Abstract
The extent and function of coastal mangrove ecosystems are likely to be influenced by future changes in sea level. Multiple proxies of past mangrove ecosystems preserved in a 780 cm long peat core (TCC2) taken from Twin Cays, Belize, record palaeoecological changes since ~8000 cal. yr BP. The proxies included pollen and the stable-isotope (C, N and O) compositions of mangrove leaf fragments. Rhizophora mangle (red mangrove) has been dominant at this site on Twin Cays for over ~8000 years. Variations in δ13 C and δ15N suggest past changes in stand structure between dwarf, transition and tall R. mangle through the Holocene. Marked changes in the δ18O (up to ~4‰) of mangrove leaf fragments throughout TCC2 most likely record variations in the proportion of seawater versus precipitation taken up by past mangroves, reflecting the degree of inundation of the site with seawater resulting from changes in the rate of Holocene sea-level rise. Notably, a decline in peat accumulation rate at ~7200 cal. yr BP correlates with a decrease in the rate of rise in sea level. This was not accompanied by a marked change in the pollen assemblages. However, changes in assemblage composition began to occur ~6300 cal. yr BP, with an increase in Myrsine-type and Avicennia germinans (black mangrove) pollen. An increase in the δ18O between 6100 and 5300 cal. yr BP, which correlates with other records from Central America, indicates a significant increase in the rate of rise in sea level.
Highlights
Mangrove ecosystems perform significant roles in global carbon cycling (Chmura et al, 2003; Dittmar et al, 2006) and in protecting tropical and subtropical coastlines from disturbances such as tsunamis (Kathiresan and Rajendran, 2005; Danielsen et al, 2005)
Core description and radiocarbon dates for core TCC2 TCC2 was almost entirely composed of peat (Figure 2), with the exception of a small section (~780–710 cm) composed of a fine grey mud that was harder than the peat (Figure 2b)
Our data have implications for predicting how mangrove ecosystems may respond to future changes in sea level
Summary
Mangrove ecosystems perform significant roles in global carbon cycling (Chmura et al, 2003; Dittmar et al, 2006) and in protecting tropical and subtropical coastlines from disturbances such as tsunamis (Kathiresan and Rajendran, 2005; Danielsen et al, 2005). The extent and function of mangrove ecosystems present along tropical coastlines are likely to be significantly influenced by fluctuations in sea level (Blasco, 1984; Woodroffe, 1995b; Ellison and Farnsworth, 1997; Swarzbach, 1999). A comprehensive review of evidence from the Brazilian coast shows that the rate of rise in sea level during the Holocene may have slowed at times, it is unlikely that sea level substantially dropped (Angulo et al, 2006)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
