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Greenhouse Gas Fluxes of Mangrove Soils and Adjacent Coastal Waters in an Urban, Subtropical Estuary
Citation:
Martin, R., C. Wigand, A. Oczkowski, Alana Hanson, S. Balogh, B. Branoff, E. Santos, AND E. Huertas. Greenhouse Gas Fluxes of Mangrove Soils and Adjacent Coastal Waters in an Urban, Subtropical Estuary. WETLANDS. The Society of Wetland Scientists, McLean, VA, 40:1469–1480, (2020). https://doi.org/10.1007/s13157-020-01300-w
Impact/Purpose:
The purpose of this research was to examine the impacts of land development and urbanization on carbon storage and emissions in the subtropical San Juan Bay Estuary (SJBE). Carbon storage is important to offset carbon dioxide and other greenhouse gas emissions that are released from vehicles, fossil fuel energy use, and other natural processes. High emissions of carbon dioxide and methane from natural mangrove systems are sometimes associated with urbanization. Long-term carbon storage resulting from plant production is usually associated with healthy mangrove systems. Carbon dioxide and methane fluxes were measured in the soils and adjacent coastal waters in mangrove systems along a gradient of urbanization in the SJBE. Elevated carbon dioxide and methane emissions were measured in the mangrove systems associated with the highly developed Martin Pena canal area and very low emissions were detected in the Pinones reserve with very low development. The results of this work provide important information on carbon emissions and storage in subtropical, urban wetlands, which are poorly understood. The mangrove carbon storage and emissions data will be of use to modelers, coastal managers, and community groups when planning how to promote carbon storage as an offset for carbon dioxide and other greenhouse gas emissions.
Description:
Mangroves are known to sequester carbon at rates exceeding even those of other tropical forests; however, to understand carbon cycling in these systems, soil-atmosphere fluxes and gas exchanges in mangrove-adjacent shallow waters need to be quantified. Further, despite the ever-increasing impact of development on mangrove systems, there is even less data on how subtropical, greenhouse gas (GHG) fluxes are affected by urbanization. We quantified carbon dioxide (CO2) and methane (CH4) fluxes from mangrove soils and adjacent, coastal waters along a gradient of urbanization in the densely-populated, subtropical San Juan Bay Estuary (PR). Edaphic (salinity, pH, surface temperature) factors among sites significantly covaried with GHG fluxes. We found that mangrove systems in more highly-urbanized reaches of the estuary were characterized by relatively lower porewater salinities and substantially larger GHG emissions, particularly CH4, which has a high global warming potential. The magnitude of the CO2 emissions was similar in the mangrove soils and adjacent waters, but the CH4 emissions in the adjacent waters were an order of magnitude higher than in the soils and showed a marked response to urbanization. This study underscores the importance of considering GHG emissions of adjacent waters in carbon cycling dynamics in urbanized, tropical mangrove systems.
URLs/Downloads:
DOI: Greenhouse Gas Fluxes of Mangrove Soils and Adjacent Coastal Waters in an Urban, Subtropical Estuary