Regional-scale disturbances drive long-term decline of inshore coral reef fish assemblages in the Great Barrier Reef Marine Park.

Anthropogenic pressure is increasing the variety and frequency of environmental disturbance events, limiting recovery and leading to long-term declines in wild plant and animal populations. Coral reefs and associated fish assemblages are inherently dynamic due to their susceptibility to a host of disturbances, but regional-scale nuances in the drivers of long-term change frequently remain poorly resolved. Here, we examine the effects of multiple potential drivers of change in coral reef fish assemblages across 4 inshore regions of the Great Barrier Reef Marine Park (GBRMP), Australia, over 12-14 years (2007-2021). Each region had a unique disturbance history, in conjunction with long-term changes in physical and habitat variables. Phases of recovery were apparent in the years between disturbance events at all locations, but these were not long enough to prevent substantial declines in reef fish density (by 33%-72%) and species richness (by 41%-75%) throughout the study period. The main drivers of change in fish assemblages varied among regions; however, the most rapid changes followed cyclone and flood events. Limited recovery periods resulted in temporal shifts in fish species composition from typically coral-associated to algae-associated. Most trophic groups declined in density except farmers, grazers, omnivores and parrotfish. No-take marine reserves (NTMRs) had small and inconsistent effects on total fish assemblages, but delivered benefits for fishery-targeted piscivores. Our findings suggest that coral reef responses to local stressors and cumulative escalating climate change impacts are highly variable at regional scales, and that small NTMRs are unlikely to mitigate the impacts of increasingly frequent climatic disturbances. Nearshore coral reefs worldwide are high-value habitats that are either already degraded or vulnerable to degradation and the loss of important fish groups. Global efforts to reduce greenhouse gas emissions must be coupled with effective local management that can support the functioning and adaptive capacity of coral reefs.

Dead foundation species create coral rubble habitat that benefits a resilient pest species.

Critical loss of habitat is the greatest threat to biodiversity, yet some species are inherently plastic to and may even benefit from changes in ecosystem states. The crown-of-thorns sea star (CoTS; Acanthaster spp.) may be one such organism. CoTS are large corallivores native to the tropical Indo-Pacific and in unexplained high densities, can adversely affect entire coral reefs. Proximal causes of CoTS outbreaks remain elusive, so this phenomenon remains a daunting and costly challenge for reef conservation and management. Amplifying anthropogenic impacts and new empirical data point to the degraded reef hypothesis to explain the episodic nature of CoTS population outbreaks. We posit that loss of live coral paradoxically benefits CoTS juveniles, which accumulate in their rubble nursery habitat before conditions trigger their pulsed emergence as coral-eaters. We review trait plasticity across the CoTS life cycle and present the degraded reef hypothesis in an integrative understanding of their propensity to outbreak.

Lessons learned during a 12-year monitoring project with the endangered Magdalena River turtle (Podocnemis lewyana): hunting pressure, habitat degradation, and methodological considerations.

Turtle species in the Family Podocnemididae, including the Colombian endemic and critically endangered Magdalena River Turtle Podocnemis lewyana, characteristically present low recapture rates that preclude estimation of population parameters using maximum likelihood modeling. In our 12-year monitoring project with this species, we evaluated changes in relative abundances, proportions of sex/size classes, and individual body sizes and body conditions in a population in four channels in the middle Magdalena River drainage. We also inspected for associations between trends in changes in these variables and differences in hunting pressure and habitat degradation. To inspect for temporal and spatial demographic dynamics, we estimated variation in relative abundances using the Catch Per Unit Effort index, the total number of turtles captured over an entire 5-day sampling period using ten baited funnel traps. Relative abundances and the proportions of sex/size classes were different between sites and years. We found a significant decline in the proportion of females and juveniles over time, along with evidence that the females still present were smaller in body size. Our results support the hypothesis that hunting eliminates adult females from these sites, perhaps also translating into a reduction in recruitment. The lack of evidence of generalized declines in body condition of all size classes suggests that habitat degradation might contribute less to the population declines in this region. Our results also illustrate that even when recapture rates are low, monitoring turtles via standardized trapping may yield insights into the population's conservation status that other relative abundance indices cannot.

Trends in habitat quality and habitat degradation in terrestrial protected areas.

Protected areas are typically considered a cornerstone of conservation programs and play a fundamental role in protecting natural areas and biodiversity. Human-driven land-use and land-cover (LULC) changes lead to habitat loss and biodiversity loss inside protected areas, impairing their effectiveness. However, the global dynamics of habitat quality and habitat degradation in protected areas remain unclear. We used the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model based on global annual remotely sensed data to examine the spatial and temporal trends in habitat quality and degradation in global terrestrial protected areas. Habitat quality represented the ability of habitats to provide suitable conditions for the persistence of individuals and populations, and habitat degradation represented the impacts on habitats from human-driven LULC changes in the surrounding landscape. Based on a linear mixed-effects modeling method, we also explored the relationship between habitat degradation trends and protected area characteristics, biophysical factors, and socioeconomic factors. Habitat quality declined by 0.005 (0.6%) and habitat degradation increased by 0.002 (11%) from 1992 to 2020 globally, and similar trends occurred even in remote or restrictively managed protected areas. Habitat degradation was attributed primarily to nonirrigated cropland (62%) and urbanization (27%) in 2020. Increases in elevation, gross domestic production per capita, and human population density and decreases in agricultural suitability were associated with accelerated habitat degradation. Our results suggest that human-induced LULC changes have expanded from already-exploited areas into relatively undisturbed areas, and that in wealthy countries in particular, degradation is related to rapid urbanization and increasing demand for agricultural products.

Tendencias en la calidad y degradación del hábitat en áreas protegidas terrestres Resumen Las áreas protegidas suelen considerarse la piedra angular de los programas de conservación y desempeñan un papel fundamental en la protección de los espacios naturales y la biodiversidad. Los cambios en el uso y la cobertura del suelo (CUCS) provocados por el hombre conducen a la pérdida de hábitats y de biodiversidad dentro de las áreas protegidas, lo que merma su eficacia. Sin embargo, la dinámica global de la calidad y la degradación del hábitat en las áreas protegidas sigue sin estar clara. Utilizamos el modelo de valoración integrada de servicios ambientales y compensaciones (InVEST), basado en datos anuales mundiales obtenidos por teledetección, para examinar las tendencias espaciales y temporales de la calidad y degradación del hábitat en las áreas terrestres protegidas de todo el mundo. La calidad del hábitat representó su capacidad para proporcionar condiciones adecuadas para la persistencia de individuos y poblaciones, y la degradación del hábitat representó los impactos sobre los hábitats de los cambios CUCS provocados por el hombre en el paisaje circundante. Con base en un método de modelo lineal de efectos mixtos, también exploramos la relación entre las tendencias de degradación del hábitat y las características de las áreas protegidas, los factores biofísicos y los factores socioeconómicos. La calidad del hábitat disminuyó en un 0.005 (0,6%) y la degradación del hábitat aumentó en un 0.002 (11%) entre 1992 y 2020 a nivel mundial, y se produjeron tendencias similares incluso en áreas protegidas remotas o gestionadas de forma restrictiva. La degradación del hábitat se atribuyó principalmente a las tierras de cultivo sin irrigación (62%) y a la urbanización (27%) en 2020. El aumento de la altitud, del producto interno bruto per cápita y de la densidad de población humana, así como la disminución de la idoneidad agrícola, se asociaron a una aceleración de la degradación del hábitat. Nuestros resultados sugieren que los cambios en el CUCS inducidos por el hombre se han extendido desde zonas ya explotadas a zonas relativamente inalteradas, y que, en particular en los países ricos, la degradación está relacionada con la rápida urbanización y la creciente demanda de productos agrícolas.

Complex and highly saturated soundscapes in restored oak woodlands reflect avian richness and abundance.

Temperate woodlands are biodiverse natural communities threatened by land use change and fire suppression. Excluding historic disturbance regimes of periodic groundfires from woodlands causes degradation, resulting from changes in the plant community and subsequent biodiversity loss. Restoration, through prescribed fire and tree thinning, can reverse biodiversity losses, however, because the diversity of woodland species spans many taxa, efficiently quantifying biodiversity can be challenging. We assessed whether soundscapes in an eastern North American woodland reflect biodiversity changes during restoration measured in a concurrent multitrophic field study. In five restored and five degraded woodland sites in Wisconsin, USA, we sampled vegetation, measured arthropod biomass, conducted bird surveys, and recorded soundscapes for five days of every 15-day period from May to August 2022. We calculated two complementary acoustic indices: Soundscape Saturation, which focuses on all acoustically active species, and Acoustic Complexity Index (ACI), which was developed to study vocalizing birds. We used generalized additive models to predict both indices based on Julian date, time of day, and level of habitat degradation. We found that restored woodlands had higher arthropod biomass, and higher richness and abundance of breeding birds. Additionally, soundscapes in restored sites had higher mean Soundscape Saturation and higher mean ACI. Restored woodland acoustic indices exhibited greater magnitudes of daily and seasonal peaks. We conclude that woodland restoration results in higher soundscape saturation and complexity, due to greater richness and abundance of vocalizing animals. This bioacoustic signature of restoration offers a promising monitoring tool for efficiently documenting differences in woodland biodiversity.

Forest fragmentation and edge effects impact body condition, fur condition and ectoparasite prevalence in a nocturnal lemur community.

Forest fragmentation and edge effects are two major threats to primate populations. Primates inhabiting fragmented landscapes must survive in a more degraded environment, often with lower food availability compared to continuous forests. Such conditions can have deleterious effects on animal physiological health, yet some primates thrive in these habitats. Here, we assessed how forest fragmentation and associated edge effects impact three different components of physiological health in a nocturnal primate community in the Sahamalaza-Iles Radama National Park, northwest Madagascar. Over two periods, 6 March 2019-30 October 2019 and 10 January 2022-17 May 2022, we collected data on body condition, fur condition scores and ectoparasite prevalence for 125 Mirza zaza, 51 Lepilemur sahamalaza, 27 Cheirogaleus medius and 22 Microcebus sambiranensis individuals, and we compared these metrics between core and edge areas of continuous forest and fragmented forest. Body condition scores for all species varied between areas, with a positive response to fragmentation and edge effects observed for M. zaza and L. sahamalaza and a negative response for C. medius and M. sambiranensis. Fur condition scores and ectoparasite prevalence were less variable, although M. zaza and L. sahamalaza had a significantly negative response to fragmentation and edge effects for these two variables. Interestingly, the impacts of fragmentation and edge effects on physiological health were variable-specific. Our results suggest that lemur physiological responses to fragmentation and edge effects are species-specific, and body condition, fur condition and ectoparasite prevalence are impacted in different ways between species. As other ecological factors, including food availability and inter/intraspecific competition, likely also influence physiological health, additional work is required to determine why certain aspects of lemur physiology are affected by environmental stressors while others remain unaffected. Although many nocturnal lemurs demonstrate resilience to fragmented and degraded habitats, urgent conservation action is needed to safeguard the survival of their forest habitats.

Impacts of estuarine habitat degradation on the modeled life history of marine estuarine-dependent and resident fish species.

Shallow coastal and estuarine habitats play an essential role in the life cycles of many fish species, providing spawning, nursery, feeding, and migration areas. However, these ecologically valuable habitats are increasingly threatened by anthropogenic activities, causing substantial changes in both habitat availability and quality. Fish species use these shallow coastal habitats and estuaries during various life stages, leading to their categorization into guilds based on how and when they rely on these areas. This differential functional use of estuaries means that changes to these habitats may affect each guild differently. To understand the impact of estuarine habitat degradation on fish populations, it is therefore necessary to consider the full life cycle of fish and when they rely on these coastal habitats. Here, we use conceptual size-structured population models to study how estuarine habitat degradation affects two functionally different guilds. We use these models to predict how reduced food productivity in the estuary affects the demographic rates and population dynamics of these groups. Specifically, we model estuarine residents, which complete their entire life cycle in estuaries, and marine estuarine-dependent species, which inhabit estuaries during early life before transitioning offshore. We find that total fish biomass for both guilds decreases with decreasing food productivity. However, the density of juveniles of the marine estuarine-dependent guild can, under certain conditions, increase in the estuary. This occurs due to a shift in the population biomass distribution over different life stages and a simultaneous shift in which life stage is most limited by food. At the individual level, somatic growth of juveniles belonging to the estuarine-dependent guild decreased with lower food supply in the estuary, due to increased competition for food. The somatic growth rates of fish belonging to the resident guild were largely unaffected by low food supply, as the total fish density decreased at the same time and therefore the per-capita food availability was similar. These outcomes challenge the assumption that responses to habitat degradation are similar between fish guilds. Our study highlights the need to assess not only fish biomass but also size distributions, survival, and somatic growth rates for a comprehensive understanding of the effects of habitat degradation on fish populations. This understanding is crucial not only for estuary fish communities but also for successful conservation and management of commercially harvested offshore population components.

Habitat degradation changes and disturbance factors in the Tibetan plateau in the 21st century.

Land use changes driven by human activities significantly impact biodiversity in plateau regions. However, current research is largely confined to identifying correlations between various factors and both habitat quality and degradation, overlooking the nonlinear relationships between them. To address this gap, we applied the PLUS-INVEST model to investigate the spatial effects of land-use changes on habitat quality and degradation patterns across the Tibetan Plateau during the 21st century. By employing a geographic detector, we determined the contribution rates of disturbance factors to habitat quality and degradation, and established constraint lines and threshold ranges between these factors. The findings reveal that: (1) The PLUS model demonstrates an exceptional performance in land-use simulation, with an overall accuracy of 0.8465. (2) The high-quality habitat area exhibits a declining trend, while the habitat degradation index steadily rises from 2000 to 2100, indicating a significant loss of biodiversity within the region. Habitat quality displays a spatial distribution pattern characterized by higher values in the south and lower values in the north, with areas in proximity to road threat sources experiencing more pronounced habitat degradation. (3) NDVI emerges as the most influential factor in promoting habitat quality, while the interaction of NDVI_Temperature exerts the greatest influence on spatial heterogeneity. The distance to resident emerges as the primary disturbance factor contributing to habitat degradation, with the interaction strength of GI_Resident being the most significant contributor. (4) Threshold intervals for ANPP, NDVI, precipitation, temperature, and distance to resident of optimal habitat quality and most severe degradation. This provides a novel scientific approach for designating areas for targeted conservation and intensive management restoration.

The low survival rate of European hare leverets in arable farmland: evidence from the predation experiment.

The low survival rate of leverets may significantly contribute to steep population declines and slow recovery of European hares (Lepus europaeus). However, the leveret survival rate in farmlands with different landscape structures is poorly understood, and the existing evidence comes mainly from Western Europe. In this study, we explored the survival of leveret hare dummies along linear semi-natural habitats in homogeneous Central European arable farmland during the main part of the European hare reproduction period (March-April) in 2019 and 2020. The survival rate of hare leverets during the 14-day period was only 22.2%, and all predation events were recorded during the first six days of the experiment. Mammalian predators were responsible for 53.1% of predation events, avian predators for 40.8%, and agricultural operations for 6.1%. The red fox (Vulpes vulpes) was the dominant predator in our study area and was the primary cause of leveret dummy mortality (32.7%), but it also had the highest use-intensity and visit frequency of all of the study plots. Predation by avian predators was associated with patches of lower vegetation height and cover (such as plowed fields) and during daylight hours, whereas the opposite was true for mammalian predators. We propose that improving the habitat quality of arable landscapes by increasing the proportion and quality of extensively used non-farmed habitats (e.g., set-asides, wildflower areas, extensive meadows, fallow land, and semi-natural habitats on arable land) providing cover and shelter for leverets could be an effective management measure for reducing predation risk on leverets.

Widespread habitat loss leads to ecosystem-scale decrease in trophic function.

Natural and anthropogenic disturbances have led to rapid declines in the amount and quality of available habitat in many ecosystems. Many studies have focused on how habitat loss has affected the composition and configuration of habitats, but there have been fewer studies that investigate how this loss affects ecosystem function. We investigated how a large-scale seagrass die-off altered the distribution of energetic resources of three seagrass-associated consumers with varied resource use patterns. Using long-term benthic habitat monitoring data and resource use data from Bayesian stable isotope mixing models, we generated energetic resource landscapes (E-scapes) annually between 2007 and 2019. E-scapes link the resources being used by a consumer to the habitats that produce those resources to calculate a habitat resource index as a measurement of energetic quality of the landscape. Overall, our results revealed that following the die-off there was a reduction in trophic function across all species in areas affected by the die-off event, but the response was species-specific and dependent on resource use and recovery patterns. This study highlights how habitat loss can lead to changes in ecosystem function. Incorporating changes in ecosystem function into models of habitat loss could improve understanding of how species will respond to future change.

Management and research efforts are failing dolphins, porpoises, and other toothed whales.

Despite being subject to intensive research and public interest many populations of dolphins, porpoises, and other toothed whales (small cetaceans) continue to decline, and several species are on the verge of extinction. We examine small cetacean status, human activities driving extinction risk, and whether research efforts are addressing priority threats. We estimate that 22% of small cetaceans are threatened with extinction, with little signs of improvement in nearly thirty years. Fisheries and coastal habitat degradation are the main predictors of extinction risk. Contrary to popular belief, we show that the causal impact of small-scale fisheries on extinction risk is greater than from large-scale fisheries. Fisheries management strength had little influence on extinction risk, suggesting that the implementation of existing measures have been largely ineffective. Alarmingly, we find research efforts for priority threats to be vastly underrepresented and so a major shift in research focus is required. Small cetaceans are among the lower hanging fruits of marine conservation; continued failure to halt their decline bodes poorly for tackling marine biodiversity loss and avoiding an Anthropocene mass extinction.

Urban tolerance does not protect against population decline in North American birds.

Population declines of organisms are widespread and severe, but some species' populations have remained stable, or even increased. The reasons some species are less vulnerable to population decline than others are not well understood. Species that tolerate urban environments often have a broader environmental tolerance, which, along with their ability to tolerate one of the most human-modified habitats (i.e. cities), might allow them to persist in the face of diverse anthropogenic challenges. Here, we examined the relationship between urban tolerance and annual population trajectories for 397 North American bird species. Surprisingly, we found that urban tolerance was unrelated to species' population trajectories. The lack of a relationship between urban tolerance and population trajectories may reflect other factors driving population declines independent of urban tolerance, challenges that are amplified in cities (e.g. climate warming, disease), and other human impacts (e.g. conservation efforts, broad-scale land-use changes) that have benefitted some urban-avoidant species. Overall, our results illustrate that urban tolerance does not protect species against population decline.

Association between gut health and gut microbiota in a polluted environment.

Animals host complex bacterial communities in their gastrointestinal tracts, with which they share a mutualistic interaction. The numerous effects these interactions grant to the host include regulation of the immune system, defense against pathogen invasion, digestion of otherwise undigestible foodstuffs, and impacts on host behaviour. Exposure to stressors, such as environmental pollution, parasites, and/or predators, can alter the composition of the gut microbiome, potentially affecting host-microbiome interactions that can be manifest in the host as, for example, metabolic dysfunction or inflammation. However, whether a change in gut microbiota in wild animals associates with a change in host condition is seldom examined. Thus, we quantified whether wild bank voles inhabiting a polluted environment, areas where there are environmental radionuclides, exhibited a change in gut microbiota (using 16S amplicon sequencing) and concomitant change in host health using a combined approach of transcriptomics, histological staining analyses of colon tissue, and quantification of short-chain fatty acids in faeces and blood. Concomitant with a change in gut microbiota in animals inhabiting contaminated areas, we found evidence of poor gut health in the host, such as hypotrophy of goblet cells and likely weakened mucus layer and related changes in Clca1 and Agr2 gene expression, but no visible inflammation in colon tissue. Through this case study we show that inhabiting a polluted environment can have wide reaching effects on the gut health of affected animals, and that gut health and other host health parameters should be examined together with gut microbiota in ecotoxicological studies.

Assessing wildfire impact on Trigonella elliptica habitat using random forest modeling.

Wildfires have a significant impact on ecosystems worldwide, especially on the degradation of arid and semi-arid rangelands. This research focuses on assessing the effects of wildfires on the habitat of Trigonella elliptica, a valuable herb species found in the central rangelands of Iran. To achieve this, the Random Forest (RF) algorithm has been deployed to predict T. elliptica habitat and fire hazard using socio-environmental variables in Yazd province, Iran. 225 fire points and 103 habitat locations were used for model training and testing. The IncNodePurity index and Probability Curves (PC) have been utilized to determine the influence of socio-environmental variables. The combination of the prediction maps of the habitat and wildfires pointed out the possible damage due to fire. The high performance of the RF model is confirmed by the area under the curve (AUC) and the true skill statistic (TSS) values (0.90 and 0.81 for the habitat; 0.92 and 0.82 for the wildfire). The importance assessment of variables revealed that elevation, slope, and precipitation are the most influential variables in the distribution of T. elliptica, while distance to roads, population density, and wind speed are the key factors affecting wildfire occurrence. In the final map, a comparison of different regions of T. elliptica habitat under fire hazard with fire-free habitats using Kruskal-Wallis and Dunn tests indicated that the fire hazard in the T. elliptica habitat is a serious concern. Since the areas with the highest fire hazard and the highest presence of T. elliptica cover approximately 2311.38 km2, neglecting these regions could lead to the gradual reduction of T. elliptica, and create conditions for secondary succession dominated by less valuable annual species. The findings of this study underscore the importance of implementing fire management strategies, protection projects, and continuous monitoring to ensure the safety and conservation of the T. elliptica habitat.

Effect of landscape attributes on the occurrence of the endangered golden-headed lion tamarin in southern Bahia, Brazil.

The golden-headed lion tamarin (Leontopithecus chrysomelas) is an endangered primate that occurs exclusively in the Atlantic Forest of southern Bahia, Brazil. Its geographic range has been severely reduced by deforestation and its populations are restricted to a human-modified landscape consisting primarily of Atlantic forest fragments and shade cacao (Theobroma cacao) agroforestry, locally known as cabrucas. In the last 30 years, there has been a 42% reduction in the geographic range and a 60% reduction in the population size of L. chrysomelas, with only 8% of its habitat represented by protected areas. Thus, we investigated the occurrence of L. chrysomelas in forest fragments and cabrucas based on interviews and using playback census, and evaluated the influence of landscape attributes on its occurrence. The occurrence was measured using a Generalized Linear Model using a set of 12 predictor variables, including fragment size and elevation. L. chrysomelas inhabited 186 (38%) of the 495 forest fragments and cabrucas. Most inhabited habitat patches (n = 169, 91%) are in the eastern portion (ca. 70 km wide region from the Atlantic coast to inland) of its geographic range. The remaining (n = 17, 9%) are in the western portion of the distribution, between 70 and 150 km from the Atlantic coast. Our models indicate a higher occurrence of L. chrysomelas in the eastern portion of its geographic range, where the landscape exhibits lower land cover diversity, greater functional connectivity, lower altitudes (<400 m), and is primarily composed of forest fragments and cabrucas with a higher core percentage. In contrast, we observed a lower occurrence of L. chrysomelas in the western portion, where the landscape is more diverse and heterogeneous due to anthropogenic activities, such as agriculture and livestock. We urge the establishment of ecological corridors via reforestation of degraded areas in the western portion of the range. This increase in habitat availability and suitability in the west together with the protection of the forests and cabrucas in the east would increase our chances of saving L. chrysomelas from extinction.

Temporal dynamics of benthic communities in a hypereutrophic bay through functional groups and abiotic variables.

This study aimed to examine the benthic structure of Guanabara Bay's (GB) rocky shores through Functional Diversity (FD) perspective. Over a five-year period, benthic communities were periodically examined using photographic samples from the meso-littoral zone. FD were analysed using the Rao Index of marine macroalgae and benthic invertebrates' functional groups (FGs) and their relationship was investigated through null models, considering temporal, geographical, and environmental variations. The entrance site exhibited exclusive FGs and overlap niches more than expected by chance, while the inner site had a higher frequency of Bacterial Biofilm and predominance of competitive exclusion. Orthophosphate and nitrate showed significant correlations with FGs inside the bay, whereas average irradiance and rainfall were at the entrance. A functional gradient was registered, with higher Rao's Index values at the entrance compared to the inner site, probably due to increased anthropogenic disturbance and abundance of FGs with opportunistic life strategies inside GB.

Habitat modification destabilizes spatial associations and persistence of Neotropical carnivores.

Spatial relationships between sympatric species underpin biotic interactions, structure ecological communities, and maintain ecosystem health. However, the resilience of interspecific spatial associations to human habitat modification remains largely unknown, particularly in tropical regions where anthropogenic impacts are often greatest. We applied multi-state multi-species occurrence models to camera trap data across nine tropical landscapes in Colombia to understand how prominent threats to forest ecosystems influence Neotropical carnivore occurrence and interspecific spatial associations, with implications for biotic interactions. We show that carnivore occurrence represents a delicate balance between local environmental conditions and interspecific interactions that can be compromised in areas of extensive habitat modification. The stability of carnivore spatial associations depends on forest cover to mediate antagonistic encounters with apex predators and structurally intact forests to facilitate coexistence between competing mesocarnivores. Notably, we demonstrate that jaguars play an irreplaceable role in spatially structuring mesocarnivore communities, providing novel evidence on their role as keystone species. With increasing global change, conserving both the extent and quality of tropical forests is imperative to support carnivores and preserve the spatial associations that underpin ecosystem stability and resilience.

Population size affected by environmental variability impacts genetics, traits, and plant performance in Trifolium montanum L.

Population size, genetic diversity, and performance have fundamental importance for ecology, evolution, and nature conservation of plant species. Despite well-studied relationships among environmental, genetic, and intraspecific trait variation (ITV), the influence of population size on these aspects is less understood. To assess the sources of population size variation, but also its impact on genetic, functional trait, and performance aspects, we conducted detailed population size estimations, assessed 23 abiotic and biotic environmental habitat factors, performed population genetic analyses using nine microsatellite markers, and recorded nine functional traits based on 260 Trifolium montanum individuals from 13 semi-dry grassland locations of Central Europe. Modern statistical analyses based on a multivariate framework (path analysis) with preselected linear regression models revealed that the variation of abiotic factors (in contrast to factors per se) almost completely, significantly explained fluctuations in population size (R 2 = .93). In general, abiotic habitat variation (heterogeneity) was not affected by habitat area. Population size significantly explained genetic diversity (N A: R 2 = .42, H o: R 2 = .67, H e: R 2 = .43, and I: R 2 = .59), inbreeding (F IS: R 2 = .35), and differentiation (G ST: R 2 = .20). We also found that iFDCV (ITV) was significantly explained by abiotic habitat heterogeneity, and to a lesser extent by genetic diversity H e (R 2 = .81). Nevertheless, habitat heterogeneity did not statistically affect genetic diversity. This may be due to the use of selectively neutral microsatellite markers, and possibly by insufficient abiotic selective pressures on habitats examined. Small T. montanum populations in nonoptimal habitats were characterized by reduced genetic and functional trait diversity, and elevated genetic inbreeding and differentiation. This indicates reduced adaptability to current and future environmental changes. The long-term survival of small populations with reduced genetic diversity and beginning inbreeding will be highly dependent on habitat protection and adequate land-use actions.

Illegal mining impacts on freshwater Potamonautid crab in a subtropical Austral highland biosphere reserve.

The contamination of surface water by heavy metals, especially mercury, has become a global issue. This problem is particularly exacerbated in rivers and reservoirs situated in developing nations. Therefore, the objective of this study was to evaluate the potential contamination effects of illegal gold mining activities on freshwater Potamonautid crabs and to quantify the mercury levels in 49 river sites under three land use classes: communal areas, national parks and timber plantations. We used a combination of field sampling, multivariate analysis and geospatial tools to quantify mercury concentrations in relation to crab abundances. Illegal mining was prevalent throughout the three land use classes, with mercury (Hg) being detected in 35 sites (71.5 %). The mean range of Hg concentrations detected across the three-land uses was: communal areas 0-0.1 mg kg-1, national parks 0-0.3 mg kg-1 and timber plantations 0-0.06 mg kg-1. Mean Hg geo-accumulation index values showed strong to extreme contamination in the national park, with strong contamination observed for communal areas and timber plantations; furthermore, the enrichment factor for Hg concentrations in the communal and national park areas showed extremely high enrichment. Two crab species (i.e., Potamonautes mutareensis, Potamonautes unispinus) were found in the Chimanimani area, with P. mutareensis being the dominant taxon in the region across all the three land use areas. The national parks had higher total crab abundances than communal and timber plantation areas. We observed negative and significant K, Fe, Cu and B effects on total Potamonautid crab abundances, but surprisingly not for other metals such as Hg which might reflect their widespread pollution. Thus, illegal mining was observed to impact the river system, having a serious impact on the crab abundance and habitat quality. Overall, the findings of this study underscores the need to address the issue of illegal mining within the developing world as well as to establish concerted effort from all stakeholders (e.g., government, mining companies, local communities, and civil society groups) to help protect the less charismatic and understudied taxa. In addition, addressing illegal mining and protecting understudied taxa aligns with the SDGs (e.g. SDG 14/15-life below water/life on land) and contributes to global efforts to safeguard biodiversity and promote sustainable development.

The Change in Habitat Quality for the Yunnan Snub-Nosed Monkey from 1975 to 2022.

The reduction in habitat quality (as shown, in part, by the increase in habitat rarity) is an important challenge when protecting the Yunnan snub-nosed monkey. We used the InVEST model to quantitatively analyze the dynamic changes in the habitat of the Yunnan snub-nosed monkey from 1975 to 2022. The results show that in the study period, the degree of habitat degradation increased, with the degradation range at its widest in the south, and the degradation intensity highest in the north, especially along a center "spine" area in the north. Over the latter part of the study period, the habitat quality of most monkey groups improved, which is conducive to the survival and reproduction of the population. However, the habitat quality and monkey populations are still at significant risk. The results provide the basis for formulating the protection of the Yunnan snub-nosed monkey and provide research cases for the protection of other endangered species.