Carbon storage and sediment trapping by Egeria densa Planch., a globally invasive, freshwater macrophyte

Science of the Total Environment
By: , and 



Invasive plants have long been recognized for altering ecosystem properties, but their long-term impacts on ecosystem processes remain largely unknown. In this study, we determined the impact of Egeria densa Planch, a globally invasive freshwater macrophyte, on sedimentation processes in a large tidal freshwater region. We measured carbon accumulation (CARs) and inorganic sedimentation rates in submerged aquatic vegetation SAV dominated by E. densa and compared these rates to those of adjacent tidal freshwater marshes. Study sites were chosen along a range of hydrodynamic conditions in the Sacramento-San Joaquin Delta of California, USA, where E. densa has been widespread since 1990. Cores were analyzed for bulk density, % inorganic matter, % organic carbon, 210Pb, and 137Cs. Our results show that E. densa patches constitute sinks for both “blue carbon” and inorganic sediment. Compared to marshes, E. densa patches have greater inorganic sedimentation rates (E. densa: 1103–5989 g m−2 yr−1, marsh: 393–1001 g m−2 yr−1, p < 0.01) and vertical accretion rates (E. densa: 0.4–1.3 cm yr−1, marsh: 0.3–0.5 cm yr−1, p < 0.05), but similar CARs (E. densa: 59–242 g C m−2 yr−1, marsh: 109–169 g C m−2 yr−1, p > 0.05). Sediment stored by E. densa likely reduces the resilience of adjacent marshes by depleting the sediment available for marsh-building. Because of its harmful traits, E. densa is not a suitable candidate for mitigating carbon pollution; however, currently invaded habitats may already contain a meaningful component of regional carbon budgets. Our results strongly suggest that E. densa patches are sinks for carbon and inorganic sediment throughout its global range, raising questions about how invasive SAV is altering biogeochemical cycling and sediment dynamics across freshwater ecosystems.

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Publication type Article
Publication Subtype Journal Article
Title Carbon storage and sediment trapping by Egeria densa Planch., a globally invasive, freshwater macrophyte
Series title Science of the Total Environment
DOI 10.1016/j.scitotenv.2020.142602
Year Published 2020
Language English
Publisher Elsevier
Contributing office(s) California Water Science Center, Pacific Coastal and Marine Science Center
Description 142602, 12 p.
Country United States
State California
Other Geospatial Sacramento-San Joaquin Delta
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