Location: Invasive Species and Pollinator HealthTitle: High salinity exposure does not preclude germination of invasive Iris pseudacorus from populations along a Delta – San Francisco Estuary salinity gradient [
|GILLARD, MORGANE - University Of California, Davis
|CASTILLO, JESUS - University Of Seville
|MESGARAN, MOHSEN - University Of California, Davis
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/18/2019
Publication Date: 10/18/2019
Citation: Gillard, M., Castillo, J.M., Mesgaran, M.B., Futrell, C.J., Grewell, B.J. 2019. High salinity exposure does not preclude germination of invasive Iris pseudacorus from populations along a Delta – San Francisco Estuary salinity gradient [. Meeting Abstract. Abstract.
Technical Abstract: The wetland species Iris pseudacorus (L.) (yellow flag iris) recently spread from tidal wetland populations in the Sacramento – San Joaquin Delta to multiple sites from Suisun Marsh to the Carquinez Straits in the San Francisco Estuary, which represents a concern considering the invasiveness of the species and the vulnerability of the ecosystem. While Pacific northwestern US populations of I. pseudacorus reproduce almost exclusively by sexual reproduction, estuaries present a wide range of aqueous salinity concentrations and increasing salinity that has been shown to alter the germination of tidal wetland plant species, depending on their sensitivity. Among future global changes, sea-level rise will broadly impact tidal wetlands, through the overall increase of salinity and inundation regimes. Thus, it appears necessary to explore to what extent salinity levels, water level and their interaction can hinder the germination of I. pseudacorus. We explored the germination responses of seeds from two populations that have invaded Delta tidal wetlands that we exposed to four salinity levels ranging from freshwater to seawater (0, 10, 20, 35 psu), and to two hydrological conditions (moist and flooded) in dishes placed in greenhouse conditions. Our results showed that germination was limited above a salinity level of 10 psu. Nonetheless, the seeds exposed to seawater salinity (35 psu) for 55 days were able to quickly germinate when exposed to freshwater. Thus, a prolongated period in seawater would not alter the germination capacities of invasive seeds of I. pseudacorus, allowing colonization of new sites following potentially long distance dispersal of buoyant seeds with tidal currents. These results will help managers to better appreciate the risk of the invasive spread of I. pseudacorus in freshwater and saline tidal environments. Oral Presentation: California Invasive Plant Council (CAL IPC).