RESUMO
The present study aimed to evaluate the antimicrobial and modulating activity of the ethanol extract obtained from the leaves, stems, and roots of Cnidoscolus urens in multiresistant bacteria. The Minimum Inhibitory Concentration (MIC) values obtained for the extracts of leaves, stems, and roots were greater than 1024 µg/mL for all isolates. In the antimicrobial resistance modulation test, the extract of the leaves of C. urens showed a better modulating effect than that of the stems and roots for gentamicin, highlighting the reduction of MIC for Escherichia coli, Lactococcus garvieae and Staphylococcus sciuri. For erythromycin, a reduction of MIC was observed in L. garvieae, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus agalactiae. The extract from the leaves of C. urens has an important modulating effect on resistance in multiresistant bacteria, especially with gentamicin and erythromycin.
Assuntos
Antibacterianos , Farmacorresistência Bacteriana Múltipla , Mastite Bovina , Testes de Sensibilidade Microbiana , Extratos Vegetais , Animais , Antibacterianos/farmacologia , Mastite Bovina/microbiologia , Bovinos , Extratos Vegetais/farmacologia , Feminino , Alismatales/microbiologia , Bactérias/efeitos dos fármacos , Bactérias/classificação , Bactérias/isolamento & purificação , Bactérias/genética , Eritromicina/farmacologia , Folhas de Planta/microbiologia , Folhas de Planta/químicaRESUMO
Background: Seagrass meadows, known for providing essential ecosystem services like supporting fishing, coastline protection from erosion, and acting as carbon sinks to mitigate climate change effects, are facing severe degradation. The current deteriorating state can be attributed to the combination of anthropogenic activities, biological factors (i.e., invasive species), and natural forces (i.e., hurricanes). Indeed, the global seagrass cover is diminishing at an alarming mean rate of 7% annually, jeopardizing the health of these vital ecosystems. However, in the Island Municipality of Culebra, Puerto Rico, losses are occurring at a faster pace. For instance, hurricanes have caused over 10% of cover seagrass losses, and the natural recovery of seagrasses across Culebra's coast has been slow due to the low growth rates of native seagrasses (Thalassia testudinum and Syringodium filiforme) and the invasion of the invasive species Halophila stipulacea. Restoration programs are, thus, necessary to revitalize the native seagrass communities and associated fauna while limiting the spread of the invasive species. Methods: Here, we present the results of a seagrass meadow restoration project carried out in Punta Melones (PTM), Culebra, Puerto Rico, in response to the impact of Hurricanes Irma and María during 2017. The restoration technique used was planting propagation units (PUs), each with an area of 900 cm2 of native seagrasses Thalassia testudinum and Syringodium filiforme, planted at a depth between 3.5 and 4.5 m. A total of 688 PUs were planted between August 2021 and August 2023, and a sub-sample of 88 PUs was monitored between August 2021 and April 2023. Results: PUs showed over 95% of the seagrass survived, with Hurricane Fiona causing most of the mortalities potentially due to PUs burial by sediment movement and uplifting by wave energy. The surface area of the planting units increased by approximately 200% (i.e., 2,459 cm2), while seagrass shoot density increased by 168% (i.e., 126 shoots by PU). Additionally, flowering and fruiting were observed in multiple planting units, indicating 1) that the action taken did not adversely affect the PUs units and 2) that the project was successful in revitalizing seagrass populations. The seagrass restoration project achieved remarkable success, primarily attributed to the substantial volume of each PUs. Likely this high volume played a crucial role in facilitating the connection among roots, shoots, and microfauna while providing a higher number of undamaged and active rhizome meristems and short shoots. These factors collectively contributed to the enhanced growth and survivorship of the PUs, ultimately leading to the favorable outcome observed in the seagrass restoration project.
Assuntos
Alismatales , Brugmansia , Hydrocharitaceae , Ecossistema , Efeitos Antropogênicos , SupuraçãoRESUMO
Desalination has been proposed as a global strategy for tackling freshwater shortage in the climate change era. However, there is a concern regarding the environmental effects of high salinity brines discharged from desalination plants on benthic communities. In this context, seagrasses such as the Mediterranean endemic and ecologically important Posidonia oceanica have shown high vulnerability to elevated salinities. Most ecotoxicological studies regarding desalination effects are based on salinity increments using artificial sea salts, although it has been postulated that certain additives within the industrial process of desalination may exacerbate a negative impact beyond just the increased salinities of the brine. To assess the potential effect of whole effluent brines on P. oceanica, mesocosm experiments were conducted within 10 days, simulating salinity increment with either artificial sea salts or brines from a desalination plant (at 43 psµ, 6 psµ over the natural 37 psµ). Morphometrical (growth and necrosis), photochemical (PSII chlorophyll a fluorometry), metabolic, such as hydrogen peroxide (H2O2), thiobarbituric reactive substances (TBARS) and ascorbate/dehydroascorbate (ASC/DHA), and molecular (expression of key tolerance genes) responses were analyzed in each different treatment. Although with a still positive leaf growth, associated parameters decreased similarly for both artificial sea salt and brine treatments. Photochemical parameters did not show general patterns, although only P. oceanica under brines demonstrated greater energy release through heat (NPQ). Lipid peroxidation and upregulation of genes related to oxidative stress (GR, MnSOD, and FeSOD) or ion exclusion (SOS3 and AKT2/3) were similarly incremented on both hypersalinity treatments. Conversely, the ASC/DHA ratio was significantly lower, and the expression of SOS1, CAT, and STRK1 was increased under brine influence. This study revealed that although metabolic and photochemical differences occurred under both hypersalinity treatments, growth (the last sign of physiological detriment) was similarly compromised, suggesting that the potential effects of desalination are mainly caused by brine-associated salinities and are not particularly related to other industrial additives.
Assuntos
Alismatales , Sais , Clorofila A , Peróxido de Hidrogênio , Salinidade , Ácido AscórbicoRESUMO
Human- and nature-induced hypersaline conditions in coastal systems can lead to profound alterations of the structure and vitality of seagrass meadows and their socio-ecological benefits. In the last two decades, recent research efforts (>50 publications) have contributed significantly to unravel the physiological basis underlying the seagrass-hypersalinity interactions, although most (â¼70%) are limited to few species (e.g. Posidonia oceanica, Zostera marina, Thalassia testudinum, Cymodocea nodosa). Variables related to photosynthesis and carbon metabolism are among the most prevalent in the literature, although other key metabolic processes such as plant water relations and responses at molecular (i.e. gene expression) and ultrastructure level are attracting attention. This review emphasises all these latest insights, offering an integrative perspective on the interplay among biological responses across different functional levels (from molecular to clonal structure), and their interaction with biotic/abiotic factors including those related to climate change. Other issues such as the role of salinity in driving the evolutionary trajectory of seagrasses, their acclimation mechanisms to withstand salinity increases or even the adaptive properties of populations that have historically lived under hypersaline conditions are also included. The pivotal role of the costs and limits of phenotypic plasticity in the successful acclimation of marine plants to hypersalinity is also discussed. Finally, some lines of research are proposed to fill the remaining knowledge gaps.
Assuntos
Alismatales , Zosteraceae , Humanos , Estresse Fisiológico/fisiologia , Alismatales/fisiologia , Fotossíntese/fisiologia , AclimataçãoRESUMO
Seagrasses may enhance the abundance and diversity of benthic invertebrates through trophic facilitation. We investigated this potential ecological function for two seagrasses in SE Brazil: Halodule emarginata, a native species, and Halophila decipiens, a tropical seagrass recently established in the region. At Halophila sites, the organic matter (or carbon) in sediments decreased steadily from seagrass patches to isolated bare grounds, indicating surplus primary production. This was not observed at Halodule sites. At one of the two Halophila sites, localized trophic enrichment was also consistently linked to increased invertebrate abundance within patches, chiefly through increased carrying capacity of small mesoherbivores. Rather than spillover, edge effects were observed at bordering bare habitats, where polychaete predators were abundant. The transition from seagrass edges to isolated bare habitats was marked by an increase of the density of sipunculid worms. The current spread of Halophila may thus change the spatial distribution of benthic ecological functions.
Assuntos
Alismatales , Invertebrados , Animais , Brasil , Conservação dos Recursos Naturais , EcossistemaRESUMO
Carbon capturing coastal and marine habitats around the world are decreasing in extent every year, habitats found in abundance in Small Island Developing States' territories. However, these habitats are under threat by increased levels of economic activities and extreme weather events. Consequently, as those ecosystems become scarce their value is expected to increase. In this paper the "value of information", the increase in knowledge that renders a system or a function more valuable, from marine habitat mapping is presented through the (monetary) valuation of one regulating service provided by the newly mapped habitats. Mapping a section of a channel with a multibeam echosounder revealed more seagrass resources than in previous studies. Using values for both the Social Cost of Carbon and Abatement Cost methods, from the literature we estimate the value of the carbon sequestration and storage service these seagrass meadows provide. The impacts of hurricanes in the newly mapped seagrasses were also investigated. Despite the costs of mapping, monitoring and of projected losses of ecosystem services provision due to hurricanes, net benefits over a time period of 50â¯years were considerably larger. The new information provided highlights carbon capturing habitats as more important, enabling the "value of information" to inform policymaking.
Assuntos
Alismatales/fisiologia , Sequestro de Carbono , Conservação dos Recursos Naturais , Ecossistema , Dispersão Vegetal , Ilhas Virgens Britânicas , Conservação dos Recursos Naturais/economiaRESUMO
Seagrasses live in highly variable light environments and adjust to these variations by expressing acclimatory responses at different plant organizational levels (meadow, shoot, leaf and chloroplast level). Yet, comparative studies, to identify species' strategies, and integration of the relative importance of photoacclimatory adjustments at different levels are still missing. The variation in photoacclimatory responses at the chloroplast and leaf level were studied along individual leaves of Cymodocea nodosa, Zostera marina and Z. noltei, including measurements of variable chlorophyll fluorescence, photosynthesis, photoprotective capacities, non-photochemical quenching and D1-protein repair, and assessments of variation in leaf anatomy and chloroplast distribution. Our results show that the slower-growing C. nodosa expressed rather limited physiological and biochemical adjustments in response to light availability, while both species of faster-growing Zostera showed high variability along the leaves. In contrast, the inverse pattern was found for leaf anatomical adjustments in response to light availability, which were more pronounced in C. nodosa. This integrative plant organizational level approach shows that seagrasses differ in their photoacclimatory strategies and that these are linked to the species' life history strategies, information that will be critical for predicting the responses of seagrasses to disturbances and to accordingly develop adequate management strategies.
Assuntos
Adaptação Biológica , Alismatales/fisiologia , Luz , Alismatales/anatomia & histologia , Alismatales/crescimento & desenvolvimento , Alismatales/metabolismo , Oceano Atlântico , Clorofila/metabolismo , Cloroplastos/metabolismo , Metabolismo , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologiaRESUMO
Macroalgal blooms can trigger adverse biogeochemical conditions at the sediment-water interface of shallow coastal areas, hence threatening critical habitats such as seagrasses meadows. The direction and magnitude of macroalgal blooms impacts on the aquatic ecosystem can be context-dependent, varying according to the local hydrodynamic conditions. Thus, studies investigating the impacts of stagnant algal depositions on the benthos may fail to address realistic situations and interactions which are common in well-flushed systems. This is especially true for the South America coast, where no study has investigated the effects of macroalgal blooms on seagrasses meadows. To fully understand the impacts of macroalgal blooms on sediment biogeochemistry and seagrass habitats across distinct environmental conditions and biogeographical regions, two independent, complementary field experiments replicated the natural temporal patterns of drift macroalgal mats depositions on unvegetated and vegetated (Ruppia maritima meadows) shoals of the Patos Lagoon estuary (PLE), a subtropical, high hydrodynamic system in southern Brazil. Transitory depositions of algal mats alleviated deleterious biogeochemical conditions in the sediment-water interface of unvegetated bottoms. Nevertheless, these unstable algal depositions promoted significant reductions in R. maritima biomass, by reducing their shoot height and density, and rhizome length. That plant biomass reductions were followed by a decrease in the abundance of the dominant infaunal tanaidacean Monokalliapseudes schubarti, indicating that algal impacts on seagrasses were transferred to higher trophic levels. Our results suggest that, although unstable deposition of drift algal mats can attenuate potential adverse impacts at the sediment-water interface, the physical stress during mats advection can still trigger small seagrass losses. This process may diminish the resilience of R. maritima meadows in the PLE, with impacts on estuarine nutrient cycling and secondary production. We conclude that, although harmful drift macroalgal blooms area global phenomenon, the mechanisms through which macroalgae impair seagrass habitats may vary according to the environmental context. Therefore, further studies are necessary to identify the underlying mechanisms of drift macroalgae-seagrass-macrofauna interactions in high hydrodynamic systems and their generality across distinct biogeographical areas.
Assuntos
Alismatales/fisiologia , Biota , Estuários , Eutrofização/fisiologia , Alga Marinha/metabolismo , Biomassa , BrasilRESUMO
Coastal areas face high variability of seawater pH. Ocean acidification (OA) and local stressors are enhancing this variability, which poses a threat to marine life. However, these organisms present potential phenotypic plasticity that can offer physiological and structural tools to survive in these extreme conditions. In this study, we evaluated the effects of elevated CO2 levels and consequent pH reduction on the physiology, anatomy and ultrastructure of the seagrass Halodule wrightii. A mesocosm study was conducted in an open system during a 30-day experiment, where different concentrations of CO2 were simulated following the natural variability observed in coastal reef systems. This resulted in four experimental conditions simulating the (i) environmental pH (control condition, without CO2 addition) and (ii) reduced pH by - 0.3 units, (iii) - 0.6 units and (iv) - 0.9 units, in relation to the field condition. The evaluated population only suffered reduced optimum quantum yield (Y(II)), leaf width and cross-section area under the lowest CO2 addition (- 0.3 pH units) after 30 days of experiment. This fitness commitment should be related to carbon concentration mechanisms present in the evaluated species. For the highest CO2 level, H. wrightii demonstrated a capacity to compensate any negative effect of the lowest pH. Our results suggest that the physiological behaviour of this primary producer is driven by the interactions among OA and environmental factors, like irradiance and nutrient availability. The observed behaviour highlights that high-frequency pH variability and multifactorial approaches should be applied, and when investigating the impact of OA, factors like irradiance, nutrient availability and temperature must be considered as well.
Assuntos
Ácidos/química , Alismatales/citologia , Alismatales/fisiologia , Oceanos e Mares , Alismatales/efeitos dos fármacos , Alismatales/ultraestrutura , Dióxido de Carbono/farmacologia , Clorofila/metabolismo , Clorofila A , Cloroplastos/metabolismo , Cloroplastos/ultraestrutura , Fluorescência , Fotossíntese/efeitos dos fármacos , Folhas de Planta/anatomia & histologia , Folhas de Planta/citologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/ultraestrutura , Teoria Quântica , Solubilidade , Amido/metabolismo , Açúcares/metabolismoRESUMO
Halodule wrightii is an ecologically important seagrass; however, little is known about the adaptation of this species in the context of environmental change, particularly changes arising from alterations in salinity of coastal ecosystems. This study aimed to determine the effects of different salinities on growth, morphology, leaf ultrastructure, and cell viability of H. wrightii. To accomplish this, plants were cultivated for 21 days in salinities of 25, 35, and 45. More hydropotens were observed in samples exposed to salinity of 45 with increased invagination of the plasma membrane and cell wall. These invaginations were also observed in other epidermal cells of the leaf blade. In particular, a significant retraction of plasma membrane was seen in samples exposed to salinity of 45, with possible deposition of compounds between the membrane and cell wall. Osmotic stress in samples exposed to salinity of 45 affected the chloroplasts through an increase in plastoglobules and thylakoids by granum in the epidermal chloroplasts of the leaf and decrease in the number of chloroplasts. Overall, this study showed that H. wrightii can survive within salinities that range between 25 and 45 without changing growth rate. However, the plant did have higher cell viability at salinity of 35. Salt stress in mesocosms, at both salinity of 25 and 45, decreased cell viability in this species. H . wrightii had greater changes in salinity of 45; this showed that the species is more tolerant of salinities below this value.