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Freeze events govern the distribution and structure of mangrove ecosystems, especially in tropical‐temperate transitional zones. Understanding mangrove responses to freezing is crucial for predicting their poleward expansion under climate change. However, there is a need for field‐based measurements of mangrove freeze resistance and resilience. After an extreme winter storm in December 2022, we measured mangrove post‐freeze damage and recovery (January and November 2023), building on a pre‐freeze baseline assessment conducted in July 2022 across 12 sites along the temperature gradient of Florida's Gulf of Mexico coast (USA). Low‐temperature thresholds for leaf damage to Avicennia germinans, Rhizophora mangle and Laguncularia racemosa were quantified near −6, −4 and − 4°C, respectively. Thresholds for mortality were found to be near −6 to −7°C for A. germinans and −4 to −5°C for R. mangle. A threshold for loss of reproductivity in A. germinans was identified near −6 to −7°C. Resprouting was observed in all three species but limited to just one individual for R. mangle. Surviving A. germinans resprouted vigorously and had the greatest number of resprout branches, which was proportional to leaf damage. Tall A. germinans had a higher resprout percentage than short trees. Strata‐specific differences in freeze damage were most pronounced for R. mangle, with higher damage in tall versus short trees, while no difference was found between A. germinans strata. These results suggest that R. mangle population recovery may depend on the growth of short trees, while A. germinans can recover from all strata. Minimum air temperature was strongly correlated with mangrove height and above‐ground biomass. Projections of future minimum temperature and species‐specific freeze degree days predict warming winters, suggesting further mangrove development and range expansion under climate change. Synthesis: Collectively, our study advances understanding of mangrove responses to freezing and identifies low‐temperature thresholds for each species, aiding predictions of mangrove range expansion. [ABSTRACT FROM AUTHOR]

Determining the factors that set species' range limits is of critical importance in an era of rapid climate and biotic change. Mangroves dominate global tropical coastlines, but their subtropical range limits are thought to be mainly constrained by cold air. However, several tropical mangrove range limits are conspicuously warm, arid, and dominated by cold water countercurrents. Despite speculation that the combination of cold water and aridity controls these range limits, investigations of this phenomenon are rare.Here, we conducted an experimental study examining the separate and interactive effects of cold water and aridity on survival, growth, and ecophysiological traits of three mangrove species from the arid, countercurrent range limit in Baja California, Mexico. It is one of the few range edges worldwide where red and white mangroves (Rhizophora mangle and Laguncularia racemosa, respectively), not the putatively stress‐tolerant black mangroves (Avicennia germinans), are the most poleward distributed mangroves, providing further opportunity to examine how mangrove ecophysiological traits affect species‐specific range limits.Black mangroves were surprisingly intolerant of cold water regardless of aridity, with no seedlings surviving in the lowest water temperature (13°C) after 8 months. In contrast, both white and red mangrove seedlings were able to survive at 13°C when humidity was 65% (but not 40%).In cold water and arid conditions, leaf stomatal conductance was consistently lowest for white mangroves, intermediate for red mangroves, and highest for black mangroves, suggesting that white mangroves were the most resistant to transpiration water loss in the arid conditions typical of Baja.Similarly, when exposed to drought after the eight‐month experiment, white mangroves grown in cold water survived longer than red and black mangroves.Synthesis: Ultimately, our results suggest that the species‐specific range limits of mangroves in Baja California reflects their species‐specific adaptations (or lack thereof) to cold water and aridity, with white and red mangroves surprisingly outperforming black mangroves. Further, the difference in our results compared to the same species in other ranges underscores the need to incorporate species and range‐specific traits when conducting distribution modelling to predict the effects of climate change on organism range limits. [ABSTRACT FROM AUTHOR]

Chronic hydrocarbon spills are a threat to coastal ecosystems, and their impact on the water quality along watercourses should be characterised to medium long term in order to assess the risk and define cost-effective and sustainable remediation strategies. For this purpose, a methodology for the measurement of total petroleum hydrocarbons (TPH) on a spatio-temporal scale was designed, implemented and validated in the Punta Carnero estuary, in the Santa Elena province, western Ecuador, which is affected by hydrocarbon pollution. The selection of monitoring stations was made according to the different inflows along the water system corresponding to the different anthropogenic activities in the area, in order to assess whether the effluents involve critical levels of pollution. Measurements of hydrodynamic, environmental and vegetation cover parameters were also carried out to assess their possible variations as a consequence of the impact of the spatio-temporal TPH concentrations. An increase in hydrocarbon concentrations was observed from 2013 to 2021. Mean annual TPH levels were above the maximum allowable limit for the protection of aquatic and other wildlife in estuarine waters according to the Ecuadorian regulation for environmental quality. An increase in mangrove tree cover could contribute to an exponential decrease in contamination levels. The methodology used in this study may support the quantifying of TPH content in future applications, which is a priority task for the restoration of degraded ecosystems. [ABSTRACT FROM AUTHOR]

Under natural conditions, most plants are exposed to a plethora of stress factors like salinity and drought which can act in synergy to undermine their growth responses. The red mangrove, Rhizophora mangle, is endemic to estuarine ecosystems and is prone to salinity and drought stresses under changing climatic conditions. This work aimed at elucidating the combined impact of drought and salinity on the growth pattern and physiology of red mangroves. The use of factorial experimental layout in a completely randomised design was employed in the study to impose either a single or a combination of different drought regimes and levels of salt stress on red mangrove plants, which culminated in nine treatments to uncover both the combined and individualistic impact of salinity and drought stresses on the red mangrove. Morphological, physiological and biochemical responses of the facultative halophyte were evaluated following the imposition of salinity and drought stress. The results revealed that application of both salinity and drought stresses simultaneously on red mangrove seedlings led to a decline in plant growth indices, chlorophyll content, transpiration rate [E], stomatal conductance [gs] and net photosynthesis rate [PN], as compared to other plants exposed to single stress treatment. Besides, combined salinity and drought treatment increased oxidative stress rapidly, thereby increasing malondialdehyde (MDA) and hydrogen peroxide (H2O2) accumulation. However, the red mangrove exhibited a certain level of stress resistance to the simulated salinity and drought stresses which was attributable to the mechanisms such as hyperactivation of catalase (CAT) and superoxide dismutase (SOD) activities and accumulation of osmoprotectants (soluble sugar, Na+ and Cl−). The results recorded indicate that gas exchange attributes, photosynthetic content, CAT and APX activities and MDA are reliable screening parameters for salinity and drought stress in the plants because they have roles in the level of combined stress tolerance exhibited by the red mangrove. [ABSTRACT FROM AUTHOR]

The effects of iron, manganese, zinc, copper, and lead on the chlorophyll content, carbon assimilation, and the antiradical activity of Rhizophora mangle and Laguncularia racemosa were evaluated in regions affected by the Fundão dam disruption in Brazil. The mine waste which settled and accumulated in the sediments could represent long-term contamination. It can be expected that the iron oxyhydroxides deposited in the sediments will be solubilized, leading to chronic contamination by trace metals and the accumulation of these metals in the biota. In this sense, biological indicators prove to be important tools to assess this type of damage. The different bioaccumulation of metals by the species revealed that R. mangle was more impacted by Mn and Cu and that L. racemosa showed alterations in its physiological responses in the presence of Cu, Zn, and Fe. The concentration of these metals in the leaves, with values above previous local reference limits, was associated with reductions in the chlorophyll-a and chlorophyll-b content and carbon assimilation, mainly in L. racemosa. The antiradical activity was also altered, suggesting a lower ability of both species to eliminate reactive oxygen species (ROS). A possible reason for the symptoms of oxidative stress may be due to the reduced efficiency of antioxidant defense by Cu2+ and Zn2+. In addition, the presence of Pb in the leaf tissue may be toxic to the fauna and the bioaccumulation of this metal and trace elements can be a way to transfer them into the food web by biomagnification.

Abstract Polyphenolics from Rhizophora mangle (R. mangle) have shown wound healing and anti- inflammatory effects that may be potentiated by being associated with ascorbic acid, an important substance for collagen and elastin synthesis that plays a role in tissue repair. In our study, we aimed to formulate an association of R. mangle and ascorbic acid in hydrogels and evaluate the association’s cytotoxic and immunomodulatory effects. In a pre-formulation study, three gelling polymers (i.e.xanthan gum, poloxamer and hydroxyethyl cellulose) were tested. The selected polymer (i.e. xanthan gum) was used to evaluate cytotoxic and immunomodulatory effects using flow cytometry. Xanthan gum (1.5%) had a homogeneous appearance, an orange colour, a smooth surface, intense brightness and the typical odour, as well as non-Newtonian pseudoplastic behaviour. With a pH of 5.0-5.3 and a non-cytotoxic profile, xanthan gum induced the proliferation and activation of CD4 +, CD8+ and NK T lymphocytes and the production of IL- 2, IL-4, IL-10, IL-17 and TNF-α cytokines in stimulated splenocytes. The results suggest that the association of R. mangle and ascorbic acid in 1.5% xanthan gum hydrogel may be promising in preparations for wound-healing processes.

Bacterial communities associated with plant propagules remain understudied, despite the opportunities that propagules represent as dispersal vectors for bacteria to new sites. These communities may be the product of a combination of environmental influence and inheritance from parent to offspring. The relative role of these mechanisms could have significant implications for our understanding of plant–microbe interactions. We studied the correlates of microbiome community similarities across an invasion front of red mangroves (Rhizophora mangle L.) in Florida, where the species is expanding northward. We collected georeferenced propagule samples from 110 individuals of red mangroves across 11 populations in Florida and used 16S rRNA gene (iTag) sequencing to describe their bacterial communities. We found no core community of bacterial amplicon sequence variants (ASVs) across the Florida range of red mangroves, though there were some ASVs shared among individuals within most populations. Populations differed significantly as measured by Bray–Curtis dissimilarity, but not Unifrac distance. We generated data from 6 microsatellite loci from 60 individuals across 9 of the 11 populations. Geographic distance was correlated with beta diversity, but genetic distance was not. We conclude that red mangrove propagule bacterial communities are likely influenced more by local environmental acquisition than by inheritance. [ABSTRACT FROM AUTHOR]

The effects of iron, manganese, zinc, copper, and lead on the chlorophyll content, carbon assimilation, and the antiradical activity of Rhizophora mangle and Laguncularia racemosa were evaluated in regions affected by the Fundão dam disruption in Brazil. The mine waste which settled and accumulated in the sediments could represent long-term contamination. It can be expected that the iron oxyhydroxides deposited in the sediments will be solubilized, leading to chronic contamination by trace metals and the accumulation of these metals in the biota. In this sense, biological indicators prove to be important tools to assess this type of damage. The different bioaccumulation of metals by the species revealed that R. mangle was more impacted by Mn and Cu and that L. racemosa showed alterations in its physiological responses in the presence of Cu, Zn, and Fe. The concentration of these metals in the leaves, with values above previous local reference limits, was associated with reductions in the chlorophyll-a and chlorophyll-b content and carbon assimilation, mainly in L. racemosa. The antiradical activity was also altered, suggesting a lower ability of both species to eliminate reactive oxygen species (ROS). A possible reason for the symptoms of oxidative stress may be due to the reduced efficiency of antioxidant defense by Cu2+ and Zn2+. In addition, the presence of Pb in the leaf tissue may be toxic to the fauna and the bioaccumulation of this metal and trace elements can be a way to transfer them into the food web by biomagnification. [ABSTRACT FROM AUTHOR]

Premise: The preservation of plant tissues in ethanol is conventionally viewed as problematic. Here, we show that leaf preservation in ethanol combined with proteinase digestion can provide high‐quality DNA extracts. Additionally, as a pretreatment, ethanol can facilitate DNA extraction for recalcitrant samples. Methods: DNA was isolated from leaves preserved with 96% ethanol or from silica‐desiccated leaf samples and herbarium fragments that were pretreated with ethanol. DNA was extracted from herbarium tissues using a special ethanol pretreatment protocol, and these extracts were compared with those obtained using the standard cetyltrimethylammonium bromide (CTAB) method. Results: DNA extracted from tissue preserved in, or pretreated with, ethanol was less fragmented than DNA from tissues without pretreatment. Adding proteinase digestion to the lysis step increased the amount of DNA obtained from the ethanol‐pretreated tissues. The combination of the ethanol pretreatment with liquid nitrogen freezing and a sorbitol wash prior to cell lysis greatly improved the quality and yield of DNA from the herbarium tissue samples. Discussion: This study critically reevaluates the consequences of ethanol for plant tissue preservation and expands the utility of pretreatment methods for molecular and phylogenomic studies. [ABSTRACT FROM AUTHOR]

Copyright of Biological Invasions is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Se determinó la composición de corales pétreos presentes en raíces sumergidas de Rhizophora mangle L. (mangle rojo), del Parque Nacional Jardines de la Reina. Se cuantificaron 300 raíces, en las que se identificaron 11 especies, pertenecientes a 7 géneros. Las especies predominantes fueron Porites astreoides y Porites divaricata. El 100% de las colonias seencontraron en asociación con algas costrosas coralinas, fundamentalmente del género Neogoniolithon. Al parecer, el éxito del asentamiento de las colonias de corales pétreos en las raíces sumergidas de los manglares, depende de la presencia de algas costrosas coralinas.

Abstract Premise The preservation of plant tissues in ethanol is conventionally viewed as problematic. Here, we show that leaf preservation in ethanol combined with proteinase digestion can provide high‐quality DNA extracts. Additionally, as a pretreatment, ethanol can facilitate DNA extraction for recalcitrant samples. Methods DNA was isolated from leaves preserved with 96% ethanol or from silica‐desiccated leaf samples and herbarium fragments that were pretreated with ethanol. DNA was extracted from herbarium tissues using a special ethanol pretreatment protocol, and these extracts were compared with those obtained using the standard cetyltrimethylammonium bromide (CTAB) method. Results DNA extracted from tissue preserved in, or pretreated with, ethanol was less fragmented than DNA from tissues without pretreatment. Adding proteinase digestion to the lysis step increased the amount of DNA obtained from the ethanol‐pretreated tissues. The combination of the ethanol pretreatment with liquid nitrogen freezing and a sorbitol wash prior to cell lysis greatly improved the quality and yield of DNA from the herbarium tissue samples. Discussion This study critically reevaluates the consequences of ethanol for plant tissue preservation and expands the utility of pretreatment methods for molecular and phylogenomic studies.

Mangroves are unique coastal ecosystems, which have many important ecological functions, as they are a reservoir of many marine species well adapted to saline conditions and are fundamental as sites of carbon storage. Although the microbial contribution to nutrient cycling in these ecosystems has been well recognized, there is a lack of information regarding the microbial composition and structure of different ecological types of mangrove forests. In this study, we characterized the microbial community (Bacteria and Archaea) in sediments associated with five ecological types of mangrove forests in a coastal lagoon dominated by Avicennia germinans and Rhizophora mangle, through 16S rRNA-V4 gene sequencing. Overall, Proteobacteria (51%), Chloroflexi (12%), Gemmatimonadetes (5%) and Planctomycetes (6%) were the most abundant bacterial phyla, while Thaumarchaeota (30%), Bathyarchaeota (21%) and Nanoarchaeaeota (18%) were the dominant archaeal phyla. The microbial composition associated with basin mangroves dominated by Avicennia germinans was significantly different from the other ecological types, which becomes relevant for restoration strategies. [ABSTRACT FROM AUTHOR]

Plant-associated microbial communities may be important sources of functional diversity and genetic variation that influence host evolution. Bacteria provide benefits for their hosts, yet in most plant systems we know little about their taxonomic composition or variation across tissues and host range. Red Mangrove (Rhizophora mangle L.) is a vital coastal plant species that is currently expanding poleward and with it, perhaps, its microbiome. We explored variability in bacterial communities across tissues, individuals, and populations. We collected samples from six sample types from 5 to 10 individuals at each of three populations and used 16S rRNA gene (iTag) sequencing to describe their bacterial communities. Core community members and dominant bacterial classes were determined for each sample type. Pairwise PERMANOVA of Bray–Curtis dissimilarity and Indicator Species Analysis revealed significant differences in bacterial communities between sample types and populations. We described the previously unexplored microbiome of the reproductive tissues of R. mangle. Populations and most sample types were associated with distinct communities. Bacterial communities associated with R. mangle are influenced by host geography and sample type. Our study provides a foundation for future work exploring the functional roles of these microbes and their relevance to biogeochemical cycling. [ABSTRACT FROM AUTHOR]

This publication serves as an introduction to identifying Rhizophora mangle (red mangrove). A brief overview of the family, genus, species, common name, description, storm tolerance, threats, and applications are summarized. The target audience is Florida homeowners who live along the coast with an interest in native plant communities and conservation. The objective is to educate the public on the correct identification, value, and benefits of red mangroves.

Top‐down effects of predators and bottom‐up effects of resources are important drivers of community structure and function in a wide array of ecosystems. Fertilization experiments impose variation in resource availability that can mediate the strength of predator impacts, but the prevalence of such interactions across natural productivity gradients is less clear. We studied the joint impacts of top‐down and bottom‐up factors in a tropical mangrove forest system, leveraging fine‐grained patchiness in resource availability and primary productivity on coastal cays of Belize. We excluded birds from canopies of red mangrove (Rhizophoraceae: Rhizophora mangle) for 13 months in zones of phosphorus‐limited, stunted dwarf mangroves, and in adjacent zones of vigorous mangroves that receive detrital subsidies. Birds decreased total arthropod densities by 62%, herbivore densities more than fivefold, and reduced rates of leaf and bud herbivory by 45% and 52%, respectively. Despite similar arthropod densities across both zones of productivity, leaf and bud damage were 2.0 and 4.3 times greater in productive stands. Detrital subsidies strongly impacted a suite of plant traits in productive stands, potentially making leaves more nutritious and vulnerable to damage. Despite consistently strong impacts on herbivory, we did not detect top‐down forcing that impacted mangrove growth, which was similar with and without birds. Our results indicated that both top‐down and bottom‐up forces drive arthropod community dynamics, but attenuation at the plant‐herbivore interface weakens top‐down control by avian insectivores. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chapingo Serie Ciencias Forestales is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Predicting the distribution, structure, and biomass of mangrove forests is an area of high research interest. Across the Atlantic East Pacific biogeographic region, three species are common and abundant members of local mangrove communities; Rhizophora mangle , Avicennia germinans , and Laguncularia racemosa . Biomass prediction for these species has relied on two approaches: site-specific allometries based on the idea that environmental/climatic differences between sites drive growth differences, or the use of common allometric equations based on the idea that site driven differences are minimal. Meta-analyses of global compilations of interspecific plot level data (e.g., mean canopy height, stand basal area) show trends in size and structure with climatic variables, however this has not been critically evaluated across these species using empirical allometric growth functions. We compared allometric equations derived from 590 individuals within and across nine broadly distributed sites at interspecific and intraspecific levels and explored the influence of climatic variables on allometric slopes and intercepts. Assessing variables that can be used to predict biomass in the field (height, diameter at breast height (DBH), canopy spread), we find interspecific root mean squared errors similar to or smaller than most intraspecific or site-specific equations, particularly when examining sites with sample sizes above recommended values. We also find significant effects of several climatic variables on growth allometries with the strongest effects from minimum temperature followed by precipitation seasonality. Our results suggest that while climate has a clear influence on mangrove allometric growth, common equations may have utility in biomass prediction. Future methodological improvements, particularly larger sample sizes across the entire available size range, combined with data from a broader range of growth conditions will further inform which allometric relationships exhibit the most variability within and across sites and which variables best predict mangrove biomass., Competing Interests: The authors declare no conflicts of interest., (© 2024 The Author(s). Ecology and Evolution published by John Wiley & Sons Ltd.)

The present study demonstrated microbial corrosion protection of MS 1010 on cooling tower water using plant-based inhibitors derived from methanolic extraction of dry mangrove leaves (R.mangle and A.marina), and its assessment of antibacterial activity against corrosive bacteria (B.megaterium) was investigated. FT-IR and GC–MS analyzed the inhibitors component and corrosion behavior of MS 1010 on cooling water, with and without inhibitors were analyzed by EIS and Tafel studies. GC–MS spectra confirmed the presence of Myo-Inositol, 4-C-methyl and chromene as major constituents presented on the R.mangle whereas Lupeol, trifluoroacetate and beta-amyrin compounds were found on the A.marina. In the cooling water, these two inhibitors demonstrated outstanding antibacterial activity and controlled biofilm growth. As plant-based inhibitors were used in cooling water systems, EIS data showed a significant increase in Rct value when compared to the control system. Tafel plot indicates inhibitors have mixed inhibitory effects and for the systems with and without inhibitors, the icorr value was 1.5649A and 2.0875A, respectively. At the optimal dose of 25 ppm, the inhibitory efficiency of MERM and MEAM was 81% and 80%, respectively. The overall discussion reveals that inhibitor substances can be absorbed on the metal surface and then act as a dual role in inhibiting corrosive bacterial growth and barrier to the corrosion process in the cooling water system.

The enemy release hypothesis (ERH) posits that introduced species often leave their enemies behind when introduced to a new range. This release from enemies may allow introduced species to achieve higher growth and reproduction and may explain why some invaders flourish in new locations. Red mangroves (Rhizophora mangle) were introduced to Hawaiʻi from Florida over a century ago. Because Hawaiʻi has no native mangroves, the arrival of R. mangle fundamentally changed the structure and function of estuarine shorelines. While numerous enemies affect red mangroves in their native range (tropical America), in Hawaiʻi, mangroves apparently experience little herbivory, which may explain why introduced mangroves are so productive, fecund, and continue to spread. In this study, we compared the effects of enemies in native and introduced populations of brackish red mangroves (R. mangle) in 8–10 sites in the native range (Florida, Belize, and Panama) and introduced range of mangroves (Hawaiʻi). At each site, we measured the (1) occurrence of enemies using timed visual surveys, (2) occurrence of damage to different mangrove structures (leaves, apical buds, dead twigs, roots, propagules, and seedlings), and (3) rate of propagule herbivory using tethering experiments. Consistent with the ERH, we found an order of magnitude less damage and fewer enemies in introduced than native mangrove sites. While introduced mangroves harbored few enemies and minimal damage, native mangroves were affected by numerous enemies, including leaf‐eating crabs, specialist bud moths, wood‐boring insects and isopods, and propagule predators. These patterns were consistent across all plant structures (roots to leaves), among marine and terrestrial enemies, and across functional groups (browsers, borers, pathogens, etc.), which demonstrates enemy escape occurs consistently among different functional groups and via trophic (e.g., herbivores) and non‐trophic (e.g., root borers) interactions. Our study is among the first biogeographical enemy release studies to take a comprehensive approach to quantifying the occurrence of damage from a broad suite of marine and terrestrial taxa across an array of wetland plant structures. Understanding how natural enemies alter this key foundation species will become increasingly relevant globally as mangroves continue to invade new regions through intentional plantings or range expansion driven by climate change. [ABSTRACT FROM AUTHOR]

Management of established non‐native plants is challenging because removal is expensive and can produce negative consequences, yet establishment can create novel ecosystems. Red mangrove propagules were introduced to Moloka'i, Hawai'i, in 1902 to mitigate the effects of soil erosion and have since spread along the coast and to adjacent islands creating novel habitat.We compared zooplankton communities between novel mangrove and historical non‐mangrove habitat both within fishponds and along open coastline to examine environmental factors, including mangrove presence, affecting zooplankton community composition.Community composition patterns were driven by lunar cycle and site characteristics, including fishpond structure, mangrove and open‐coast shoreline length, percent of mangrove shoreline length, total percent mangrove leaf carbon and upstream watershed disturbance.Our findings indicate that during the tropical summer reproductive season, non‐native mangroves support diversity, richness and community composition similar to non‐mangrove areas, though some widespread taxa have lower abundance, and some rare taxa are more abundant in mangroves.Additionally, fishpond zooplankton community structure is significantly different from open‐coast areas, indicating fishponds, themselves, create novel habitat.Synthesis and application. In the face of declining fisheries, threatened reef habitat and changing climatic conditions, non‐native mangroves may provide, rather than impede, zooplankton habitat availability in novel locations. [ABSTRACT FROM AUTHOR]

Predictions of climate-related shifts in species ranges have largely been based on correlative models. Due to limitations of these models, there is a need for more integration of experimental approaches when studying impacts of climate change on species distributions. Here, we used controlled experiments to identify physiological thresholds that control poleward range limits of three species of mangroves found in North America. We found that all three species exhibited a threshold response to extreme cold, but freeze tolerance thresholds varied among species. From these experiments, we developed a climate metric, freeze degree days (FDD), which incorporates both the intensity and the frequency of freezes. When included in distribution models, FDD accurately predicted mangrove presence/absence. Using 28 years of satellite imagery, we linked FDD to observed changes in mangrove abundance in Florida, further exemplifying the importance of extreme cold. We then used downscaled climate projections of FDD to project that these range limits will move northward by 2.2-3.2 km yr(-1) over the next 50 years.

El estudio de la Biología reproductiva del mangle rojo (Rhizophora mangle L.) en Puerto El Morro, Provincia del Guayas, Ecuador, tiene por objetivo determinar que la especie es hermafrodita, describiendo sus órganos reproductivos, su estado y proceso de maduración en la flor, desde capullo hasta la antesis, estableciendo las características morfológicas y tamaño de estos. Además, de clasificar el estado reproductivo con respecto a las otras especies de mangle rojo en los manglares de Puerto El Morro, que al momento mantiene pocos árboles de R. mangle florecidos y una relación baja de representatividad en los manglares de Puerto El Morro. Para tal efecto, se realizaron dos parcelas correspondientes a 0,25 ha., tanto a la entrada del canal como a la salida del canal de El Morro, lo cual permitió establecer la morfología de R. mangle, su densidad y volumen en cada parcela y en relación con las otras especies de mangles rojos presentes.

Many coastal foundation plant species thrive across a range of environmental conditions, often displaying dramatic phenotypic variation in response to environmental variation. We characterized the response of propagules from six populations of the foundation species Rhizophora mangle L. to full factorial combinations of two levels of salinity (15 ppt and 45 ppt) reflecting the range of salinity measured in the field populations, and two levels of nitrogen (N; no addition and amended at approximately 3 mg N per pot each week) equivalent to comparing ambient N to a rate of addition of 75 kg per hectare per year. The response to increasing salinity included significant changes, i.e., phenotypic plasticity, in succulence and root to shoot biomass allocation. Propagules also showed plasticity in maximum photosynthetic rate and root to shoot allocation in response to N amendment, but the responses depended on the level of salinity and varied by population of origin. In addition, propagules from different populations and maternal families within populations differed in survival and all traits measured except photosynthesis. Variation in phenotypes, phenotypic plasticity and propagule survival within and among R. mangle populations may contribute to adaptation to a complex mosaic of environmental conditions and response to climate change.

Mangrove microbiomes play an essential role in the fate of mangroves in our changing planet, but the factors regulating the biogeographical distribution of mangrove microbial communities remain essentially vague. This paper contributes to our understanding of mangrove microbiomes distributed along three biogeographical provinces and ecoregions, covering the exuberant mangroves of Amazonia ecoregion (North Brazil Shelf) as well as mangroves located in the southern limit of distribution (Southeastern ecoregion, Warm Temperate Southwestern Atlantic) and mangroves localized on the drier semi-arid coast (Northeastern ecoregion, Tropical Southwestern Atlantic), two important ecotones where poleward and landward shifts, respectively, are expected to occur related to climate change. This study compared the microbiomes associated with the conspicuous red mangrove (Rhizophora mangle) root soils encompassing soil properties, latitudinal factors, and amplicon sequence variants of 105 samples. We demonstrated that, although the northern and southern sites are over 4,000 km apart, and despite R. mangle genetic divergences between north and south populations, their microbiomes resemble each other more than the northern and northeastern neighbors. In addition, the northeastern semi-arid microbiomes were more diverse and displayed a higher level of complexity than the northern and southern ones. This finding may reflect the endurance of the northeast microbial communities tailored to deal with the stressful conditions of semi-aridity and may play a role in the resistance and growing landward expansion observed in such mangroves. Minimum temperature, precipitation, organic carbon, and potential evapotranspiration were the main microbiota variation drivers and should be considered in mangrove conservation and recovery strategies in the Anthropocene. In the face of changes in climate, land cover, biodiversity, and chemical composition, the richness and complexity harbored by semi-arid mangrove microbiomes may hold the key to mangrove adaptability in our changing planet.

Mangrove microbiomes play an essential role in the fate of mangroves in our changing planet, but the factors regulating the biogeographical distribution of mangrove microbial communities remain essentially vague. This paper contributes to our understanding of mangrove microbiomes distributed along three biogeographical provinces and ecoregions, covering the exuberant mangroves of Amazonia ecoregion (North Brazil Shelf) as well as mangroves located in the southern limit of distribution (Southeastern ecoregion, Warm Temperate Southwestern Atlantic) and mangroves localized on the drier semi-arid coast (Northeastern ecoregion, Tropical Southwestern Atlantic), two important ecotones where poleward and landward shifts, respectively, are expected to occur related to climate change. This study compared the microbiomes associated with the conspicuous red mangrove (Rhizophora mangle) root soils encompassing soil properties, latitudinal factors, and amplicon sequence variants of 105 samples. We demonstrated that, although the northern and southern sites are over 4,000 km apart, and despite R. mangle genetic divergences between north and south populations, their microbiomes resemble each other more than the northern and northeastern neighbors. In addition, the northeastern semi-arid microbiomes were more diverse and displayed a higher level of complexity than the northern and southern ones. This finding may reflect the endurance of the northeast microbial communities tailored to deal with the stressful conditions of semi-aridity and may play a role in the resistance and growing landward expansion observed in such mangroves. Minimum temperature, precipitation, organic carbon, and potential evapotranspiration were the main microbiota variation drivers and should be considered in mangrove conservation and recovery strategies in the Anthropocene. In the face of changes in climate, land cover, biodiversity, and chemical composition, the richness and complexity harbored by semi-arid mangrove microbiomes may hold the key to mangrove adaptability in our changing planet. [ABSTRACT FROM AUTHOR]

Sargassum spp. strandings in the tropical Atlantic harm local ecosystems due to toxic sulfide levels. We conducted a mesocosm experiment to test the efficacy of iron(III) (hydr)oxides in (a) mitigating sulfide toxicity in mangroves resulting from Sargassum and (b) reducing potentially enhanced greenhouse gas emissions. Our results show that iron addition failed to prevent mangrove mortality caused by highly toxic sulfide concentrations, which reached up to 15,000 μmol l−1 in 14 days; timely removal may potentially prevent mangrove death. Sargassum -impacted mesocosms significantly increased methane, nitrous oxide, and carbon dioxide emissions, producing approximately 1 g CO 2 -equivalents m−2 h−1 during daylight hours, thereby shifting mangroves from sinks to sources of greenhouse gasses. However, iron addition decreased methane emissions by 62 % and nitrous oxide emissions by 57 %. This research reveals that Sargassum strandings have multiple adverse effects related to chemical and ecological dynamics in mangrove ecosystems, including greenhouse gas emissions. [Display omitted] • Mangrove trees died from sulfide toxicity after experimental Sargassum additions. • Iron addition reduced sulfide insufficiently to prevent mangrove death. • Sargassum removal within 15 days can improve the chances of survival for mangroves. • Ex-situ N 2 O and CH 4 emissions from decomposing sargassum were substantial. • Iron addition decreased GHG production during sargassum decomposition. [ABSTRACT FROM AUTHOR]

Increases in minimum air temperatures have facilitated transitions of salt marshes to mangroves along coastlines in the southeastern United States. Numerous studies have documented mangrove expansion into salt marshes; however, a present‐day conversion of oyster reefs to mangrove islands has not been documented. Using aerial photographs and high‐resolution satellite imagery, we determined percent cover and number of mangrove patches on oyster reefs in Mosquito Lagoon, FL, USA over 74 years (1943–2017) by digitizing oyster reef and "mangrove on oyster reef" areas. Live oyster reefs present in 1943 were tracked through time and the mangrove area on every reef calculated for seven time periods. There was a 103% increase in mangrove cover on live oyster reefs from 1943 (6.6%) to 2017 (13.4%). Between 1943 and 1984, the cover remained consistent (~7%), while between 1984 and 2017, mangrove cover increased rapidly with a 6% year−1 increase in mangrove area on oyster reefs (198% increase). In 1943, 8.7% of individual reefs had at least one mangrove patch on them; by 2017, 21.8% of reefs did. Site visits found at least one mature Avicennia germinans on each tracked mangrove reef, with large numbers of smaller Rhizophora mangle, suggesting the post‐1984 mangrove increases were the result of increased R. mangle recruitment and survival. Escalation in the coverage and number of mangrove stands on oyster reefs coincided with a period that lacked extreme freeze events. The time since a temperature of ≤−6.6°C (A. germinans mortality threshold) and ≤−4°C (R. mangle mortality threshold) were significantly correlated with the increased ratio of mangrove area:oyster area, total mangrove area, and number of mangrove patches, with greater variation explained by time since ≤ −4°C. The lack of freezes could lead globally to an ecosystem shift of intertidal oyster reefs to mangrove islands near poleward mangrove range limits. [ABSTRACT FROM AUTHOR]

Foundation species structure communities by creating habitat and modifying environmental conditions, and there is increasing interest in how foundation species, such as corals and mangroves, interact with one another as these interactions can have cascading effects on diversity and abundance of associated organisms. Given recent reports of corals living on or between mangrove roots under the canopy, we hypothesized that mangroves can serve as a refuge for corals from stresses such as high solar irradiance and temperatures that are associated with the adjacent shallow reef. Using field surveys and a reciprocal transplant experiment, we tested the effects of light and habitat (e.g., reef or mangrove) on coral community structure (i.e., coral species richness, abundance, and diversity) and condition (i.e., level of bleaching, tissue loss, and mortality). The surveys revealed higher coral richness in mangroves than on the adjacent reef, indicating that mangroves can serve as refugia for numerous coral species. Our experimental manipulation of light in mangrove and reef habitats indicated that light intensity is a key environmental parameter mediating coral bleaching and survival, with mangrove habitats providing a refuge from the light stress experienced on nearby shallow reefs. Moreover, our experiment revealed that reef corals bleached less than mangrove corals following transplantation, regardless of whether they were transplanted into mangrove or reef habitats. We suggest that the lower coral richness of the shallow reef is the result of the extreme environmental conditions that select for a subset of coral species able to tolerate these conditions. The facilitative interactions that allow mangroves to act as coral refugia by reducing environmental stress will likely become increasingly important with global climate change. [ABSTRACT FROM AUTHOR]

Hawai‘ian ecosystems evolved in relative isolation and support an abundance of native and endemic species. As such, they are particularly vulnerable to introduced species that alter habitat and interfere with species interactions. Although mangroves are valued globally for shoreline protection and other services, their invasion of the Hawai‘ian islands may have negative effects on the abundance and functions of native species. On an island in Kāne‘ohe Bay, O‘ahu, we explored the relationship between invasion of the red mangrove, Rhizophora mangle, and abundance of the native burrowing shrimp Alpheus rapax, which shares its burrows with the endemic goby Psilogobius mainlandi in a mutualism that reduces predation on both. We hypothesized that the abundance of shrimp/goby burrows is reduced beneath mangroves due to increased cover associated with mangrove prop roots, which trap leaves and debris and may harbor the invasive red alga Gracilaria salicornia. At 3 mangrove-invaded sites, we conducted a survey of burrow density and benthic debris and found ~4–5× lower burrow density and 4× greater cover of debris under the mangrove edge compared to sandflats that were 1.5 and 5.0 m away. Burrow density was negatively correlated with total cover of benthic debris and with subgroups of that cover composed of G. salicornia or leaves. We tested the effect of debris removal over 2 weeks, which resulted in 3–8× more burrows. Thus, we provide evidence that invasive red mangroves, through trapping leaves and promoting presence of invasive G. salicornia among their prop roots, have strong negative effects on shrimp/goby burrow density. Although our study was limited in spatial scope, we propose that current efforts to remove mangroves in Hawai‘i, for both cultural and ecological reasons, will mitigate negative effects on endemic goby and native shrimp habitat.

Ongoing losses to mangrove forests globally have prompted increased interest in restoration programs that seek to restore vital ecosystem functions and services. In many cases, data on local‐scale environmental tolerances of mangrove species used in reforestation efforts is lacking, and failure of restoration projects has been attributed to incorrect species selection in plantations. Here, we assess the impact of soil salinity on the early establishment success of monospecific red mangrove Rhizophora mangle reforestation projects in the Saloum Delta, Senegal, a region where widespread mangrove restoration efforts are ongoing. At soil salinities >60 ppt, stomatal conductance, photosystem II operating efficiency, and growth of planted R. mangle seedlings were severely reduced. Similarly, after 1–3 years, survival of mangrove seedlings decreased in soil salinities of >60 ppt. In contrast, we recorded naturally occurring black mangrove Avicennia germinans growing in exceptionally hypersaline conditions (90 ppt), representing some of the most saline vegetated ecosystems on Earth. The findings reported herein can be used to inform species choice in reforestation projects and help improve success rates of coastal wetland restoration projects in semiarid regions. [ABSTRACT FROM AUTHOR]

Hawai'ian ecosystems evolved in relative isolation and support an abundance of native and endemic species. As such, they are particularly vulnerable to introduced species that alter habitat and interfere with species interactions. Although mangroves are valued globally for shoreline protection and other services, their invasion of the Hawai'ian islands may have negative effects on the abundance and functions of native species. On an island in Kāne'ohe Bay, O'ahu, we explored the relationship between invasion of the red mangrove, Rhizophora mangle, and abundance of the native burrowing shrimp Alpheus rapax, which shares its burrows with the endemic goby Psilogobius mainlandi in a mutualism that reduces predation on both. We hypothesized that the abundance of shrimp/goby burrows is reduced beneath mangroves due to increased cover associated with mangrove prop roots, which trap leaves and debris and may harbor the invasive red alga Gracilaria salicornia. At 3 mangrove-invaded sites, we conducted a survey of burrow density and benthic debris and found ~4-5× lower burrow density and 4× greater cover of debris under the mangrove edge compared to sandflats that were 1.5 and 5.0 m away. Burrow density was negatively correlated with total cover of benthic debris and with subgroups of that cover composed of G. salicornia or leaves. We tested the effect of debris removal over 2 weeks, which resulted in 3-8× more burrows. Thus, we provide evidence that invasive red mangroves, through trapping leaves and promoting presence of invasive G. salicornia among their prop roots, have strong negative effects on shrimp/goby burrow density. Although our study was limited in spatial scope, we propose that current efforts to remove mangroves in Hawai'i, for both cultural and ecological reasons, will mitigate negative effects on endemic goby and native shrimp habitat. [ABSTRACT FROM AUTHOR]

Due to climate warming, tannin-rich Rhizophora mangle migrates into tannin-poor salt marshes, where the tannins interfere with the biogeochemistry in the soil. Changes in biogeochemistry are likely associated with changes in microbial communities. This was studied in microcosms filled with salt marsh soil and amended with leaf powder, crude condensed tannins, purified condensed tannins (PCT), all from senescent R. mangle leaves, or with tannic acid. Size and composition of the microbial communities were determined by denaturing gradient gel electrophoresis, high-throughput sequencing and real-time PCR based on the 16S and 18S rRNA genes. Compared with the control, the 16S rRNA gene abundance was lowered by PCT, while the 18S rRNA gene abundance was enhanced by all treatments. The treatments also affected the composition of the 16S rRNA and 18S rRNA gene assemblies, but the effects on the 18S rRNA gene were greater. The composition of the 18S rRNA gene, but not of the 16S rRNA gene, was significantly correlated with the mineralization of carbon, nitrogen and phosphorus. Distinctive microbial groups emerged during the different treatments. This study revealed that migration of mangroves may affect both the prokaryotic and the eukaryotic communities in salt marsh soils, but that the effects on the eukaryotes will likely be greater. [ABSTRACT FROM AUTHOR]

Key message: Wood density varies among mangrove tree species and diameter size classes, reflecting ontogenetic strategies influenced by environmental conditions, such as the salinity gradient. Wood density is one of the most widely used parameters for the description of the structure of a plant and its production of biomass/carbon, as well as its strategies of growth and survival in the context of varying environmental conditions. Data were compiled on the wood density of the three mangrove tree species [Rhizophora mangle L., Avicennia germinans (L.) L., and Laguncularia racemosa (L.) C. F. Gaertn.] that predominate on the Ajuruteua Peninsula in Bragança on the Amazon coast of the Brazilian state of Pará, focusing on the stem position and diameter classes. The influence of the salinity gradient on the wood density of A. germinans was analyzed based on the definition of the three zones of salinity defined from the mean salinity values ascertained from the principal tidal channels found on the peninsula. Wood density varied significantly among species, diameter classes, and saline zones, but not in relation to the position on the stem. Our findings indicate that the inter- and intra-specific variation found in the wood density of the mangrove trees is the result of the different levels of salinity found in the study area, mediated by the variation in the growth of the plant in response to desiccation and hypersalinity that occur at higher elevation in the intertidal zone. In addition, the A. germinans trees with the highest wood density were found in the most saline zone, where these mangrove trees present a reduced assimilation of carbon, which affects the spatial distribution of this species, its production of biomass, and carbon storage. [ABSTRACT FROM AUTHOR]

Mangrove forests play an important role in climate change adaptation and mitigation by maintaining coastline elevations relative to sea level rise, protecting coastal infrastructure from storm damage, and storing substantial quantities of carbon (C) in live and detrital pools. Determining the efficacy of mangroves in achieving climate goals can be complicated by difficulty in quantifying C inputs (i.e., differentiating newer inputs from younger trees from older residual C pools), and mitigation assessments rarely consider potential offsets to CO2 storage by methane (CH4) production in mangrove sediments. The establishment of non‐native Rhizophora mangle along Hawaiian coastlines over the last century offers an opportunity to examine the role mangroves play in climate mitigation and adaptation both globally and locally as novel ecosystems. We quantified total ecosystem C storage, sedimentation, accretion, sediment organic C burial and CH4 emissions from ~70 year old R. mangle stands and adjacent uninvaded mudflats. Ecosystem C stocks of mangrove stands exceeded mudflats by 434 ± 33 Mg C/ha, and mangrove establishment increased average coastal accretion by 460%. Sediment organic C burial increased 10‐fold (to 4.5 Mg C ha−1 year−1), double the global mean for old growth mangrove forests, suggesting that C accumulation from younger trees may occur faster than previously thought, with implications for mangrove restoration. Simulations indicate that increased CH4 emissions from sediments offset ecosystem CO2 storage by only 2%–4%, equivalent to 30–60 Mg CO2‐eq/ha over mangrove lifetime (100 year sustained global warming potential). Results highlight the importance of mangroves as novel systems that can rapidly accumulate C, have a net positive atmospheric greenhouse gas removal effect, and support shoreline accretion rates that outpace current sea level rise. Sequestration potential of novel mangrove forests should be taken into account when considering their removal or management, especially in the context of climate mitigation goals. [ABSTRACT FROM AUTHOR]

Mangroves are dynamic ecosystems due to influence of abiotic and biotic factors, but the latter are far less studied. Interactions between key invertebrate groups, trees, and soil properties, among others, determine the community structure throughout mangrove stand developing. Covariation among these factors, however, obscures their mutual relationships in shaping mangrove community assemblage patterns. In the estuary of Pacoti River (Ceará State, northeast Brazil), we compared the diversity and distribution of brachyurans and trees among several mid-littoral areas, and their relation with sediment features, to understand their relationships in community assemblage of new mangrove stands in developing. To discriminate the relation among these variables, ordination of data (PCA) and multivariate multiple correlation (PLS) were used. Data show that intertidal establishment of Brachyura was determined primarily by sediment properties, but further spatial distribution and diversity of this key faunal group, and the tree species that establishes, can influence each other. The prop roots habitat of Rhizophora mangle supports a higher brachyuran richness, since it allows the existence of multispecific crab burrow systems underground. Our results show that Rhizophora and brachyurans are key engineer organisms involved in shaping the physical and, hence, the ecological structure of newly established mangrove stands at Neotropics. [ABSTRACT FROM AUTHOR]

Fringe mangroves face waves daily and are thought to protect against erosion in low wave energy sites and undergo erosion if exposed to high wave energy. We aimed to understand the effects of fringe mangroves on erosion and sediment dynamics and of wave exposure on seedling density at three sites of increasing wave energy. Sediment properties (mean grain size, sorting, and bulk density) were assessed within each site in unvegetated and mangrove-vegetated shores in wet and dry seasons. In addition, we estimated seasonal erosion/accretion rates for 2.4 years and seedling density in two zones from the forest edge with contrasting wave exposure. Regression analysis was carried out to explain sediment properties and erosion rate variance in response to the vegetation volume that opposes wave energy and to explain erosion rates in response to wave energy. Mangrove-vegetated shores reduced erosion rates from 3 to 15 times in the two sites with higher wave energy, while the vegetated site with the lowest wave energy experienced accretion compared to minor erosion along the unvegetated shore. Shores with greater Rhizophora mangle basal areas and vegetation volumes favored deposition of particles with low settling rates, different sediment classes, reduced erosion rates, and increased shoreline stability. Mangrove seedling density decreased between 2 and 43 times from the low wave exposure zone to the high wave exposure zone at the forest edge in studied sites. In order to increase vegetation volume, coastal adaptation based on mangroves must limit human disturbances and facilitate epiphytic relationships with oysters. [ABSTRACT FROM AUTHOR]

The objective of this work was characterize the floristic diversity and the phytosociological structure of the mangrove in the São Francisco River estuary in order to contribute to the conservation of this ecosystem. Thirtyfour sampling sites were selected, according to ongoing structural mosaic in the region ranging from 100 to 400 m between themselves, in a total useful area of 0.7625 ha. The evaluated parameters were: density of live and dead trunks; living and dead Basal Area; Absolute Frequency, Relative Frequency and Importance Value. Three typical mangrove species of the São Francisco estuary were found such as Avicennia germinans (L.) Stearn, Rhizophora mangle L. and Laguncularia racemosa (L.) Gaertn. F. Gaertn. The forest height ranged from 2.88 to 15.63 m, the DBH from 3.95 to 19.74 cm, live basal area from 4.22 to 47.83 m² ha-1 and dead basal area from 0.50 to 59.63 m² ha-1. The living trunks density ranged from 375.00 to 9100.00 trunks ha-1 and dead trunk density from 100-2800 trunks ha-1. The described results in this study demonstrated that the mangrove forests presents a structural variability that may be associated with environmental characteristics (marine erosion) and anthropogenic factors. The peculiarities of each site emphasize the importance of preventive actions in the ecosystem conservation. [ABSTRACT FROM AUTHOR]

França, M.C.; Cohen, M.C.L.; Pessenda, L.C.R.; Francisquini, M.I.; de Jesus Ribeiro, C.M., and de Oliveira, T.R., 2019. Tannin as a new indicator of paleomangrove occurrence within an Amazonian coastal region. Journal of Coastal Research, 35(1), 82–90. Coconut Creek (Florida), ISSN 0749-0208. Three sediment cores, sampled from a (1) mangrove zone, (2) mangrove–várzea zone, and (3) várzea zone at the Marajó Island–Amazonian coastal region were studied to compare the pollen and the sedimentological signals with tannin concentrations in sediments accumulated during the last millennium. The integration of these data allowed the interpretation of mangrove paleoecology based on pollen content along stratigraphic sequences. Most stratigraphy of the cores indicated a direct relationship between Rhizophora mangle (red mangrove) pollen content and tannin content. Some stratigraphic intervals showed a high percentage of R. mangle pollen, which may be interpreted as the mangrove forest mainly being occupied by R. mangle. A decrease of tannin content suggests a decrease of R. mangle density or a late mangrove colonization. The spectrophotometric method using tannin concentrations, proposed in this paper and supported by pollen data, may be considered an additional tool for the paleoenvironmental reconstruction of mangrove areas and an innovative tool that will allow reduction of costs in the studies of paleomangrove environment identification. [ABSTRACT FROM AUTHOR]

The present study was conducted to identify the antifungal activity of phenolic compounds extracted from the mangrove, Rhizophora mangle against the Fusarium verticillioides isolates DA42, F64 and PO3. The total phenolic content was calculated using the Folin-Ciocalteu method. The in vitro inhibition test was performed according to the poisoned food technique. Stem extracts had the highest total phenolic content (9.5 mg gallic acid equivalents/g dry biomass) and displayed major inhibition percentages against all Fusarium verticillioides isolates. Furthermore, the concentration of the stem extract required to inhibit the three fungal isolates by 50 %, is 2 to 3 times greater on average than that required for leaf and root extracts. This study demonstrated the inhibitory activity of ethanol extracts of Rhizophora mangle roots, stems and leaves against different isolates of Fusarium verticillioides. [ABSTRACT FROM AUTHOR]

Crown displacement in trees is an adaptive response driven by neighbours that optimizes space use and reduces competition. But it can also be the result of wind force. Although morphological responses to neighbours have been well studied, the interplay between neighbours and wind in driving crown shape, and the implications for plant interactions remain poorly understood. However, it is crucial to predict such changes in vegetation structure and function under the scope of global change. We test the hypothesis that aboveground interactions are reduced with increasing soil stress and that wind becomes the main driver of crown shape in mangrove forests.We investigated the effect of neighbours and wind intensity and direction on crown displacement of mangrove canopy and below canopy trees along a salinity gradient, and assessed crown asymmetry for three mangrove tree species, as well as the contribution of crown displacement on reducing crown‐projected area overlap and thus neighbourhood competition.Results show that crown displacement of canopy trees is strongly influenced by winds at all salinities. At low salinities, competition for space accounted for 48% of crown displacement away from neighbours, compared to 49% found for the synthetized effects of wind and neighbours. While trees below the canopy displace their crowns away from their neighbours, no response to wind could be detected. This can be due to the wind protection conferred by a dense canopy stand related to bigger crowns that effectively reduce wind drag. At higher salinities, there was a reduction in canopy overlap due to crown displacement, which suggests reduced aboveground plant interactions with increasing soil stress.While neighbourhood avoidance is a fundamental strategy for optimal light foraging, this study shows that wind strength and directionality are main drivers of crown shape with increasing stress and highlights their potential influence in plant interactions and forest structure, pointing to an increased susceptibility of trees to disturbances that should be further studied. A plain language summary is available for this article. Plain Language Summary [ABSTRACT FROM AUTHOR]

Background and aims: Due to global warming, it is to be expected that mangroves will move north- and southwards and enter salt marshes, which will then be enriched with mangrove-derived organic compounds. Little is known about the effects that tannins, which are abundantly present in leaf litter of Rhizophora mangle, will have on the biogeochemical cycles in salt marsh soils.Methods: In microcosms, soil from a Distichlis spicata salt marsh was enriched with R. mangle-derived leaf powder (LP), crude condensed tannins (CCT) and purified condensed tannins (PCT), or with commercially available tannic acid (TA). Each treatment received a fixed amount of tannins, i.e. 10 mg /g dry soil. Due to the enrichment with tannins in each fraction, the amount of carbon added increased from C < TA = PCT < CCT < LP. At Day 7, 21, 35 and 42 of the incubation period, CO2 emission rates were determined after closing the microcosms for 24 h. Net nitrogen and phosphorous mineralization rates were also determined for the entire incubation period. Experiments were done at Practical Salinity Units of 20, 28 and 35 to cover the range in salinities observed in the field (20 and 35 PSU).Results: For the whole incubation period, the CO2 emission increased significantly (p < 0.05) in the order of C < PCT < CCT = TA < LP microcosms. The microcosms with LP showed immobilization of mineral nitrogen and phosphorus, while the other microcosms revealed net nitrogen and phosphorus mineralization in the order of CCT < TA < PCT < C for N mineralization, and CCT = TA < C < PCT for P mineralization. The C and N mineralization rates measured at a salinity of 20 PSU were significantly larger than at 28 and 35 PSU.Conclusion: The results showed that mangrove leaf litter stimulated net C mineralization and N and P immobilization. Purified condensed tannins of senescing R. mangle leaves enhanced C and P, and suppressed net N mineralization. [ABSTRACT FROM AUTHOR]

Mangroves are coastal ecosystems in transition between sea and land, localized worldwide on the tropical and subtropical regions. However, anthropogenic pressure in coastal areas has led to the conversion of many mangrove areas to other uses. Due to the increased awareness of the importance of mangroves worldwide, restoration methods are being studied. Our aim is to develop a framework for selecting suitable sites for red mangrove planting using Geographic Information Systems (GIS). For this reason, the methodology is based on abiotic factors that have an influence on the zonation (distribution) and growing of the Rhizophora mangle. A total suitable area of 6,12 hectares was found, where 15.300 propagules could be planted.

Mangrove forests have a simple architecture. They shelter a few number of arboreal species that grow in a saline environment subject to tidal activity. The research objective was to evaluate possible interactions between physical-chemical soil attributes and plant-leaf nutrient concentrations of different mangrove species. Different mangrove species growing in the same soil, and the same mangrove species growing in two different soil classes were evaluated as to their leaf nutrient concentration patterns. The study was carried out in mangrove areas of the State of Paraná, southern Brazil, in two distinct soil classes: HISTOSOL THIOMORPHIC Salic sodic and GLEYSOL THIOMORPHIC Salic sodic; and three different species: Avicennia schaueriana, Laguncularia racemosa and Rhizophora mangle. Two subareas were delimited within each area from which soil and leaf samples were collected. Samplings from five individuals of each dominant mangrove species were taken from the soil (0-10 cm deep) under each tree crown projection. The data was submitted to statistical analysis using a set of simple and multivariate analysis in order to determine possible differences among mangrove species leaf nutrient concentrations, and whether these differences might be correlated with the soil attributes or not. The results exposed that the nutritional state of the mangrove species is different and independent form the soil attributes in which they grow. Few correlations were found among leaf nutrient concentrations and soil attributes, suggesting differential selective nutrient uptake among species.