Human-induced Disturbances Research Articles

Evaluating the Effectiveness of a Conservation Project on Two Threatened Birds: Applying Expert-Based Threat Analysis and Threat Reduction Assessment in a Mediterranean Wetland

We applied two recent approaches largely used in biological conservation: Threat Analysis (TAN) and Threat Reduction Assessments (TRAs), assessing the effectiveness of a project focused on two water-related bird species (common tern, Sterna hirundo and little tern, Sternula albifrons), commonly breeding in some wetlands of Italy. We used the IUCN standardized lexicon for the classification of threats, utilizing a panel of experts to assess a set of regime attributes (extent, severity and magnitude) of each human-induced disturbance. Our aims were: (i) through the TAN approach, to carry out an arrangement and quantification of the main threats acting on our focal species and select the priority ones; (ii) through the TRA approach, to test the effectiveness of an operational project focused on mitigating the threats and improving the breeding success of species (i.e., building rafts and floating islands to encourage their nesting). Using the TAN approach, experts identified the following human-induced threats (IUCN code): 6.1—Generic disturbance; 7.2—Water stress; 7.3—Salinization; 8.8—Vagrant dogs; 8.8—Mediterranean gulls; 8.8—Wild boars, all significantly different in their magnitude. Among them, wild boars and Mediterranean gulls appeared the priority threats with the greatest extent, intensity and magnitude. Using the TRA approach, after the project, we assessed an overall decrease in the threat magnitude of 23.08% (21.42% when considering only the threats directly affected by our project). These data suggest that further efforts should be devoted to achieving greater effectiveness of conservation actions focused on our target species. With limited time and resources to quantify threats, expert-based approaches could be useful for rapidly assessing the effectiveness of small conservation projects by providing a range of scores obtained following an analytical procedure. In this regard, Threat Analysis and Threat Reduction Assessment could be considered useful tools to support adaptive management in project management cycles.

Biodiversity and vector-borne diseases: Host dilution and vector amplification occur simultaneously for Amazonian leishmaniases.

Changes in biodiversity may impact infectious disease transmission through multiple mechanisms. We explored the impact of biodiversity changes on the transmission of Amazonian leishmaniases, a group of wild zoonoses transmitted by phlebotomine sand flies (Psychodidae), which represent an important health burden in a region where biodiversity is both rich and threatened. Using molecular analyses of sand fly pools and blood-fed dipterans, we characterized the disease system in forest sites in French Guiana undergoing different levels of human-induced disturbance. We show that the prevalence of Leishmania parasites in sand flies correlates positively with the relative abundance of mammal species known as Leishmania reservoirs. In addition, Leishmania reservoirs tend to dominate in less diverse mammal communities, in accordance with the dilution effect hypothesis. This results in a negative relationship between Leishmania prevalence and mammal diversity. On the other hand, higher mammal diversity is associated with higher sand fly density, possibly because more diverse mammal communities harbor higher biomass and more abundant feeding resources for sand flies, although more research is needed to identify the factors that shape sand fly communities. As a consequence of these antagonistic effects, decreased mammal diversity comes with an increase of parasite prevalence in sand flies, but has no detectable impact on the density of infected sand flies. These results represent additional evidence that biodiversity changes may simultaneously dilute and amplify vector-borne disease transmission through different mechanisms that need to be better understood before drawing generalities on the biodiversity-disease relationship.

Abiotic factors are more important than land management and biotic interactions in shaping vascular plant and soil fungal communities

Human-induced disturbances to ecosystems cause a direct loss of biodiversity, and also alter the inherent processes that shape ecosystems even after the main disturbance has ceased. Therefore, is it important to understand the ongoing consequences of past and present land use practices on both above- and belowground components of agroecosystems. Our study takes a detailed investigation of what shapes communities in semi-natural grasslands under long-term management as either pastures or meadows. We investigated the relative importance of land use (land management (LM) and land use intensity (LUI)) and abiotic conditions (soil, topographic, climatic) across five grassland sites in central Germany in explaining species occurrence patterns of vascular plants and soil fungi. Analyses included a hierarchical joint-species distribution modeling approach to uncover the role of possible drivers shaping the local communities. Our results show that abiotic factors are of particularly high importance compared to LM and LUI for both vascular plant and soil fungal communities. In general, the relative importance of explanatory variables was similar across both taxon groups, however, for plant communities, local climate conditions were more important, while for fungal communities the soil variables (e.g., soil acidity and fertility including soil carbon and potassium concentrations) played a more prominent role. Species-specific responses to the respective variables showed some similarity across the taxon groups, however less so than expected given the long legacy of past LM. Here we found that approximately 50% of the plant and fungi species had clear LM preferences and responses to LUI. More plant species were positively related to pasture than meadow management, while the opposite was found for fungal species. Our findings advance the understanding of how abiotic conditions and human land use impact local species communities in managed semi-natural grasslands, aiding further research and policy development for conserving multitrophic diversity within these biodiversity rich habitats. Our results highlight the importance of controlling for soil and climate in studying the impact of land use, and of considering the environmental context at both small and larger spatial grains when making land management and biodiversity conservation decisions. In so doing, the complexity of ecological processes within managed systems are accounted for and prioritized, promoting both conservation and ecological functioning of the agroecosystem. Plant data is archived on PANGAEA (Kautzner, Auge, Roscher, Baessler & Slabbert, 2020; https://doi.org10.1594/PANGA EA.919343) and the soil microbial data on the National Center for Biotechnology Information (NCBI) Sequence Read Archive (SRA) under the accession PRJNA563995 (Kautzner, Baessler, Auge, Roscher & Wubet, 2020)

Fungal root colonization and arbuscular mycorrhizal fungi diversity in soils of grasslands with different mowing intensities

Grasslands are among the most dynamic and threatened plant communities, largely due to their dependence on management that has changed in recent decades. The intensity of human-induced disturbances (primarily removal of plant biomass by various methods) has decreased, leading to changes in plant species composition and declines in plant diversity in these communities. So far, no studies have shown how mowing affects fungal communities in both roots and soils and their relation with plant community parameters and soil chemical properties in different grassland types. We thus compared the impact of mowing intensity (low, moderate, high) on root colonization by common root-inhabiting fungi, namely arbuscular mycorrhizal fungi (AMF), dark septate endophytes (DSE), and Olpidium spp., as well as on AMF spore number, species richness and composition in soils for three seasons (spring, summer, autumn), in grasslands differing in soil moisture (wet, moderately wet, and dry). Mowing intensity had no effect on the fungal root colonization. The number of AMF spores and species, and AMF species composition did not differ between types of management as well. However, most of the fungal parameters in roots and soils varied across the types of grassland and/or seasons. Our results suggest that AMF, DSE, and Olpidium spp. colonization of plants as well as AMF diversity in soils in the studied grasslands are resilient to the mowing disturbance. This may be due to the low impact of the management on plant species richness and soil chemical properties, as well as the adaptation of these fungal communities to recurrent human-induced disturbances in semi-natural habitats.

Effects of recreational use on restored urban floodplain vegetation in urban areas

Urban river restorations focus on restoring aquatic and riparian habitats, increasing flood protection, and enhancing recreational potential. The increased recreational value such newly created urban green spaces is a key benefit of these measures as urban riparian areas are highly valued for recreation. However, high recreational pressure may contribute to the loss of natural vegetation and of biodiversity in restored riparian sites. This study investigates the impact of different recreational intensities and use types on the vegetation structure and vegetation quality by documenting direct (foot-traffic, breaking of branches, stems and roots) and indirect damages (litter and excrements). The major results are fourfold. First, while the proportion of some vegetation types can be correlated to the recreational intensity, neither recreation intensity nor recreation types enhanced the colonization success of invasive species. However, monitoring data showed that human-induced disturbances such as hydro-morphological changes favor alien plant establishment. Second, the study suggests a tipping point for pioneer vegetation at around a density of one user per 10 m river stretch. Already at lower user densities, pressure from trampling can slow down vegetation development. Third, the results indicate that users prefer urban greening and gravel bar elements rather than natural vegetation. Finally, while intensity of direct damages on the vegetation are weakly correlated with the user density, indirect damages increase with the user density. This study concluded that the identification of user hotspots would be helpful in developing a resilient restoration design, which in addition to information about the sensitive vegetation types in relation to recreational users and nature friendly recreational behavior could decrease vegetation damages. In particular, younger recreational users should be targeted by environmental protection campaigns.

Effects of Soil Properties, Temperature and Disturbance on Diversity and Functional Composition of Plant Communities Along a Steep Elevational Gradient on Tenerife

Elevational variation of vegetation has been of interest for centuries, and a prominent example for such pronounced vegetation changes can be found along the steep elevational gradient on Tenerife, Canary Islands, 200 km off the West-African cost. The 3,718-m ascent to the peak of the island volcano, Teide, offers a unique opportunity to investigate associated changes in vegetation. However, elevation is not a directly acting factor, but represents several natural environmental gradients. While the elevational variation of temperature is globally rather uniform and temperature effects on plant communities are well understood, much less is known about the region-specific elevational change of chemical soil properties and their impact on plant communities along elevational gradients. Because human interference takes place even at high-elevation areas, we considered human-induced disturbance as important third factor acting upon plant community assemblages. In our study, we compared the effects of soil properties, temperature and disturbance on species richness, functional identity and functional diversity of plant communities along the elevational gradient on Tenerife. We used pairs of study plots: directly adjacent to a road and in natural vegetation close by. In each plot, we did vegetation relevées, took soil samples, and installed temperature loggers. Additionally, we collected leaf samples to measure leaf functional traits of 80% of the recorded species. With increasing elevation, soil cation concentrations, cation exchange capacity (CEC) and pH decreased significantly, while the soil carbon to phosphorus ratio slightly peaked at mid-elevations. Temperature had the strongest effects, increasing species richness and favoring communities with fast resource acquisition. Species richness was higher at road verges, indicating the positive effect of reduced competition and artificially generated heterogeneity. However, we did not detect road effects on plant functional characteristics. Vice versa, we did not find soil effects on species richness, but increased concentrations of soil cations favored acquisitive communities. Surprisingly, we could not reveal any influence on community functional diversity. The importance of temperature aligns with findings from large-scale biogeographic studies. However, our results also emphasize that it is necessary to consider the effects of local abiotic drivers, like soil properties and disturbance, to understand variation in plant communities.

Responses of Functional Traits of Macrobenthic Communities to Human Activities in Daya Bay (A Subtropical Semi-Enclosed Bay), China

The biological trait analysis (BTA) is regarded as a promising approach to unravel how ecosystem functions respond to human-induced disturbances. This study considered the four sampling locations associated with different human activities in Daya Bay, that is, the domestic and industrial sewage discharge area (SED), mariculture area (MRC), nuclear power plants thermal discharge area (NTD), and an area with relatively low human disturbance as a reference (REF). Thirty modalities of nine traits were selected in BTA. Our results showed a clear shift in the functional structure of macrobenthic communities between the sampling locations, except for the case between NTD and REF. The trait composition in the communities did not highlight any seasonal patterns. Bioturbation, longevity, tolerance, body size, feeding habit, and environmental position were the key traits to characterize the functional structure of macrobenthic communities and demonstrated predictable responses along the environmental gradients. Water depth, DO, Chl-a, NH4+, and petroleum contaminants in sediments were the main variables influencing the trait composition. In addition, the taxonomic index (H′) and functional diversity index (Rao’s Q) showed clear differences among the sampling locations. Although there were no significant differences between NTD and REF in terms of the trait composition and functional diversity, a potential function loss in NTD still can be detected through the integrated analysis with taxonomic diversity. We suggest that the traits (except for fragility, larval development, and living habits) selected and the diversity indices (H′ and Rao’s Q) could serve as promising indicators of ecological conditions in Daya Bay.

Local variations in the response of birds to human presence in urban areas

Studies that seek to understand the local variations in the response of birds to human disturbance in urban areas are important for conservation. This article investigated the contribution of human population density in the different urban land use zones of Harare (high, medium and low-density residential areas, as well as industrial areas), among other variables, to the models explaining the flight initiation distance (FID) of twenty-five urban bird species. The specific objectives of the study were: to test whether the variables significantly predict FID; to investigate their relative contribution to the ‘best-performing’ models; and to determine the relationship between FID and the individual predictor variables. Generalised linear models were used to predict FID as a function of: flock size, intruder starting distance, urban land use zone, perch height, average bird mass and species. We predicted that FID would increase in tandem with flock size and average bird mass, and decrease inversely proportional to population density, intruder starting distance and perch height. We also expected FID to differ by species. Results illustrated that twelve models best explained the FID of birds in the study area. Urban land use zone, intruder starting distance and species were the only predictors that appeared in all the twelve models. However, flock size and average bird mass appeared in only six of the twelve models making them the least important predictor variables. These findings add to current knowledge on local variation in the FID of certain bird species within the different land use zones. The results could be used to create buffers aimed to minimise human-induced disturbance on bird species.

Patterns of Structural and Functional Bacterioplankton Metacommunity along a River under Anthropogenic Pressure

Bacteria, an integral part of aquatic ecosystems, are responsible for the circulation of matter and flow of energy. Since bacterioplankton rapidly responds to any natural and human-induced disturbances in the environment, it can serve as a bioindicator of these changes. Knowing factors that shape the microbial community structure may help the sustainable management of the water environment. However, the identification of environmental signals affecting the structure and function of bacterioplankton is still a challenge. The study analyses the impact of environmental variables on basic microbial parameters, which determines the effectiveness of ecological processes in rivers. Measurements of bacterioplankton abundance (BA) and extracellular enzyme activity (EEA) were based on fluorescent markers. The bacterial community structure was determined by 16S rRNA gene amplicon sequencing (Illumina). The results indicate spatial variation in bacterioplankton abundance. Temporal variation was not significant. Lipase and aminopeptidase had the highest level of activity. EEA was not correlated with bacterial abundance but was significantly correlated with temperature. Moreover, differences in lipase, α-glucosidase and β-glucosidase activity levels between spring and summer were noted. At the same time, the location of sampling site had a significant influence on aminopeptidase activity. The taxonomic analysis of bacterioplankton communities in the Brda River indicated that, although different numbers of OTUs were recorded in the studied river sections, bacterioplankton biodiversity did not change significantly along the river with distance downstream. Anthropogenically modified river sections were characterized by the dominance of Flavobacterium (Bacterioidetes) and hgcl clade (Actinobacteria) taxa, known for their ability to produce extracellular enzymes. PCoA analysis revealed that the sites located in the lower river course (urban area) had the most similar bacterial community structure (β-diversity). The study provides new insight into the changes in microbial communities along the river and emphasizes the potential impact of anthropogenization on these processes.

Autonomous Runtime Composition of Sensor-Based Skills Using Concurrent Task Planning

Constraint-based robot programming allows for implementing sensor-based skills that react to disturbances on the one hand, and composable skills that dynamically create and reconfigure complex robot behaviors on the other hand. In this letter, we address a class of problems where composing appropriate skills prior to execution is inconvenient due to unpredictable events of disturbances. To this end, we propose an autonomous replanning and acting framework that computes and executes reactive composed skills at runtime. We formulate a model of constraint-based skills and present methods for executing concurrent skill compositions at runtime without interrupting the ongoing task execution. In order to autonomously compute reactive composed skills at runtime, we propose a temporal description of planning actions, corresponding to robot skills, that ensures concurrency at the task planning level. We validate our work on a dual-arm robot system that performs an industrial assembly task while reacting to obstacle and human-induced disturbances at runtime.

Current and potential carbon stock in the forest communities of the Białowieża Biosphere Reserve

Specifying the upper bound of C storage in forest ecosystems allows an estimate of the amount of C that can be stored in the future. The Białowieża Forest in NE Poland is the last relic forest in the European lowlands. Still, it has been subject to various natural and human-induced disturbances and its C stock has been reduced. The main goal of our study was therefore to assess the current and potential C stock in the forest communities of the Białowieża Biosphere Reserve (597 km2), taking into account the diversity of habitats as well as different protection and management practices. For this we identified 13 forest communities and quantified their current C stock stored in all major pools (living trees, deadwood and soil). We used vegetation and soil data collected in 2018 at 1391 systematically distributed 0.04 ha forest plots (sampling grid 650 × 650 m). We used the concept of potential natural vegetation (PNV) and randomized upscaling of plot level current biomass C stock values to estimate the upper bounds of biomass C stocks possible to obtain at the stand level. We showed that the Białowieża Forest stores currently 300 Mg C ha−1 (17.2 Tg C), of which 41% is accumulated in biomass, with significant variation among different forest communities and management regimes. We obtained the upper bounds of biomass C stocks ranging from 94 Mg ha−1 for swamp pine forest to 223 Mg ha−1 for lime-oak-hornbeam forest. We estimated the gap between the current and potential C stock in biomass at 66 Mg ha−1 (3.8 Tg); 62% of the potential level is achieved in managed forests, and 76% in the National Park. Our findings may be used in planning forest management aimed toward long-term C storage, and the obtained upper bounds can serve as benchmarks in assessing C storage potential of similar forest types elsewhere. We also suggest that the potential of ecosystems to store C should be considered in the landscape context, i.e. by taking into account the spatial extent of PNV habitats and their unequal capacity to provide C storage service.

Spontaneous regeneration of Collembola assemblages in a raised bog after human-induced disturbance

Peatlands in anthropogenically transformed landscapes play an important role in biodiversity conservation. Most Baltic raised bogs have been completely destroyed by drainage and peat extraction. Collembolan and plant assemblages from an old peat mine (post-excavation pits and dykes overgrown by pine trees) were compared to those of intact ombrotrophic raised bog habitats (open bog and bog-pine forest) 70 years after excavation cessation. The plant cover and collembolan structure in regenerating pits were similar to those of the assemblages in natural open raised bogs. Rare tyrphobiont and tyrphofilous Collembola species occurred in both habitats. The assemblages in open bog habitats differed significantly from those in natural pine bog forest and dykes overgrown by pine trees. The assemblages of the natural open raised bog and pine bog forest were the most diverse and included numerous highly specialized Collembola species. The assemblages occurring on wooded dykes were significantly different from those at other peatland sites and were more similar to those of upland pine forests. The analysis of environmental factors (determined by moss Ellenberg numbers) showed that moisture was the most important factor affecting Collembola occurrence in natural and disturbed habitats. The occurrence of moss species also had a significant influence on the species composition of the collembolan assemblages. Our study revealed that seventy years of spontaneous ecosystem regeneration after peat excavation have led to habitat restoration for peat bog mesofauna. These results have important implications for conservation and restoration planning in disturbed peatlands.

Woody Plant Dynamics in a Foundation Conifer Woodland of the Appalachian Foothills, Alabama

We documented the structure and composition of a Pinus palustris (Longleaf Pine) woodland community in the Appalachian foothills of Alabama using field measurements and investigated the drivers of forest dynamics using dendroecology paired with historical records of disturbance. Longleaf Pine dominated the canopy, exhibiting a reverse-J–shaped diameter distribution not related with age distribution. Longleaf Pines dated as far back as 1669 to as recently as the early 2000s. In contrast to many other forests, the spatial distribution of Longleaf Pine stems in our site trended toward a random distribution when trees were weighted by DBH or age. Based on ring patterns from 322 Longleaf Pine individuals, growth releases from disturbances occurred continuously from the early 1900s through the 1940s and between 1985 and 1995, with Longleaf Pine establishment peaking 3 times: in the 1880s, 1940s, and 1990s. A superposed epoch analysis revealed that release events were not related with recorded large-scale meteorological (e.g., hurricanes) or local human-induced disturbances, suggesting that other factors have influenced the dynamics of this community. This Longleaf Pine community in the Piedmont shared similarities in composition and structure to other Longleaf Pine communities of the southeastern United States. A combination of fire suppression over the last 80 years and high-intensity arson fires over the last decade has caused an increase in density of both live and dead Longleaf Pine and recruitment of fire-sensitive pines and hardwoods into the seedling/sapling classes and canopy. Restoration of the historical fire regime may be needed for Longleaf Pine to maintain its dominance in this community, as fire may have appeared to exert strong control over the dynamics of this community.

Ephemeroptera (Mayflies) Assemblages and Environmental Variation along Three Streams Located in the Dry-Hot Valleys of Baima Snow Mountain, Yunnan, Southwest China.

Simple SummaryMayflies are among the most susceptible insect groups in mountain freshwater bodies, where they are facing different environmental threats, resulting in loss of species assemblage and diversity. In this study, we described the structure of the community of mayflies in three different streams in the dry-hot valley of Baima Snow Mountain, China, and assessed the potential effect of environmental variation over this specific group of insects. The results showed clear shifts in the community structure of mayflies between the streams. From the study area, 18 taxa were identified, with Baetis sp. and Baetiella marginata being the most prevalent. Overall, the Yeri stream hosted suitable habitats for several taxa of mayflies than the other two streams, as demonstrated by the highest species richness and diversity. Moreover, there was high environmental heterogeneity between the streams, in turn influencing the species of mayflies, particularly in the Sharong stream. As expected, the results also showed that some of the environmental factors such as altitude, conductivity, total dissolved solids, water temperature, dissolved silicon, and pH explained most of the variation in species composition.Mountain freshwater ecosystems are threatened all over the world by a range of human-induced stresses, ensuing in a rapid loss of habitats and species diversity. Many macroinvertebrates are reactive to habitat disturbance, and mayflies (Ephemeroptera) are amongst the most sensitive groups. Despite they are susceptible to environmental deviation, knowledge concerning their species richness and diversity is still unknown in remote areas. The objectives of this study were to (1) investigate the mayfly species assemblage and community composition along different mountain streams and assess potential differences, and (2) identify the environmental variation and its influence on the structure of mayfly communities within such freshwater systems. We collected biological and environmental data from 35 sites situated along elevation gradients in the Baima Snow Mountain, northwest Yunnan, China. Multivariate analyses were performed on the environmental variables and the mayfly species composition, as well as on richness and diversity indices. We found that the community composition of mayflies was different across all three watercourses. Among the 18 Ephemeroptera taxa identified, Baetis sp. and Baetiella marginata were highly dominant, accounting for over 50% of the dissimilarity of each stream. In terms of species assemblages, almost all sites in the Yeri stream hosted good-quality habitats for several mayfly species, as reflected by the highest species richness. The Benzilan stream followed, whereas the Sharong stream showed relatively low mayfly assemblage. This variation was explained by the high environmental heterogeneity between the three watercourses. In particular, the RDA model revealed that among the different environmental factors analyzed, altitude, conductivity, total dissolved solids, water temperature, dissolved silicon, and pH explained most of the variation in species composition. Moreover, the altitude alone explained 17.74% of the variation, and in-depth analysis confirmed its significant effect on diversity indices. Further research should focus on evaluating the scale of threats to this important group of insects in the mountain freshwater ecosystem, particularly the impact of human-induced disturbances such as land use/landcover alterations.

Effect of shrubs on soil saturated hydraulic conductivity depends on the grazing regime in a semi-arid shrub-encroached grassland

Encroachment of woody plants has a positive effect on hydrological functions (e.g., infiltration), but few studies have examined the effects of shrub patches on infiltration under different grazing scenarios. We examined differences in characteristics of plants and soils and saturated hydraulic conductivity between shrubs and their associated interspaces in two grazing regimes at three sites in a semi-arid grassland encroached by Caragana microphylla, a leguminous N-fixing shrub. The results showed that the shrub patches had greater plant height, cover, and biomass compared to interspaces, and the shrubs positively affected the characteristics of soils such as porosity and water holding capacity, whereas grazing had a strong opposite effect. The effect of the relative interaction intensity (RII) of shrubs on the saturated hydraulic conductivity of the soil was greater under grazed (0.60) than ungrazed conditions (-0.01), and the negative effect of grazing was mainly achieved in interspaces. Generally, structural equation modeling revealed positive indirect effects of shrubs on saturated hydraulic conductivity via a greater root mass, with 3.5 times of that in interspaces and a lower bulk density (90% of that in interspaces) under conditions of overgrazing. Our findings highlight the critical role that shrubs play in maintaining infiltration under overgrazing conditions and suggest that they might partially offset the damaging effects of overgrazing on infiltration. Thus, shrub encroachment might be an adaptive mechanism of grassland ecosystems to encounter intensive human induced disturbance such as overgrazing.

Northern Mid-Atlantic Ridge Hydrothermal Habitats: A Systematic Review of Knowledge Status for Environmental Management

Highly specialised biota occurring at hydrothermally active vents on the northern Mid-Atlantic Ridge (nMAR: from south of Iceland to the Equator) have been the subject of numerous research projects over the 36-year period since these habitats were first discovered in the region. When hydrothermal activity ceases, biota endemic to hydrothermally active habitats are lost, and a new biota colonise these sites. Little is known about the biota colonising hydrothermally inactive sulphide habitats on the nMAR, although these sites may be the target of deep-sea mining within the next decade. In this review, we seek to clarify the current knowledge of biological communities colonising hydrothermally active habitats and inactive sulphide habitats on the nMAR. To achieve this, we (1) used a systematic review process to update the species list of benthic invertebrates associated with hydrothermally active habitats, (2) conducted a regional biogeographic analysis of hydrothermally active vent fields on the nMAR, (3) undertook a comprehensive literature review to provide a descriptive account of biological communities, and (4) identified key knowledge gaps in the current understanding of nMAR hydrothermally active and inactive ecosystems. Our updated species list increases the number of benthic invertebrates recorded from hydrothermally active habitats on the nMAR to 158 taxa. Our regional biogeographic analysis separates nMAR hydrothermal vent fields into distinct clusters based on depth/latitude and chimney composition. Vent fields close to the Azores (Menez Gwen, Lucky Strike, Rainbow) formed a separate cluster from those at greater depths south of the Azores (Broken Spur, TAG, Snake Pit, Logatchev, and Ashadze-1). Moytirra, located north of the Azores, clustered separately, as did Lost City with its unique carbonate chimneys. We present detailed information on the biological communities at hydrothermally active and inactive habitats in this region, and discuss the information available on the diversity, ecosystem function, trophic relationships, connectivity, temporal variability, and resilience and recovery of these communities. Many knowledge gaps still exist, with detailed information needed on all aspects of the biological communities at hydrothermally active habitats and inactive sulphide habitats on the nMAR to understand and predict impacts from natural and human-induced disturbances in the region.

Forests Without Frugivores and Frugivores Without Forests – An Investigation Into the Causes of a Paradox in One of the Last Archipelagos Colonized by Humans

The Mascarenes are sadly famous worldwide for the massive extinction of their native vertebrates since recent human colonization. However, extinction patterns show astonishing disparities between the two main islands and between lineages of forest vertebrates. On Réunion (2,512 km2, 3,070 m) where about a third of native habitats remains, most large-bodied vertebrates, especially frugivores, collapsed by the first half of the 18th century, while several have survived longer and some still exist on Mauritius (1,865 km2, 828 m) where more than 95% of native habitats have been transformed. Considering lineages of forest vertebrates shared by both islands (23 genera, 53 species), we test the hypothesis that differing patterns of lowland suitable habitat destruction is the main cause behind this paradox. Before that, we assess the potential impact of other major drivers of extinctions since first contact with humans. Firstly, Mauritius shows earlier and more numerous introductions of mammal predators known for their devastating impact (except northern islets which have thus become important sanctuaries for several squamates). Secondly, settlers were inveterate hunters on both islands, but while Réunion was overhunted before Mauritius, the burst of human population in the latter in late 18th century has not led to the rapid extinction of all large native vertebrates. These two factors alone therefore cannot explain the observed paradox. Rather, the early destruction of lowland habitats (<400 m) on Réunion is concomitant with most extinctions of forest vertebrate, notably frugivores that rapidly lost most lowland habitats dominated by large fleshy-fruited plants. Moreover, landform-induced fragmentation has likely decreased the ability of adjacent habitats to act as effective refuges. Conversely, Mauritius retained suitable low-fragmented habitats until the late 19th which probably allowed, at least for a time, several native vertebrates to escape from multiple human-induced disturbances. Despite the almost total destruction of native habitats since then on Mauritius, conservation actions have saved several threatened vertebrate species that play a fundamental role in the functioning of native ecosystems. The fact that there are now more favorable habitats on Réunion than on Mauritius argues for the rewilding of Réunion with these extant large vertebrates.

Disentangling the relative roles of natural and anthropogenic-induced stressors in shaping benthic ciliate diversity in a heavily disturbed bay

Coastal areas are facing biodiversity loss and degradation of habitats due to intensified human activities. However, our understanding of the relative contribution of natural gradients and human induced disturbance to biodiversity is limited. Here, we investigated the response of three facets of alpha and beta diversity of benthic ciliates to environmental gradients in a highly disturbed estuarine bay in China. We used linear regression and distance-based redundancy analysis to determine the key driving factors for biodiversity. Variation partitioning was further used to examine the relative influence of natural gradients and anthropogenic disturbances on ciliate communities. Our results revealed that ciliate alpha diversity and functional composition remained similar despite notable variation in species composition along salinity gradient. Sediment grain size, together with heavy metals were the strongest determinants in shaping both alpha and beta diversity. After controlling for the effect of natural factors, heavy metals still had significant impacts on beta diversity. Human induced nitrogen enrichment was positively correlated with algivorous functional group with possible impacts on benthic food webs. These results suggest that beta diversity is overall more sensitive to anthropogenic stressors than alpha diversity and give important insights into the role of anthropogenic disturbance on coastal diversity, being also useful for developing ecosystem protection and conservation strategies.

Patch, matrix and disturbance variables negatively influence bird community structure in small-sized managed green spaces located in urban core areas

Patch, matrix and human-induced disturbance variables are important in determining the structure of urban bird communities. Although green spaces in urban core areas are usually small and disturbed, they can be important for local bird diversity. Because such areas are often overlooked, their study is critical for successfully incorporating biodiversity conservation in urban planning. Furthermore, comparing bird communities from different biogeographical areas would help identify generalizable patterns and propose common management actions. We compared the structure of breeding season bird assemblages of managed small public green spaces in the urban core areas of two similar-sized European cities, Kavala (Greece) and Rovaniemi (Finland), and studied the influence of environmental variables on community structure. Species composition differed between the cities. Abundance and evenness were higher in Kavala, while richness and diversity did not differ between the cities. Abundance did not respond in a general way to the same variables in the two cities. It increased with decreasing shrub cover and distance from the city center and with increasing midday noise and ground cover in Kavala, but increased with increasing distance from the city center and decreased with increasing car traffic and midday noise in Rovaniemi. This might be explained by the lower abundance of bird dwellers in Rovaniemi. Primarily gray cover, but also other variables, at both the patch and matrix levels (e.g., noise, car traffic, distance from the city center), negatively affected richness, evenness and diversity in both cities. Green space size was positively correlated with richness and diversity in Kavala, but not in Rovaniemi, possibly due to the smaller size variation in Rovaniemi. Results emphasized that increasing gray cover is harmful for birds in small-sized green spaces in urban core areas. However, urban managers should note that not all bird community metrics responded in similar ways to same environmental variables.

Taxonomic, functional and phylogenetic bat diversity decrease from more to less complex natural habitats in the Amazon.

The high levels of biodiversity in the Amazon are maintained mostly due to its composition as a natural mosaic of different habitats, including both unflooded and flooded forests, campinaranas, and savannahs. Here, we compared multiple dimensions of α- and β- bat biodiversity between four natural Amazonian habitats (savannah, campinarana, forest patches, and continuous forest). In addition, we explored the extent to which bat communities in the different habitats are nested within one another, and compared the community-level functional uniqueness and community-weighted mean traits between habitats. Our results show that taxonomic, functional and phylogenetic α-diversity of bats is higher in continuous forest than in any of the other habitat types. The continuous forest also harbours more unique species, and indeed, the bat community assemblages in the less-complex habitats, including forest patches, campinarana and savannahs, are taxonomic, functional and phylogenetic sub-sets of the assemblage found in the continuous forest. By examining β-diversity partitions and species composition, we are able to shed light on the mechanisms behind the variation in diversity between the four habitat types, which reflect a process of environmental sorting along a habitat gradient going from a more complex to a less complex habitat. We conclude that nesting patterns along the mosaic of habitats are determined by differences in complexity between habitats and that taxonomic and functional uniqueness contribute to overall regional bat diversity and functionality. Ongoing human-induced disturbances of these habitats could provoke an unprecedented loss of bat diversity and functionality with negative consequences for biodiversity and ecosystem services.