Effects of zonation on mangrove health on San Salvador Island, Bahamas : Analyzing Soil Salinity, Tree Health, and Leaf Health of Mangrove Communities

Abstract

Mangrove communities play a significant role in shaping coastal communities such as San Salvador Island, Bahamas. Communities consisting of red, black, white, and buttonwood trees are commonly divided into specific regions of growth through the process of zonation with red mangroves growing along the coast, black mangroves along the muddy soils, white mangroves farther inland, and buttonwood located the farthest inland, which is dependent on soil salinity concentrations. Our goal was to define how salinity stress impacts the four mangrove species and their current health. We collected data across two sites: a high salinity body of water and a low salinity body of water. We expected an inverse relationship between salinity concentrations with tree diameter at breast height (DBH) and height. We also predicted chlorophyll content, specific leaf area (SLA), and stomata density would be greater for trees with lower salinity. Contrary to our predictions, DBH, height, and SLA did not depend on the salinity of the soil. White mangroves and buttonwoods from both sites differed in stomatal density (p-value < 0.001); however, stomatal density was not affected by salinity between sites. There was a higher chlorophyll content in higher salinity conditions compared to lower (p-value < 0.001).