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Publication
Carbon and nitrogen stocks and burial rates in intertidal vegetated habitats of a Mesotidal coastal lagoon
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Advisor(s)
Abstract(s)
Coastal vegetated ecosystems such as saltmarshes
and seagrasses are important sinks of organic carbon (OC) and total nitrogen (TN), with large global
and local variability, driven by the confluence of
many physical and ecological factors. Here we
show that sedimentary OC and TN stocks of intertidal saltmarsh (Sporobolus maritimus) and seagrass
(Zostera noltei) habitats increased between two- and
fourfold along a decreasing flow velocity gradient
in Ria Formosa lagoon (south Portugal). A similar
twofold increase was also observed for OC and TN
burial rates of S. maritimus and of almost one order
of magnitude for Z. noltei. Stable isotope mixing models identify allochthonous particulate organic
matter as the main source to the sedimentary pools
in both habitats (39–68%). This is the second estimate of OC stocks and the first of OC burial rates in
Z. noltei, a small, fast-growing species that is widely
distributed in Europe (41,000 ha) and which area is
presently expanding (8600 ha in 2000s). Its wide
range of OC stocks (29–99 Mg ha-1
) and burial
rates (15–122 g m2 y-1
) observed in Ria Formosa
highlight the importance of investigating the drivers of such variability to develop global blue carbon models. The TN stocks (7–11 Mg ha-1
) and
burial rates (2–4 g m-2 y-1
) of Z. noltei were generally higher than seagrasses elsewhere. The OC
and TN stocks (29–101 and 3–11 Mg ha-1
, respectively) and burial rates (19–39 and 3–5 g m-2 y-1
)
in S. maritimus saltmarshes are generally lower than
those located in estuaries subjected to larger accumulation of terrestrial organic matter.
Description
Keywords
Stable isotopes Flow current velocity Blue carbon Nitrogen Seagrass Saltmarsh Sediment stocks Burial rates