Pristine Sites Research Articles

Spontaneous progression of experimental peri-implantitis in augmented and pristine bone: A pre-clinical in vivo study.

To examine the progression of experimental peri-implantitis around different implants placed in augmented and pristine sites. Six labrador dogs were used. Three months after tooth extraction, four implants with different surface modifications were installed on each side of the mandible. A standard osteotomy was applied on one side, while on the contralateral side the osteotomy was modified, resulting in a gap between the implant and the bone wall. The gap was filled with a bone substitute and covered by a resorbable membrane. Three months after implant installation, implants were exposed and healing abutments were connected. Two months later, oral hygiene procedures were abandoned and a cotton ligature was placed in a submarginal position around the neck of all implants and kept in place for 4weeks. Following ligature removal, plaque formation continued for 6months (spontaneous progression period). Radiographs were obtained throughout the experiment, and biopsies were collected and prepared for histological evaluation at the end of the spontaneous progression period. Differences in bone loss during the spontaneous progression period between pristine and augmented sites were small. The size and vertical dimension of the peri-implantitis lesion were larger at augmented than at pristine sites. Implants with non-modified surfaces exhibited smaller amounts of bone loss and smaller dimensions of peri-implantitis lesions than implants with modified surfaces. Small differences in spontaneous progression of peri-implantitis were detected between pristine and augmented sites. Implants with modified surfaces exhibited more bone loss and larger lesions than implants with non-modified surfaces, irrespective of the type of surrounding bone.

The effect of heavy metal contamination pre-conditioning in the heat stress tolerance of native and invasive Mediterranean halophytes

Abstract Salt marshes are worldwide recognized for their unique and important ecological role. According to the Intergovernmental Panel on Climatic Change (IPCC), the frequency and intensity of warming events will rise due to global changes. Halophyte plants, inhabiting salt marshes are known for being highly tolerant to various abiotic stresses, nonetheless, although it has been acknowledged that the tolerance response is species specific there could also be differences at the population level. The present work aims to determine if the life history of two halophytes (Halimione portulacoides and Spartina patens), namely in terms of contaminant exposure, influences inter-populational heat tolerance. For this purpose, individuals from both species collected at pristine and contaminated sites were exposed to normal and increased temperature conditions, and its physiological fitness evaluated throughout biochemical and biophysical analysis. The photobiological traits, pigment and fatty acid profiles and oxidative stress biomarkers analyses of warming treated individuals, indicate that chronic heavy metal pre-conditioning significantly influences the heat stress tolerance of the native halophyte plants. Halimione portulacoides individuals collected at heavy metal contaminated salt marsh appeared more tolerant to heat stress. On the other hand, the invasive S. patens from the pristine site showed higher tolerance to heat stress. Thus, the pre-conditioning influences the tolerance mechanisms can affect the way in which salt marsh communities will evolve in the future, possibly being different through salt marshes. The contaminated marsh can be more resilient to invasion than the non-contaminated marsh, since the native species has benefited from this pre-conditioning. Moreover, and from the ecophysiological point the set of biophysical and biochemical indicators were tested, show a high efficiency in describing the ecophysiological traits, both between species and populations, facing different pre-conditioning histories.

Arsenic speciation in the bracket fungus Fomitopsis betulina from contaminated and pristine sites.

Uptake, distribution and speciation of arsenic (As) were determined in the bracket fungus Fomitopsis betulina (previously Piptoporus betulinus), commonly known as the birch polypore, collected from a woodland adjacent to a highly contaminated former mine in the Southwest UK and at an uncontaminated site in Quebec, Canada, with no past or present mining activity. The fruiting body was divided into cap, centre and pores representing the top, middle and underside to identify trends in the distribution and transformation of As. Total As, determined by inductively coupled plasma-mass spectrometry (ICP-MS), was approximately tenfold higher in the mushroom from the contaminated compared to the uncontaminated site. Overall, accumulation of As was low relative to values reported for some soil-dwelling species, with maximum levels of 1.6mg/kg at the contaminated site. Arsenic speciation was performed on aqueous extracts via both anion and cation high-performance liquid chromatography-ICP-MS (HPLC-ICP-MS) and on whole dried samples using X-ray absorption near edge structure (XANES) analysis. Seven As species were detected in F. betulina from the contaminated site by HPLC-ICP-MS: arsenite (AsIII), arsenate (AsV), dimethylarsinate (DMAV), methylarsonate (MAV), trimethylarsine oxide (TMAO), tetramethylarsonium ion (Tetra) and trace levels of arsenobetaine (AB). The same As species were observed at the uncontaminated site with the exception of TMAO and Tetra. Arsenic species were localized throughout the fruiting body at the contaminated site, with the cap and pores containing a majority of AsV, only the cap containing TMAO, and the pores containing higher concentrations of DMAV and MAV as well as tetra and a trace of AB. XANES analysis demonstrated that the predominant form of As at the contaminated site was inorganic AsIII coordinated with sulphur or oxygen and AsV coordinated with oxygen. This is the first account of arsenic speciation in F. betulina or any fungi of the family Fomitopsidaceae.

Phosphorus and suspended matter retention in mangroves affected by shrimp farm effluents in NE Brazil.

This study compares two mangroves with different land uses in the Jaguaribe River estuary, harboring large shrimp farms, and in the more pristine Pacotí River estuary. Normalized Difference Vegetation Index (NDVI) was used to compare the overall health of the forests. Measures of suspended matter (TSS), total (TP), particulate (PartP) and soluble reactive phosphorus (SRP) in the inflow and outflow waters of tidal channels draining the mangroves were performed during tidal cycles. NDVI varied from 0.65 in the Jaguaribe estuary to 0.85 in the Pacotí, suggesting the impact of shrimp farm effluents on mangrove canopy cover. The shrimp farm influenced site showed 10 times larger absolute ∑P (TP + PartP + SRP) = 1.2-5.2 kg.hr-1) flux than the pristine site (∑P = 0.22 kg.hr-1). Tidal balances showed smaller retentions of the total influx: 28-54%; 44-45%; 38-65% and 8-53% for TSS; TP; SRP; and PartP respectively, in the shrimp farm influenced site to over 93% of the total tidal input of TSS and all P fractions in the pristine mangrove. This suggests that mangrove phosphorus accumulation is decreased in the forest with lower NDVI and limits mangrove's potential as a natural barrier to the nutrient transport to adjacent estuarine and coastal waters.

Burrowing behavior and burrowing energetics of a bioindicator under human disturbance.

Bioindicator species are extensively used for rapid assessment of ecological changes. Their use commonly focuses on changes in population abundance and individual sizes in response to environmental change. These numerical and demographic shifts likely have behavioral and physiological mechanistic drivers that, if understood, could provide additional insights into the use of these species as bioindicators of habitat health.The Atlantic ghost crab, Ocypode quadrata, is a global bioindicator species of human disturbance on sandy shores. Individual size and population abundance of O. quadrata decline dramatically at sites with human disturbance, and the causes of this phenomenon remain unclear.Here, we test the hypothesis that individual and population‐level changes at disturbed sites reflect changes in burrowing behavior and energetics. Specifically, we examine whether or not the burrowing behavior (e.g., burrow fidelity and longevity) of O. quadrata changes because of human disturbance. We also examine energy required for burrowing by O. quadrata across different levels of human disturbance.We show that O. quadrata have the highest burrow fidelity and longevity at sites with low level of human impact, and weakest burrow fidelity and longevity at pristine sites. O. quadrata reduce the burrowing energy allocation by manipulating the burrow dimension and increasing the burrow longevity even under low levels of human disturbance.Overall, this study shows that human disturbances not only change the behavior of organisms, but also shift energetic balance. Our results support the use of a bioenergetic approach to better understand how human disturbances influence natural populations, and the specific use of this approach with this bioindicator species.

Community Structure of Soil Nematodes Associated with the Rhizosphere of Solanum Lycopersicum in a Major Production Area in Argentina: a Case Study Among Agroecosystem Types

The objective of this work was to describe the status of the assemblages of soil nematodes associated with tomato crops, in a major tomato production area in Argentina, by studying ecological indices of nematode food web and determining which indices describe alterations in horticultural soils. Three agroecosystem types were compared: agroecological, conventional with organic amendments, and conventional with methyl bromide (MeBr) application. A pristine site without anthropogenic intervention was also studied. Abundance, frequency, diversity indices, maturity indices, trophic groups, colonizer-persister values (cp), and guilds of nematodes were analyzed and compared statistically between the sampling sites. The most abundant genera in the agroecosystems were Rhabditis, Helicotylenchus, and Filenchus belonging to the guilds bacterivorous (Ba1), plant feeders (Pl3), and fungivorous (Fu2). Within agroecosystems, the agroecological site showed the highest values of diversity and maturity, while the lowest values were found in the site treated with MeBr. Trophic groups, cp, guilds, and the indices provided useful information on the state of maturity and enrichment that effectively contrasted and differentiated the practices of horticultural management. This updated report of the nematode fauna constitutes one of the most important for the horticultural region of La Plata considering the scarcity of studies on this subject.

Graphene oxide supported Pd-Fe nanohybrid as an efficient electrocatalyst for proton exchange membrane fuel cells

The experimental realization and computational validation for graphene oxide (GO) supported palladium (Pd)-iron (Fe) nanohybrids as a new generation electrocatalyst for proton-exchange membrane fuel cells (PEMFCs) has been reported. The experimental apprehension of the present catalyst system has been initiated with the graphene oxide, followed by the doping of Pd and Fe via thermal inter calation of palladium chloride and iron chloride with the in-situ downstream reduction to get nanohybrids of the GO-Pd-Fe. These nanohybrids are subsequently characterized by RAMAN, FT-IR, UV–Vis, XRD, SEM, EDS, TEM and HRTEM analysis. Furthermore, the first principle calculations based on Density Functional Theory (DFT) with semi-empirical Grimme DFT-D2 correction has been performed to support the experimental findings. Computational results revealed the alteration of graphene electronic nature from zero-band gaped to metallic/semi-metallic on adsorption of transition metal clusters. Moreover, the defect sites of the graphene surface are more favorable than the pristine sites for transition metal adsorption owing to the strong binding energies of the former. Electrochemical studies show that GO-Pd-Fe nanohybrids catalyst (Pd: Fe = 2:1) demonstrates excellent catalytic activity as well as the higher electrochemical surface area of (58.08 m2/g Pd–Fe)−1 which is higher than the commercially available Pt/C catalyst with electrochemical surface area 37.87 m2/(g Pt)−1.

Chemical characterization and phytotoxicity assessment of peri-urban soils using seed germination and root elongation tests.

The peri-urban soil is exposed to pollutants because of its proximity to the city, which may influence the quality of agricultural products. In this study, the occurrence of 16 trace elements (TEs), 16 polycyclic aromatic hydrocarbons (PAHs), and 33 contaminants of emerging concern (CECs) was analyzed in two soil sites of the peri-urban area of Barcelona (Spain) (S2 and S3) and a pristine site (S1). Levels of Pb (S2 164 and S3 150 mg kg-1) are around 2.5 times higher than the guideline values. Values for Cu (178 mg kg-1) in S2 are 1.8-fold higher, whereas for Zn, levels are slightly above the threshold in S2 (208 mg kg-1) and S3 (217 mg kg-1). The total concentrations of PAHs are significantly below the limits: 24 ng g-1 dw (S1), 38 ng g-1 dw (S2), 49 ng g-1 dw (S3), whereas only some CECs are detected with low concentrations. We also developed a simple and rapid method to assess soil pollution. Here, we use two plant growth indexes (seed germination rate and root elongation at the initial stage) of three seeds (lettuce, tomato, and cauliflower) to assess soil chemical contamination on agriculture. In the peri-urban soil, the concentration of Pb was 2.5 times higher than the guideline values, whereas for Cu and Zn, values were slightly above their limits, while only few PAHs and CECs were detected. Results for principal component analysis suggest that root elongation is a more sensitive measurement endpoint than germination rate, especially for lettuce. The germination rate of tomato relied on the nitrate in the soil and decreased sharply in the site with pollution of Cu and As. Under the specific conditions of this study, cauliflower should not be recommended to assess environmental pollution due to its low sensitivity to pollutants. In conclusion, this is a low-cost, simple, and rapid method for evaluating the effects of chemical pollution of agriculture soils on seed growth.

Physiological and behavioral responses to anthropogenic stressors in a human-tolerant mammal

Abstract As humans continue to alter natural habitats, many wild animals are facing novel suites of environmental stimuli. These changes, including increased human–wildlife interactions, may exert sublethal impacts on wildlife such as alterations in stress physiology and behavior. California ground squirrels (Otospermophilus beecheyi) occur in human-modified as well as more pristine environments, where they face a variety of anthropogenic and naturally occurring threats. This makes this species a valuable model for examining the effects of diverse challenges on the physiology and behavior of free-living mammals. To explore potential sublethal effects of habitat modification on O. beecheyi, we compared body masses, behaviors, and fecal glucocorticoid metabolite (FGM) levels for free-living squirrels in human-disturbed versus undisturbed habitats. Prior to these analyses, we validated the use of FGMs in this species by exposing captive O. beecheyi to pharmacological and handling challenges; both challenges produced significant increases in FGMs in the study animals. While FGM responses were repeatable within captive individuals, responses by free-living animals were more variable, perhaps reflecting a greater range of life-history traits and environmental conditions within natural populations of squirrels. Animals from our human-disturbed study site had significantly higher FGMs, significantly lower body masses, and were significantly less behaviorally reactive to humans than those from our more pristine study site. Thus, despite frequent exposure of California ground squirrels to human impacts, anthropogenic stressors appear to influence stress physiology and other phenotypic traits in this species. These findings suggest that even human-tolerant mammalian species may experience important sublethal consequences due to human modifications of natural habitats.

Effect of soil disturbance by agricultural activities on the life history traits of monkey frog (Pithecopus azureus)

We assessed whether soil disturbance by agricultural activity influences the growth, development, and survival of individuals in the larval, metamorphic, and postmetamorphic stages of amphibians. Tadpoles of Pithecopus azureus (Cope, 1862) were reared in microcosms assembled with soil from two sites, a pristine site and a rice field. For 5 weeks, we recorded tadpole growth and development as well as physicochemical variable of the water: temperature, conductivity, dissolved oxygen, and pH. The results show that rice field soil produced a level of acidification in the water that influenced the growth and development rates of tadpoles. Tadpoles reared in rice soil had a significantly lower growth rate and body length, and during a specified period, the development rate of the tadpole was significantly lower than that of tadpoles in pristine soil. Overall, tadpoles in rice soil took 3 days longer to reach metamorphosis and 1 additional day to complete metamorphosis compared with tadpoles exposed to pristine soil. Our study shows that disturbed soils modify the physicochemical conditions of temporary ponds, impacting on the initial life stage of the anurans.

Extensive variability in the gut microbiome of a highly-specialized and critically endangered lemur species across sites.

Deforestation continues to jeopardize Malagasy primates as viable habitats become smaller, more fragmented, and more disturbed. This deforestation can lead to changes in diet, microhabitat, and gene flow between populations of endangered species, and it remains unclear how these changes may affect gut microbiome (GM) characteristics. The black-and-white ruffed lemur (Varecia variegata), which is among Madagascar's most threatened lemur species, provides a critical model for understanding the relationships between historical and on-going deforestation (habitat disturbance), feeding ecology, and GM composition and diversity. We studied four populations inhabiting two rainforests (relatively pristine vs. highly disturbed) in southeastern Madagascar. We conducted full-day focal animal behavioral follows and collected fecal samples opportunistically across a three-month period. Our results indicate that lemurs inhabiting sites characterized by habitat disturbance and low dietary diversity exhibited reduced gut microbial alpha diversity. We also show that these same factors were associated with high community dissimilarity using weighted and unweighted UniFrac metrics. Finally, an indicator species analysis showed that the most pristine site was characterized by an abundance of methanogenic archaea. While it is impossible to disentangle the relative contributions of each confounding variable presented by our sampling design, these results provide crucial information about GM variability, thereby underscoring the importance of monitoring endangered species at the population-level.

Strengths and potential pitfalls of hay transfer for ecological restoration revealed by RAD-seq analysis in floodplain Arabis species.

Achieving high intraspecific genetic diversity is a critical goal in ecological restoration as it increases the adaptive potential and long-term resilience of populations. Thus, we investigated genetic diversity within and between pristine sites in a fossil floodplain and compared it to sites restored by hay transfer between 1997 and 2014. RAD-seq genotyping revealed that the stenoecious floodplain species Arabis nemorensis is co-occurring with individuals that, based on ploidy, ITS-sequencing and morphology, probably belong to the close relative Arabis sagittata, which has a documented preference for dry calcareous grasslands but has not been reported in floodplain meadows. We show that hay transfer maintains genetic diversity for both species. Additionally, in A.sagittata, transfer from multiple genetically isolated pristine sites resulted in restored sites with increased diversity and admixed local genotypes. In A.nemorensis, transfer did not create novel admixture dynamics because genetic diversity between pristine sites was less differentiated. Thus, the effects of hay transfer on genetic diversity also depend on the genetic make-up of the donor communities of each species, especially when local material is mixed. Our results demonstrate the efficiency of hay transfer for habitat restoration and emphasize the importance of prerestoration characterization of microgeographic patterns of intraspecific diversity of the community to guarantee that restoration practices reach their goal, that is maximize the adaptive potential of the entire restored plant community. Overlooking these patterns may alter the balance between species in the community. Additionally, our comparison of summary statistics obtained from de novo- and reference-based RAD-seq pipelines shows that the genomic impact of restoration can be reliably monitored in species lacking prior genomic knowledge.

Periodontal healing by periodontal ligament fiber with or without cells: A preclinical study of the decellularized periodontal ligament in a tooth replantation model.

The periodontal ligament (PDL) comprises cells embedded in the extracellular matrix (ECM) and is required for periodontal healing upon tooth transplantation. However, the extent to which the ECM contributes to periodontal regeneration remains unknown. This study aimed to evaluate effects of separate PDL matrix without cells on periodontal healing. Mandibular premolars extracted from six beagle dogs, were 1) left untreated, 2) decellularized, or 3) surface planed. Cytologic, histologic, scanning electron microscopy, and transmission electron microscopy analyses confirmed that detergents could be used to decellularize the PDL. An additional circumferential osteotomy was performed to replant dental roots into extraction sockets. Radiography and histology were used to evaluate periodontal regeneration 8weeks later, with the data adjusted for multiple testing. In pristine extraction sites, total root resorption (P=0.034), recovered PDL space (P=0.012), and new cementum (P=0.004) were greater in untreated teeth than in roots that underwent surface planing. There were no significant changes when comparing untreated teeth with teeth having a decellularized PDL (P=0.081, P=0.170, and P=1.000, respectively), and decellularized teeth showed significant increase of new cementum compared to surface planed teeth (P=0.048). In the defect area, only the recovered PDL space (P=0.034) was greater in untreated teeth when comparing with denuded roots. These results suggest that in addition to untreated PDL, decellularized PDL also partially supports reattachment (particularly cementogenesis) in pristine extraction sites but not in defect areas.

Impact of local and regional emission sources on air quality in foothills of the Himalaya during spring 2016: An observation, satellite and modeling perspective

Chitwan National Park in south-central Nepal is one of the few remaining protected forest ecosystems in South Asia with rich flora and fauna. However, in recent years, southern Nepal including the region of the National park area have experienced deteriorating air quality, which has raised concerns about its impact on ecosystem and public health. The region experiences forest fires during pre-monsoon season and thus, provide an ideal opportunity not only to study its impact on air quality but also to provide source specific diagnostic ratios. In this study, we report measurements of black carbon (BC), trace gases as well as particulate matter (PM10, PM2.5 and PM1) from Chitwan Air Quality Monitoring Station (CAQMS) during pre-monsoon season (February–May 2016). Average concentrations of BC, PM10, PM2.5, PM1 were found to be 10.9 ± 6.9 μg m−3, 156.4 ± 68.2 μg m−3, 95.9 ± 49.0 μg m−3, 80.1 ± 45.5 μg m−3 which are much higher than the prescribed 24 h limits of World Health Organization (25 μg m−3 for PM10 and 10 μg m−3 for PM2.5). Furthermore, average concentrations of trace gases, CO, CO2 and CH4 were 713.4 ± 476.6 ppbv, 446.0 ± 15.3 ppm and 2.182 ± 0.117 ppm respectively which are also higher than those in the surrounding regions. We identified two pollution events (Event #1 from 16 to 28 March 2016 and Event #2 from 6 to 17 April 2016) and found that surface concentrations of all measured species increased by a factor of 2–3 during these events. The BC/CO ratio of 16.3 ± 2.0, 11.1 ± 3.7 and 9.9 ± 4.2 ng m−3 ppbv−1 was observed during Event#1, Event#2 and during non-event period. Based on MODIS active fire counts and Ängstrȯm absorption exponent (AAE values of 1.8 and 1.9 during Event #1 and #2 respectively), we found that biomass burning (BB) activities were an important source during these events. This is further substantiated by relatively higher contribution of BB to observed BC concentration during both the events (73% and 75% during Event#1 and #2 respectively). Furthermore, a Langrangian modeling framework was used to quantify the contribution of local and regional fires to BC concentration. The contribution of local fires to modelled BC at CAQMS during Event #1 and #2 is estimated to be ~70% and ~78%, respectively. The satellite retrievals of AOD, NO2 and CO also exhibit a significant increase in columnar concentration during these pollution events. The CALIOP retrieved vertical profile of extinction coefficient further confirmed that these pollutants are not only confined near the surface but are lifted up to 2 km altitude, which can subsequently be transported to high-altitude pristine sites and can impose serious implications on the cryosphere.

Histological Findings in Wild Rodents of the Great Basin

In the western United States, significant environmental change is expected through the combined effects of climate change, tree mortality, drought, and invasive species. Wild animals can be used as indicators of threats to populations and even entire communities by looking for histopathological changes in their tissues. This method may identify threats to wild populations quickly and more accurately than waiting to observe population declines; however, baseline data are needed for comparisons. Here, rodents are surveyed at 5 sites in the Great Basin to record histopathological changes. Additionally, one site is next to a copper mine that was in operation for nearly 100 years. This site is compared to the other more pristine sites. Liver, lung, heart, and kidney tissues of 143 rodents from 10 species were processed and examined using standard histological methods. Thirty percent of rodents had histopathological changes. The most common histopathological changes were extramedullary hematopoiesis (11.9%), hyperplastic BALT (6.3%), and pyelitis (4.9%). Two pathogens were found: the nematode Capillaria hepatica (0.7%) and the fungus Emmonsia crescens (2.8%). The most common rodent captured, Peromyscus maniculatus (n = 116), was used to determine whether sex and mass predict histopathological changes. Body mass, not sex, was the best predictor, suggesting that heavier, older individuals should be selectively sampled if the goal is to assess potential threats to rodent populations. Data such as these can be compared to future data to assess populations and communities for effects of environmental change.

ЗАСТОСУВАННЯ НОВІТНЬОГО ІНТЕГРАЛЬНОГО ІНДЕКСУ ОКИСНОГО СТРЕСУ В ОЦІНЦІ ВПЛИВУ ДОВКІЛЛЯ НА ПРІСНОВОДНИХ МОЛЮСКІВ

The adverse environmental impacts cause the oxidative stress responsein the aquatic animals. However, depending on the severity and duration of impact, this response can be highly different. The aim of this study was the analysis of available results of the evaluation of antioxidant activities in the freshwater mollusks in the sense of the successfulness of the oxidative stress response. The recently proposed integrative index ‘Preparation to the oxidative stress’ (POS) was applied. Three populations of bivalve mollusks from the basin of the river Dniester were compared during three seasons, and in their ability to withstand heating (25o C and 30o C during 14 days) and exposure to ionizing radiation (14 days after the acute exposure to 2 mGy). The musselswere sampled in the low disturbed pristine site, highly polluted agricultural region and the cooling pond of the nuclear power plant with the constantly elevated temperature. The parameters for the calculation of POS included superoxide dismutase activity, catalase activity, glutathione S-transferase activity, glutathione concentration, and metallothionein (from its thiol groups) concentration. The values were calculated as the magnitude of change (as % change) in comparison to the corresponding control (less disturbed field group or non-exposed group). Three criteria for POS were applied. The number of the positive and negative changes and their limits were indicated. The analysis have shown that the POS responses were in the limits of adaptive ability in all studied cases. However, the results of POS calculation allowed the distinguishing of the responses that arerealized in the field and experimental exposures of mollusks.The most distinct responses were shown for the glutathione (mainly positive changes) whereas the metalothionein level was mainly oppressed, particularly under the heating. The depressive direction was estimated in the cases of extreme temperatures, irradiation and, mainly for the mollusks from the highly polluted sites. The key importance of POS as a survival strategy of the mussels exposed to adverse impact depending on the life historyis evident.

Are drivers of microbial diatom distributions context dependent in human-impacted and pristine environments?

Species occurrences are influenced by numerous factors whose effects may be context dependent. Thus, the magnitude of the effects and their relative importance to species distributions may vary among ecosystems due to anthropogenic stressors. To investigate context dependency in factors governing microbial bioindicators, we developed species distribution models (SDMs) for epilithic stream diatom species in human-impacted and pristine sites separately. We performed SDMs using boosted regression trees for 110 stream diatom species, which were common to both data sets, in 164 human-impacted and 164 pristine sites in Finland (covering ~1,000km, 60° to 68°N). For each species and site group, two sets of models were conducted: climate model, comprising three climatic variables, and full model, comprising the climatic and six local environmental variables. No significant difference in model performance was found between the site groups. However, climatic variables had greater importance compared with local environmental variables in pristine sites, whereas local environmental variables had greater importance in human-impacted sites as hypothesized. Water balance and conductivity were the key variables in human-impacted sites. The relative importance of climatic and local environmental variables varied among individual species, but also between the site groups. We found a clear context dependency among the variables influencing stream diatom distributions as the most important factors varied both among species and between the site groups. In human-impacted streams, species distributions were mainly governed by water chemistry, whereas in pristine streams by climate. We suggest that climatic models may be suitable in pristine ecosystems, whereas the full models comprising both climatic and local environmental variables should be used in human-impacted ecosystems.

Contamination impact and human health risk assessment of heavy metals in surface soils from selected major mining areas in Ghana.

Analysis of soil samples around pristine and major gold-mining areas in Ghana was carried out for heavy metals as part of a larger soil contamination and metal background study. The surface soil samples were digested using microwave digester (aqua regia) and analyzed with ICP-MS for As, Cd, Hg, Zn, Co, Cu, Mn, Fe, Al, V, Cr, and Pb. The average concentrations (mg/L) for the metals ranged from 0.01 ± 0.01 (Cd) to 86,859.36 ± 47.07 (Fe) for the pristine sites, and 0.01 ± 0.01 (Cd) to 59,006.95 ± 79.06 (Fe) for the mining sites. Mercury was below the detection limit of the analytical instrument (0.029). The concentrations of heavy metals from this study were used to assess their contamination levels, and health risks. The results showed that, the metals ranked by severity of health risks as As > Pb > Cr > Cd. Principal component analysis (PCA) and cluster analysis showed two groupings with the PCA showing metals variability explained by 79.02%. Results from the PCA and Cluster analysis indicate anthropogenic sources of the metals which may be emanating from gold-mining activities. Results from multi-criteria ranking and pattern recognition employing PROMETHEE and GAIA revealed major contribution of the metals from the mining sites with metal variability explained by 72.83%. This is the first time a multi-criteria approach is employed to characterize heavy metal contamination in Ghana, and the study nevertheless brought to light the impact of mining on human health and the environment with implications for other mineral areas around the globe.

Environmental and spatial factors drive diatom species distribution in Alpine streams: Implications for biomonitoring

Abstract Given their documented capacity to track changes in environmental conditions and human alterations, benthic diatom communities are at present widely used in biomonitoring programs to evaluate stream water quality. However, it is becoming more and more evident that species ecological preferences are not the only drivers of diatom community composition, since dispersal-related processes also play a role. This is particularly compelling in Alpine streams, where orographic conformation and human-related impacts limit dispersal of organisms. In addition, several environmental variables may influence diatom community in pristine or impacted sites. We here investigate the differential role of environmental and spatial factors in driving the community assemblages of diatoms in streams of the Eastern Italian Alps, focusing on both taxonomic and functional composition. We analysed data from 110 samples collected on two different geological substrates, i.e. calcareous and siliceous, during the last eight years of biomonitoring programs, among which 64 collected in reference sites and 46 in impacted sites. We first evaluated whether diatom communities in reference and impacted sites are differentially shaped by environmental and spatial factors, highlighting the major role of spatial constraints in both of them. In particular, anthropogenic disruption of longitudinal connectivity in streams likely shaped impacted communities, as demonstrated by the increasing abundance of motile taxa, which are associated with physical disturbance. Conversely, reference communities were mostly affected by spatially structured environmental variables, especially those related to streambed lithology. We then compared the taxonomic and functional composition of diatom communities between the two geological substrates in both reference and impacted sites to better highlight the differential role of this factor. Our results demonstrate that lithology strongly drives diatom community composition in reference but not in impacted sites, confirming our previous observations. The analysis of functional traits, however, highlighted how differences were due not only to the geological substrates, but also to other environmental variables, like flow velocity. Overall, the effect of the spatial component on the structure of diatom assemblages can represent a background noise in the framework of the river quality assessment, and this should be taken into account especially in those countries, like Italy, covering a broad range of mountain areas.

Сокращение площади малонарушенных лесных территорий на примере Двинско-Пинежского междуречья

Area reduction of intact forest landscapes (IFL) is one of the worldʼs problems. Disappearing of pristine forests endangers endemic species of animals that are not able to survive on the lands transformed and fragmented by human. The pristine forest site located in the European North of Russia in the Dvina-Pinega interfluve is a clear example of the forest area changed over the last 17 years. According to the World Wildlife Fund, the survival of the reindeer, which is listed in the Red Book of Russia, in Arkhangelsk region directly depends on this territory. Borders determination of IFLs is carried out by the procedures developed by environmental organizations. Medium-resolution satellite images are used to define the borders, which can be used for recognition of cuttings, burnings, and forest roads. Hereafter, the selected items are excluded from the boders of this territory. In the research, we had used layers with the previously defined (in 2000 and 2013) borders of the IFL; data on the IFL borders in 2017 were obtained through the decoding satellite images and updating the previous border in 2013. The territory of the Dvina-Pinega IFL decreased by 375 520 ha from 2000 to 2017. The reduction of this territory was directly caused by human activity, namely the ongoing logging and development of a forest road network. As the data analysis of the last 17 years has shown, the main factor negatively influencing this process is development of the road network in the region.For citation: Karpov A.A. Area Reduction of Intact Forest Landscapes on the Example of the Dvina-Pinega Interfluve. Lesnoy Zhurnal [Forestry Journal], 2019, no. 3, pp. 152–158. DOI: 10.17238/issn0536-1036.2019.3.152