Domestic wood collection affects plant communities through constant biomass removal. We assessed the effects of wood collection for firewood and fence construction on tree community structure in a ...seasonally dry tropical forest in Brazil. We described the harvest patterns of wood products. Further, we evaluated the effects of rainfall levels and wood collection on tree community structure. Most wood collection for firewood was concentrated within a small subset of dominant species. Wood collection for building fences was less influenced by species abundance. Species richness was positively associated with rainfall. Wood collection increased community evenness and negatively affected total density. The dominant species were not affected by wood collection. Domestic use of wood has a low impact on tree diversity in human-dominated dry forests. Nevertheless, some of the most used species for building fences are potentially threatened. The effects of firewood collection can be mitigated through (1) offering subsidies aimed at fuel transition to liquefied petroleum gas or (2) developing and distributing more efficient cookstoves. The effects of wood collection for building fences can be mitigated through promoting the use of (1) living fences or (2) fewer stakes. In addition, the populations of the most commonly used species should be recovered.
•Local people display an indiscriminate behaviour during firewood collection.•Wood collection for building fences seems to be guided by local preferences.•Low scale wood collection increases tree community evenness in dry forests.•Low scale wood collection reduces the total abundances in the dry forests.
Spatial and temporal patterns in microbial biodiversity across the Amazon river-ocean continuum were investigated along ∼675 km of the lower Amazon River mainstem, in the Tapajós River tributary, and ...in the plume and coastal ocean during low and high river discharge using amplicon sequencing of 16S rRNA genes in whole water and size-fractionated samples (0.2-2.0 μm and >2.0 μm). River communities varied among tributaries, but mainstem communities were spatially homogeneous and tracked seasonal changes in river discharge and co-varying factors. Co-occurrence network analysis identified strongly interconnected river assemblages during high (May) and low (December) discharge periods, and weakly interconnected transitional assemblages in September, suggesting that this system supports two seasonal microbial communities linked to river discharge. In contrast, plume communities showed little seasonal differences and instead varied spatially tracking salinity. However, salinity explained only a small fraction of community variability, and plume communities in blooms of diatom-diazotroph assemblages were strikingly different than those in other high salinity plume samples. This suggests that while salinity physically structures plumes through buoyancy and mixing, the composition of plume-specific communities is controlled by other factors including nutrients, phytoplankton community composition, and dissolved organic matter chemistry. Co-occurrence networks identified interconnected assemblages associated with the highly productive low salinity near-shore region, diatom-diazotroph blooms, and the plume edge region, and weakly interconnected assemblages in high salinity regions. This suggests that the plume supports a transitional community influenced by immigration of ocean bacteria from the plume edge, and by species sorting as these communities adapt to local environmental conditions. Few studies have explored patterns of microbial diversity in tropical rivers and coastal oceans. Comparison of Amazon continuum microbial communities to those from temperate and arctic systems suggest that river discharge and salinity are master variables structuring a range of environmental conditions that control bacterial communities across the river-ocean continuum.
Wild food plants (WFPs) are important components of the diet and a source of income for local communities in semiarid regions, given that these populations are commonly characterized by high ...socioeconomic vulnerability and dependence on natural resources for subsistence. In periods of food scarcity and crop failure, WFPs emerge as strategic resources for ensuring food and nutrition security. However, these little-researched plants may also be affected by climate change. Here, our objective was to determine the spatiotemporal dynamics of WFPs in the Brazilian semiarid and evaluate their potential availability in future climate change scenarios. We constructed habitat suitability models for economically and nutritionally important WFPs used in this region and projected future scenarios (2041–2060). Furthermore, we determined the geographical distribution, species richness, and composition (on local and regional scales) of WFPs in current and future scenarios. Our results showed that WFPs exhibited varied responses to climate change. The more pessimistic the future scenario, the greater the negative effects. Most WFP species exhibited a reduction in climatically suitable areas in future scenarios, resulting in a shrinkage of geographical ranges, a reduction in species richness, and alterations in community composition. These changes could have important implications for economic development, subsistence, and food and nutrition security in the region. Our findings offer insights that can guide actions for adaptation and mitigating the effects of climate change and promoting species conservation not only in the Brazilian semiarid but also in other semiarid regions worldwide.
Metatranscriptomics and metagenomics data sets benchmarked with internal standards were used to characterize the expression patterns for biogeochemically relevant bacterial and archaeal genes ...mediating carbon, nitrogen, phosphorus and sulfur uptake and metabolism through the salinity gradient of the Amazon River Plume. The genes were identified in 48 metatranscriptomic and metagenomic data sets summing to >500 million quality-controlled reads from six locations in the plume ecosystem. The ratio of transcripts per gene copy (a direct measure of expression made possible by internal standard additions) showed that the free-living bacteria and archaea exhibited only small changes in the expression levels of biogeochemically relevant genes through the salinity and nutrient zones of the plume. In contrast, the expression levels of genes in particle-associated cells varied over orders of magnitude among the stations, with the largest differences measured for genes mediating aspects of nitrogen cycling (nifH, amtB and amoA) and phosphorus acquisition (pstC, phoX and phoU). Taxa varied in their baseline gene expression levels and extent of regulation, and most of the spatial variation in the expression level could be attributed to changes in gene regulation after removing the effect of shifting taxonomic composition. We hypothesize that changes in microbial element cycling along the Amazon River Plume are largely driven by shifting activities of particle-associated cells, with most activities peaking in the mesohaline regions where N
fixation rates are elevated.
In April of 2010, the Macondo well blowout in the northern Gulf of Mexico resulted in an unprecedented release of oil into the water column at a depth of approximately 1500 m. A time series of ...surface and subsurface sediment samples were collected to the northwest of the well from 2010 to 2013 for molecular biomarker and bulk carbon isotopic analyses. While no clear trend was observed in subsurface sediments, surface sediments (0–3 cm) showed a clear pattern with total concentrations of n-alkanes, unresolved complex mixture (UCM), and petroleum biomarkers (terpanes, hopanes, steranes) increasing from May to September 2010, peaking in late November 2010, and strongly decreasing in the subsequent years. The peak in hydrocarbon concentrations were corroborated by higher organic carbon contents, more depleted Δ14C values and biomarker ratios similar to those of the initial MC252 crude oil reported in the literature. These results indicate that at least part of oil discharged from the accident sedimented to the seafloor in subsequent months, resulting in an apparent accumulation of hydrocarbons on the seabed by the end of 2010. Sediment resuspension and transport or biodegradation may account for the decrease in sedimented oil quantities in the years following the Macondo well spill.
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•Deep sea sediments were collected from 2010 to 2013 to the NW of the Macondo well.•Oil-derived biomarkers increased from May to September, peaking in November 2010.•Peak in hydrocarbon concentrations were corroborated by more depleted Δ14C values.•Fraction of oil introduced due to blowout had sedimented by late fall 2010.•Hydrocarbon concentrations from 2011-2013 can be used as a post-spill benchmark.
Weathered Macondo hydrocarbons associated with marine oil snow reached the seafloor months after the accident, peaking in late fall of 2010.
Skeletal muscle disuse results in myofibrillar atrophy and protein degradation, via inflammatory and oxidative stress-mediated NF-kB signaling pathway activation. Nutritional interventions, such as ...l-glutamine (GLN) supplementation have shown antioxidant properties and cytoprotective effects through the modulation on the 70-kDa heat shock protein (HSP70) expression. However, these GLN-mediated effects on cell signaling pathways and biochemical mechanisms that control the myofibrillar protein content degradation in muscle disuse situations are poorly known yet. This study investigated the effects of oral GLN plus l-alanine (ALA; GLN + ALA-solution) supplementation, either in their free or dipeptide (L-alanyl-l-glutamine-DIP) form, on GLN-glutathione (GSH) axis and cytoprotection mediated by HSP70 protein expression in the slow-twitch soleus and fast-twitch gastrocnemius skeletal muscle of rats submitted to 14-days of hindlimb immobilization-induced disuse muscle atrophy. Forty-eight Wistar rats were distributed into 6 groups: hindlimb immobilized (IMOB group) and hindlimb immobilized orally supplemented with either GLN (1 g kg−1) plus ALA (0.61 g kg−1) (GLN + ALA-IMOB group) or 1.49 g kg−1 of DIP (DIP-IMOB group) and; no-immobilized (CTRL) and no-immobilized supplemented GLN + ALA and DIP baselines groups. All animals, including CTRL and IMOB rats (water), were supplemented via intragastric gavage for 14 days, concomitantly to immobilization period. Plasma and muscle GLN levels, lipid (thiobarbituric acid reactive substances-TBARS) and protein (carbonyl) peroxidation, erythrocyte concentration of reduced GSH and GSH disulfide (GSSG), plasma and muscle pro-inflammatory TNF-α levels, muscle IKKα/β-NF-kB signaling pathway and, the myofibrillar protein content (MPC) were measured. The MPC was significantly lower in IMOB rats, compared to CTRL, GLN + ALA, and DIP animals (p < 0.05). This finding was associated with reduced plasma and muscle GLN concentration, equally in IMOB animals. Conversely, both GLN + ALA and DIP supplementation restored plasma and muscle GLN levels, which equilibrated GSH and intracellular redox status (GSSG/GSH ratio) in erythrocytes and skeletal muscle even as, increased muscle HSP70 protein expression; attenuating oxidative stress and TNF-α-mediated NF-kB pathway activation, fact that reverberated on reduction of MPC degradation in GLN + ALA-IMOB and DIP-IMOB animals (p < 0.05). In conclusion, the findings shown herein support the oral GLN + ALA and DIP supplementations as a therapeutic and effective nutritional alternative to attenuate the deleterious effects of the skeletal muscle protein degradation induced by muscle disuse.
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•Disuse periods are characterized by skeletal muscle protein degradation (MPD).•MPD is associated to oxidative stress-mediated NF-kB signaling pathway activation.•Glutamine (GLN) supplementation has antioxidant and anti-inflammatory properties.•GLN supplementation induced HSP70 protein expression.•GLN supplementation attenuates oxidative stress-mediated NF-kB activation.
The Galápagos Archipelago is located at the intersection of several major oceanographic features that produce diverse environmental conditions around the islands, and thus has the potential to serve ...as a natural laboratory for discerning the underlying environmental factors that structure marine microbial communities. Here we used quantitative metagenomics to characterize microbial communities in relation to archipelago marine habitats, and how those populations shift due to substantial environmental changes brought on by El Niño. Environmental conditions such as temperature, salinity, inorganic dissolved nutrients, and dissolved organic carbon (DOC) concentrations varied throughout the archipelago, revealing a diversity of potential microbial niches arising from upwelling, oligotrophic to eutrophic gradients, physical isolation, and potential island mass effects. The volumetric abundances of microbial community members shifted with these environmental changes and revealed several taxonomic indicators of different water masses. This included a transition from a
Synechococcus
dominated system in the west to an even mix of
Synechococcus
and
Prochlorococcus
in the east, mirroring the archipelago’s mesotrophic to oligotrophic and productivity gradients. Several flavobacteria groups displayed characteristic habitat distributions, including enrichment of
Polaribacter
and
Tenacibaculum
clades in the relatively nutrient rich western waters,
Leeuwenhoekiella
spp. that were enriched in the more nutrient-deplete central and eastern sites, and the streamlined MS024-2A group found to be abundant across all sites. During the 2015/16 El Niño event, both environmental conditions and microbial community composition were substantially altered, primarily on the western side of the archipelago due to the reduction of upwelling from the Equatorial Undercurrent. When the upwelling resumed, concentrations of inorganic nutrients and DOC at the western surface sites were more typical of mesopelagic depths. Correspondingly,
Synechococcus
abundances decreased by an order of magnitude, while groups associated with deeper water masses were enriched, including streamlined roseobacters HTCC2255 and HIMB11,
Thioglobacaceae
, methylotrophs (
Methylophilaceae
), archaea (
Nitrosopumilaceae
), and distinct subpopulations of
Pelagibaceriales
(SAR11 clade). These results provide a quantitative framework to connect community-wide microbial volumetric abundances to their environmental drivers, and thus incorporation into biogeochemical and ecological models.
We analyzed the molecular composition of dissolved organic matter (DOM) in the lower Amazon River (ca. 850 km from Óbidos to the mouth) using ultrahigh-resolution mass spectrometry and geochemical ...tracers. Changes in DOM composition along this lower reach suggest a transition from higher plant-derived DOM to more algal/microbial-derived DOM. This result was likely due to a combination of autochthonous production, alteration of terrigenous DOM as it transits down the river, and increased algal inputs from floodplain lakes and clearwater tributaries during high discharge conditions. Spatial gradients in dissolved organic carbon (DOC) concentrations varied with discharge. Maximal DOC concentrations were observed near the mouth during high water, highlighting the importance of lateral inputs of DOM along the lower river. The majority of DOM molecular formulae did not change within the time it takes the water in the mainstem to be transported through the lower reach. This is indicative of molecules representing a mixture of compounds that are resistant to rapid alteration and reactive compounds that are continuously replenished by the lateral input of terrestrial organic matter from the landscape, tributaries, and floodplains. River water incubations revealed that photo- and bio-transformation alter at most 30% of the DOM molecular formulae. River discharge at the mouth differed from the sum of discharge measurements made at Óbidos and the main gauged tributaries in the lower Amazon. This indicates that changes in hydrology and associated variations in the source waters along the lower reach affected the molecular composition of the DOM that is being transported from the Amazon River to the coastal ocean.
Bulk aerosols (>1
μm) were collected continuously above the canopy at the Howland Experimental Forest, Maine, USA from May to October 2002. Each sample integrated over an approximately 2-week period. ...Mono- and disaccharide sugars were extracted using a microscale technique and were analyzed as their TMS derivatives by gas chromatography–mass spectrometry (GC–MS). Concentrations of total aerosol sugars ranged from 10 to 180
ng
m
−3. Glucose was the most abundant sugar (40–75% of the total sugars). The monosaccharides arabinose, fructose, galactose, mannose, arabitol and mannitol, and the disaccharides sucrose, maltose and mycose (aka trehalose) were also present in lower concentrations. The sugar composition in the aerosols varied seasonally. Fructose and sucrose were prevalent in early spring and decreased in relative abundance as the growing season progressed. Sugar polyols (arabitol and mannitol) and the disaccharide mycose (a fungal metabolite) were more prevalent in autumn during the period of leaf senescence. The changes in the sugar composition in the aerosol samples appear to reflect the seasonality of sugar production and utilization by the ecosystem. Plant waxes were present as significant components also indicating an input from biogenic background.
Smoke plumes from Quebec forest fires passed over the Howland site in early July 2002. Levoglucosan, a biomarker of biomass burning, increased by an order of magnitude in the aerosol samples collected during this time. Glucose, mannose, arabinose, galactose, and also, plant waxes increased in concentration by factors of 2–5 in the smoke-impacted samples, indicating that wildfires enhance atmospheric emissions of uncombusted organic compounds. In contrast, concentrations of fructose, sugar polyols and disaccharides were not significantly higher in the smoke-impacted samples and indicated that biomass burning was not a significant source of these compounds in the aerosols.
In coastal regions and marginal bodies of water, the increase in partial pressure of carbon dioxide (
p
CO
2
) in many instances is greater than that of the open ocean due to terrestrial (river, ...estuarine, and wetland) influences, decreasing buffering capacity and/or increasing water temperatures. Coastal oceans receive freshwater from rivers and groundwater as well as terrestrial-derived organic matter, both of which have a direct influence on coastal carbonate chemistry. The objective of this research is to determine if coastal marshes in Georgia, USA, may be “hot-spots” for acidification due to enhanced inorganic carbon sources and if there is terrestrial influence on offshore acidification in the South Atlantic Bight (SAB). The results of this study show that dissolved inorganic carbon (DIC) and total alkalinity (TA) are elevated in the marshes compared to predictions from conservative mixing of the freshwater and oceanic end-members, with accompanying pH around 7.2 to 7.6 within the marshes and aragonite saturation states (Ω
Ar
) <1. In the marshes, there is a strong relationship between the terrestrial/estuarine-derived organic and inorganic carbon and acidification. Comparisons of pH, TA, and DIC to terrestrial organic material markers, however, show that there is little influence of terrestrial-derived organic matter on shelf acidification during this period in 2014. In addition, Ω
Ar
increases rapidly offshore, especially in drier months (July). River stream flow during 2014 was anomalously low compared to climatological means; therefore, offshore influences from terrestrial carbon could also be decreased. The SAB shelf may not be strongly influenced by terrestrial inputs to acidification during drier than normal periods; conversely, shelf waters that are well-buffered against acidification may not play a significant role in mitigating acidification within the Georgia marshes.
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