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...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(δ^(13)C),sulfur(δ^(34)S),and nitrogen(δ^(15)N)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 significantδ^(15)N 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.展开更多
基金This work was supported by the U.S.Fish and Wildlife Service[4500067653].
文摘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(δ^(13)C),sulfur(δ^(34)S),and nitrogen(δ^(15)N)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 significantδ^(15)N 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.
