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Sediment carbon storage differs in native and non-native Caribbean seagrass beds

Published Article

Caribbean

Publication date: December 18, 2023

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Invasive H. stipulacea seagrass in the Caribbean stores less carbon than native species, with lower biomass and sediment Corg. Though exceeding unvegetated areas, its spread may reduce overall carbon storage, affecting ecosystem services and climate mitigation.

 

Subject Tags

  • Carbon storage
  • Coastal
  • Invasive Species

Abstract

Non-native species are expanding globally and can alter ecosystem functions, including food web dynamics, community structure and carbon storage. Seagrass are foundation species that contribute a variety of ecosystem services in near-shore coastal ecosystems, including a significant sink of carbon. In the Caribbean, the rapidly expanding non-native Halophila stipulacea has unknown impacts on carbon storage. To investigate the impacts on carbon storage, we quantified organic carbon (Corg) content in sediment and seagrass tissues from monotypic H. stipulacea beds, mixed native seagrass beds dominated by Thalassia testudinum and Syringodium filiforme, and unvegetated substrate in St. John, USVI. We found native seagrass-vegetated sediment contained 1.3 times more Corg than sediment covered by H. stipulacea, and 1.6 times more Corg than unvegetated areas on average. Whereas, H. stipulacea-dominated substrate stored 1.2 times more Corg than unvegetated substrate. Likewise, native species contained 2.2 times more aboveground biomass and 6.0 times more belowground biomass than H. stipulacea. Since seagrasses are critical sources of carbon sequestration, our results suggest that invading H. stipulacea is associated with lower carbon stocks which has potential implications for conservation activities and climate change mitigation.

Citation

Brenner, C.L., Valdez, S.R., Zhang, Y.S., Shaver, E.C., Hughes, B.B., Silliman, B.R. and Morton, J.P., 2024. Sediment carbon storage differs in native and non-native Caribbean seagrass beds. Marine Environmental Research, 194, p.106307. https://doi.org/10.1016/j.marenvres.2023.106307

TNC Authors