Ecosystem resilience and threshold response in the Galápagos Coastal Zone

Seddon, Alistair W.R.; Froyd, Cynthia A.; Leng, Melanie J. ORCID: https://orcid.org/0000-0003-1115-5166; Milne, Glenn A.; Willis, Katherine J.. 2011 Ecosystem resilience and threshold response in the Galápagos Coastal Zone. PLoS one, 6 (7), e22376. https://doi.org/10.1371/journal.pone.0022376

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Abstract/Summary

Background: The Intergovernmental Panel on Climate Change (IPCC) provides a conservative estimate on rates of sea-level rise of 3.8 mm yr21 at the end of the 21st century, which may have a detrimental effect on ecologically important mangrove ecosystems. Understanding factors influencing the long-term resilience of these communities is critical but poorly understood. We investigate ecological resilience in a coastal mangrove community from the Gala´pagos Islands over the last 2700 years using three research questions: What are the ‘fast and slow’ processes operating in the coastal zone? Is there evidence for a threshold response? How can the past inform us about the resilience of the modern system? Methodology/Principal Findings: Palaeoecological methods (AMS radiocarbon dating, stable carbon isotopes (d13C)) were used to reconstruct sedimentation rates and ecological change over the past 2,700 years at Diablas lagoon, Isabela, Gala´pagos. Bulk geochemical analysis was also used to determine local environmental changes, and salinity was reconstructed using a diatom transfer function. Changes in relative sea level (RSL) were estimated using a glacio-isostatic adjustment model. Non-linear behaviour was observed in the Diablas mangrove ecosystem as it responded to increased salinities following exposure to tidal inundations. A negative feedback was observed which enabled the mangrove canopy to accrete vertically, but disturbances may have opened up the canopy and contributed to an erosion of resilience over time. A combination of drier climatic conditions and a slight fall in RSL then resulted in a threshold response, from a mangrove community to a microbial mat. Conclusions/Significance: Palaeoecological records can provide important information on the nature of non-linear behaviour by identifying thresholds within ecological systems, and in outlining responses to ‘fast’ and ‘slow’ environmental change between alternative stable states. This study highlights the need to incorporate a long-term ecological perspective when designing strategies for maximizing coastal resilience.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1371/journal.pone.0022376
Programmes:	BGS Programmes 2010 > NERC Isotope Geoscience Laboratory
Additional Information. Not used in RCUK Gateway to Research.:	Article also available for free download from URL above
Date made live:	26 Sep 2011 15:17 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/15187

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