Name: | Description: | Size: | Format: | |
---|---|---|---|---|
3.96 MB | Adobe PDF |
Advisor(s)
Abstract(s)
Tidal coastal wetlands, common home to seagrass and salt marshes, are relevant carbon sinks due to their high
capacity to accumulate and store organic carbon in their sediments. Recent studies demonstrated that the spatial
variability of this organic carbon within the same wetland system can be significant. Some of the environmental
drivers of this spatial variability remain understudied and the selection of the most relevant ones can be context
dependent. Here we investigated the role of bed elevation, hydrodynamics, and habitat type (salt marsh and
seagrass) on the organic matter (OM) net deposition-resuspension rate and superficial sedimentary stocks (top 5
cm) at the tidal wetlands of the Ria Formosa, a mesotidal coastal lagoon in South Portugal. Results showed that
two vectors of spatial variation need to be considered to describe the intertidal sedimentary OM stocks: the bed
elevation that imposes a decrease of the hydroperiod and thus the change of habitat from the lower seagrass
Z. noltei to the upper saltmarsh S. maritimus, and the horizontal spatial variation along the secondary channels of
the lagoon that imposes a decrease in the current flow velocity magnitude. The multiple linear regression analyses, using data from 40 sampling points, explained 59% of the variation of the superficial sedimentary stocks
of OM in salt marshes and seagrasses of the Ria Formosa lagoon and revealed that stocks generally decrease with
elevation, yet with variation among sites and habitats. It was also found that the decrease of the OM net
deposition-resuspension rate with bed elevation was exponential. Our study emphasizes the importance of
considering multiple environmental drivers and spatial variation for regional estimations of organic matter (and
organic carbon) sedimentary stocks in coastal wetlands.
Description
Keywords
Organic matter Sediment deposition Hydroperiod Tidal wetland Seagrass Salt marsh
Citation
Publisher
Elsevier