Mangrove forests associated with salt flats: a case study from southeast Brazil

Abstract

No presente estudo, a variabilidade estrutural de uma floresta de mangue associada a uma planície hipersalina na Baía de Sepetiba (SE-Brasil) é analisada. A estrutura vegetal e a salinidade da água intersticial foram medidas em 32 parcelas estabelecidas ao longo de 3 transectos localizados desde a margem do estuário até a transição com a planície hipersalina. O desenvolvimento estrutural foi altamente variável, com altura média variando entre 0,54 m e 7,96 m, diâmetro médio entre 1,58 cm e 9,46 cm e densidade de troncos entre 2.733 troncos vivos.ha . A variabilidade da estrutura vegetal respondeu ao gradiente de aumento da salinidade da água intersticial à planície hipersalina, com a altura e o diâmetro médios diminuindo e a densidade de troncos aumentando no mesmo sentido. O seguinte padrão de dominância de espécies foi observado: Rhizophora mangle nas proximidades da margem do estuário; Laguncularia racemosa na transição com a planície hipersalina; e Avicennia schauerianna nas zonas intermediárias. O entendimento das características estruturais das florestas de mangue e suas relações com estressores naturais (ex. salinidade) contribuirá para a melhor compreensão da dinâmica das espécies ao longo de planícies costeiras associadas à planícies hipersalinas bem preservadas como em Guaratiba. In this study, forest structure variability of a mangrove associated to a salt flat in Sepetiba Bay (SE-Brazil) was assessed. Forest structure and interstitial water salinity were measured in 32 plots established along three transects ranging from the margin of the estuary to the transition with the salt flat. Structural development was shown to be highly variable, with mean height ranging from 0.54 m to 7.96 m, mean diameter ranging from 1.58 cm to 9.46 cm and trunk density ranging from 2,733 live trunks.ha -1 to 106,667 live trunks.ha -1 . Forest structure variability responded to the gradient of increasing interstitial water salinity towards the salt flat, with mean height and diameter decreasing and trunks density increasing progressively in the same direction. The following pattern of species dominance was observed: Rhizophora mangle near the estuary margin; Laguncularia racemosa at the transition with the salt flat; and Avicennia schaueriana on intermediate zones. The assessment of structural characteristics of mangrove forests and their relationships with natural stressors (e.g., salinity) contribute to better understand the dynamics of the species along coastal plains associated with preserved salt flats, such as the one found in Guaratiba. AbstrAct resumoDescritores: Manguezal, Fitossociologia, Planícies hipersalinas, Gradientes ecológicos.

Evaluation of the Inhibitory Potential of Casuarictin, an Ellagitannin Isolated from White Mangrove (Laguncularia racemosa) Leaves, on Snake Venom Secretory Phospholipase A2

“…In Brazil, mangroves occur on almost the whole coast and cover approximately 13,762 km 2 . Only four plant species are available in Brazilian mangroves: Avicennia schaueriana , Avicennia germinans , Laguncularia racemosa, and Rhizophora mangle [6].…”

Hypersaline tidal flats as important “blue carbon” systems: a case study from three ecosystems

“…This conservation area is surrounded by the urban expansion area of the city of Rio de Janeiro, and Sepetiba Bay receives discharges of nutrients and organic matter from its watershed dominated by agriculture, pasture and urban uses (Rezende et al, 2010). The HTF covers an area of approximately 7.4 km 2 , equivalent to almost 36 % of the fringing mangrove forest (Estrada et al, 2013;Soares et al, 2017) (Table 1). There is little variation in topography, and the tidal range is 0.1-2.0 m (Masuda and Enrich-Prast, 2016;Bento et al, 2017).…”

“…These environments are generally located in an intermediary position between mangrove forests or saltmarshes and the terrestrial environment and are common in many tropical arid, and to a lesser extent non-arid, intertidal zones. These systems occur in many regions around the world including northern Australia, Africa, Spain, the Gulf of Mexico and throughout Brazil where they are referred to as apicum ecosystems (Ridd and Stieglitz, 2002;Albuquerque et al, 2013Albuquerque et al, , 2014Soares et al, 2017). In arid and semi-arid estuaries (Ridd and Stieglitz, 2002) or humid tropical supratidal zones with less fluvial contribution (Soares et al, 2017), HTF ecosystems cover an area that exceeds mangrove forests and occupy a substantial proportion of tropical intertidal zones.…”

“…These systems occur in many regions around the world including northern Australia, Africa, Spain, the Gulf of Mexico and throughout Brazil where they are referred to as apicum ecosystems (Ridd and Stieglitz, 2002;Albuquerque et al, 2013Albuquerque et al, , 2014Soares et al, 2017). In arid and semi-arid estuaries (Ridd and Stieglitz, 2002) or humid tropical supratidal zones with less fluvial contribution (Soares et al, 2017), HTF ecosystems cover an area that exceeds mangrove forests and occupy a substantial proportion of tropical intertidal zones. HTFs occupy the area just below the highest astronomical tides and are thus only flooded for short periods of the year (Ridd and Stieglitz, 2002;Bento et al, 2017).…”

Socio-environmental tensioning in coastal communities: an interdisciplinary study in the mangroves of southern Bahia

“…Thus, when analyzing the structural types of mangrove forests, as well as the salinity values of the interstitial water (table 3), we observe that the forests with the highest salinity have, in general, low and intermediate structural development, are located in the innermost parts of mangroves, with low tidal flooding frequency, thus characterizing forests subjected to physiological stress, which would be more sensitive to the additional impacts associated with contamination by oil. Such pattern of reduction in the structural development of mangrove forests submitted to low flood frequency by tides and higher salinity is described and analyzed by Soares et al (2017).…”