Structural variation in two mangrove areas of the southern coast of Brazil

Background/Question/Methods

Environmental degradation, mainly by anthropogenic influences, affects the dynamics of species in different environments, including mangroves. Increasing urbanization, erosion, pollution, domestic and industrial accidents, and environmental contamination are several examples that contribute to its destructive process. Considering this, your question is: Does the structural composition of mangroves reflect the effects of environmental degradation? We expect to find differences between two mangroves areas which differ in the degree of disturbance, degradation and anthropogenic influences.We characterized the structural composition of two mangrove areas (Guaratuba/PR and Antonina/PR), located on the southern coast of Brazil.  The inventory of species was based on the multiple parcels method, using 15 plots of 10x10m, equivalent to 0.015 ha, for each area. All individuals with at least one meter high, were indentified at species level and their height and circumference were measured, for subsequent phytosociological survey. Antonina is subjected to higher levels of disturbance, has more extensive anthropic influence and depicts higher rate of environmental contamination due the proximity of harbor activities. 

Results/Conclusions

Three species represent all the individuals encountered in Guaratuba (n=475) and in Antonina (n=532):  Rhizophora mangle L., Laguncularia racemosa (L.) C. F. Gaertn. and Avicennia shaueriana Stapf & Leechman.  The two areas present high heterogeneity of distribuition of species.  They are equivalently distributed in the less disturbed area (Guaratuba), having A. schaueriana as the most frequent species, represented by higher individuals with high steam diameter. In  Antonina, we recorded fewer specimens of A. schaueriana (n=34) and more individuals of R. mangle (n=240) and L. racemosa (n=258). There is an evident heterogeneous distribution of species considering the studies areas. The area with apparently greater structural development presents high number of A. schaueriana, whereas the most disturbed area has predominance of L. racemosa.  These differences highlight the peculiarity of each mangrove and emphasize the need of specific management plans for ecosystem maintenance.