Species-specific Distributions Research Articles

Bioinformatics-aided function exploration of GH29 fucosidases from human gut Parabacteroides.

Gut microbes produce α-l-fucosidases critical for utilizing human milk oligosaccharides, mucosal and dietary glycans. Although gut Parabacteroides have garnered attention for their impact on host health and disease, their CAZymes remain poorly studied. CAZome analysis of eleven gut Parabacteroides type strains revealed their capacity to degrade mucin O-glycans. Their abundance of GH29 fucosidases caught our attention, and we predicted the functional profiles of 46 GH29 fucosidases using in silico approaches. Our findings showed diverse linkages specificities and species-specific distributions, with over half of GH29 enzymes functioning as α1,3/4 fucosidases, essential for acting on Lewis antigen epitopes of mucin O-glycans. We further enzymatically validated 4 novel GH29 sequences from poorly characterized groups. PgoldGH29A (cluster37 GH29BERT, GH29:75.1 CUPP) does not act on tested natural substrates. PgoldGH29B (cluster1 GH29BERT, GH29:84.1 CUPP) functions as a strict α1,3/4 fucosidase. PgoldGH29C (cluster14 GH29BERT, GH29:29.1 CUPP) displays unprecedented substrate specificity for α1,2/3/4 disaccharides. PgoldGH29D (cluster4 GH29BERT, GH29:6.2 CUPP) acts on α1,2/3/4/6 linkages similar to enzymes from GH29:6.1 CUPP but prefers disaccharides over trisaccharides. These results suggest that PgoldGH29B and PgoldGH29D can contribute to mucin O-glycan degradation via their α1,3/4 and α1,2 fucosidase activity, respectively, while the natural substrates of PgoldGH29A and PgoldGH29C may be irrelevant to host-glycans. These insights enhance our understanding of the ecological niches inhabited by gut Parabacteroides and may guide similar exploration in other intriguing gut microbial species.

Twenty Years in EUCAST Anti-Fungal Susceptibility Testing: Progress & Remaining Challenges.

Since its inception in 2002, the EUCAST Antifungal Susceptibility Testing Subcommittee (AFST) has developed and refined susceptibility testing methods for yeast, moulds and dermatophytes, and established epidemiological cut-off values and breakpoints for antifungals. For yeast, three challenges have been addressed. Interpretation of trailing growth in fluconazole susceptibility testing, which has been proven without impact on efficacy if below the 50% endpoint. Variability in rezafungin MIC testing due to laboratory conditions, which has been solved by the addition of Tween 20 to the growth medium in E.Def 7.4. And third, interpretation of MICs for rare yeast with no breakpoints, where recommendations have been established for MIC-based clinical advice. For moulds, refinements include the validation of spectrophotometer reading for A. fumigatus to facilitate objective MIC determination, and for dermatophytes the establishment of a microdilution method with automated reading and a selective medium to minimise the risk of contaminations. Recent initiatives involve development and validation of agar-based screening assays for detection of potential azole and echinocandin resistance in A. fumigatus and Aspergillus species, respectively, and of terbinafine resistance in Trichophyton species. Moreover, the development of a EUCAST guidance document for molecular resistance testing represents an advancement, particularly for identifying target gene alterations associated with resistance. In summary, EUCAST AFST continues to play a pivotal role in standardizing AFST and facilitating accurate interpretation of susceptibility data for clinical decision-making. Adoption of EUCAST breakpoints for commercial test methods, however, requires thorough validation to ensure concordance with EUCAST reference testing species-specific MIC distributions.

Model-based indices of juvenile Pacific salmon abundance highlight species-specific seasonal distributions and impacts of changes to survey design

Changes in survey implementation can bias traditional design-based indices of abundance, particularly for migratory species where local abundance can vary at short temporal scales. Spatiotemporal model-based estimators provide a flexible alternative that can better account for changes in the timing and location of surveys. Here we develop a geostatistical model, a generalized linear mixed effects model with Gaussian Markov random fields, that is sufficiently flexible to account for changes in survey design, as well as seasonal and interannual variability in abundance and spatial distribution. We then apply this model to a suite of migratory species—juvenile Pacific salmon—with survey data collected from southern British Columbia’s continental shelf over the previous 25 years. Juvenile Pacific salmon showed species-specific spatial distributions with considerable seasonal variability. While the location of species-specific hot spots varied among years, seasonal variation in distributions were greater than interannual variation. We found that a shift from standard transects and opportunistic sampling to a random stratified survey design resulted in lower estimates of abundance for four of five juvenile Pacific salmon species; however, these differences were not significant after accounting for other sampling attributes. Trends in abundance for several species shifted when models included survey and diel effects. Our approach provides a means of deriving indices of abundance for migratory species from surveys with variable effort in time and space. Ultimately such indices can be used to better understand the ecological mechanisms regulating productivity by linking distribution and abundance to environmental drivers.

Involvement of transposable elements in Alzheimer's disease pathogenesis.

Alzheimer's disease affects an average of 5 % of the population with a significant increase in prevalence with age, suggesting that the same mechanisms that underlie aging may influence this pathology. Investigation of these mechanisms is promising for effective methods of treatment and prevention of the disease. Possible participants in these mechanisms are transposons, which serve as drivers of epigenetic regulation, since they form species-specific distributions of non-coding RNA genes in genomes in evolution. Study of miRNA involvement in Alzheimer's disease pathogenesis is relevant, since the associations of protein-coding genes (APOE4, ABCA7, BIN1, CLU, CR1, PICALM, TREM2) with the disease revealed as a result of GWAS make it difficult to explain its complex pathogenesis. Specific expression changes of many genes were found in different brain parts of Alzheimer's patients, which may be due to global regulatory changes under the influence of transposons. Experimental and clinical studies have shown pathological activation of retroelements in Alzheimer's disease. Our analysis of scientific literature in accordance with MDTE DB revealed 28 miRNAs derived from transposons (17 from LINE, 5 from SINE, 4 from HERV, 2 from DNA transposons), the expression of which specifically changes in this disease (decreases in 17 and increases in 11 microRNA). Expression of 13 out of 28 miRNAs (miR-151a, -192, -211, -28, -31, -320c, -335, -340, -378a, -511, -576, -708, -885) also changes with aging and cancer development, which indicates the presence of possible common pathogenetic mechanisms. Most of these miRNAs originated from LINE retroelements, the pathological activation of which is associated with aging, carcinogenesis, and Alzheimer's disease, which supports the hypothesis that these three processes are based on the primary dysregulation of transposons that serve as drivers of epigenetic regulation of gene expression in ontogeny.

Modeling the Distribution of Atlantic Croaker and Spot in a Dynamic Seascape Using Metabolic Scope

In estuarine and coastal systems, anthropogenic activities and directional changes in global air temperatures have led to increased water temperatures, as well as increased frequency and severity of episodic hypoxia. These alterations have had population-level effects on aquatic organisms, including changes in species-specific distributions. Because physiology is the transfer function connecting environmental conditions to individual behaviors and eventually to population-level effects, we used individual-based models (IBMs) that incorporate changes in metabolic scope as motivation for movement. Our objective was to investigate the effects of temperature and hypoxia on the distribution of Atlantic croaker and spot in Chesapeake Bay. We compared the predicted monthly fish distributions from the IBMs with apparent fish distributions recorded by the VIMS Juvenile Fish Trawl Survey during 1988–2014. IBMs failed to reproduce accurately the apparent spatial distributions of Atlantic croaker and spot. More specifically, compared with the trawl survey, IBMs predicted larger proportions of these two species would be captured in the lower regions of Chesapeake Bay and smaller proportions in the York and Rappahannock rivers. We postulate that, because similar thermal and oxygen conditions were occupied by fish in the IBMs and in the wild, temperature may not be the most important factor motivating the movement of Atlantic croaker and spot in Chesapeake Bay, and other spatial factors (e.g., prey availability) act in concert with temperature and hypoxia to determine the spatial distributions of Atlantic croaker and spot in Chesapeake Bay. Alternatively, surveys used to estimate species occurrences could be biased if gear vulnerability is affected by temperature or oxygen conditions (or both). Additional research is needed to clarify which condition is true or if a combination of these factors (and others) led to discrepancies between predicted and apparent fish distributions based on trawl survey data.

Assessing the agreement between the pneumatic and the flow-centrifuge method for estimating xylem safety in temperate diffuse-porous tree species.

The increasing frequency of global change-type droughts has created a need for fast, accurate and widely applicable techniques for estimating xylem embolism resistance to improve forecasts of future forest changes. We used data from 12 diffuse-porous temperate tree species covering a wide range of xylem safety to compare the pneumatic and flow-centrifuge method, two rapid methods used for constructing xylem vulnerability curves. We evaluated the agreement between parameters estimated with both methods and the sensitivity of pneumatic measurements to the duration of air discharge (AD) measurements. There was close agreement between xylem water potentials at 50% air discharged (PAD), estimated with the Pneumatron, and 50% loss of hydraulic conductivity (PLC), estimated with the flow-centrifuge method (mean signed deviation: 0.12 MPa, Pearson correlation: 0.96 after 15 s of gas extraction). However, the relationship between the estimated slopes was more variable, resulting in lower agreement in the xylem water potential at 12% and 88% PAD/PLC. The agreement between the two methods was not affected by species-specific vessel length distributions. All pneumatic parameters were sensitive to AD time. Overall agreement was highest at relatively short AD times, with an optimum at 16 s. Our results highlight the value of the Pneumatron as an easy and reliable tool to estimate 50% embolism thresholds for a wide range of diffuse-porous temperate angiosperms. Further, our study provides a set of useful metrics for methodological comparisons of vulnerability curves in terms of systematic and random deviations, as well as overall agreement.

Belowground spectroscopy — Novel spectral approach for estimation of vertical and species-specific distributions of forest soil characteristics and heterotrophic respiration

Spatial variations in soil moisture and characteristics (nutrients and organic components) are important for understanding the heterogeneity of soil heterotrophic respiration (Rh) in forest ecosystems. In this study, "belowground spectroscopy", a new method for estimating soil characteristics and Rh in the field, was developed by measuring the spectral reflectance in the short-wave infrared (SWIR) spectral region. In the cool temperate forest of Hokkaido, 184 training samples were collected from litter, organic, and mineral soil layers on the forest floors of 13 tree species. First, a multiple regression model was developed for Rh estimation using the soil characteristics as substrates. Next, the partial least squares regression (PLSR) model was calibrated to estimate soil characteristics using spectral reflectance observed under various moisture conditions, and then spectroscopy-based Rh estimation model was constructed by combining the two models. In the multiple regression model, soil water content and concentrations of total nitrogen and cellulose were selected as explanatory variables of Rh. The PLSR model for these parameters showed estimation accuracies of 23.1–31.8% of relative root mean square error (rRMSE) in the validation analysis. The combined model showed 68.4% of rRMSE in Rh estimation. Furthermore, this method was applied to field observations using a small spectrometer to estimate vertical and species-specific variations in Rh. The estimated vertical profiles of soil characteristics showed specific variations related to vertical changes in the soil layer. The accumulated value of the estimated vertical Rh was significantly correlated with the Rh measured using a gas analyzer on 12 tree species, except Alnus species. The rRMSE of the modeled Rh compared to that of gas analyzer was 29.8%. These results indicate that belowground spectroscopy calibrated using a dataset under varied moisture conditions is effective for developing new, rapid, and non-destructive monitoring of soil characteristics and Rh in the field.

Antimicrobial susceptibility testing and tentative epidemiological cut-off values for Lactobacillaceae family species intended for ingestion

IntroductionIn this work, 170 strains covering 13 species from the Lactobacillaceae family were analyzed to determine minimal inhibitory concentration (MIC) distributions to nine antimicrobial agents, and genes potentially conferring resistance. This allows a proposal of tentative Epidemiological Cut-Offs (ECOFFs) that follows the phylogeny for interpretation of resistance in the 13 species.MethodsThe 170 strains originated from different sources, geographical areas, and time periods. MICs for nine antibiotics were determined according to the ISO 10932 standard for lactobacillia and by a modified CLSI-method for Leuconostoc and Pediococcus which ensured sufficient growth. The strains were whole genome sequenced, subtyped by core genome analysis, and assessed for the presence of antibiotic resistance genes using the ResFinder and NCBI AMRFinder databases.Results and discussionThe data provide evidence that antimicrobial susceptibility follows phylogeny instead of fermentation pattern and accordingly, tentative ECOFFs were defined. For some species the tentative ECOFFs for specific antibiotics are above the cut-off values set by the European Food Safety Authority (EFSA) which are primarily defined according to fermentation pattern or at genus level. The increased tolerance for specific antibiotics observed for some species was evaluated to be innate, as only for one strain phenotypic resistance was found to be related to an acquired resistance gene. In general, more data are needed to define ECOFFs and since the number of isolates available for industrial relevant bacterial species are often limited compared to clinically relevant species, it is important; 1) that strains are unambiguously defined at species level and subtyped through core genome analysis, 2) MIC determination are performed by use of a standardized method to define species-specific MIC distributions and 3) that known antimicrobial resistance genes are determined in whole genome sequences to support the MIC determinations.

The Re-parametrization of the DAS Model Based on 2016-2021 Data of the National Forestry Database: New Results on Cutting Age Distributions

This paper presents the DAS forest model (Distributions Applied on Stands model), a forest stand-based model suitable for projecting standing volume, increment, harvest, and carbon sequestration on the stand, regional, or country levels. The forest subcompartment is the modelling unit of the DAS model, which uses National Forestry Database (NFD) data, including geospatial data. The model is suitable for further processing spatially explicit input parameters such as climate change forecasts. The model output is also georeferenced and can be further processed using GIS software. The model handles the data of approximately 600,000 forest subcompartments. Data on tree species, origin, age, growing stock, increment etc. of each subcompartment are stored in “tree-species rows”, which are the sub-units of the model. The DAS model simultaneously processes the data of 1.2 million tree species rows and describes their development in time. It uses parameters based on the actual processes of the reference period. It also uses empiric cutting age distributions and a regeneration matrix derived from historic NFD data. The ForestLab project (TKP2021-NKTA-43) is currently engaged in the re-parametrization of the model based on 2016–2021 data. This study discusses the functions of the harvesting ratio distribution in the modelling process and in determining the subcompartments selected for harvest. The paper presents the latest results regarding the 2016–2021 cutting age distributions and the preparation of the new set of species-specific and yield class-specific average harvesting ratio distributions.

Priority effects, environmental filtering and neutral coexistence explain large- to small-scale distribution of invasive sun corals in the SW Atlantic

Two sun coral species, Tubastraea tagusensis and T. coccinea, have successfully colonized reef habitats along the Southwest Atlantic. However, their invasive biology has been largely addressed without considering species-specific distribution patterns. Here, we assessed the distribution and abundance of Tubastraea spp. at vertical rocky reef sites within a number of islands along 120 km of coastline off the northern coast of São Paulo State, Brazil, to (1) investigate possible mechanisms underlying the invasion dynamics in the region, (2) test species-specific distributions according to a key environmental filter (depth), and (3) examine within-patch patterns to assess whether competition, niche-based or neutral processes are best candidates to modulate local species coexistence. Sun corals were found in the great majority of the studied locations, and the probability of finding them at any given reef site was estimated to be 0.54. There was substantial species segregation across locations, consistent with primary priority effects. Within locations, results suggest environmental filtering, with T. coccinea apparently advantaged in more hydrodynamic environments just below the surf zone. At sun coral patches with extensive co-occurrence of T. tagusensis and T. coccinea, the presence of each species can be, remarkably, modeled as an independent event, suggesting neutral coexistence. The spread of sun corals is an ongoing and increasingly invasive process that may be explained by the enemy-release hypothesis and the lack of negative interactions between Tubastraea species. The stochastic nature of small-scale distributions sets an additional challenge to predict (and thus control) sun coral invasion.

Combining Weibull distribution and k-nearest neighbor imputation method to predict wall-to-wall tree lists for the entire forest region of Northeast China

Key messageWe propose a coupled framework to combine the strengths of the Weibull function in modeling diameter distributions and the ability of the k-nearest neighbor (kNN) method to impute spatially continuous forest stand attributes for the prediction of wall-to-wall tree lists (lists of stems per hectare by species and diameter at breast height (DBH)) at regional scales. The tree lists of entire Northeast China’s forests predicted by the above framework reasonably reflect the species-specific tree density and diameter distributions.ContextDetailed tree lists provide information about forest stocks disaggregated by species and size classes, which are crucial for forest managers to accurately characterize the current forest stand state to formulate targeted forest management strategies. However, regional tree list information is still lacking due to limited forest inventory.AimsWe aimed to develop a coupled framework to enable the prediction of wall-to-wall tree lists for the entire forest region of Northeast China, then analyze the species-specific diameter distributions and reveal the spatial patterns of tree density by species.MethodsA two-parameter Weibull function was used to model the species-specific diameter distributions in the sample plots, and a maximum likelihood estimation (MLE) was used to predict the parameters of the Weibull distributions. The goodness-of-fit of the predicted species-specific Weibull diameter distributions in each plot was evaluated by Kolmogorov-Smirnov (KS) test and an error index. The kNN model was used to impute the pixel-level stand mean DBH.ResultsWeibull distribution accurately described the species-specific diameter distributions. The imputed stand mean DBH from the kNN model showed comparable accuracy with earlier studies. No difference was detected between predicted and observed tree lists, with a small error index (0.24–0.58) of diameter distributions by species. The fitted species-specific diameter distributions generally showed a right-skewed unimodal or reverse J-shaped pattern.ConclusionOverall, the coupled framework developed in this study was well-suited for predicting the tree lists of large forested areas. Our results evidenced the spatial patterns and abundance of tree species in Northeast China and captured the forest regions affected by disturbances such as fire.

Spatiotemporal patterns of riparian bat assemblages in a novel riparian ecosystem

AbstractDespite increasing awareness of the ecological roles and ecosystem services that bats provide, spatiotemporal patterns in bat abundance and community assembly remain poorly understood outside of select sites in the tropics. We conducted systematic full-spectrum acoustic surveys of bats over the course of a year at eight permanent sites spanning nearly 50 km along Putah Creek, a stream in California’s Central Valley that has been subject to restoration efforts and changes to its in-stream flow regime over the past two decades. We surveyed all sites for 1 week each month. In 158 sampling nights over 11 months, we recorded 157,762 identifiable calls, thereby documenting a rich bat assemblage comprising 15 species from eight genera and two families. Seven species appeared to occur here year-round, whereas six others evidently migrated seasonally, and two were incidental visitors. Species richness and activity diversity were effectively invariant across this 50-km gradient, but assemblage composition varied both spatially and temporally. Spatial patterns suggest species-specific distributions that presumably reflect individualistic habitat preferences and responses to extrinsic factors. Species also varied temporally, with bat activity generally declining in winter, with an unexpected dip in richness and activity in late spring. For the three most commonly detected species, generalized linear models further highlighted the species-specific and individualistic nature of spatiotemporal activity patterns. When integrated with available data from other temperate sites, our results suggest that local species richness is high in temperate riparian systems. Additionally, our observations suggest that species responses to environmental variation are individualistic (e.g., “Gleasonian”) in nature and that local composition varies greatly over spatiotemporal gradients, but that emergent assemblage characteristics do not. The generality of these observations, and the underlying mechanism(s) leading to invariance in emergent characters, warrant further investigation. Similarly, the extent to which greater bat species richness provides complementary ecosystem services (hence, ecological insurance) is of both ecological and economic interest.

Estimating Species-Specific Stem Size Distributions of Uneven-Aged Mixed Deciduous Forests Using ALS Data and Neural Networks

Sustainable forest management requires accurate fine-scale description of wood resources. Stem size distribution (SSD) by species is used by foresters worldwide as a representative overview of forest structure and species composition suitable for informing management decisions at shorter and longer terms. In mixed uneven-aged deciduous forests, tree data required for SSD estimation are most often collected in the field through traditional forest management inventories (FMIs), but these are time-consuming and costly with respect to the sampled area. Combining FMIs with remote sensing methods such as airborne laser scanning (ALS), which has high potential for predicting forest structure and composition, and is becoming increasingly accessible and affordable, could provide cheaper and faster SSD data across large areas. In this study, we developed a method for estimating species-specific SSDs by combining FMIs and dual-wavelength ALS data using neural networks (NNs). The proposed method was tested and validated using 178 FMI plots within 22,000 ha of a mixed uneven-aged deciduous forest in Belgium. The forest canopy was segmented, and metrics were derived from the ALS point cloud. A NN with a custom architecture was set up to simultaneously predict the three components required to compute species-specific SSDs (species, circumference, and number of stems) at segment level. Species-specific SSDs were thereafter estimated at stand level by aggregating the estimates for the segments. A robustness test was set up using fully independent plots to thoroughly assess the method precision at stand-level on a larger area. The global Reynolds index for the species-specific SSDs was 21.2 for the training dataset and 54.0 for the independent dataset. The proposed method does not require allometric models, prior knowledge of the structure, or the predefinition of variables; it is versatile and thus potentially adaptable to other forest types having different structures and compositions.

Net design for selective control of the "plague minnow" Gambusia holbrooki that minimises impact on native Australian fishes.

Gambusia holbrooki is one of the world's most environmentally damaging introduced species, being notoriously difficult to control once established. A composite double-winged fyke net comprising four vertically stacked compartments was developed to determine the potential to control G. holbrooki, while reducing negative interactions of this aggressive species with small threatened fishes. The stacked fyke net captured three times as many G. holbrooki as a conventional fyke net while maintaining consistent catches of native fishes relative to that from a conventional fyke net, and detected species-specific vertical distributions. This stratified net design represents a valuable management option for controlling this agonistic species or for limiting antagonistic interactions between G. holbrooki and native species during typical fyke sampling of native ecosystems.

Spatial distribution of parrotfishes and groupers in an Okinawan coral reef: size-related associations in relation to habitat characteristics.

Parrotfishes (Labridae: Scarini) and groupers (Epinephelidae) are important fish groups that are regarded as the fisheries targets of primary importance in coral reefs. In order to establish ecosystem-based management of these two fish groups, clarifying the spatial distribution relative to habitat characteristics is of central importance. The present study investigated the spatial distributions of 12 parrotfishes species and seven groupers species in relation to environmental characteristics in an Okinawan coral reef. Ten out of the 12 parrotfish species and all seven grouper species showed species-specific spatial distributions. Four substrate types in the inner reefs (branching Acropora, bottlebrush Acropora, dead branching Acropora, and dead bottlebrush Acropora), three substrate types in the exposed reefs (massive coral, other coral, and calcium carbonate substratum), and water depth showed significant associations with the spatial distribution of fishes. Among the 12 parrotfish species, two species (Scarus spinus and S. forsteni) and four species (S. psittacus, S. hypselopterus, S. dimidiatus and S. ghobban) were primarily found in exposed reefs and inner reefs, respectively. Among the seven grouper species, two species (Cephalopholis argus and C. urodeta) and two other species (C. miniata and Epinephelus ongus) were primarily found in exposed reefs and inner reefs, respectively. Size-related spatial distribution was also found for three parrotfish species (Chlorurus microrhinos, Scarus rivulatus and S. hypselopterus), indicating that smaller-sized and larger-sized individuals were respectively found at sites with greater coverage of substrates with fine structure (live bottlebrush Acropora and dead bottlebrush Acropora) and coarse structure (live branching Acropora, dead branching Acropora and calcium carbonate substratum). The present study suggested that the spatial distribution of parrotfishes and groupers is not necessarily associated with the higher coverage of living corals, but positively associated with high substrate complexity. Thus, actual spatial distributional patterns of species should be considered to select candidate sites for protection and conservation for the two fish groups.

Trace element concentrations in seaweeds of the Arabian Gulf identified by morphology and DNA barcodes

Abstract Even though seaweeds have been considered a nutrient-rich dietary source of minerals in other parts of the world, there is little knowledge about trace element accumulation in seaweeds of the Arabian Gulf. The Arabian Gulf is of particular interest due to being an extreme environment, as it features some of the highest temperatures and salinities observed in any marine waters in the world. This study determined the minerals contents using inductively-coupled plasma-mass spectrometry (ICP-MS) in 10 of the most common seaweeds of this region (Iyengaria stellata, Padina boergesenii, Chondria sp., Feldmannia indica, Codium papillatum, Sargassum aquifolium, Ulva chaugulii, Ulva tepida and Ulva sp.) supported by morphological and molecular (DNA barcode)-based identification. The finding of U. chaugulii reported here is a new record for Kuwait. Most of the seaweeds were rich in essential minerals including Ca, Mg, Na, K, Fe and Zn and their contents were higher than those of other mineral-rich foods. Principal component analysis revealed species-specific distributions of minerals in seaweeds. U. tepida and I. stellata were found to be exceptionally rich in most of the macro- and trace elements along with low As and Se, and thus can be utilized for food and feed applications.

Habitat Use of Constant Frequency Echolocating Bats in North-West Madagascar with Acoustic Evidence for a Possible New Species

Bioacoustics can be a non-invasive, cost-effective way of studying echolocating bats, and is especially useful for detecting and identifying rare or cryptic species. The insectivorous bats of Madagascar are understudied in comparison to the rest of the island's fauna, and very little is known about their habitat use. Here, we used a remote bioacoustic surveying technique in a bat survey of the Sahamalaza-Îles Radama National Park, northwest Madagascar, to study constant frequency echolocating bats (Hipposideridae and Rhinonycteridae). We used two passive acoustic monitoring units to automatically record bat activity from dusk until dawn in a range of habitat types that are characteristic of the region. Analysis of call acoustic parameters revealed three distinct constant-frequency phonic types within the national park, which we identified as Commerson's leaf-nosed bat (Macronycteris commersoni), the red trident bat (Triaenops menamena) and an unknown phonic type of ca. 78 kHz. We found significant differences in the habitat usage of these three species, suggesting species-specific habitat preferences among Madagascar's bats. Our statistical analyses revealed significant differences between the acoustic echolocation calls of these three phonic types. The 78 kHz calls do not match any of the other constant frequency-calling bat species currently described for Madagascar, indicating either acoustic divergence among bat sub-populations or the possible existence of a new undescribed species. These results highlight the need for increased survey efforts to gain an understanding of species-specific geographic distributions and habitat usage among Malagasy bats and to disentangle their cryptic species complexes.

Water column structure defines vertical habitat of twelve pelagic predators in the South Atlantic

Abstract Quantifying vertical distributions of pelagic predators elucidates pelagic ecosystem structure and informs fisheries management. In the tropical South Atlantic Ocean, the recently designated large-scale marine protected area around Ascension Island hosts diverse pelagic predators for which basin-specific vertical habitat information is minimal or absent. We used pop-up satellite archival tags to analyse vertical habitat use in 12 species (bigeye tuna Thunnus obesus, blue marlin Makaira nigricans, blue shark Prionace glauca, dolphinfish Coryphaena hippurus, Galapagos shark Carcharhinus galapagensis, oceanic whitetip Carcharhinus longimanus, sailfish Istiophorus albicans, silky shark Carcharhinus falciformis, swordfish Xiphias gladius, tiger shark Galeocerdo cuvier, wahoo Acanthocybium solandri, and yellowfin tuna Thunnus albacares) and quantify parameters (temperature, dissolved oxygen, diel cycles, lunar phase) known to constrain vertical movements. Predator depth distributions varied widely, and classification trees grouped predators into four clades: (i) primarily epipelagic; (ii) partial thermocline use; (iii) oscillatory diving with thermocline/sub-thermocline use; and (iv) extensive use of sub-thermocline waters. Vertical habitat differences were linked to thermal physiology and foraging ecology, and species-specific physical constraints from other ocean basins were largely conserved in the South Atlantic. Water column features defined species-specific depth distributions, which can inform fisheries practices and bycatch risk assessments and population estimates.

A demographic equilibrium approach to stocking control in mixed, multiaged stands in Bialowieża Forest, northeast Poland

Manifold benefits and advantages of mixed tree stands have been known for many decades. However, while developing and maintaining multiaged and mixed-species forests with complex stand structures has often been advocated and has recently become a worldwide priority, it is not a simple task. One important reason for this is a lack of appropriate methods for controlling long-term development of such stands. Here, we present a possible solution for this problem by applying the demographic equilibrium approach to guide stocking and structure regulation in mixed stands. We tested the practical usefulness of this approach using permanent-plot inventories from 2002, 2011 and 2018, in mixed tree stands in the Experimental Sustainability Unit (ESU) Browsk 28C, in the managed part of Białowieża Forest (NE Poland). For our analysis, ESU Browsk 28C (about 30 ha) was treated as a silvicultural planning unit. First, on the basis of target stand types defined in Polish Silvicultural Guidelines (2012) and forest sites occurring at the study site, desirable tree species composition was determined. Eleven tree species of varying life histories and ecological attributes were included: aspen, birch, alder, pine, oak, maple, ash, elm, spruce, lime, and hornbeam. In the second step equilibrium diameter distributions were constructed for each species, taking into account species-specific growth and mortality rates, as well as targeted proportional representation. Next, theoretical species-specific equilibrium diameter distributions were visually and quantitatively compared with empirical distributions from permanent sample plots. Finally, departures of empirical from theoretical distributions served as a basis for silvicultural recommendations and prescriptions. We prioritized silvicultural measures (such as patch cuts opening larger gaps in forest canopy, proper site treatment, planting, protection against browsing by large herbivores), promoting compositionally diverse forest reproduction and recruitment as essential to long-term maintenance of demographic sustainability in mixed forest stands. We conclude that the demographic equilibrium approach is particularly valuable for creating and maintaining complex forest structures in multi-species stands.

Spatial distribution and feeding substrate of butterflyfishes (family Chaetodontidae) on an Okinawan coral reef.

Coral reefs support diverse communities, and relationships among organisms within these communities are quite complex. Among the relationships, clarifying the habitat association and foraging substrate selection relative to habitat characteristics is of central importance to ecology since these two aspects are the fundamentals for survival and growth of organisms. The aims of the present study were to investigate the spatial distribution and feeding substrate selection of 14 species of butterflyfishes on an Okinawan coral reef in Japan. Species-specific spatial distributions varied with habitat characteristics (e.g., encrusting corals, massive corals, branching Acropora and rock). For feeding substrates, seven species of obligate coral polyp feeders exhibited significant positive selectivity for tabular Acropora, corymbose Acropora, encrusting corals and massive corals but significant negative selectivity for dead corals, coral rubble and rock. Among six species of facultative coral polyp feeders, two species exhibited significant positive selectivity for encrusting corals and massive corals, and one species showed significant positive selectivity for dead corals as feeding substrates. In contrast, three species exhibited no significant positive selectivity for any feeding substrates. A similar result was observed for one non-coralline invertebrate feeder. Among the 14 species, 12 species showed a relatively close relationship between spatial distribution and feeding substrates but the remaining two species did not. The present study is the first study to elucidate species-specific spatial distributions and feeding substrate selection of butterflyfishes on an Okinawan coral reef. The results of the present study suggest that diverse substrates, including various types of living corals (especially encrusting corals, massive corals, tabular Acropora, corymbose Acropora and branching Acropora) and non-coralline substrates (rock) are the primary determinants of spatial distributions and feeding sites. Thus, diverse substrates are important for maintaining high species diversity of butterflyfishes and changes of the substrates would likely change the spatial patterns and foraging behavior, although species-specific responses may be found, depending on their species-specific dependence on vulnerable substrates.