Watching Grass Grow: The Impact of Mangrove Degradation and Decoupling on Nearby Seagrass Productivity

Abstract

Mangroves and seagrasses are important stocks of blue carbon, as they are able to sequester at rates wildly disproportionate to their areal extent. Due to their spatial coincidence, these two ecosystems typically exchange nutrients that benefit each other’s growth. However, both habitats are undergoing global declines, primarily from anthropogenic activities. Akumal, Mexico is actively supporting programming to preserve seagrasses, and yet construction projects continue to remove mangroves for the sake of roads and beach front properties. In this study, I sought to investigate if mangrove condition (measured by biomass, basal area, habitat complexity and sediment depth) had an effect on the rates of primary productivity of seagrass beds nearby. This is the first study to analyze semi-decoupled mangrove-seagrass systems that only exchange water through underground mechanisms when human development prevents a direct interface. I found that each qualifier of mangrove condition had a significant effect on seagrass productivity, and that the belowground conditions of connectivity, sediment depth, and structural complexity had the greatest leverage on a multiple linear regression model. This demonstrates that mangroves should be considered in any seagrass conservation efforts, and all efforts should be made to allow direct connectivity between the two ecosystems.