatic macroinvertebrates in ditches and remnant pools, and whether this effect can be alleviated by constructing mitigation waterbodies. For comparison we also collected data from natural pools in three undrained forest plots. Before DNM, ditches supported greater number of higher taxa compared to remnant and natural pools and more strictly aquatic taxa, whereas natural pools in undrained plots supported more Trichoptera shredders. After DNM, the diversity in remnant pools decreased. Moreover, majority of the pools dried out, which resulted in further reduction of the richness and abundance of macroinvertebrates. In ditches the diversity dropped immediately after DNM, but recovered in two to three years. Nevertheless, plot-scale richness and abundance did not completely recover. Assemblage shift in ditches took place right after DNM and remained distinct after the four year survey period. Mitigation pools provided habitat for several taxa (especially Odonata) uncommon in other waterbodies in drained and undrained plots. Our results show that DNM in forests substantially impoverishes habitat availability and reduces the abundance and diversity of aquatic macroinvertebrates. We recommend retaining uncleaned sections in ditches and constructing mitigation pools as tools for supporting wetland biodiversity in drained forests.

Restoration dilemmas between future ecosystem and current species values: The concept and a practical approach in Estonian mires.

Ecosystem restoration is gaining political and economic support worldwide, but its exact targets and costs often remain unclear. A key issue, both for predicting restoration success and assessing the costs, is the uncertainty of post-restoration development of the ecosystem. A specific combination of uncertainties emerges when ecosystem restoration would negatively affect pre-restoration species conservation values. Such dilemma appears to be common, but largely ignored in restoration planning; for example, in historically degraded forests, wetlands and grasslands that provide novel habitats for some threatened species. We present a framework of linked options for resolving the dilemma, and exemplify its application in extensive mire restoration in Estonia. The broad options include: redistributing the risks by timing; relocating restoration sites; modifying restoration techniques; and managing for future habitats of the species involved. In Estonia, we assessed these options based on spatially explicit mapping of expected future states of the ecosystem, their uncertainty, and the distribution of species at risk. Such planning documentation, combined with follow-up monitoring and experimentation, can be used for adaptive management, by funding organizations and for academic research.

Time-restricted flight ability influences dispersal and colonization rates in a group of freshwater beetles.

Variation in the ability to fly or not is a key mechanism for differences in local species occurrences. It is increasingly acknowledged that physiological or behavioral mechanisms rather than morphological differences may drive flight abilities. However, our knowledge on the seasonal variability and stressors creating nonmorphological differences in flight abilities and how it scales to local and regional occurrences is very limited particularly for small, short-lived species such as insects. Here, we examine how flight ability might vary across seasons and between two closely related genera of freshwater beetles with similar geographical ranges, life histories, and dispersal-related morphology. By combining flight experiments of >1,100 specimens with colonization rates in a metacommunity of 54 ponds in northern and eastern Europe, we have analyzed the relationship between flight ability and spatio-environmental distribution of the study genera. We find profound differences in flight ability between the two study genera across seasons. High flight ability for Acilius (97% of the tested individuals flew during the experiments) and low for Graphoderus (14%) corresponded to the different colonization rates of newly created ponds. Within a 5-year period, 81 and 31% of the study ponds were colonized by Acilius and Graphoderus, respectively. While Acilius dispersed throughout the season, flight activity in Graphoderus was restricted to stressed situations immediately after the emergence of adults. Regional colonization ability of Acilius was independent of spatial connectivity and mass effect from propagule sources. In contrast, Graphoderus species were closely related to high connectivity between ponds in the landscape. Our data suggest that different dispersal potential can account for different local occurrences of Acilius and Graphoderus. In general, our findings provide some of the first insights into the understanding of seasonal restrictions in flight patterns of aquatic beetles and their consequences for species distributions.

Local-scale spatial structure and community composition of orchid mycorrhizal fungi in semi-natural grasslands.

Orchid mycorrhizal (OrM) fungi play a crucial role in the ontogeny of orchids, yet little is known about how the structure of OrM fungal communities varies with space and environmental factors. Previous studies suggest that within orchid patches, the distance to adult orchids may affect the abundance of OrM fungi. Many orchid species grow in species-rich temperate semi-natural grasslands, the persistence of which depends on moderate physical disturbances, such as grazing and mowing. The aim of this study was to test whether the diversity, structure and composition of OrM fungal community are influenced by the orchid patches and management intensity in semi-natural grasslands. We detected putative OrM fungi from 0 to 32 m away from the patches of host orchid species (Orchis militaris and Platanthera chlorantha) in 21 semi-natural calcareous grasslands using pyrosequencing. In addition, we assessed different ecological conditions in semi-natural grasslands but primarily focused on the effect of grazing intensity on OrM fungal communities in soil. We found that investigated orchid species were mostly associated with Ceratobasidiaceae and Tulasnellaceae and, to a lesser extent, with Sebacinales. Of all the examined factors, the intensity of grazing explained the largest proportion of variation in OrM fungal as well as total fungal community composition in soil. Spatial analyses showed limited evidence for spatial clustering of OrM fungi and their dependence on host orchids. Our results indicate that habitat management can shape OrM fungal communities, and the spatial distribution of these fungi appears to be weakly structured outside the orchid patches.

Correction: Patterns of Assemblage Structure Indicate a Broader Conservation Potential of Focal Amphibians for Pond Management.

[This corrects the article DOI: 10.1371/journal.pone.0160012.].

Patterns of Assemblage Structure Indicate a Broader Conservation Potential of Focal Amphibians for Pond Management.

Small freshwater ponds host diverse and vulnerable biotic assemblages but relatively few conspicuous, specially protected taxa. In Europe, the amphibians Triturus cristatus and Pelobates fuscus are among a few species whose populations have been successfully restored using pond restoration and management activities at the landscape scale. In this study, we explored whether the ponds constructed for those two target species have wider conservation significance, particularly for other species of conservation concern. We recorded the occurrence of amphibians and selected aquatic macro-invertebrates (dragonflies; damselflies; diving beetles; water scavenger beetles) in 66 ponds specially constructed for amphibians (up to 8 years post construction) and, for comparison, in 100 man-made ponds (created by local people for cattle or garden watering, peat excavation, etc.) and 65 natural ponds in Estonia. We analysed nestedness of the species assemblages and its dependence on the environment, and described the co-occurrence patterns between the target amphibians and other aquatic species. The assemblages in all ponds were significantly nested, but the environmental determinants of nestedness and co-occurrence of particular species differed among pond types. Constructed ponds were most species-rich irrespective of the presence of the target species; however, T. cristatus was frequent in those ponds and rare elsewhere, and it showed nested patterns in every type of pond. We thus conclude that pond construction for the protected amphibians can serve broader habitat conservation aims in the short term. However, the heterogeneity and inconsistent presence of species of conservation concern observed in other types of ponds implies that long-term perspectives on pond management require more explicit consideration of different habitat and biodiversity values. We also highlight nestedness analysis as a tool that can be used for the practical task of selecting focal species for habitat conservation.