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The study proposes to evaluate the photosynthetic plasticity of Rhizophora mangle L. in four mangrove sites distributed along with the Great Vitória Estuarine System. The variation in organic matter content, which implies the higher essential nutrient availability, contributed to better energy flux performance related to electron transport. Furthermore, salinity damaged the reaction centers (RC), since the site with the highest salinity showed changes in the number and size of active photosynthetic RC and in the specific energy flows per active RC (absorption flux, trapped energy flux, and dissipated energy flux), but the plasticity of the species in response to salt stress was confirmed by the increase of performance index for energy conservation (PITotal), net photosynthetic rate (PN), and the water-use efficiency (WUE). Also, the results showed that the luminous intensity available compromises the functionality of PSII, in turn, it increases WUE. The results indicate the effect of the chlorophyll a content, which provides more substrate for light absorption, on the electron flow and PITotal is related to PN and WUE. The study indicates the ecological plasticity of R. mangle to the conditions of the evaluated area. [ABSTRACT FROM AUTHOR]

Studies in the long-term recruitment and mortality of mangrove seedlings can help to understand mangrove demography and its relationship with climatic variables, environmental restoration and advances in the ecology of this ecosystem. A seven-year population dynamics study of seedling recruitment and mortality in cohorts of Rhizophora mangle L. was carried out to identify expansion processes and patterns of survival in the understory of mangrove forests on the Atlantic coast of Brazil. The present study aimed to evaluate the relationship between recruitment and mortality R. mangle seedlings at the population level, salinity, and climatic variables (precipitation, temperature and humidity). On an annual scale, seedling recruitment was positively correlated with mean temperature. Seedling density was negatively correlated with the number of recruits and positively with the number of deaths. The number of recruits was associated with dead seedlings, temperature and precipitation considering a population scale, without grouping the data. The seedling density in the stands increased with the number of dead seedlings. Our findings described the relationship between climate variability (durability and magnitude of the dry/rainy season) and the long-term population dynamics of R. mangle seedlings in a poorly studied region and from what moment, on a monthly and annual time scale, did this relationship become significant and changes occur. The findings of this study provide information on the population dynamics of the species that will help in understanding mangrove demography. These results have important implications for projections about the recruitment and survival of the species thinking about to long-term climate change that will modify current weather patterns and mangrove conservation efforts.