Blue carbon storage and environmental influences in mangroves, Puerto Rico

Abstract

Mangrove ecosystems are important coastal carbon sinks, with soil carbon storage strongly influenced by site-specific hydrological, sedimentary, and climatic conditions. This study quantified soil carbon stocks in two mangrove systems in Puerto Rico—La Parguera and Laguna Grande—and evaluated the relative influence of hydrology, sediment deposition, and climate on carbon accumulation. Depth-standardized soil carbon stocks (0–50 cm) were higher at Laguna Grande (166 ± 66 Mg C ha−1) than at La Parguera (115 ± 68 Mg C ha−1), with a marginal difference (p < 0.10). Differences between sites are consistent with contrasting hydrological regimes: La Parguera experiences greater tidal flushing, which may enhance organic matter export and decomposition, whereas Laguna Grande is a semi-enclosed lagoon with restricted tidal exchange and higher standing biomass, conditions that may promote organic matter retention and carbon accumulation. Although regional climatic differences—higher temperatures and precipitation near Laguna Grande relative to La Parguera—may influence productivity and decomposition dynamics, hydrological setting and sediment retention appear to be primary controls on soil carbon storage. These findings emphasize the importance of incorporating hydrological processes and geomorphic context into blue carbon assessments and mangrove conservation strategies. Understanding how tidal exchange, sediment dynamics, and precipitation patterns interact is critical for predicting mangrove carbon responses to future climate change.