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Salinization is a threat that affects aquatic ecosystems worldwide. As primary producers, freshwater macrophytes are of paramount importance in these ecosystems, however, information regarding the potential impacts of salinization upon these organisms is still scarce. In this review we provide a comprehensive and updated discussion of how freshwater macrophytes deal with salinity increase in freshwaters. We reviewed the salinity tolerance of widespread non-halophyte macrophytes through an overview of salinity tolerance mechanisms, their tolerance classification, and salinity effects at different levels of organization: from individuals to ecosystems. Thus, we demonstrated that widespread macrophytes that inhabit freshwaters display efficient salinity tolerance to salinity levels between 5 and 10 g L-1, and only a few species display tolerance to salinities higher than 10 g L-1. Widespread macrophytes demonstrated salinity tolerance of approximately 5 g L-1. Widespread macrophytes demonstrated salinity tolerance of approximately 5 g L-1. Emergent, floating and submerged species showed no significant difference in salinity tolerance. Salinity stress symptoms in freshwater macrophytes are somewhat similar to those of terrestrial plants and can show up even at slight salinity increases. Salinities higher than 1 g L-1 can negatively affect both physiology and diversity of non-halophyte macrophytes and cause long-term - and not well understood - changes in freshwater ecosystems. Salinization of freshwater ecosystems, among others threats, in combination with climate change, raise concerns about the future ecological status of freshwater ecosystems and the services they can provide.

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Introducción: Las características de los humedales costeros son resultado de las interacciones hidrogeomorfológicas entre el continente y el océano, que causan un gradiente ambiental, que resulta en diferentes tipos de vegetación como manglares, popales, tulares, selvas y palmares inundables. Objetivo: Caracterizar las variables del hidroperiodo y fisicoquímicas del agua y suelo para determinar la relación que existe en el patrón de distribución de la vegetación en el Sistema de Humedales El Castaño (SHC). Metodología: Se establecieron 11 unidades de muestreo (UM) permanentes por estrato definidos: cinco en el manglar, dos en selvas inundables, dos en tular y dos en pastizal inundable. De mayo 2016 a octubre 2017 se caracterizó la vegetación y se muestreó mensualmente los niveles de inundación y parámetros fisicoquímicos del agua (superficial, intersticial y subterránea): salinidad, conductividad y pH; y el suelo: densidad aparente, porcentaje de humedad y potencial redox. Resultados: El manglar es el más cercano al mar, tiene la menor diversidad (H:1.66) y especies registradas (14), está dominado por Laguncularia racemosa y Rhizophora mangle y tiene los valores más altos de salinidad intersticial y subterránea, mayores a 10.8 ups, se mantiene inundado de 4 a 12 meses, su potencial redox es de 14.57 mV. Seguido está el manglar, tierra adentro, se ubican los remanentes de la selva inundable, (H:2.18 y 18 especies), dominada por Pachiraaquatica, la salinidad intersticial y subterránea de 4.95 ups, permanece inundada de 0 a 6 meses y el potencial redox es de 119.07 mV. El tular, después de la selva, (H:1.92 y 16 especies), dominado por Typha domingensis, salinidad intersticial y subterránea de 6.1 ups, el tiempo de inundación es de 5 a 8 meses y potencial redox es de 125.9 mV. El pastizal inundable, con menor influencia marina, es un humedal herbáceo modificado para uso ganadero, presentó los valores más altos de diversidad (H:3.44 y 50 especies), Paspalum conjugatum es la especie dominante, la salinidad intersticial y subterránea es menor a 0.5 ups, se mantiene inundado de 5 a 9 meses y el potencial redox es de 151.23 mV. Conclusiones: En cada tipo de vegetación, la estructura, composición y diversidad es diferente, con un alto recambio de especies que indica un gradiente definido por la salinidad. La vegetación en el SHC sigue los patrones de organización típica de los humedales costeros tropicales, manglares, selvas inundables y humedales herbáceos, en este caso los tulares y pastizales inundables. El factor que define la distribución de la vegetación, es salinidad y el gradiente que se observa está en función de la dinámica hidrológica que depende de entradas de agua marina y de la bajada de agua dulce del interior del continente.

Introduction: The characteristics of coastal wetlands are the result of hydrogeomorphological interactions between the continent and the ocean, which cause an environmental gradient, hat results in different vegetation types such as mangroves, freshwater marshes, swamp forests and palm swamps. Objective: To characterize the hydroperiod and physicochemical variables of water and soil and their effect on the distribution of vegetation in the Sistema de Humedales El Castaño. Methods: A total of 11 permanent sampling units (UM) were established by defined strata: five in the mangrove, two in swamp forest, two in freshwater marshes and two in the flooded pasture. From May 2016 to October 2017 the vegetation was characterized and the water levels and physicochemical parameters (superficial, interstitial and groundwater) were sampled monthly for: salinity, and pH; and the soil for: bulk density, humidity percentage, and redox potential. Results: Mangroves are the closest to the sea, have the lowest diversity (H: 1.66) and species richness (14), they are dominated by Laguncularia racemosa and Rhizophora mangle, have the highest values of interstitial and groundwater salinity, (> 10.8 ups), remain flooded for 4 to 12 months per year, and have a redox potential of 14.57 mV. Immediately, inland, there are remnants of the swamp forests (H: 2.18 and 18 species), dominated by Pachira aquatica, with 5 ups interstitial and groundwater salinity, flooded from 0 to 6 months per year, with a redox potential of 119.07 mV. These forests are followed inland by freshwater marshes (H: 1.92 and 16 species), dominated by Typha domingensis with 6.1 ups interstitial and groundwater salinity, flooded for 5 to 8 months per year and a redox potential of 125.9 mV. Finally, furthest inland is the flooded pasture, a modified herbaceous wetland for cattle grazing (H: 3.44 and 50 species) dominated by Paspalum conjugatum, where interstitial and groundwater salinity is less than 0.5 ups, it stays flooded for 5 to 9 months and the redox potential is 151.23 mV. Conclusions: In each type of vegetation, the structure, composition, and diversity are different, with a high turnover of species that indicates a gradient defined by salinity. The vegetation in the SHC follows the patterns of typical organization of the tropical coastal wetlands, mangroves, swamp forests and herbaceous wetlands, in this case the freshwater marshes and flooded pastures. The factor that define the distribution of the vegetation is the salinity and the gradient that is observed are a function of the hydrological dynamics that depends on the mixing of marine and freshwater.

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The species diversity of hydrophytes suitable for human consumption and the possibility of their introduction into the practice of organic farming and sustainable polyculture are explored in the article. The economic and environmental potential of shallow freshwater areas and waterlogged areas are discussed from the perspective of sustainable agriculture. The possibility of using some hydrophyte plants for food and drugs is indicated. The necessity of using the practice of traditional nature management by the native population in relation to water and near-water food plants is mentioned. The relevant issues of providing the growing population of the Earth with food and technical plant raw materials from hydrophytes are discussed. It has been established that a necessary condition for the operation of the market for wild-growing medicinal hydrophytes in accordance with the concept of sustainable development is its efficient legal regulation at all levels.

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Numerous plant species are easily established in the wide flood plains of the Pantanal wetlands due to the environmental heterogeneity. The aquatic macrophytes excel in permanently flooded areas, particularly Nymphaeaceae species. Victoria amazonica, popularly known as the vitória-régia, is hallmarked for its beauty. However, the biology and conditions necessary for the seed germination of this flowering plant remain unknown. In the present study, the fruit and seed morphology and biometry were described and the seed germination was evaluated under different abiotic conditions. To this end, mature fruits of V. amazonica were collected from the bays near Paraguay River in the south Pantanal floodplain. The fruits and seeds were described and measured using digital caliper. Intact and mechanically scarified seeds were germinated under different temperature, light and substratum conditions, and the initial development was described. The fruits measured 67.5 x 119.7 mm in size and contained 100-700 seeds. The average seed measured 10.6 mm in length and 9.8 mm in width. The highest germination occurred at 25o C, independent of the light condition. The seeds were considered neutral photoblastic. The seedlings showed heterophylly, and the main root was degenerated, forming adventitious roots. Morphological differences were observed in seedlings developed under different light conditions.(AU)

O Pantanal, ampla planície inundável, facilita o estabelecimento de inúmeras espécies vegetais por sua heterogeneidade ambiental. As macrófitas aquáticas se destacam em áreas permanentemente alagadas, com destaque para a família Nymphaeaceae. A espécie Victoria amazonica, conhecida popularmente como vitória-régia, é marcada por sua beleza. Entretanto, sua biologia e as condições necessárias à germinação de suas sementes permanecem desconhecidas. Nesse estudo foram descritas a biometria e a morfologia do fruto e da semente, e avaliada a germinação em diferentes condições abióticas. Para isso, frutos de V. amazonica foram coletados em baias próximas ao rio Paraguai no Pantanal sul. Os frutos e as sementes foram descritos e mensurados usando paquímetro digital. Sementes íntegras e escarificadas mecanicamente foram submetidas a testes de germinação em diferentes condições de temperatura, luz e substrato, e o desenvolvimento inicial das plântulas foi descrito. Os frutos mediram 67,5 x 119,7 mm, e portavam 100-700 sementes. As sementes mediram 10,6 mm de comprimento e 9,8 mm de largura em média. A maior porcentagem de germinação ocorreu a 25o C independente da condição de luz. As sementes foram consideradas fotoblásticas neutras, e as plântulas possuem heterofilia, degeneração da raiz principal e formação de raízes adventícias. Foram observadas diferenças morfológicas nas plântulas desenvolvidas na presença e na ausência de luz.(AU)

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Banco de semillas y vegetación establecida en los últimos remanentes de los humedales de la Meseta Central Mexicana: las ciénagas de Lerma. Seed banks play a central role in vegetation dynamics of many wetlands. Therefore, knowledge of seed reservoirs in the soils of aquatic communities should provide useful tools for conservation and restoration efforts. This study was conducted in the Lerma marshes, one of the last remnants of the vast wetlands that were once in the Mexican Central Plateau. The main objective was to determine the composition and abundance of seed bank and its relationship with established vegetation of the three Lerma marshes. In each marsh, we systematically selected 18 to 40 sampling sites. In each site, the composition of vascular plant vegetation was evaluated in two 10m lines perpendicular to the shore. Every 0.5m, we determined the coverage of species by measuring the intercepted length for each plant or group of plants. At each sampling site where we had evaluated the established vegetation, we collected a sample of the top 10cm of sediment; the soil cores were divided into an upper layer (0-5cm) and a lower layer (5-10cm). These samples were used to evaluate the seed bank by the seedling emergence method. All samples were placed in a greenhouse at 20-25ºC and remained flooded for 15 weeks. Fortynine species were recorded in the vegetation. Chiconahuapan had the richest and most diverse flora and the greatest number of perennial species. A life-forms analysis showed that perennial herbs, especially rooted-emergent hydrophytes, dominated in the three wetlands. Sixty-one species were identified in the total seed bank; Chimaliapan had the most diverse total seed bank, whereas the mean seedling density was higher in Chignahuapan. Only two species of the total seed bank of each marsh had a density greater than 10% of the total, and more than half were uncommon. The upper layer of sediment (0-5cm) contained two times more seeds/m² and species per sample than the lower layer (5-10cm), and there was a significant decrease of seed density with depth. The detrended correspondence analysis produced a clear separation between the composition of the seed banks and established vegetation. In general, in each marsh there was less species diversity in the established vegetation than in the seed bank. Dominance by a few species in the seed bank, the presence of opportunistic species, and the low representation of established species in the seed bank suggest wetland degradation and a low probability of regenerating the natural communities from the seed bank. To ensure the permanence of these marshes, their biodiversity, and therefore the environmental services they provide, up to date planning is a must, and efforts to control and monitor hydrology, water quality, and the influence of human activities are suggested.

Los bancos de semillas desempeñan un papel central en la dinámica de la vegetación de muchos humedales. Por lo tanto, el conocimiento de los depósitos de semillas en los suelos de las comunidades acuáticas debe proporcionar herramientas útiles para los esfuerzos de conservación y restauración. Este estudio se llevó a cabo en las ciénegas de Lerma, uno de los últimos vestigios de las grandes zonas inundadas que antes cubrían la Meseta Central Mexicana. El objetivo principal fue determinar la composición y abundancia de los bancos de semillas y su relación con la vegetación establecida en las tres ciénegas de Lerma. En cada humedal se seleccionaron sistemáticamente de 18 a 40 sitios de muestreo. En cada sitio se colocaron dos líneas de 10m perpendiculares a la orilla sobre las que se evaluó la composición y cobertura de plantas vasculares a intervalos de 0.5m. En los sitios de muestreo donde se evaluó la vegetación establecida, se recolectó una muestra de los 10cm superiores de sedimento y se separó en una capa superior (0 a 5cm) y otra inferior (5-10cm). Estas muestras se utilizaron para evaluar el banco de semillas por el método de emergencia de plántulas. Todas las muestras se colocaron en un invernadero a 20-25ºC y se mantuvieron inundadas durante 15 semanas. Cuarenta y nueve especies se registraron en la vegetación. Chiconahuapan presentó la flora más rica y diversas, así como el mayor número de especies perennes. El análisis de las formas de vida mostró que las hierbas perennes y especialmente las hidrófitas arraigada emergente dominaron en los tres humedales. Sesenta y un especies se identificaron en el banco de semillas total, Chimaliapan presentó el banco de semillas total más diverso, mientras que la densidad promedio de plántulas fue mayor en Chignahuapan. Sólo dos especies de todo el banco de semillas de cada ciénega presentaron una densidad mayor del 10% del total y más de la mitad de las especies fueron poco frecuentes. La capa superior de sedimentos (0-5cm) exhibió dos veces más semillas/m² y especies por muestra que la capa inferior (5-10cm), se observó una disminución significativa de la densidad de semillas con la profundidad. El análisis de correspondencia sin tendencia produjo una separación clara entre la composición de los bancos de semillas y la de la vegetación establecida. En general, en cada ciénega hay menos diversidad de especies en la vegetación establecida que en el banco de semillas. El dominio de pocas especies en el banco de semillas, la presencia de especies oportunistas y la escasa representación de las plantas establecidas en el banco de semillas sugiere degradación de los humedales y una baja probabilidad de regeneración de las comunidades naturales desde el banco de semillas. Para garantizar la permanencia de estos sistemas, su biodiversidad y por tanto los servicios ambientales que ofrecen, se requiere de esfuerzos para controlar y supervisar la hidrología y la influencia de las actividades humanas.

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Foi realizado o estudo florístico das macrófitas do Município de General Carneiro, localizado no sul do Estado do Paraná, entre as coordenadas 26º 19' 37"/ 26º 26' 40" S e 51º 26' 51"/ 51º 19' 14" W. Os locais de coleta foram as fazendas São Pedro, São Pedro II, Santa Cândida e Lageado Grande, entre os Rios São Pedro, São João, São Manoel, Iratim, Lajeado Grande e Neno. Com a finalidade de se conhecer a flora dos rios e lagoas da região foram realizadas coletas aleatórias das macrófitas entre 2004 e 2006. Os exemplares encontram-se depositados no herbário UPCB e MBM. Registraram-se 45 famílias, 42 de angiospermas, 70 gêneros e 117 espécies. Os ambientes aquáticos são caracterizados floristicamente pelas Cyperaceae, representada por 22 táxons, o que significa cerca de 21 por cento de todos os táxons encontrados, seguidos pelas Poaceae (8), Asteraceae (7) e Polygonaceae (6). Dentre as espécies registradas podemos destacar o primeiro registro para o estado de Lilaeopsis minor Prez-Mor., Apiaceae.

A floristic study of macrophyte communities was conducted at General Carneiro township, situated in Southern Parana State, among 26º 19' 37"/ 26º 26' 40" S and 51º 26' 51"/ 51º 19' 14" W. Samples were collected at São Pedro, São Pedro II, Santa Cândida and Lageado Grande farms, between the rivers São Pedro, São João, São Manoel, Iratim, Lajeado Grande and Neno, in order to study the flora of the rivers and ponds in this region. Macrophyte samples were randomly collected between 2004 and 2006 and registered in the UPCB and MBM herbaria. A total of 45 families was found, 42 of them being angiosperms, 70 genera and 117 species. The aquatic environments are floristicaly characterized by Cyperaceae, represented by 22 taxa, what means approximately 21 percent of all the encountered taxa, followed by Poaceae (8), Asteraceae (7) and Polygonaceae (6). Among the registered species we can highlight the first record in this state of Lilaeopsis minor Prez-Mor, Apiaceae.