Environmental drivers and sampling techniques influence neotropical hyphomycetes composition in lakes and streams

Freshwater hyphomycetes are decomposer fungi whose community composition is shaped by multiple environmental factors, including temperature, water velocity, nutrient availability, substrate type, and habitat type, such as lakes and streams. This poses a challenge for accurate monitoring of these fungal communities, requiring the use of diverse sampling strategies to better represent and understand their dynamics, particularly in tropical ecosystems. In this study, the composition of aquatic hyphomycetes was compared between two habitat types (lakes and streams), over two substrate types (leaves and twigs), and over time, using two different sampling methods: moist chamber and submerged incubation. The relationship between freshwater hyphomycetes composition and physicochemical variables was also investigated. Substrates and water samples were collected from two lakes and two streams in a coastal region of Northeastern Brazil. The results indicated that time, and its interaction with habitat types, were the main drivers of changes in hyphomycetes composition. However, total phosphorus, ammonia, dissolved oxygen, temperature, and water velocity also significantly influenced community assembly. Furthermore, the study showed that different sampling methods can lead to varied conclusions in ecological and taxonomic studies. For instance, a significant species turnover between substrates was detected only with the submerged incubation method, whereas the effect of time and its interaction with habitat was evident only with the moist chamber method. Moreover, a high rate of taxon substitution was observed between sampling methods. These observed differences emphasize the need to combine different sampling strategies and habitat types to achieve a more comprehensive and accurate representation of the richness, diversity, and distribution of fungal communities in continental aquatic ecosystems.

Investigating the distribution of a unique crustacean microendemic to tree hollows

Water-filled tree hollows constitute phytotelmata that harbor specialized organisms. One striking example of extreme adaptation to these microhabitats is the case of the microcrustacean Micromoina arboricola, which has been found inhabiting the hollow of a single tree individual in the Atlantic Forest. We investigated the spatial distribution and influence of microhabitat characteristics such as hollow volume and height from the ground in the occurrence of M. arboricola. We surveyed all the trunks present in ca. 5000 m2 of an Atlantic old-growth forest area. We found M. arboricola individuals in 75% of the hollows, thus expanding the known distribution of the species. Spatial analysis suggested a clustered pattern of population densities across hollows, indicating that the dispersal capacity to new microhabitat patches may vary in space. Although we did not find an effect of hollow volume, population density was negatively related to hollow height. This suggests that more restrictive abiotic conditions at greater heights limit the occurrence of the species, emphasizing its vulnerability to environmental changes. Hollow-mediated ecosystem engineering depends on the occasional formation of cavities that require time and ancient trees. Preserving old forests with hollows under varying conditions tends to maintain ecosystem functionality and the conservation of this unique microendemic species.

Commodity risk assessment of Acer platanoides plants from the UK

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. This Scientific Opinion covers plant health risks posed by plants of Acer platanoides imported from the United Kingdom (UK) as: (a) 1- to 7-year-old bare root plants for planting, (b) 1- to 7-year-old plants in pots and (c) bundles of 1- to 2-year-old whips and seedlings, taking into account the available scientific information, including the technical information provided by the UK. All pests associated with the commodity were evaluated against specific criteria for their relevance for this opinion. Six EU quarantine pests and four pests not regulated in the EU fulfilled all relevant criteria and were selected for further evaluation. For the selected pests, the risk mitigation measures implemented in the technical dossier from the UK were evaluated taking into account the possible limiting factors. For these pests, an expert judgement is given on the likelihood of pest freedom taking into consideration the risk mitigation measures acting on the pest, including uncertainties associated with the assessment. The degree of pest freedom varies among the pests evaluated, with Meloidogyne mali or M. fallax being the pest most frequently expected on the imported plants. The Expert Knowledge Elicitation indicated with 95% certainty that 9,792 or more plants in pots per 10,000 will be free from Meloidogyne mali or M. fallax.

Aquatic islands in the sky: 100 years of research on water-filled tree holes

Water-filled tree holes are unique ecosystems that may occur high up in tree crowns and are essentially aquatic islands in the sky. Insect larvae, mesofauna, and other organisms colonize the waterbodies and feed on the accumulating detritus. Water-filled tree holes are not only important habitats for these species but have been used as model systems in ecology. Here, we review more than 100 years of research on tree-hole inhabiting organisms and show that most studies focus on selected or even single species (most of which are mosquitoes), whereas only few studies examine groups other than insects, especially in the tropics. Using a vote counting of results and a meta-analysis of community studies, we show that the effects of tree-hole size and resources on abundance and richness were investigated most frequently. Both were found to have a positive effect, but effect sizes were modulated by site-specific environmental variables such as temperature or precipitation. We also show that parameters such as the height of the tree holes above ground, tree-hole density, predation, and detritus type can be important drivers of organism abundance or richness but are less often tested. We identify several important research gaps and potential avenues for future research. Specifically, future studies should investigate the structure, functions, and temporal dynamics of tree-hole food webs and their cross-system interactions, for example, with terrestrial predators that act as a connection to their terrestrial surroundings in meta-ecosystems. Global observational or experimental tree-hole studies could contribute pivotal information on spatial variation of community structure and environmental drivers of community assembly. With a better understanding of these unique aquatic habitats in terrestrial ecosystems, natural and artificial tree holes can not only serve as model systems for addressing fundamental ecological questions but also serve as indicator systems of the impacts of environmental change on ecosystems.

Phylogeny and a new species of Polylobatispora

During surveys conducted on freshwater fungi from Vietnam, a new aquatic anamorphic fungus was isolated from decaying leaves in Vietnam. The fungus produced phialidic, swollen conidiophore and conidiogenous cells with one-celled conidia with four very tiny lobes. Based on its conidial development and other morphological characteristics, we confirmed that this is a novel fungus and described it as P. ambigua sp. nov. Phylogenetic analyses of P. ambigua based on the LSU nrDNA sequences showed that this fungus clusters in a single clade with the two known Polylobatispora spp. with 97% bootstrap value which is sister with Pseudoprobiscisporaceae. The Polylobatispora clade is nested in the Attracrosporales, Sordariomycetes. Furthermore, in this study two known species of Polylobatispora (P. deltoidea and P. quinquecornuta) were also isolated and illustrated.