Multidisciplinary assessment of a restored mangrove ecosystem in Guanabara Bay, Brazil: linking science and conservation

Abstract

Due to their coastal location, mangrove ecosystems are especially susceptible to various human-caused disturbances. These disturbances can result in a loss of original mangrove cover, a decline in biodiversity, and a degradation of their ecological functions. This study examines a restored mangrove area within the Barão de Mauá Natural Municipal Park (PNMBM) in Guanabara Bay, Brazil, two decades after the initiation of a restoration project. We used a multidisciplinary approach, combining remote sensing analyses, assessment of the vegetation structure, and genetic diversity analysis to evaluate this restored mangrove forest. Remote sensing data demonstrated high Normalized Difference Vegetation Index values following the restoration project’s completion, indicating the revegetation’s success. Exploring the structure of the new forest, we found Laguncularia racemosa to be the most abundant species, with a higher density and dominance for adults and seedlings. Conversely, Avicennia schaueriana was the least abundant in all areas, indicating a need for species enrichment. Planting age affected the forest structure, suggesting the capacity of this mangrove to achieve a natural maturity state. There was a genetic erosion in L. racemosa individuals, both adults and seedlings and low diversity was observed in A. schaueriana individuals. The PNMBM mangrove forest has shown remarkable resilience in maintaining its vegetation cover after restoration despite previous deforestation cycles. Moreover, as a young mangrove forest, it will continue to go through successional stages naturally. The loss of genetic diversity could be a concern for long-term survival, highlighting the need for genetic management. Integrating remote sensing, phytosociology, and genetic diversity analyses provided a comprehensive and detailed view of the park’s restoration outcome. These results should be used as guidelines for future interventions outlined in this work and can help ensure the resilience and sustainability of any restored mangrove.