Specific Habitat Research Articles

Habitat specificity modulates the bacterial biogeographic patterns in the Southern Ocean.

Conceptual biogeographic frameworks have proposed that the relative contribution of environmental and geographical factors on microbial distribution depends on several characteristics of the habitat (e.g. environmental heterogeneity, species diversity, proportion of specialist/generalist taxa), all of them defining the degree of habitat specificity, but few experimental demonstrations exist. Here, we aimed to determine the effect of habitat specificity on bacterial biogeographic patterns and assembly processes in benthic coastal ecosystems of the Southern Ocean (Patagonia, Falkland/Malvinas, Kerguelen, South Georgia and King George Islands), using 16S rRNA gene metabarcoding. The gradient of habitat specificity resulted from a 'natural experimental design' provided by the Abatus sea urchin model, from the sediment (least specific habitat) to the intestinal tissue (most specific habitat). The phylogenetic composition of the bacterial communities showed a clear differentiation by site, driven by a similar contribution of geographic and environmental distances. However, the strength of this biogeographic pattern decreased with increasing habitat specificity: sediment communities showed stronger geographic and environmental divergence compared to gut tissue. The proportion of stochastic and deterministic processes contributing to bacterial assembly varied according to the geographic scale and the habitat specificity level. For instance, an increased contribution of dispersal limitation was observed in gut tissue habitat. Our results underscore the importance of considering different habitats with contrasting levels of specificity to better understand bacterial biogeography and assembly processes over oceanographic scales.

Mass occurrences of Sandeels (Ammodytes spp.) causing aggregations of diving ducks

In autumn 1999, large, compact flocks of foraging diving ducks, particularly Common Eiders Somateria mollissima, were observed within and at the mouth of Trondheimsfjord in Central Norway. Some of these aggregations were at places previously not known as particularly rich feeding grounds. This situation continued through the winter, and still existed in March 2000. Investigations on these feeding grounds showed that the only possible prey species occurring in significant quantities was Sandeel (only Ammodytes tobianus was verified). Although most of the fish were swallowed before the birds reached the surface, some ducks (including Velvet Scoter Melanitta fusca and Goldeneye Bucephala clangula) were observed eating Sandeels. Sandeel populations fluctuate in size annually and shoals are very patchily distributed. Consequently, the very variable occurrence in time and space of this food resource may occasionally bring about unusually dense and patchy aggregations of various species of diving ducks. Due to the specific habitat requirements of the Sandeel, these aggregations may also occur at localities that are not generally preferred feeding grounds for diving ducks, as was the case here. These findings may be relevant for some monitoring projects involving populations of diving ducks in marine environments.

Agricultural pesticides in feathers of the burrowing owl (Athene cunicularia) and its relationship to land-use in the argentinean pampas

The pampas of South America represent one of the most productive lands for agriculture in the world, and consequently this activity has expanded throughout the region, especially in Argentina. In this context, native fauna faces various risks associated with agriculture, with exposure to pesticides being one of the most dangerous and deadly. Assessing the impact of pesticides on wildlife becomes fundamental and the use of sentinel species emerges as an important tool to monitor environmental health. In this study, we determined pesticide levels in the burrowing owl Athene cunicularia nesting in both rural and urban areas of the argentinean pampas. We used a multiple scale approach to evaluate the influence of land-uses (urban, crops, and grazing fields) at the nesting site on the contaminant load of A. cunicularia individuals, and assessed the potential use of this owl as a sentinel species. From March 2018 to January 2020, A. cunicularia feathers were collected at their nest sites in one urban and two rural areas. These samples were analyzed for the presence of contaminants, including chlorpyrifos and 18 organochlorine pesticides. All the compounds analyzed were detected in A. cunicularia samples. The chlorpyrifos showed the highest frequency of occurrence and concentration, thus denoting the exposure of owls to current-use pesticides. ∑DDTs showed the highest occurrence among organochlorines, followed by ∑HCHs > ∑Endosulfans > ∑Heptachlors > ∑Drins = ∑Chlordanes > methoxychlor. Principal Component Analysis showed that most of the compounds found in A. cunicularia samples showed a positive association with grazing fields, suggesting that exposure to contaminants does not depend on specific habitat use at the local scale, but probably the regional scale. Our results evidenced the exposure of A. cunicularia individuals to past and current-use pesticides in the pampas of Argentina, and indicate that this owl would be useful as a sentinel species.

A A new species of Graffenrieda (Melastomataceae) from the northern Andes, Caquetá, Colombia, and a key for the Graffenrieda group with calyptrate flowers

Background and Aims: Graffenrieda is a Neotropical genus with more than 70 species, mainly distributed in the Guiana Shield and the Andes. This work describes a new species of Graffenrieda and provides a key to identify all species with calyptrate flowers in the genus.Methods: The description of this new species was made from collections deposited in the Colombian herbaria JBB and COAH. Measurements of vegetative parts and inflorescence were made from dried material, while floral structures and fruits were measured from fresh material preserved in alcohol. Their conservation status was assessed according to IUCN guidelines. A key for the recognition of all species of the genus with calyptrate flowers, including the new species and Centronia species to be transferred to Graffenrieda is also provided here, for which lists of species in Neotropical countries, collection databases, and literature on both genera were consulted.Key results: Graffenrieda cardenasii sp. nov. is endemic to the southern Cordillera Oriental of Colombia and is characterized by its indumentum of irregular lepidote trichomes on the vegetative parts, leaves with incomplete lateral anisophylly, leafy bracteoles as large as the flower buds, 5-merous flowers, calyptrate calyx and 2-locular ovary. It is categorized as Endangered in view of its endemicity and habitat specificity. A key is provided for 30 species of the genus Graffenrieda that share the character of calyptrate flowers.Conclusions: This species is named in honor of the Colombian botanist Dairon Cárdenas López, a great collector and connoisseur of the Colombian Amazonian flora. It is so far known only from the type localities. The key to the species with calyptrate flowers included in this article allows 43% of the species in the genus Graffenrieda to be recognized, including four Centronia species.

The ecological and evolutionary dynamics of inselbergs.

Islands are fundamental model systems in ecology, biogeography, and evolutionary biology. However, terrestrial islands, unlike their aquatic counterparts, have received comparatively less attention. Among these land islands, inselbergs (i.e. isolated rock outcrops with diverse lithologies and a modest topographical prominence) stand out as iconic examples distributed worldwide across global biomes. Due to their durable lithology, inselbergs change slowly, persisting for tens of millions of years. In this review, we propose a biological definition for inselbergs that captures three fundamental characteristics of inselbergs from the perspective of biota. These are old age, isolation and the presence of unique microhabitats that are rare or absent in the surrounding matrix, fostering distinct communities often with unique and endemic biota. We synthesise the state of the art and formulate a set of testable hypotheses to deepen our understanding of the origins and maintenance of diversity on inselbergs, which are increasingly exposed to anthropogenic threats. By offering different habitats compared to the surrounding habitat matrix (e.g. moist microhabitats in dryland landscapes and xeric environments in humid tropical landscapes), inselbergs may allow specific lineages to thrive beyond their typical geographical limits. Particularly in drylands and degraded landscapes, inselbergs may not just provide different habitats but also act as ecological refuges or evolutionary refugia by providing a wider range of potential microhabitats than the surrounding matrix, enhancing resilience and promoting regional biodiversity. The central role of the matrix ensures that the ecological and evolutionary dynamics of inselbergs differ from those of true islands such as oceanic islands. Given that inselberg biota coexist within a terrestrial matrix, interactions between inselberg and matrix populations impact each other significantly. Over evolutionary timescales, matrix species may contract to inselberg refugia, preserving lineages while cycles of isolation and reconnection may drive speciation via a species pump. Although inselberg biodiversity has been studied predominantly from an island biogeography perspective, we argue that depending on the spatial scale, habitat specificity and mobility of the organisms considered, a range of different theories and paradigms can help explain the biogeography and local distribution patterns of different taxonomic and functional groups of inselberg species.

Functional diversity dynamics of waterbird communities driven by water levels at Shengjin Lake, a small river-connected shallow lake in the middle and lower Yangtze River floodplain.

Gate-controlled activities in lakes can directly or indirectly influence the assembly of waterbird communities. Shengjin Lake, a Ramsar site, is a typical river-connected and gate-controlled shallow lake in the lower and middle Yangtze River floodplain in China, comprising three sub-lakes (upper, middle, and lower) based on topographical features. We surveyed wintering waterbirds at Shengjin Lake from October 2022 to March 2023. We divided the winter water level period into nine phases based on the characteristics of water level changes. By measuring functional diversity, we aimed to provide insights into the differences in waterbird communities among the three sub-lakes under different water level conditions. Multiple linear regression was used to analyze the relationship between habitat factors and functional diversity. We further explored the relationship between specific functional traits and habitat factors through a combination of the R-mode linked to the Q-mode and the trait-environment correlation matrix (fourth-corner analyses) to explain the mechanism underlying waterbird community assembly. When the water level fluctuated in the range of 10.43-10.74 m (Huanghai elevation), the three sub-lakes had significant habitat differences and high habitat heterogeneity, increasing functional richness and functional dispersion of the upper and lower lakes, both of which significantly differed from those of the middle lake. Habitat heterogeneity and mudflat habitats have positive effects on functional diversity. The difference in functional diversity was primarily determined based on the foraging traits and strata of waterbirds. Habitat filtering of particular traits is a major driving force underlying the assembly of waterbird communities. Overall, we suggest that the minimum water level in the wintering period at Shengjin Lake should be regulated between 10.43 and 10.74 m. These findings provide reasonable suggestions for water level regulation and a theoretical basis for conserving waterbird diversity at Shengjin Lake.

Immediate impacts of fire on koala movement in a fragmented landscape

Hazard reduction burns could pose a significant conservation challenge to threatened habitat specialists, such as koalas Phascolarctos cinereus. This study examines the immediate effects of a medium to hot hazard reduction burn on a small number of koalas occupying a fragmented agricultural area. Three koalas being monitored using GPS telemetry were inadvertently exposed to fire in a small strip of roadside vegetation in an agricultural landscape, providing an unexpected opportunity to assess their immediate responses to the fire. Nearly 81% of available trees were burnt to some degree, with 31% of tree foliage scorched up to 10.2m above the ground. The koalas reduced their home range sizes by 20–54% post-fire, where two avoided burnt areas while one remained within them. These findings highlight the importance of maintaining unburnt patches and corridors in fragmented landscapes and developing comprehensive conservation plans to mitigate the adverse effects of fire on koalas and other arboreal fauna.

Occurrence of Fox Squirrels Influenced by Fine-Scale Landscape Characteristics on a College Campus.

Urbanization and urban sprawl generally degrade and diminish wildlife habitat, threatening to extirpate local populations. However, certain synanthropic species (e.g., coyotes, white-tailed deer, and squirrels) are able to persist in urban environments and may even occur at greater densities than they do in their natural habitats. Eastern fox squirrels (Sciurus niger) are large tree squirrels that are known to be present in greater densities within urban areas. To determine how landscape characteristics may affect fox squirrel presence, we conducted line-transect surveys along sidewalks on the Texas A&M University-College Station campus to record presence of fox squirrels and nearest tree species. We calculated Jacobs' index of selectivity (D) for use of trees by fox squirrels along the transects. Squirrel density was calculated for all transects and modeled using linear regression with environmental (e.g., tree density) and survey (e.g., transect distance) variables. Fox squirrels preferred only a small number of the available tree species, primarily Quercus and Ulmus species. Observed fox squirrel density significantly increased with time of day, temperature, density of oaks (Quercus spp.), and density of all trees, and decreased with distance and area of the transect. These results suggest that even when urban areas contain suitable habitat, use of urban environments by wildlife is still highly selective and dependent on specific habitat requirements.

Variation of parental and chick diet in opportunistic insectivorous European Bee-eaters

Insectivorous Palaearctic bird species associated with open habitats rely on high prey abundances, which are currently declining due to habitat loss and intensive agricultural practices. The European Bee-eater (Merops apiaster) is an opportunistic insectivore of open habitats, preying mainly on medium to large-sized flying insects. Its diet composition received some attention in the past, but the current variation in diet composition of birds breeding across different habitats, and between adults and chicks remains poorly known. In this study, we determine variation in bee-eaters’ diet in colonies located in five common habitats at the Iberian Peninsula. We also assess differences in the diet composition of chicks and adults and investigate seasonal diet selectivity of adults. Finally, we explore the variability in the size of prey provided to chicks throughout their growth period. Hymenoptera and Coleoptera were the most important groups for bee-eaters, with adults and chicks consuming 58.8% and 64.1% of hymenopterans and 37.6% and 28.6% of coleopterans, respectively. The proportion of Hymenoptera (42.3–55.7%) and Coleoptera (43.3–53.5%) in the diet was similar in colonies in pasture and oak habitats. But Hymenoptera dominated (83.8% and 95.7%) in meadow and mixed forest colonies. Despite being a generally opportunistic predator, adult bee-eaters provide their progeny with an increasing proportion of larger insects through chick development. Moreover, they equally take Hymenoptera and Coleoptera for themselves and their chicks, even when the abundance of these insects decreases seasonally. Overall, these results suggest that local prey availability associated with specific habitats influences diet composition and that regional declines in certain groups may, therefore, affect insectivore species differently according to their dietary and habitat preferences.

Overlooked Bird Extinctions in Semideciduous Atlantic Forests.

The semideciduous forest is a prominent yet highly degraded phytophysiognomy within the Atlantic Forest. Historically, bird species inhabiting these forests occurred throughout central and western São Paulo state, south-eastern Brazil, until the mid-20th century. Many of these species have not been observed again or are nearing extinction within the state's inland forest fragments. This study reviews and compares historical and recent ornithological records, using museum specimens, literature, citizen science and recent field surveys to understand these species' current lack of records. In the early 20th century, extensive deforestation occurred statewide, resulting in the current forest fragments, which are currently in various stages of regeneration, conservation and isolation. Many of these fragments lack the specific habitats some species require, or they have not been recolonised due to insufficient connectivity with other forest fragments where these species still exist (particularly in the eastern Atlantic Forest). The non-detection of forest species in semideciduous forest fragments strongly suggests an unprecedented and largely unnoticed extinction scale. This pattern of defaunation, as predicted 30 years ago, may be prevalent across numerous Semideciduous Atlantic Forests in Brazil.

Conservation with hard borders: Ethiopian wolves are threatened by fragmentation and isolation

Unlike most canids, versatile and capable of navigating vast landscapes, endangered Ethiopian wolves (Canis simensis) are endemic to an archipelago of Afroalpine islands. As a habitat specialist, the Ethiopian wolf is ill‐equipped to move across a highly transformed and densely populated agriculture matrix. Hard borders imposed by expanding subsistence agriculture lock Ethiopian wolves into further isolation, with few opportunities for dispersal and recolonisation. We report and evaluate empirical information from long‐term monitoring across the species' range to understand processes of habitat loss, recolonisation and extinction in recent and historical times, and to assess what conservation measures and strategies would ensure their persistence. Ethiopian wolves occurred in six isolated populations, totalling 454 wolves (population sizes ranged between 281 and 24) occupying 2700 km2 of Afroalpine habitat. We describe three population extinctions and three local extinctions within fragmented populations, and present evidence of factors accelerating the extinction process, such as disease (rabies and canine distemper virus), persecution, road kills and poisoning. Of all the suitable habitat available to wolves, 86% was included within nine protected areas, including three new Community Conservation Areas and two national park extensions in the past 10 years. As all Ethiopian wolf populations are small and vulnerable to stochastic events and environmental perturbation, conservation efforts to ensure the long‐term survival of the species need to integrate: 1) support for protected areas to halt agriculture encroachment and to regulate sustainable uses of natural resources; 2) efforts to minimise all causes of mortality, including but not limited to disease; and 3) conservation translocations to overcome fundamental barriers to dispersal in the highlands of Ethiopia.

Plastid marker variation reveals immigration history in Scandinavian Syntrichia norvegica and S. ruralis (Pottiaceae, Bryophyta)

ABSTRACT Introduction Based on previous analyses of Syntrichia norvegica and S. ruralis, the idea of panmictic populations in Scandinavia can be rejected, despite the high dispersal capacities of wind-dispersed spores. We tested, using comprehensive European datasets, whether intraspecific phylogeographical structure reflects glacial and post-glacial history. We expected different entities to indicate immigration from known Late Glacial Maximum refugial areas, and habitat differentiation. Methods Using plastid markers (atpB–rbcL and rpl16), we investigated 45 and 190 Scandinavian and 17 and 15 non-Scandinavian specimens of Syntrichia norvegica and S. ruralis, respectively. Key results We revealed four intraspecific entities in Syntrichia norvegica. Two were from the Scandinavian mountains and the Alps, and one from the Scandinavian mountains only. The fourth was widespread across the Scandinavian mountains, the northern lowlands, and the Baltic Sea islands Öland and Gotland. For S. ruralis, we recovered five entities, of which three were from both Scandinavia and the Alps. One of these occurred in strongly calcareous habitats in southern Scandinavia and the Alps and dominated on Öland and Gotland. One entity was widely distributed only in Scandinavia. One was restricted to the border between boreo-nemoral and southern-boreal Scandinavia. Conclusions The plastid haplotype distribution patterns suggest glacial survival of Syntrichia norvegica and S. ruralis in refugia south, east and possibly within ice-covered areas of Scandinavia. We hypothesise that one S. ruralis entity evolved adaptations to strongly calcareous habitats. The dominance or prevalence of specific haplotypes of both species on Öland and Gotland contributes to the unique biodiversity of these islands.

Macrofungal sporocarp community in the lichen Scots pine forests.

The lichen-rich pine forests of Cladonio-Pinetum represent special habitats protected under the Natura 2000 scheme. A rapid decline in their density has been observed in recent years. Macrofungi are an important component of the community and sensitive bioindicators; therefore, observations of the response of their sporocarps can be used to draw conclusions about changes induced in habitats. In our study, we tried to detect differences in species richness, composition, and biomass of the ectomycorrhizal fungal communities in areas rich in lichens indicating the good state of the community, and rich in bryophytes signaling its progressive degradation. The influence of precipitation and temperature on species richness and biomass was checked, and the possibility of using the sporocarps-based method to assess the effectiveness of active protection treatments, which are a form of partial protection carried out to maintain specific natural habitats. For detailed studies, six plots were selected from which sporocarps were collected, dried and weighed. A total of 1,575 sporocarps, representing 49 taxa were collected. A higher number of taxa (39) in lichen-rich plots were found. In bryophyte-rich areas, 27 taxa were recorded. The total yield was 13,151 g dry weight ha-1. In lichen-rich plots, the biomass was almost half lower.

Naivety dies with the calf: calf loss to human hunters imposes behavioral change in a long-lived but heavily harvested ungulate

BackgroundIn prey, patterns of individual habitat selection and movement can be a consequence of an individuals’ anti-predator behavior. Adjustments of anti-predator behavior are important for prey to increase their survival. Hunters may alter the anti-predator behavior of prey. In long-lived animals, experience may cause behavioral changes during individuals’ lifetime, which may result in altered habitat selection and movement. Our knowledge of which specific events related to hunting activity induce behavioral changes in solitary living species is still limited.MethodsWe used offspring loss in a solitary and long-lived ungulate species, moose (Alces alces), as our model system. We investigated whether offspring loss to hunters induces behavioral changes in a species subjected to heavy human harvest but free from natural predation. To test for behavioral change in relation to two proxies for experience (calf fate and age), we combined movement data from 51 adult female moose with data on their offspring survival and female age. We tested for adjustments in females’ habitat selection and movement following calf harvest using Hidden Markov Models and integrated Step Selection Analysis to obtain behavioral state specific habitat selection coefficients.ResultsWe found that females with a harvested calf modified habitat selection and movement during the following hunting season. Female moose selected for shorter distance to roads during the night, selected for shorter distance to forests and greater distance to human settlements following calf harvest than females who had not lost a calf. The survival of twins in a given hunting season was related to female age. Older females we more likely to have twins survive the hunting season.ConclusionsOur findings suggest that losing offspring to human harvest imposes behavioral changes in a long-lived ungulate species, leading to adjustments in females' habitat selection and movement behavior, which may lower the risk of encountering hunters. In our study, female moose that experienced calf loss selected for lower distance to forest and selected for greater distance to human settlements during periods of high hunting pressure compared to females without the experience of calf loss during the previous hunting season. We interpret this as potential learning effects.

Delineating population structure of resilient sea/river‐type sockeye salmon

AbstractConserving wild fisheries requires identifying and monitoring distinct populations, yet prevalent genetic approaches often do not integrate habitat data and may not fully delineate these structures. This issue is critical in sea/river‐type sockeye salmon (Oncorhynchus nerka), an ecotype whose specific spawning habitats better define distinct breeding populations. Despite possessing traits that confer greater resilience to climate change and significant contributions to wild fisheries, gene flow among groups dilutes genetic structure, making it difficult to track populations. We focus on sea/river sockeye from one of the Pacific Rim's largest Sockeye fisheries, combining river strontium (Sr) isotope predictions, otolith Sr isotope measurements, and a Bayesian assignment model with a 4‐yr radiotelemetry and genetic dataset (n = 1994) to delineate the geographic structure of spawning habitats. Our results identify four distinct subpopulations with unique natal habitat Sr isotope ratios previously undifferentiated by genetic methods, providing a novel approach to monitor critical groups over multiple years.

Potential applications of microbial genomics in nuclear non-proliferation.

As nuclear technology evolves in response to increased demand for diversification and decarbonization of the energy sector, new and innovative approaches are needed to effectively identify and deter the proliferation of nuclear arms, while ensuring safe development of global nuclear energy resources. Preventing the use of nuclear material and technology for unsanctioned development of nuclear weapons has been a long-standing challenge for the International Atomic Energy Agency and signatories of the Treaty on the Non-Proliferation of Nuclear Weapons. Environmental swipe sampling has proven to be an effective technique for characterizing clandestine proliferation activities within and around known locations of nuclear facilities and sites. However, limited tools and techniques exist for detecting nuclear proliferation in unknown locations beyond the boundaries of declared nuclear fuel cycle facilities, representing a critical gap in non-proliferation safeguards. Microbiomes, defined as "characteristic communities of microorganisms" found in specific habitats with distinct physical and chemical properties, can provide valuable information about the conditions and activities occurring in the surrounding environment. Microorganisms are known to inhabit radionuclide-contaminated sites, spent nuclear fuel storage pools, and cooling systems of water-cooled nuclear reactors, where they can cause radionuclide migration and corrosion of critical structures. Microbial transformation of radionuclides is a well-established process that has been documented in numerous field and laboratory studies. These studies helped to identify key bacterial taxa and microbially-mediated processes that directly and indirectly control the transformation, mobility, and fate of radionuclides in the environment. Expanding on this work, other studies have used microbial genomics integrated with machine learning models to successfully monitor and predict the occurrence of heavy metals, radionuclides, and other process wastes in the environment, indicating the potential role of nuclear activities in shaping microbial community structure and function. Results of this previous body of work suggest fundamental geochemical-microbial interactions occurring at nuclear fuel cycle facilities could give rise to microbiomes that are characteristic of nuclear activities. These microbiomes could provide valuable information for monitoring nuclear fuel cycle facilities, planning environmental sampling campaigns, and developing biosensor technology for the detection of undisclosed fuel cycle activities and proliferation concerns.

Microhabitat coverage influences avian species composition more than habitat heterogeneity in Hong Kong urban parks

The relationship between habitat heterogeneity and diversity can underpin design of urban spaces for biodiversity conservation. The area-heterogeneity trade-off hypothesis predicts that higher habitat heterogeneity should result in an increase in species richness but only up to a point, beyond which habitat micro-fragmentation leads to decreases in species diversity. However, the strength of area-heterogeneity trade-offs at small spatial scales is not well studied. We studied the relationship between avian diversity and habitat heterogeneity in 16 small urban parks across Hong Kong during the winter dry season across 2016 and 2017 (ten repeated surveys in total for each park). Habitat heterogeneity was assessed by measuring the evenness of microhabitat coverage of seven habitats as well as vertical canopy cover. In total, 12,973 individuals of 73 bird species were recorded in the study. Habitat heterogeneity had a small but negligible effect on total bird species richness or abundance. However, water coverage was positively related to total, intermediately rare and habitat specialist bird species richness, and shrub coverage was positively related to total and common bird species richness. These results demonstrate that environmental heterogeneity had little effect on avian species richness in urban green spaces at small spatial scales. We also found that microhabitat coverage can affect avian diversity and abundance, and these effects are specific to certain groups of bird species. When managing urban green spaces for biodiversity conservation in densely urbanized cities, a decrease in management disturbance (e.g. tree topping or pesticide application) will likely benefit avian species. Together with the fact that some locally uncommon species were observed throughout the study, capacity exists for environmental enhancement of these small urban parks to contribute to local avian conservation.

Studies on the influence of water quality on community assemblage of immature mosquitoes in different ecosystems along the Vaigai river, Tamil Nadu, South India

BackgroundOver the last few decades, river ecosystem is highly modified through various anthropogenic activities which are resulted to alter ecosystem functions and services. This modified ecosystem rendering conducive environment to mosquitoes through various ecological links for the self-sustaining populations. However, deciphering the community assemblage of immature mosquitoes with reference to water quality at modified ecosystem is very essential to make suitable control measure to curtail mosquito populations. In order to understand how the water quality influences the larval density, habitat specificity and community assemblage of immature mosquito populations, a study was conducted at different ecosystems (urban, semi-urban and rural) along the Vaigai river. The physicochemical parameters such as pH, TDS, salinity, conductivity, turbidity, DO, were analyzed at each study site.ResultsOur results clearly revealed that Anopheline species were highly preferred to breed less polluted habitat than Culicine species. Community assemblage by Anopheline and Culicine mosquitoes were found to be higher at all the studies whilst community assemblage by Anopheline were maximum at rural and semi-urban sites. Among the Anopheline species, Anopheles subpictus able to breed at high polluted habitat, particularly higher turbid level (28.49 ± 2.18 NTU) than other Anopheles species. Cx. gelidus mostly breed at sewage disposal habitats with high salinity level (1.01 ± 0.08) whilst Cx. bitaeniorhynchus bred in only fresh water bodies particularly low turbid habitats (3.97 ± 0.40 NTU). Grouping of immature mosquitoes based on the habitat similarity, An. subpictus, Cx. vishnui, An. vagus, Cx. tritaeniorhynchus, Cx. gelidus and Cx. quinquefasciatus were able to breed in highly polluted habitats which are resulted fell in group A than group B mosquitoes. Cx. vishnui and An. subpictus have strong habitat similarity (0.96) and can able to share their habitats with more number of Anopheline and Culicine mosquitoes.ConclusionsFrom the study we concluded that, Cx. vishnui and An. subpictus were most prevalent species and strong habitats similarity along the Vaigai river basin. An. subpictus and An. vagus can adapt to breed in polluted habitats and this may be adequate to extend the vectorial capacity and disease outbreak along the Vaigai river basin.

Widespread homogenization in vegetation activities along the elevational gradients across the Himalaya over the past 40 years

Mountainous regions are vital biodiversity hotspots with high heterogeneity, providing essential refugia for vegetation. However, climate change threatens this diversity with the potential homogenization of the distinct environmental conditions at different elevations. Here, we used a time-series (1985–2023) of Normalized Difference Vegetation Index (NDVI) from Landsat archives (30 m) to quantify vegetation changes across an elevation gradient on Himalaya Mountain. Our analysis revealed that over the past 40 years, the Himalayas have experienced widespread greening, accompanied by homogenization of vegetation across elevations. This homogenization, characterized by a reduction in the differences between high and low elevations, can be attributed to two main factors: (1) increased warming and a higher snowmelt rate at high elevations, facilitating rapid changes in high-elevation vegetation activities; and (2) higher anthropogenic disturbance at low and mid elevations, thus inhibiting low-elevation vegetation. These factors have resulted in a reduction of habitat differentiation along the mountain slopes, homogenizing vegetation and potentially threatening the unique biodiversity adapted to specific elevational zones. Our findings emphasize the urgent need for conservation strategies that prioritize the protection of heterogeneous mountain habitats to preserve their rich biodiversity in the face of climate change.

Simply the green: Urban refuges

Large refugia and small refuges have always been crucial for species survival, particularly during periods like the Ice Age. When their original habitats became uninhabitable, they provided important shelters in space and time. Drawing from a biological and philosophical perspective, we propose creating and preserving refuges as socio-ecological solutions in an epoch primarily shaped by human activity, the Anthropocene. Our focus lies on green refuges within urban settings, given that urbanization is one of the large drivers of insect decline and has adverse effects on humans, such as increased heat. Refuges can be beneficial for both biodiversity and human well-being.After clarifying the relevant terminology on four levels of abstraction, we conducted a systematic biological literature review - as a case study. Here, we summarize the current state of research on the effects of unmown refuges on insects and spiders. The mere existence of refuges proved beneficial for arthropods, with over 70 % of studies reporting positive responses among these species.While insects and spiders have specific habitat requirements, humans are able to create a habitable environment for themselves. However, ecological crises for humans and arthropods are increasing, as are human populations. Therefore, refuges offer a way to address both ecological and social challenges simultaneously, enhancing biodiversity and human well-being.