Spatio-temporal effects of river regulation on habitat quality for Atlantic salmon fry

Many upland rivers in the Northern Hemisphere contain important habitat for Atlantic salmon (Salmo salar L.). Owing to their sensitivity to environmental change, salmon are often used as bio-indicators. In Scotland, rivers containing potentially suitable habitat for salmon fry are often also regulated for hydropower. Regulated flow regimes can differ substantially spatially and temporally. Thus, where river management may be needed to maintain, restore, and protect their ecological functioning, this needs to be based on evidence of such spatio-temporal effects. This study investigated the effects of different types of river regulation on the hydraulic characteristics of downstream river reaches and the inferred consequences for salmon fry using hydraulic habitat quality models. The study focussed on the River Lyon (390 km²), a tributary of the Tay (4587 km²), Scotland, UK. Hydraulic habitat variability was assessed for three reach-scale sites with contrasting flow regimes characterised by (a) releases from hydropower generation, (b) compensation flow and (c) partly re-naturalised flow conditions. For each site, high resolution Digital Terrain Models (DTMs) were developed from bathymetric surveys and 2D hydraulic models were used to assess hydraulic characteristics. Discharge time series were used to simulate hydraulic conditions for regulated and simulated natural flows. Depth and velocity data were extracted from the hydraulic models and used to infer habitat quality using a habitat model developed for Atlantic salmon fry in similar-sized Scottish rivers. Results showed the effects of regulation can vary substantially within reaches and between seasons. Comparison to natural flow regimes suggested that flow alteration has a variable influence on habitat quality depending on the type of regulation and time of year. This work has improved understanding of the effects of regulation on biophysical processes and may also be useful for managing trade-offs between management, restoration, and societal benefits.     

Habitat characteristics and trophic structure of benthic macroinvertebrates in a forested headwater stream

Three channel reaches with different habitat characteristics were selected to test the variability in community structure of benthic macroinvertebrates by comparing the relative abundance of functional feeding groups among the reaches. The important factors influencing the spatial and temporal organization of community structure were explored using nonmetric multidimensional scaling (NMS). The habitat characteristics in the reaches were different in terms of habitat type, hydrological factors, and substrate composition. The first headwater reach was classified as a step-pool reach with similar relative areas of riffle and pool habitats. The second mid-reach and the third down reach had greater areas of pool habitat followed by runs and riffles whose proportions were similar between the latter two reaches. The relative abundances of functional feeding groups were different among the surveyed reaches. Gammarid shredders predominated in the upper reach, and chironomid collector–gatherers and collector–filterers were in greater abundance in the two lower reaches. The proportions of gammarids were minor in the mid and downstream reaches. NMS ordination indicated that the proportion of substrates < 8 mm, discharge, and water depth mainly determined the spatial and temporal distribution of samples based on the macroinvertebrate community in the study reaches. These results suggest that different habitat characteristics result in a distinct community structure in each reach.     

Restocking a keystone species in a biodiversity hotspot: Recovering the European rabbit on a landscape scale

Rabbit populations in Iberia remain at low densities in several areas in which their endangered predators still coexist, and the recovery of these populations is therefore urgent if the integrity of Iberian Mediterranean ecosystems is to be maintained. The enhancement of wild rabbit populations has been attempted through the use of in situ extensive rabbit captive breeding enclosures (restocking plots), which reduce mortality caused by terrestrial predators and dispersal movements and permit the breeding of young individuals which can then naturally disperse to settle in the surrounding areas. However, their effectiveness, the role of its size, the optimal habitat management that should be promoted around them and the habitat features remains uncertain. Here, we show results from a four year study of an ambitious rabbit restocking plan on a landscape scale. We measured rabbit abundance in a vast area in which thirty-two restocking plots were built to create an initial rabbit population for further dispersion, in addition to an intensive habitat management program. We also compared rabbit abundance between managed and unmanaged UTM cells of 2.5 km × 2.5 km. Our results showed that rabbit abundance was three times higher in managed cells, but four years after restocking, rabbit abundances had only reached the threshold needed to support stable Iberian lynx presence (at least 10 latrines per km^?1) in 9 of the 23 managed cells. Rabbit abundance was strongly affected by habitat treatment and scrub coverage. The increase of shelter was useful in low cover areas but ineligible in places with high scrub cover, where the increase of refuge plus scrub clearing to create pastures improve rabbit abundance more effectively. In the light of our results, restocking plots should be built only in places with suitable habitat, whereas pastures should be created in dense scrublands and refuge in low cover areas.     

Mapping multiple plant species abundance patterns - A multiobjective optimization procedure for combining reflectance spectroscopy and species ordination

Nature conservation and ecological restoration crucially depends on the knowledge about spatial patterns of plant species that control habitat conversion and disturbance regimes. Especially, species abundances are capable of indicating early development tendencies for setting habitat management strategies. This study demonstrates the transfer of field spectroscopy to hyperspectral imagery to map multiple plant species abundances in an open dryland area using two imaging spectrometers in two different phenological phases. We show that species abundances can partially be described by multiple gradients forming different coordinates in a contour map. For this purpose, species abundances were projected into an ordination space using non-metric multidimensional scaling and subsequent spatial interpolation. It was demonstrated that different gradients can be modeled in a Partial Least Squares regression framework resulting in distinct spectral features for certain gradient directions. We combine both objectives in a multiobjective NSGA-II procedure to maximize the quantitative determination of species abundance in ordination and spectral predictability in related field spectra, simultaneously. NSGA-II was finally used to select optimal spectral models for n = 35 single species that were transferred to hyperspectral imagery for mapping purpose. We can show that abundance predictabilities can be evaluated on the basis of individual model performances that hold different spectral features for each species in a designated phenological phase. Finally, we present spatially explicit multi-species maps for the best n = 18 and abundance maps for n = 8 models that could be linked to patterns of species richness, coexistence, succession stages and habitat type conditions.     

Using climatic suitability thresholds to identify past,present and future population viability

Often climatic niche models predict that any change in climatic conditions will impact species abundance or distribution. However, the accuracy of models that just incorporate climatic information to predict future species habitat use is widely debated. Alternatively, environmental conditions may simply need to be above some minimum threshold of climatic suitability, at which point, other factors drive population size. Using the example of nesting sites of loggerhead sea turtles (Caretta caretta) in the Mediterranean (n = 105), we developed climatic niche models to examine whether a climatic suitability threshold could be identified as a climatic indicator in order for large populations of a widespread species to exist. We then assessed the climatic suitability of sites above and below this threshold in the past (∼1900) and future (∼2100). Most large sites that are currently above the climatic threshold were above the threshold in the past and future, particularly when future nesting seasonality shifted to start 1–2 months earlier. Our analyses highlight the importance of future phenological shifts for maintaining suitability. Our results provide a positive outlook for sea turtle conservation, suggesting that climatic conditions may remain suitable in the future at sites that currently support large nesting populations. Our study also provides an alternative way of interpreting the outputs of climatic niche models, by generating a threshold as an index of a minimum climatic suitability required to sustain large populations. This type of approach offers the possibility to benefit from information provided by climate-driven models, while reducing their inherent uncertainties.     

Response of freshwater macroinvertebrates to rainfall-induced high flows: A hydroecological approach

Hydraulic-habitat and biological data were integrated within a twofold-purpose study: (i) to investigate the response of freshwater macroinvertebrates to a rainfall-induced high flow event of moderate magnitude and (ii) to derive hydroecological relationships between habitat variability and macroinvertebrate microdistribution. 142 microhabitats (unique combinations of flow velocity, water depth and substrate type) allocated in four sites of no or very minor anthropogenic influence were sampled and analyzed, before and after the event. Freshwater macroinvertebrates were additionally collected and specific community metrics were derived. To identify possible pre- and post- impact benthic community differences, independent sample t-tests were applied, while Boosted Regression Tree models were developed to quantify the response of macroinvertebrates to flow alteration. Macroinvertebrate abundance, taxonomic richness, EPT richness and diversity decreased significantly by 90%, 60%, 50% and 25% respectively between the pre- and post- impact microhabitats. The relative abundance of macroinvertebrate predators and passive filter feeders increased after the event, mainly in specific substrate types (boulders and large stones), which served as flow refugia, maintaining less degraded (compared to finer substrates), still heavily impacted, benthic communities. According to the hydroecological analysis, the high flow event exerted the strongest impact on all macroinvertebrate metrics. Optimal (suitable) ranges of the hydraulic-habitat variables for benthic macroinvertebrates were identified (optimal flow velocity from 0.3 m/s to 0.7 m/s, optimal water depth at 0.2 m), while boulders and large stones were the most suitable substrate types. The aforementioned data provide valuable information for the provisioning of biologically-derived environmental flows and an essential input of hydrodynamic habitat models to facilitate the selection of the optimal environmental flow scenario towards ensuring the integrity of aquatic ecosystems downstream of anthropogenic activities provoking hydrological alteration.     

The importance of grazing regime in the provision of breeding habitat for grassland birds: The case of the endangered little bustard (Tetrax tetrax)

In Mediterranean dry grasslands, grazing by domestic animals is an important agricultural activity on dry grasslands. Several bird species occur in these grazed habitats and are now experiencing a near continuous decline. We investigated the impact of livestock grazing on the threatened little bustard (Tetrax tetrax L.). The study was conducted at the NATURA 2000 Site/Important Bird Area of Cabrela, Portugal. Our main goals were to investigate responses of little bustard territorial males and breeding females to different livestock management practices, namely pasture types, stocking rates and sward structure. Bird distribution was surveyed using car and foot surveys. Data on grazing was supplied by land managers every 10 days from February to June through field interviews. Generalised additive models and model averaging were used to compute predictive models. Results indicate that higher probabilities of occurrence were found in long-term pastures and under light-moderate grazing conditions (stocking rates around 0.4 LU/ha). Conversely, lower probabilities of occurrence were found in ungrazed or heavy grazed fields. Males occurred mostly in large fields, but this variable seemed to be less important for females. On the other hand, green plant cover and the vegetation height were good predictors for the occurrence of females but not for males. Females used mostly pastures with vegetation height around 20–25 cm. Our results suggest that grazing management plans that aim to conserve little bustard populations should consider (1) the maintenance of the larger long-term pastures and (2) the use of light-moderate stocking rates (0.2–0.6 LU/ha).     

Shrub encroachment affects mammalian carnivore abundance and species richness in semiarid rangelands

Shrub encroachment due to overgrazing has led to dramatic changes of savanna landscapes and is considered to be one of the most threatening forms of rangeland degradation e.g. via habitat fragmentation. Mammalian carnivores are particularly vulnerable to local extinction in fragmented landscapes. However, our understanding of how shrub encroachment affects mammalian carnivores is poor. Here we investigated the relative sensitivities of ten native carnivores to different levels of shrub cover ranging from low (<5%) to high shrub cover (>25%) in 20 southern Kalahari rangeland sites. Relative abundance of carnivores was monitored along 40 sand transects (5 m × 250 m) for each site.Our results show that increasing shrub cover affects carnivore species differently. African wild cats, striped polecats, cape foxes and suricates were negatively affected, whereas we found hump-shaped responses for yellow mongooses, bat-eared foxes and small-spotted genets with maximum abundance at shrub covers between 10 and 18%. In contrast, black-backed jackals, slender mongooses and small spotted cats were not significantly affected by increasing shrub cover. However, a negative impact of high shrub cover above 18% was congruent for all species.We conclude that intermediate shrub cover (10–18%) in savanna landscapes sustain viable populations of small carnivores.     

Vertical habitat segregation as a mechanism for coexistence in sympatric rodents

Coexistence has been widely studied in small mammals and frequently is assumed to be facilitated by habitat segregation. Using live trapping and spool-and-line experiments, we analyzed habitat selection and segregation across multiples scales for Peromyscus leucopus and Ochrotomys nuttalli. At the habitat scale of a forest stand (∼1–100s ha) P. leucopus co-occurred at all sites where O. nuttalli was found, and we did not detect evidence of positive or negative associations or habitat segregation. However, O. nuttalli was restricted to early successional forests, and P. leucopus had significantly lower abundances in early successional forests than in other habitats. We found similar patterns at the mesohabitat scale of the study site (400 m²). O. nuttalli abundance increased with increasing shrub and tree densities, while increases in P. leucopus abundance were associated with open understories. At the microhabitat scale of the individual movement trail, we found vertical segregation. Movement trails for O. nuttalli were at significantly higher elevation (mean height = 142.93 ± 37.10 cm) than P. leucopus trails (mean height = 15.4 ± 4.98 cm; F-value = 35.29, p < 0.001). We concluded that microhabitat segregation was driven by differential use of vertical space for movement and foraging. We suggest O. nuttalli is superior to P. leucopus in its ability to acquire food especially in shrubby subcanopies where few acorns are available. However, P. leucopus is superior in its ability to forage and avoid predators.     

Microhabitat selectivity underpins regional indicators of fish abundance and replenishment

Species with specialized resource use can display strong spatial heterogeneity in abundance according to the availability of their preferred habitats. If these preferences shift with ontogeny, then a wide range of habitats may need to be protected in order to support both adult populations and their replenishment. We explored whether microhabitat selectivity interacts with habitat availability to provide an effective suite of indicators for regional fish abundance and replenishment, using offshore rocky reefs in south-eastern Australia as a case study. We examined generalized additive mixed models (GAMMs) in a full subsets approach to infer the best predictors for adult and juvenile fish density in four diverse families (Labridae, Odacidae, Pomacentridae, Serranidae), based on rapid underwater visual surveys across transects (⿼500 m²), wave exposures (0.3⿿1 km), and sites (0.3⿿48 km). We then examined whether these regional fish-habitat models aligned with the microhabitat electivity of individuals (at scale of <1 m²). Microhabitat selection by reef fishes at the local scale underpinned the most effective habitat indicators for regional heterogeneity in fish abundance, and pointed to critical nursery habitats that support hotspots of juvenile recruitment. Strong species-habitat relationships, such as these, can be combined with broad-scale habitat mapping to assess the potential carrying capacity of focal areas, spatial management zone placements, and nursery habitats that warrant special protection. A number of emerging threats to these key habitat types indicates an urgent need for habitat-based protection and monitoring as a key part of holistic marine ecosystem conservation and management.     

Adult odonate abundance and community assemblage measures as indicators of stream ecological integrity: A case study

Water resources demand constant conservation actions due to several problems (e.g. riparian vegetation cut-off, construction of dams, acidification, sewage and pesticide spills) that degrade the aquatic systems worldwide and affect its physicochemical parameters and habitat characteristics. Odonata is a potential group of organisms that could indicate these habitat alterations once they have aquatic and terrestrial life forms. In this study, we tested the use of adult odonate individual species and community assemblage measures to evaluate the effect of riparian vegetation cut-off and sewage discharges. The study was performed at Turvo Sujo River, in Viçosa, Southern Brazil. We selected twelve sites, six of them were upstream and six were downstream the city. Species abundance and species richness estimates of adult odonates were performed on sunny days during summer and winter. We analyzed the goodness-of-fit of the species abundances to geometric and lognormal series. We also measured the Habitat Physical Integrity Score (HPIS), pasture and forest proportions and physicochemical water parameters at each site. Only few species were abundant in up- and downstream regions. Abundance of Argia modesta was higher at the upstream (t = 3.188; df = 17; p = 0.005) than at the downstream region and this species is a potential habitat bioindicator organisms. Species richness was statistically different only in the wet season and species–abundance relations at the two regions fitted well to both geometric and lognormal series. The lack of riparian vegetation indicates a loss of habitat integrity and heterogeneity at Turvo Sujo River basin, which was mainly dominated by lake-dwelling odonate species. Low species richness differences are caused by species pool biases toward those ones capable to survive at degraded ecosystems, suggesting that the effects of water parameters are much less important than a landscape dominated by pastures and practically without forests. We suggest the use of species–abundance models (like geometric and lognormal series) to determine the degree of impacts over a given community once they are simple models and can show intrinsic processes structuring communities.     

Substitution of the catalytic acid–base Glu237 by Gln suppresses hydrolysis during glucosylation of phenolic acceptors catalyzed by Leuconostoc mesenteroides sucrose phosphorylase

Stereoselective glycosylation of a phenolic hydroxyl is a key transformation in the (bio)synthesis of natural products. Biocatalytic transglycosylation usually provides the desired glycosidic product in exquisite anomeric purity. However, loss of substrate and product to hydrolysis often limits application of the method. Kinetic studies and in situ proton NMR analysis of reaction time courses were used here to characterize glucosylation of substituted phenol acceptors by Leuconostoc mesenteroides sucrose phosphorylase in the presence of α-d-glucose 1-phosphate (αG1P) as donor substrate. In the wild-type enzyme, hydrolysis of the sugar 1-phosphate strongly prevailed (about 10-fold, ∼1.6 U/mg) over glucosyl transfer to the 2,6-difluorophenol acceptor (∼0.17 U/mg) used. A mutated phosphorylase in which the catalytic acid–base Glu²³⁷ had been replaced by Gln (E237Q) did not display hydrolase activity under transglucosylation conditions and therefore provided substantial (∼7-fold) enhancement of transfer yield. Utilization of the donor substrate was however slowed down (about 400-fold, ∼0.004 U/mg) in E237Q as compared to wild-type enzyme (∼1.6 U/mg). In a series of mono- and disubstituted phenols differing in hydroxyl pK_a between 7.02 and 8.71, the transferase activity of E237Q was found to be dependent on steric rather than electronic properties of the acceptor used. Both wild-type and mutated enzyme employed 4-nitrophenyl-α-d-glucopyranoside (4-NPG) as a slow artificial substrate for phosphorolysis and hydrolysis (native: ∼0.12 U/mg; E237Q: ∼0.02 U/mg).     

Extinction thresholds and negative responses of Afrotropical ant-following birds to forest cover loss in oil palm and agroforestry landscapes

Afrotropical ant-following birds are vulnerable to forest loss and disturbance, but critical habitat thresholds regarding their abundance and species richness in human-dominated landscapes, including industrial oil palm plantations, have never been assessed. We measured forest cover through Landsat imagery and recorded species richness and relative abundance of 20 ant-following birds in 48 plots of 1-km², covering three landscapes of Southwest Cameroon: Korup National Park, smallholder agroforestry areas (with farms embedded in forest), and an industrial oil palm plantation. We evaluated differences in encounter frequency and species richness among landscapes, and the presence of critical thresholds through enhanced adaptive regression through hinges. All species were detected in Korup National Park and the agroforestry landscape, which had similar forest cover (>85%). Only nine species were found in the oil palm plantation (forest cover = 10.3 ± 3.3%). At the 1-km² scale, the number of species and bird encounters were comparable in agroforests and the protected area: mean species richness ranged from 12.2 ± 0.6 in the park and 12.2 ± 0.6 in the agroforestry matrix to 1.0 ± 0.4 in the industrial oil palm plantation; whereas encounters decreased from 34.4 ± 3.2 to 26.1 ± 2.9 and 1.3 ± 0.4, respectively. Bird encounters decreased linearly with decreasing forest cover, down to an extinction threshold identified at 24% forest cover. Species richness declined linearly by ca. one species per 7.4% forest cover lost. We identified an extinction threshold at 52% forest cover for the most sensitive species (Criniger chloronotus, Dicrurus atripennis, and Neocossyphus poensis). Our results show that substantial proportions of forests are required to sustain complete ant-following bird assemblages in Afrotropical landscapes and confirm the high sensitivity of this bird guild to deforestation after industrial oil palm development. Securing both forest biodiversity and food production in an Afrotropical production landscape may be best attained through a combination of protected areas and wildlife-friendly agroforestry.     

Positive and negative unintended human-induced effects on Iberian mole abundance at the edge of its distribution area

Humans can unintentionally induce both positive and negative effects on wildlife presence and abundance, with organisms living in or associated with agricultural areas being good examples. Our study focused on a 1500 ha area (75 sampled 100 m × 50 m plots) at the driest edge of the endemic Iberian mole Talpa occidentalis distribution range, where the species is listed as “Vulnerable”. Here, poplar cultivations dominate wasteland and other irrigated and non-irrigated crops. The poplar irrigation system was traditionally based on a network of straight ridges, although it is rapidly being replaced with a sophisticated procedure which permits water to spread with ridges no longer being needed. In these habitats, ridges are relevant for moles because they provide dry shelters for nests. In this paper we explore (a) mole local habitat preferences and (b) the impact of changes in poplar irrigation systems on mole abundance. Iberian mole abundance positively related to earthworm biomass and numbers; however, multivariate analyses highlighted the effect of herbaceous cover (positive relationship), rocks cover and soil hardness (negative relationship), and habitat type (poplar being the preferred one). Furthermore, mole abundance was substantially higher in poplar groves where ridges were still present than where they were not. We conclude that Iberian moles in semi-arid environments are favoured by poplar plantations but, at the same time, they are highly vulnerable to recent changes in traditional agriculture practices. Therefore, this study shows how agricultural habitats can benefit some species of conservation concern, especially some temperate species at the edge of their range or in extreme ecological conditions. Changes in agricultural practices that negatively affect the suitability of such habitats can compromise these species's conservation, as we found for the Iberian mole.     

The effect of semi-natural habitats on aphids and their natural enemies across spatial and temporal scales

Semi-natural habitats in agricultural landscapes are generally assumed to enhance the biological control of insect pests based on native beneficial insects, by providing alternative prey and hosts, resources and refuges for overwintering. We hypothesized that natural enemies of winter wheat aphids should arrive sooner in fields near semi-natural habitats. We compared aphid, hoverfly (larvae and eggs) and parasitized aphid (mummies) abundances in 54 winter wheat fields located in southern France from 2003 to 2007. Six surveys were recorded each spring and were split into the early period (defined as the period before the peak of aphid growth) and the late period (after the peak). The wheat fields differed by their surrounding landscape composition measured as the proportion of semi-natural habitats (woods, hedges and grasslands), at three different spatial scales: 200 m, 500 m, and 1200 m. Despite great variability in abundance data between years, the abundance of hoverflies appeared more sensitive to landscape composition than aphid abundance was. Early abundance for both aphids and hoverflies was positively related to wood cover, but not late abundance in spring. The abundance of hoverflies was positively related to hedge and grassland cover at all spatial scales and both periods considered. Aphid parasitism was higher near hedges at the small spatial scale late in the spring. Our results confirmed that higher proportions of semi-natural habitats in agricultural landscapes enhance the biological control of pests, but this effect depends on the spatial scale, the time period in the spring and the natural enemies considered.     

Determinants of smooth-coated otter occupancy in a rapidly urbanizing coastal landscape in Southeast Asia

Urbanization often has negative impacts on wildlife, nevertheless many species can persist in heavily modified habitats. Understanding factors that promote species persistence in urbanizing landscapes is therefore important for maintaining biodiversity in changing landscapes and may inform more biodiversity-friendly development. We investigated effects of landscape-scale variables on habitat occupancy of Smooth-coated otter (Lutrogale perspicillata) in the Inner Gulf of Thailand. In this internationally important wetland complex, 86% of natural habitats have been altered and are now highly urbanized. We conducted track and sign surveys in 60, 25 km² grid cells encompassing 1,474 km². Within each cell, we quantified the landscape cover types including urban areas, natural habitat (predominately thin ribbons of mangrove along waterways), agriculture, aquaculture, and potential prey availability using a GIS and field surveys. We used occupancy models to identify habitat variables that affected probability of detection and occupancy. Estimated otter occupancy, based on the top model, was 0.33 ± 0.07 (95% CI 0.18–0.48) and detection probability was 0.50 ± 0.05 (95% CI 0.41–0.60). Otter occupancy was positively associated with the proportion of natural habitat and the cover of traditional aquaculture ponds, but negatively associated with agriculture and urban cover. The remaining natural patches appear to act as critical refuges for otter, allowing them to persist in an otherwise heavily transformed landscape. Because aquaculture ponds are likely important prey sources for otters, it may lead to conflict with aquaculture farmers. Further studies of feeding and movement patterns in cooperation with aquaculture farmers would be beneficial for developing detailed management plans for the species in this human dominated landscape.     

Modelling large spotted genet (Genetta tigrina) and slender mongoose (Galerella sanguinea) occupancy in a heterogeneous landscape of South Africa

Drivers of distribution patterns of poorly known species are among the most important aspects in conservation biology. We studied the proportion of area occupied by the large spotted genet (Genetta tigrina) and the slender mongoose (Galerella sanguine) in response to land use variables using camera-trapping data in Drakensberg Midlands, South Africa. Average estimated occupancy of large spotted genet and slender mongoose were 0.42 ± 0.10 and 0.41 ± 0.04 respectively using single season occupancy models. Altitudinal variation was found to be significant in the distribution of both species, along with human abundance for genet and availability of bushland for mongoose. Autumn influenced detection probability of both species negatively, while summer influenced slender mongoose positively. Relative human abundance was positively associated with detection probability of slender mongoose, and for large spotted genet, availability of bushland influenced positively while relative abundance of jackal (Canis mesomelas) influenced negatively. Occurrence of both species suggests that high elevations may not provide favourable ecological conditions, and bush cover appeared to be favourable habitats for both species. Either positive occurrence or detection of small carnivores to human abundance indicated their tendency to subsist in low-lying human populated areas. The present study shows the influence of a range of factors on the distribution of lesser known carnivores.     

Trentepohlia umbrina on Scots pine as a bioindicator of alkaline dust pollution

The present study was driven by the wish to broaden the selection of ecological indicators for estimating the alkaline dust pollution. The abundance of the algal species Trentepohlia umbrina was studied on Pinus sylvestris trunks, an acidic substrate that it normally does not occupy. The study was carried out in northern Estonia in the surroundings of four major limestone quarries, considerable local-level sources of dust pollution. The cover of T. umbrina on tree trunks was clearly higher near the quarries, evidently due to the elevated bark pH, its maximum values reaching ca. 30% (mean of five trees studied per sample plot). The cover of the species decreased steeply at the distance of 800–900 m from the quarries; further than 1000 m from the quarries the maximum cover was already less than 4%, and further than 2000 m less than 1%. The correlation between the cover of T. umbrina and measured bark pH values indicated a steep increase in cover at about pH 3.8–3.9; the cover values varied between 0 and 4% below and between 10 and 31% above that pH. These results confirm that T. umbrina could be used as an indicator species of alkaline dust pollution. The species forms reddish powdery coating on tree trunks, and in case of high abundance can be very conspicuous looking, being easily detectable at field.     

Butterfly communities along an elevational gradient in the Tons valley,Western Himalayas: Implications of rapid assessment for insect conservation

As time and money is limited, explicit, cost-effective, quick, and appropriate methods are needed to assist conservation planners and managers for making quick decisions. Butterflies promise to be a good model for rapid assessment and habitat monitoring studies because they are widespread, conspicuous, and easily recognizable and they are effective indicators of forest health. We conducted a rapid assessment of butterflies at five disturbance gradient sites that varied in elevation from 900 m a.s.l. to 3500 m a.s.l. for 20 days during March–April 2010 and recorded 79 butterfly species and 1504 individuals in the Tons valley in Western Himalayas. We were able to sample approximately 77% (123 species) of the estimated species richness on continuing the sampling until July 2010. Species richness at the study site is estimated to be 159 (95% CI: 145–210) species. Diversity was highest in heterogeneous habitats and decreased towards homogeneous habitats. Unique species were highly restricted to lowest disturbed sites. Using Pearson's correlation analysis, the strongest vegetative predictors of butterfly richness were plant species richness, canopy cover, and herb and shrub density. Butterfly species richness and abundance were highly correlated with altitude, temperature, relative humidity, fire signs, and livestock abundance. We also found positive cross-taxon correlation among butterflies, moths, and beetles across sites, indicating that butterflies can be used as surrogate or indicator taxa for insect conservation. Short sampling periods providing comprehensive estimates of species richness were reliable for identifying habitats and sites with the most conservation value in the Tons valley landscape.     

Bacterial diversity and community structure of the intestinal microbiome of Channel Catfish (Ictalurus punctatus) during ontogenesis

The acquisition of gut microbes does not occur randomly and is highly dependent on host factors, environmental cues, and self-assembly rules exerted by the microbes themselves. The main objective of this project was to characterize how the gut microbiome develops during the early life stages of Channel Catfish and to identify i) which bacteria are the main constituents of the gut microbiome at different ontogenesis stages, and ii) at which time point(s) the gut microbiome stabilizes. High-throughput Illumina Miseq DNA sequencing of the V4 domain of the 16S rRNA gene was used to assess the microbial community composition during the life stages of Channel Catfish along with water and feed samples. Microbiomes from fertilized eggs, sac fry, swim up fry, pre-fingerlings, and fingerlings were all significantly distinct. OTUs analyses showed that the phylum Proteobacteria, Firmicutes, Fusobacteria and Cyanobacteria dominated the Channel Catfish gut microbiome. During the early stages of ontogenesis, the fish microbiome was dynamic and highly diverse, with significant shifts occurring between fertilized eggs to sac fry (6 dph), and from sac fry to swim up fry (15 dph). The gut microbiome stabilized between the pre-fingerlings and fingerlings stage (≤90 dph) with an observed reduction in species richness. Feed had a more significantly contribution to the microbial colonization of the gut than water. We have identified the period in which the gut microbiome changes rapidly from 15 dph until 21 dph before stabilizing after 90 dph.