Structuring forces and β-diversity of benthic diatom metacommunities in soda pans of the Carpathian Basin

Small soda lakes represent one of the most vulnerable ecosystem types due to their high hydrological sensitivity to climate change and anthropogenic interventions. Since diatoms are excellent bioindicators, determining the β-diversity and the structuring dynamics of diatom metacommunities can provide valuable information for conservation planning for soda pans. In this study, two diatom metacommunities were surveyed monthly during a one-year period from distinct regions of the Carpathian basin: the Fert?-Hanság National Park (FH) between 2013 and 2014, and the Danube-Tisza Interfluve (DT) between 2014 and 2015. We explored whether β-diversity of diatom assemblages in the two regions is enhanced by species turnover or nestedness (related to richness differences) and investigated the role of deterministic and stochastic processes in shaping β-diversity patterns. Furthermore, we evaluated the contribution of environmental variables, geographic distance and temporal variation to community structure. High β-diversity (>90%) was revealed for both metacommunities, and was maintained primarily by species turnover. Within the metacommunity of the DT where the natural hydrological cycle of soda pans is not disturbed, diatom communities assembled mainly due to the selection force of environment at a spatiotemporal scale. In the soda pans located in the habitat reconstruction area of the FH, besides species-sorting, significant temporal variation in community structure appeared as a result of water management and periodic water supply. Our results point to the need for a conservation management strategy which maintains the natural hydrological regime of small saline lakes, and therefore their habitat heterogeneity which is of high conservation value.     

Assessment of the habitat conditions of a rare and endangered inland saline wetland community with Bolboschoenus maritimus (L.) Palla dominance in Southeastern Europe: the effects of physical–chemical water and soil properties

Wetlands Ecology and Management - Continental inland saline wetlands are among the most endangered habitats in Europe. In the Danube-Tisza-Danube canal network (Serbia, Southeastern Europe), which...     

A temporal comparison of a benthic infaunal community southwest of St. Lawrence Island, Bering Sea between 2006 and 1970–1974

Benthic infaunal biomass and abundance may be changing in Bering Sea communities. This study compared benthic infaunal biomass, abundance, and community composition southwest of St. Lawrence Island in an important forage area for benthic-feeding birds and mammals between 1970–1974 and 2006. Invertebrate biomass and abundance were significantly greater in 2006 than in 1970–1974 primarily due to high nuculid (Bivalvia) biomass and abundance that contributed 13.2% (biomass) and 8.5% (abundance) to differences in community structure between the sampling periods. This is in contrast to St. Lawrence Island Polynya studies conducted in the 1980s and 1990s that documented decreases in benthic biomass and abundance. Spatial scale of sampling, selective predation, a strong recruitment event, and/or sampling design may account for the difference in trends among the studies.     

A mosaic of opportunities? Spatio-temporal patterns of bat diversity and activity in a strongly humanized Mediterranean wetland

The Baixo Vouga Lagunar (BVL) landscape, in the Portuguese central-west coast, harbours a mosaic of wetland habitat types, interspersed by intensive and extensive agricultural fields, pastures, production forests and urban areas. In this study, we aimed to determine the species composition and the structure of the bat assemblages of the different habitats that constitute this heterogeneous landscape and to investigate seasonal changes in the patterns of bat diversity and activity across habitats. We acoustically sampled bats across 24 sampling sites representative of the eight main habitat types that shape the landscape—Bocage, forests, maize fields, marshlands, reed beds, rice fields, sea rushes and urban settlements. We compared bat richness, diversity and evenness across habitat types and seasons. We analysed habitat-specific and season-specific overall bat activity, and because habitat selection by bats is known to reflect morphological characters, foraging strategies and echolocation call structures, we also analysed the activity of individual species and of eco-morphological guilds. From 1,544 bat-passes recorded, we identified 12 species. Pipistrellus pygmaeus, Pipistrellus pipistrellus and Eptesicus serotinus/Eptesicus isabellinus were the most frequently recorded. Species composition and activity were similar across habitats, whilst exhibiting strong seasonal dynamics within habitats. Our results suggest that the mosaicism of the landscape provides several opportunities for bats, enabling them to explore different resources in distinct habitat patches. However, it may also reflect a forced exploitation of less optimal habitats and resources by bats, due to the scarcity of opportunities provided by fragmented landscapes.     

What triggers seizures in neurocysticercosis? A MRI-based study in pig farming community from a district of North India

Colloidal and calcified cysts are considered responsible for seizure in neurocysticercosis (NCC); however, calcified cysts have also been reported in asymptomatic individuals. We carried out a MRI-based study in a rural pig farming community of North India to detect the various stages, locations and numbers of the cyst in asymptomatic individuals and compared them with symptomatic NCC cases to see its association with occurrence of seizures. A total of 107 asymptomatic family members of 29 symptomatic NCC confirmed cases were evaluated clinically, immunologically and by neuroimaging for NCC. MRI-based staging of the parasite was done in both groups, and compared to look for the differences, if any. Thirty-one (29.0%) asymptomatic family members of symptomatic cases were diagnosed to have NCC. There was no difference in proportion of colloidal/degenerating and calcified stages of the parasite between symptomatic and asymptomatic groups; however, significantly higher proportion of the asymptomatic populations had vesicular stage of the parasite (P = 0.029). Our findings show that a large number of individuals harboring different stages of cysticerci in their brain remain symptoms free and question the belief that the degenerating/calcified stages of the parasite are primarily responsible for seizure occurrence in NCC.     

Filling of a wetland (Seine estuary,France): natural eutrophication or anthropogenic process? A sedimentological and geochemical study of wetland organic sediments

Hydrobiologia - For over a century the Seine estuary has been highly affected by human activities, resulting in a reduction of the surface of wetland habitat. Several ponds of the Vernier Marsh,...     

Do spider diversity and assemblages change in different contiguous habitats? A case study in the protected habitats of the humid chaco ecoregion, northeast Argentina

Spiders are a megadiverse group that can be useful indicators of the overall species richness and health of biotic communities. The spider diversity in subtropical forests of the Neotropical region are not yet well known, especially in Argentinean subtropical forests where systematic fieldwork has not been done until recently. The Great Chaco is very important as the unique dry subtropical forest of the earth, but it is suffering increasing degradation by the advance of agriculture. Spider communities have been shown to be more directly influenced by vegetation architecture than vegetation species composition. In this study, we aim to assess whether spider diversity and assemblages change in adjacent habitats with different types of vegetation. We compare the diversity and spider assemblages in two different contiguous protected habitats (hygrophilous woodland and savannah parkland) of the Mburucuyá National Park, (Humid Chaco ecoregion). Seasonal samples were obtained using three types of sampling methods: pitfall trapping, beating, and manual litter extraction. The spider assemblages were different in the studied areas, and the abundance, diversity, evenness, and species richness were higher in the hygrophilous woodland than the savannah parkland. These differences in spider diversity and assemblages indicate that both types of habitats are important if the biodiversity is to be conserved in the Chaco ecoregion, where different types of habitat are shown as a patchy distribution.     

Can biochemical traits bridge the gap between genomics and plant performance? A study in rice under drought

The possibility of introducing metabolic/biochemical phenotyping to complement genomics-based predictions in breeding pipelines has been considered for years. Here we examine to what extent and under what environmental conditions metabolic/biochemical traits can effectively contribute to understanding and predicting plant performance. In this study, multivariable statistical models based on flag leaf central metabolism and oxidative stress status were used to predict grain yield (GY) performance for 271 indica rice (Oryza sativa) accessions grown in the field under well-watered and reproductive stage drought conditions. The resulting models displayed significantly higher predictability than multivariable models based on genomic data for the prediction of GY under drought (Q² = 0.54–0.56 versus 0.35) and for stress-induced GY loss (Q² = 0.59–0.64 versus 0.03–0.06). Models based on the combined datasets showed predictabilities similar to metabolic/biochemical-based models alone. In contrast to genetic markers, models with enzyme activities and metabolite values also quantitatively integrated the effect of physiological differences such as plant height on GY. The models highlighted antioxidant enzymes of the ascorbate–glutathione cycle and a lipid oxidation stress marker as important predictors of rice GY stability under drought at the reproductive stage, and these stress-related variables were more predictive than leaf central metabolites. These findings provide evidence that metabolic/biochemical traits can integrate dynamic cellular and physiological responses to the environment and can help bridge the gap between the genome and the phenome of crops as predictors of GY performance under drought.

Biochemical traits outperform the explanatory power of genetic markers when used as variables in models for predicting yield performance in rice under drought stress.     

Influence of ionic strength and conductivity on benthic diatom communities in a tropical river (Monjolinho), S?o Carlos-SP, Brazil

Benthic diatoms are important indicators of ecological conditions in lotic systems. The objective of this study was to elucidate the confounding effects of eutrophication, organic pollution and ionic strength and conductivity on benthic diatom communities. Benthic diatoms and water quality sampling was done at 10 sites during summer base flow period (2008 and 2009). Detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to determine environmental gradients along which species vary with respect to ionic strength and conductivity and other environmental variables. Using variance partitioning, we assessed the individual importance of a set of environmental variables (eutrophication and organic pollution) versus ionic strength and conductivity on diatom community structure. The effects of ionic strength and conductivity and organic pollution, eutrophication and other environmental variables were integrated into overall resultant benthic diatom communities. Through partial CCA, we partitioned the variance in diatom data between two sets of exploratory variables, i.e. ionic strength and conductivity (26.9%); other variables, particularly eutrophication and organic pollution (23.0%); shared variance (11.3%) and unexplained variance (38.8%). Due to the interaction of the effects of ionic strength and conductivity and other variables in this study, laboratory experiments must be performed to confirm the observed effects of ionic strength and conductivity.     

Which components of plant diversity are most correlated with ecosystem properties? A case study in a restored wetland in northern China

The relationship between plant diversity and ecosystem services is a controversial topic in ecology that may be due, at least in part, to the variety of methods used to define and quantify diversity. This study examined the relationship between plant diversity and 11 ecosystem properties of a restored wetland in northern China by considering four primary components of diversity (dominance, richness, evenness, and divergence). Each diversity component was expressed by eight taxonomic and functional diversity indices respectively. Results showed that trait-based functional diversity had a stronger correlation with ecosystem processes than non-trait taxonomic diversity did. Among the four components of diversity, dominance (in terms of mean trait value index) was the best in explaining the variation in ecosystem processing. Richness and divergence also had significant correlations with ecosystem properties in some instances. By contrast, evenness had no significant correlation with most of the studied ecosystem properties. Our results indicated that wetland ecosystem properties are significantly related to certain traits of the dominant species. Thus, the dominant species and functional traits should be considered before the number of species in managing diversity and enhancing certain ecosystem functions of wetlands, especially in the case of conservation.     

Can the dietary fat type facilitate memory impairments in adulthood? A comparative study between Mediterranean and Western-based diet in rats

A balanced intake of fatty acids (FA) of both omega-6 (n-6) and -3 (n-3) series is essential for memory. The Mediterranean diet (MD), rich in n-3 polyunsaturated FA (PUFA) and low n-6/n-3 PUFA ratio, has shown beneficial influences on health. Inversely, the Western diet contains saturated fats, including hydrogenated vegetable fat (HVF, rich in trans fat) and interesterified fat (IF), making the n-6/n-3 PUFA ratio high. Due to the health impairments caused by HVF, it has been replaced by IF in processed foods. We compared an MD (balanced n-6/n-3 PUFA ratio) with Western diets 1 (WD1, rich in trans fat) and 2 (WD2, rich in IF) on memory process per se and following scopolamine (SCO) administration, which induces amnesia in rats. While MD exerted protective effects, WD1 and WD2 showed declined memory per se, showing higher susceptibility to SCO-induced memory deficits. In addition, WD1 and WD2 showed increased proinflammatory cytokines [tumor necrosis factor-α, interleukin (IL)-1β, IL-6] and decreased anti-inflammatory cytokines (IL-10) in plasma. IL-1β was higher in the hippocampus of WD1, which was reflected on histological assessments. Significant correlations between cognitive decline and inflammatory markers reinforce our hypothesis: MD-like fats may act preventively on cognitive loss, while WD-like fats may facilitate this.     

Is flexoelectricity the coupling factor between chemical energy and osmotic work in the pump? A model of pump

The following pump model is proposed. A gate is responsible for pump specificity. The actual driving force of the transport of ions against the electrochemical potential gradient is the electric field originating from an altered curvature of the phospholipid bilayer around the pump. The physical origin of this curvature-induced electric field arises from a basic liquid crystal property of lipid bilayers called flexoelectricity. Alterations occurring in phospholipid bilayer arrangement are due to changed conformation of protein; the main energy source of this change is ATP. Consequently, the energy of ATP is transformed, in our pump model, into osmotic work in following steps: ATP + protein (conformation I)----protein (conformation II)----alterations in phospholipid bilayer arrangement----electric field----active transport of ions. This model is the most simple one. In Na, K-pump there is a bidirectional ion transport. In our model of Na, K-pump three conformational states of pump proteins and two different electric fields formed sequentially in opposite directions are supposed.     

Can vegetation corridors support a small mammal community similar to that found within forest fragments? A case study in southeastern Brazil

Vegetation corridors are generally proposed as a strategy to reduce forest fragment isolation in fragmented landscapes. In southern Minas Gerais, Brazil, vegetation corridors emerged naturally after native trees colonized excavations used as boundaries by farm owners in the eighteenth century. We tested the use of these structures by small mammals and compared diversity among corridors and forest fragments. Community richness and abundance were similar in corridors and forest fragments, and we identified movements of small mammals between corridors and forest fragments. We suggest that governmental policies should encourage farm owners to conserve vegetation corridors, especially in this fragmented landscape.     

Can the problem of hybridization in threatened species be evaluated using a fieldwork research? A case study in snapdragons

Hybridization, natural or artificial, is considered disadvantageous for species biodiversity when it threatens the population integrity of endangered species. Frequently, studies investigating whether hybridization poses a legitimate risk to rare species are based on genetic data obtained in molecular biology laboratories. In this study, we used field research to approach the problem that hybridization could cause for the viability of a population of a rare species and to be able to propose the most appropriate initial conservation strategy. Specifically, using the model genus Antirrhinum, the reproductive barriers between the rare A. pulverulentum and its common congener A. litigiosum have been analysed under the reproductive isolation index (RI). A. pulverulentum had a high value of total RI, indicating that there are barriers to gene flow from A. litigiosum towards this species, and also had a high value for the intrinsic RI, reflecting a low inherent capacity for production of hybrid plants; in addition, the possibility of successful backcrosses between this species with hybrids produced from A. litigiosum ovules were low, given the high intrinsic RI of A. litigiosum. These data indicate the current existence of strong and permanent barriers to hybridization between the two species, suggesting that hybridization does not seem to be a serious problem for the conservation of A. pulverulentum in the studied population, nor for the near future. This study shows how the RI index can provide useful information for conservation purposes and proposes different management recommendations.     

Is there a correlation between taurine levels and xenobioticinduced perturbations in protein synthesis?: A study with tetracycline in rats

Summary Changes in urinary levels of taurine have been reported in rats following treatment with various xenobiotics including those which alter protein synthesis and/or are hepatotoxic. This paper reports on the time course of the urinary elevation of taurine following treatment of rats with tetracycline (50, 150 and 200mg.kg^-1). Maximum taurine excretion occurred 8–12h following dosing. Serum albumin and total protein were significantly lower after 24h (200mg.kg^-1). The increase in urinary taurine was dose-related and reflected in the raised serum levels of taurine 24h after dosing. Serum and urinary protein and [³H]-leucine incorporation into acid precipitable protein in liver and muscle were reduced by tetracycline (100, 150 and 200mg.kg^-1) 10h after dosing. The reduction in protein synthesis was correlated with increased urinary and serum levels of taurine at 10h. The use of taurine as a non-invasive marker of protein synthesis is discussed.     

Is escaping deer browse just a matter of time in Picea sitchensis? A chemical and dendroecological approach

We combined chemical and dendroecological analyses to understand the mechanisms that are involved in escaping deer browse by young Sitka spruce (Picea sitchensis) exposed to browsing by Sitka black-tailed deer (Odocoileus hemionus sitchensis) on Haida Gwaii (British Columbia, Canada). We compared chemical defences (terpenes), nutritive compounds (nitrogen, non-structural constituents, cellulose, and lignin), as well as age and radial growth of two young spruce categories growing side by side: (1) stunted spruces that were heavily browsed, shorter than the browse line, and (2) escaped spruces that were taller than the browse line but still browsed below the browse line. Escaped and stunted spruces did not differ in terpene concentrations, or in nutritive compound contents, suggesting that they had similar palatability. Escaped spruces were older that stunted spruces. Stunted and escaped trees had similar slow growth when young, suggesting no difference in initial browsing between the two spruce categories. For escaped spruce, there was a dramatic increase in radial growth at about 12-13 years old, suggesting that the apex of the trees had escaped deer browse. Because the two categories of spruces were equally accessible and did not differ in chemical defences or in nutritive compounds, and because escaped spruces were older than stunted trees and had a similar slow radial growth in their first 12-13 years, we conclude that morphological differences between stunted and escaped browsed trees are due to age and that it is only a matter of time before spruce escape deer on Haida Gwaii.