Lessons from the past: isotopes of an endangered rail as indicators of underlying change to tidal marsh habitats

Ecosystem Health and Sustainability
By: , and 

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Abstract

Introduction: Tidal marsh systems along the Pacific coast of the United States have experienced substantial stress and loss of area and ecosystem function, which we examined by using the endangered California Ridgway’s Rail, Rallus obsoletus obsoletus (‘rail’) as an indicator of its tidal marsh habitat in the San Francisco Estuary. We organized a collection of historical (1885-1940) and modern (2005-2014) rail feathers and analyzed the feather isotope means for delta carbon (δ13C), sulfur (δ34S), and nitrogen (δ15N) by region and time period.

Outcomes: Feather isotopes represented the primary foraging habitat during historical then modern time periods. Neither individual nor regional rail feather isotopes suggested freshwater or terrestrial foraging by the rail. Three regions with both historic and modern feather isotopes revealed non-uniform spatial shifts in isotope levels consistent with a marine based food web and significant δ15N enrichment.

Discussion: Our results supported the rail’s status as a generalist forager and obligate tidal marsh species throughout the historic record. The variable isoscape trends generated from feather isotope means illustrated a modern loss of the isotopic homogeneity between regions of historical tidal marsh, which correlated with spatially-explicit habitat alterations such as increasing biological invasions and sewage effluent over time.

Conclusion: These findings have reinforced the importance of tidal marsh conservation in the face of ongoing underlying changes to these important ecosystems.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Lessons from the past: isotopes of an endangered rail as indicators of underlying change to tidal marsh habitats
Series title Ecosystem Health and Sustainability
DOI 10.1080/20964129.2017.1410451
Volume 3
Issue 11
Year Published 2017
Language English
Publisher Taylor & Francis
Contributing office(s) Western Ecological Research Center
Description Article 1410451; 16 p.
First page 1
Last page 16
Country United States
State California