Functional traits of selected mangrove species in Brazil as biological indicators of different environmental conditions

Abstract

Ecological studies on phenotypic plasticity illustrate the relevance of this phenomenon in nature. Conditions of biota reflect environmental changes, highlighting the adaptability of resident species that can be used as bioindicators of such changes. We report the morpho-anatomical plasticity of leaves of Avicennia schaueriana Stapf & Leechm. ex Moldenke, Laguncularia racemosa (L) C.F.Gaertn. and Rhizophora mangle L, evaluated in three estuaries (Vitoria bay, Santa Cruz and Itaunas River; state of Espirito Santo, Brazil), considering five areas of mangrove ecosystems with diverse environmental issues. Two sampling sites are part of the Ecological Station Lameirao Island in Vitoria bay, close to a harbor. A third sampling site in Cariacica (Vitoria bay) is inside the Vitoria harbor and also is influenced by domestic sewage. The fourth studied area (Santa Cruz) is part of Piraque Mangrove Ecological Reservation, while the fifth (Itaunas River) is a small mangrove, with sandy sediment and greater photosynthetically active radiation, also not strongly influenced by anthropic activity. Results pointed out the morpho-anatomical plasticity in studied species, showing that A. schaueriana and L. racemosa might be considered the most appropriate bioindicators to indicate different settings and environmental conditions. Particularly, the dry mass per leaf area (LMA) of A. schaueriana was the main biomarker measured. In our study, LMA of A. schaueriana was positively correlated with salinity (Spearman 0.71), Mn content (0.81) and pH (0.82) but negatively correlated with phosphorus content (-0.63). Thus, the evaluation of modification in LMA of A. schaueriana pointed out changes among five studied sites, suggesting its use to reflect changes in the environment, which could be also useful in the future to evaluate the climate change. (C) 2014 Elsevier B.V. All rights reserved.