Improving Salicornia ramosissima photochemical and biochemical resilience to extreme heatwaves through rhizosphere engineering with Plant Growth-Promoting Bacteria.

The anticipated rise in the length, frequency, and intensity of heatwaves (HW) in the Mediterranean region poses a danger to the crops, as these brief but high-intensity thermal stress events halt plant productivity. This arises the need to develop new eco-friendly sustainable strategies to overcome food demand. Halophytes such as Salicornia ramosissima appear as cash crop candidates, alongside with new biofertilization approaches using Plant Growth Promoting Bacteria (PGPB). In the present work, S. ramosissima plants exposed to heatwave (HW) treatments with and without marine PGPB inoculation is studied to evaluate the physiological responses behind eventual thermal adaptation conditions. Plants exposed to HW inoculated with ACC deaminase and IAA-producing PGPB showed a 50% reduction in the photochemical energy dissipation, when compared to their non-inoculated counterparts, indicating higher light-use efficiency. The observed concomitant increase (76-234%) in several pigments indicates improved inoculated HW-exposed individuals' light harvesting and photoprotection under stressful conditions. This reduction of the physiological stress levels in inoculated plants was also evident by the significant reduction of several antioxidant enzymes as well as of membrane lipid peroxidation products. Additionally, improved membrane stability could also be observed, through the regulation of fatty acid unsaturation levels, decreasing the excessive fluidity imposed by HW treatment. All these improved physiological traits associated with specific PGP traits highlight a key potential of the use of these PGPB consortiums as biofertilizers for S. ramosissima cash crop production in the Mediterranean, where increasing frequency in HW-events is a major drawback to plant production, even to warm-climate plants.

Improving Grapevine Heat Stress Resilience with Marine Plant Growth-Promoting Rhizobacteria Consortia.

Amid climate change, heatwave events are expected to increase in frequency and severity. As a result, yield losses in viticulture due to heatwave stress have increased over the years. As one of the most important crops in the world, an eco-friendly stress mitigation strategy is greatly needed. The present work aims to evaluate the physiological fitness improvement by two marine plant growth-promoting rhizobacteria consortia in Vitis vinifera cv. Antão Vaz under heatwave conditions. To assess the potential biophysical and biochemical thermal stress feedback amelioration, photochemical traits, pigment and fatty acid profiles, and osmotic and oxidative stress biomarkers were analysed. Bioaugmented grapevines exposed to heatwave stress presented a significantly enhanced photoprotection capability and higher thermo-stability, exhibiting a significantly lower dissipation energy flux than the non-inoculated plants. Additionally, one of the rhizobacterial consortia tested improved light-harvesting capabilities by increasing reaction centre availability and preserving photosynthetic efficiency. Rhizobacteria inoculation expressed an osmoprotectant promotion, revealed by the lower osmolyte concentration while maintaining leaf turgidity. Improved antioxidant mechanisms and membrane stability resulted in lowered lipid peroxidation product formation when compared to non-inoculated plants. Although the consortia were found to differ significantly in their effectiveness, these findings demonstrate that bioaugmentation induced significant heatwave stress tolerance and mitigation. This study revealed the promising usage of marine PGPR consortia to promote plant fitness and minimize heatwave impacts in grapevines.

Interactive Temperature and CO2 Rise, Salinity, Drought, and Bacterial Inoculation Alter the Content of Fatty Acids, Total Phenols, and Oxalates in the Edible Halophyte Salicornia ramosissima.

In this work, we studied the combined effect of increased temperature and atmospheric CO2, salt and drought stress, and inoculation with plant-growth-promoting rhizobacteria (PGPR) on the growth and some nutritional parameters of the edible halophyte Salicornia ramosissima. We found that the increase in temperature and atmospheric CO2, combined with salt and drought stresses, led to important changes in S. ramosissima fatty acids (FA), phenols, and oxalate contents, which are compounds of great importance for human health. Our results suggest that the S. ramosissima lipid profile will change in a future climate change scenario, and that levels of oxalate and phenolic compounds may change in response to salt and drought stress. The effect of inoculation with PGPR depended on the strains used. Some strains induced the accumulation of phenols in S. ramosissima leaves at higher temperature and CO2 while not altering FA profile but also led to an accumulation of oxalate under salt stress. In a climate change scenario, a combination of stressors (temperature, salinity, drought) and environmental conditions (atmospheric CO2, PGPR) will lead to important changes in the nutritional profiles of edible plants. These results may open new perspectives for the nutritional and economical valorization of S. ramosissima.

Harnessing the Full Power of Chemometric-Based Analysis of Total Reflection X-ray Fluorescence Spectral Data to Boost the Identification of Seafood Provenance and Fishing Areas.

Provenance and traceability are crucial aspects of seafood safety, supporting managers and regulators, and allowing consumers to have clear information about the origin of the seafood products they consume. In the present study, we developed an innovative spectral approach based on total reflection X-ray fluorescence (TXRF) spectroscopy to identify the provenance of seafood and present a case study for five economically relevant marine species harvested in different areas of the Atlantic Portuguese coast: three bony fish-Merluccius merluccius, Scomber colias, and Sparus aurata; one elasmobranch-Raja clavata; one cephalopod-Octopus vulgaris. Applying a first-order Savitzky-Golay transformation to the TXRF spectra reduced the potential matrix physical effects on the light scattering of the X-ray beam while maintaining the spectral differences inherent to the chemical composition of the samples. Furthermore, a variable importance in projection partial least-squares discriminant analysis (VIP-PLS-DA), with k - 1 components (where k is the number of geographical origins of each seafood species), produced robust high-quality models of classification of samples according to their geographical origin, with several clusters well-evidenced in the dispersion plots of all species. Four of the five species displayed models with an overall classification above 80.0%, whereas the lowest classification accuracy for S. aurata was 74.2%. Notably, about 10% of the spectral features that significantly contribute to class differentiation are shared among all species. The results obtained suggest that TXRF spectra can be used for traceability purposes in seafood species (from bony and cartilaginous fishes to cephalopods) and that the presented chemometric approach has an added value for coupling with classic TXRF spectral peak deconvolution and elemental quantification, allowing characterization of the geographical origin of samples, providing a highly accurate and informative dataset in terms of food safety.

Bioaugmentation Improves Phytoprotection in Halimione portulacoides Exposed to Mild Salt Stress: Perspectives for Salinity Tolerance Improvement.

Plant growth-promoting rhizobacteria (PGPR) can promote plant growth through mechanisms such as mineral phosphates solubilization, biological N2 fixation and siderophores and phytohormones production. The present work aims to evaluate the physiological fitness improvement by PGPR in Halimione portulacoides under mild and severe salt stress. PGPR-inoculated plants showed improved energy use efficiencies, namely in terms of the trapped and electron transport energy fluxes, and reduced energy dissipation. Allied to this, under mild stress, inoculated plants exhibited a significant reduction of the Na and Cl root concentrations, accompanied by a significant increase in K and Ca leaf content. This ion profile reshaping was intrinsically connected with an increased leaf proline content in inoculated plants. Moreover, bioaugmented plants showed an increased photoprotection ability, through lutein and zeaxanthin leaf concentration increase, allowing plants to cope with potentially photoinhibition conditions. Reduced Na leaf uptake in inoculated plants, apparently reduced the oxidative stress degree as observed by the superoxide dismutase and peroxidase activity reduction. Additionally, a reduced lipid peroxidation degree was observed in inoculated plants, while compared to their non-inoculated counterparts. These results, point out an important role of bioaugmentation in promoting plant fitness and improving salt tolerance, with a great potential for applications in biosaline agriculture and salinized soil restoration.

Potential of Asparagopsis armata as a Biopesticide for Weed Control under an Invasive Seaweed Circular-Economy Framework.

Marine macroalgae have been increasingly targeted as a source of bioactive compounds to be used in several areas, such as biopesticides. When harvesting invasive species, such as Asparagopsis armata, for this purpose, there is a two-folded opportunity: acquiring these biomolecules from a low-cost resource and controlling its spreading and impacts. The secondary metabolites in this seaweed's exudate have been shown to significantly impact the physiology of species in the ecosystems where it invades, indicating a possible biocidal potential. Considering this in the present work, an A. armata exudate cocktail was applied in the model weed Thellungiella halophila to evaluate its physiological impact and mode of action, addressing its potential use as a natural biocide. A. armata greatly affected the test plants' physiology, namely, their photochemical energy transduction pathway (impairing light-harvesting and chemical energy production throughout the chloroplast electron transport chain), carotenoid metabolism and oxidative stress. These mechanisms of action are similar to the ones triggered when using the common chemical pesticides, highlighting the potential of the A. armata exudate cocktail as an eco-friendly biopesticide.

Heavy Metal Pre-Conditioning History Modulates Spartina patens Physiological Tolerance along a Salinity Gradient.

Land salinization, resulting from the ongoing climate change phenomena, is having an increasing impact on coastal ecosystems like salt marshes. Although halophyte species can live and thrive in high salinities, they experience differences in their salt tolerance range, being this a determining factor in the plant distribution and frequency throughout marshes. Furthermore, intraspecific variation to NaCl response is observed in high-ranging halophyte species at a population level. The present study aims to determine if the environmental history, namely heavy metal pre-conditioning, can have a meaningful influence on salinity tolerance mechanisms of Spartina patens, a highly disperse grass invader in the Mediterranean marshes. For this purpose, individuals from pristine and heavy metal contaminated marsh populations were exposed to a high-ranging salinity gradient, and their intraspecific biophysical and biochemical feedbacks were analyzed. When comparing the tolerance mechanisms of both populations, S. patens from the contaminated marsh appeared to be more resilient and tolerant to salt stress, this was particularly present at the high salinities. Consequently, as the salinity increases in the environment, the heavy metal contaminated marsh may experience a more resilient and better adapted S. patens community. Therefore, the heavy metal pre-conditioning of salt mash populations appears to be able to create intraspecific physiological variations at the population level that can have a great influence on marsh plant distribution outcome.

Structural diversity and tree density drives variation in the biodiversity-ecosystem function relationship of woodlands and savannas.

Positive biodiversity-ecosystem function relationships (BEFRs) have been widely documented, but it is unclear if BEFRs should be expected in disturbance-driven systems. Disturbance may limit competition and niche differentiation, which are frequently posited to underlie BEFRs. We provide the first exploration of the relationship between tree species diversity and biomass, one measure of ecosystem function, across southern African woodlands and savannas, an ecological system rife with disturbance from fire, herbivores and humans. We used > 1000 vegetation plots distributed across 10 southern African countries and structural equation modelling to determine the relationship between tree species diversity and above-ground woody biomass, accounting for interacting effects of resource availability, disturbance by fire, tree stem density and vegetation type. We found positive effects of tree species diversity on above-ground biomass, operating via increased structural diversity. The observed BEFR was highly dependent on organismal density, with a minimum threshold of c. 180 mature stems ha-1 . We found that water availability mainly affects biomass indirectly, via increasing species diversity. The study underlines the close association between tree diversity, ecosystem structure, environment and function in highly disturbed savannas and woodlands. We suggest that tree diversity is an under-appreciated determinant of wooded ecosystem structure and function.

Fatty acid profiles of estuarine macroalgae are biomarkers of anthropogenic pressures: Development and application of a multivariate pressure index.

Transitional ecosystems are among the most degraded ecosystems worldwide, with several groups of organisms investigated for their reliability as biological indicators of human-driven disturbances. Recently non-traditional biochemical biomarkers such as an individual's fatty acids profile have been identified as promising tools for assessing contaminant exposure. In this work, two abundant Atlantic benthic macroalgae (Ulva lactuca and Fucus vesiculosus species) were surveyed in three mudflat areas of the highly urbanized Tejo estuary, with increasing anthropogenic disturbance degrees (Alcochete, Rosário and Seixal mudflats, increasing in contamination by this order) and their fatty acids evaluated as potential biomarkers for exposure to contaminants known to have toxic effects on biota. In terms of contamination the metal pollution index of all the compartments analysed (sediment bioavailable and total metal concentrations and thallus metal concentrations) revealed the same tendencies with lower contamination levels in Alcochete, intermediate in Rosário and high contamination levels in Seixal. In the thallus of U. lactuca thallus could be observed a strong decrease in C18-fatty acids along the contamination gradient, likely due to lipid peroxidation from metal-generated reactive oxygen species. Nevertheless, an increase in stearic and hexadecatrienoic acids in the thallus from the most contaminated site suggested counteractive mechanisms maintain the production of C18-fatty acid pool. A similar response was found in F. vesiculosus but with palmitic acid acting as precursor for the synthesis of stearic acid, allowing the maintenance of oleic and linoleic acids levels in the membranes to counteract oxidative stress. Beyond the physiological interest of these mechanisms, fatty acid profiles were used to develop a novel multivariate pressure index (Multi-PI), that beyond the contaminant concentration would reflect the response of these biomonitor species towards anthropogenic disturbance, through the evaluation of fatty acid profiles, which are also key molecules from a trophic perspective within the estuarine system. The Multi-PI efficiency in responding to different environmental contamination degrees, was substantiated by strong and positive correlations with thallus and sediment contamination. This indicated that fatty acid profiles reflect thallus and benthic habitat contamination and are efficient biomarkers of environmental metal contamination. Therefore, the sessile and abundant nature of benthic macroalgae allied to their fatty acid responses can be leveraged as suitable biomarkers for contaminant monitoring in future impact assessment and ecotoxicology studies.

Improved tree height estimation of secondary forests in the Brazilian Amazon / Estimativa melhorada de altura de árvores em florestas secundárias da Amazônia brasileira

This paper presents a novel approach for estimating the height of individual trees in secondary forests at two study sites: Manaus (central Amazon) and Santarém (eastern Amazon) in the Brazilian Amazon region. The approach consists of adjusting tree height-diameter at breast height (H:DBH) models in each study site by ecological species groups: pioneers, early secondary, and late secondary. Overall, the DBH and corresponding height (H) of 1,178 individual trees were measured during two field campaigns: August 2014 in Manaus and September 2015 in Santarém. We tested the five most commonly used log-linear and nonlinear H:DBH models, as determined by the available literature. The hyperbolic model: H = a.DBH/(b+DBH) was found to present the best fit when evaluated using validation data. Significant differences in the fitted parameters were found between pioneer and secondary species from Manaus and Santarém by F-test, meaning that site-specific and also ecological-group H:DBH models should be used to more accurately predict H as a function of DBH. This novel approach provides specific equations to estimate height of secondary forest trees for particular sites and ecological species groups. The presented set of equations will allow better biomass and carbon stock estimates in secondary forests of the Brazilian Amazon.

Este trabalho apresenta uma nova abordagem para a estimativa de altura de árvores em florestas secundárias em duas áreas de estudo na Amazônia brasileira: Manaus (Amazônia central) e Santarém (Amazônia oriental). A abordagem consistiu em ajustar modelos hipsométricos separados por área de estudo e grupos ecológicos de espécies: pioneiras, secundárias iniciais e secundárias tardias. No total, 1178 árvores foram medidas em diâmetro e altura em duas etapas de campo: agosto de 2014 em Manaus e Setembro de 2015 em Santarém. Foram testados cinco modelos log-lineares e não lineares mais utilizados na literatura. O modelo hiperbólico: H = a.D/(b+D) foi o que apresentou o melhor ajuste quando avaliado com os dados de validação. Diferenças significativas nos parâmetros de ajuste foram observadas entre as espécies pioneiras e secundárias de Manaus e Santarém pelo teste F, significando que equações específicas por grupos ecológicos e área de estudo deveriam ser utilizadas para estimar a altura (H) a partir do diâmetro (D) com maior acurácia. Esta nova abordagem fornece equações específicas para localidade e grupo ecológico, para estimar a altura das árvores em florestas secundárias. O conjunto de equações desenvolvidas permitirá melhorar as estimativas de biomassa e a quantificação dos estoques de carbono nas florestas secundárias da Amazônia brasileira.

Spatial and temporal dimensions of landscape fragmentation across the Brazilian Amazon.

The Brazilian Amazon in the past decades has been suffering severe landscape alteration, mainly due to anthropogenic activities, such as road building and land clearing for agriculture. Using a high-resolution time series of land cover maps (classified as mature forest, non-forest, secondary forest) spanning from 1984 through 2011, and four uncorrelated fragmentation metrics (edge density, clumpiness index, area-weighted mean patch size and shape index), we examined the temporal and spatial dynamics of forest fragmentation in three study areas across the Brazilian Amazon (Manaus, Santarém and Machadinho d'Oeste), inside and outside conservation units. Moreover, we compared the impacts on the landscape of: (1) different land uses (e.g. cattle ranching, crop production), (2) occupation processes (spontaneous vs. planned settlements) and (3) implementation of conservation units. By 2010/2011, municipalities located along the Arc of Deforestation had more than 55% of the remaining mature forest strictly confined to conservation units. Further, the planned settlement showed a higher rate of forest loss, a more persistent increase in deforested areas and a higher relative incidence of deforestation inside conservation units. Distinct agricultural activities did not lead to significantly different landscape structures; the accessibility of the municipality showed greater influence in the degree of degradation of the landscapes. Even with a high proportion of the landscapes covered by conservation units, which showed a strong inhibitory effect on forest fragmentation, we show that dynamic agriculturally driven economic activities, in municipalities with extensive road development, led to more regularly shaped, heavily fragmented landscapes, with higher densities of forest edge.

Season-modulated responses of Neotropical bats to forest fragmentation.

Seasonality causes fluctuations in resource availability, affecting the presence and abundance of animal species. The impacts of these oscillations on wildlife populations can be exacerbated by habitat fragmentation. We assessed differences in bat species abundance between the wet and dry season in a fragmented landscape in the Central Amazon characterized by primary forest fragments embedded in a secondary forest matrix. We also evaluated whether the relative importance of local vegetation structure versus landscape characteristics (composition and configuration) in shaping bat abundance patterns varied between seasons. Our working hypotheses were that abundance responses are species as well as season specific, and that in the wet season, local vegetation structure is a stronger determinant of bat abundance than landscape-scale attributes. Generalized linear mixed-effects models in combination with hierarchical partitioning revealed that relationships between species abundances and local vegetation structure and landscape characteristics were both season specific and scale dependent. Overall, landscape characteristics were more important than local vegetation characteristics, suggesting that landscape structure is likely to play an even more important role in landscapes with higher fragment-matrix contrast. Responses varied between frugivores and animalivores. In the dry season, frugivores responded more to compositional metrics, whereas during the wet season, local and configurational metrics were more important. Animalivores showed similar patterns in both seasons, responding to the same group of metrics in both seasons. Differences in responses likely reflect seasonal differences in the phenology of flowering and fruiting between primary and secondary forests, which affected the foraging behavior and habitat use of bats. Management actions should encompass multiscale approaches to account for the idiosyncratic responses of species to seasonal variation in resource abundance and consequently to local and landscape scale attributes.

Modelling land cover change in the Brazilian Amazon: temporal changes in drivers and calibration issues.

Land cover change (LCC) models are used in many studies of human impacts on the environment, but knowing how well these models predict observed changes in the landscape is a challenge. We used nearly three decades of LCC maps to run several LCC simulations to: (1) determine which parameters associated with drivers of LCC (e.g. roads) get selected for which transition (forest to deforested, regeneration to deforested or deforested to regeneration); (2) investigate how the parameter values vary through time with respect to the different activities (e.g. farming); and (3) quantify the influence of choosing a particular time period for model calibration and validation on the performance of LCC models. We found that deforestation of primary forests tends to occur along roads (included in 95 % of models) and outside protected areas (included in all models), reflecting farming establishment. Regeneration tends to occur far from roads (included in 78 % of the models) and inside protected areas (included in 38 % of the models), reflecting the processes of land abandonment. Our temporal analysis of model parameters revealed a degree of variation through time (e.g. effectiveness of protected areas rose by 73 %, p < 0.001), but for the majority of parameters there was no significant trend. The degree to which model predictions agreed with observed change was heavily dependent on the year used for calibration (p < 0.001). The next generation of LCC models may need to embed trends in parameter values to allow the processes determining LCC to change through time and exert their influence on model predictions.

Land use and land cover change dynamics across the Brazilian Amazon: insights from extensive time-series analysis of remote sensing data.

Throughout the Amazon region, the age of forests regenerating on previously deforested land is determined, in part, by the periods of active land use prior to abandonment and the frequency of reclearance of regrowth, both of which can be quantified by comparing time-series of Landsat sensor data. Using these time-series of near annual data from 1973-2011 for an area north of Manaus (in Amazonas state), from 1984-2010 for south of Santarém (Pará state) and 1984-2011 near Machadinho d'Oeste (Rondônia state), the changes in the area of primary forest, non-forest and secondary forest were documented from which the age of regenerating forests, periods of active land use and the frequency of forest reclearance were derived. At Manaus, and at the end of the time-series, over 50% of regenerating forests were older than 16 years, whilst at Santarém and Machadinho d'Oeste, 57% and 41% of forests respectively were aged 6-15 years, with the remainder being mostly younger forests. These differences were attributed to the time since deforestation commenced but also the greater frequencies of reclearance of forests at the latter two sites with short periods of use in the intervening periods. The majority of clearance for agriculture was also found outside of protected areas. The study suggested that a) the history of clearance and land use should be taken into account when protecting deforested land for the purpose of restoring both tree species diversity and biomass through natural regeneration and b) a greater proportion of the forested landscape should be placed under protection, including areas of regrowth.

Using landscape history to predict biodiversity patterns in fragmented landscapes.

Landscape ecology plays a vital role in understanding the impacts of land-use change on biodiversity, but it is not a predictive discipline, lacking theoretical models that quantitatively predict biodiversity patterns from first principles. Here, we draw heavily on ideas from phylogenetics to fill this gap, basing our approach on the insight that habitat fragments have a shared history. We develop a landscape 'terrageny', which represents the historical spatial separation of habitat fragments in the same way that a phylogeny represents evolutionary divergence among species. Combining a random sampling model with a terrageny generates numerical predictions about the expected proportion of species shared between any two fragments, the locations of locally endemic species, and the number of species that have been driven locally extinct. The model predicts that community similarity declines with terragenetic distance, and that local endemics are more likely to be found in terragenetically distinctive fragments than in large fragments. We derive equations to quantify the variance around predictions, and show that ignoring the spatial structure of fragmented landscapes leads to over-estimates of local extinction rates at the landscape scale. We argue that ignoring the shared history of habitat fragments limits our ability to understand biodiversity changes in human-modified landscapes.