Anthropogenic impacts on nitrogen fixation rates between restored and natural Mediterranean salt marshes |
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| Authors: | Serena Moseman‐Valtierra Lisa A Levin Rose M Martin |
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| Affiliation: | 1. Biological Sciences Department, University of Rhode Island, Kingston, RI, USA;2. Integrative Oceanography Division, Scripps Institution of Oceanography, La Jolla, CA, USA |
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| Abstract: | To test the effects of site and successional stage on nitrogen fixation rates in salt marshes of the Venice Lagoon, Italy, acetylene reduction assays were performed with Salicornia veneta‐ and Spartina townsendii‐vegetated sediments from three restored (6–14 years) and two natural marshes. Average nitrogen fixation (acetylene reduction) rates ranged from 31 to 343 μmol C2H4·m?2·h?1 among all marshes, with the greatest average rates being from one natural marsh (Tezze Fonde). These high rates are up to six times greater than those reported from Southern California Spartina marshes of similar Mediterranean climate, but substantially lower than those found in moister climates of the Atlantic US coast. Nitrogen fixation rates did not consistently vary between natural and restored marshes within a site (Fossei Est, Tezze Fonde, Cenesa) but were negatively related to assayed plant biomass within the acetylene reduction samples collected among all marshes. Highest nitrogen fixation rates were found at Tezze Fonde, the location closest to the city of Venice, in both natural and restored marshes, suggesting possible site‐specific impacts of anthropogenic stress on marsh succession. |
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| Keywords: | Invasive
Salicornia
sea level rise
Spartina
succession |
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