Abstract Detail


Gillard, Morgane [1], Castillo, Jesús M.  [2], Mesgaran, Mohsen B.  [3], Futrell, Caryn J. [4], Grewell, Brenda J. [5].

High aqueous salinity exposure does not preclude germination of invasive Iris pseudacorus.

The wetland species Iris pseudacorus (L.) (yellow flag iris) recently spread from freshwater tidal wetland populations in the Sacramento – San Joaquin Delta to multiple brackish estuarine sites in the San Francisco Estuary, which represents a concern considering the invasiveness of the species and the vulnerability of the wetland ecosystem. 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 affect the germination of I. pseudacorus. We explored the germination responses of seeds from two invasive populations from extreme points of the salinity gradient of the Delta tidal wetlands by exposing them 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 (21.4±5.1°C). 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. Hydrological conditions had no impact on the germination fraction, and there was no evidence of local adaptation of the two studied populations. Thus, we conclude that a prolongated period of exposure to seawater will not impede the germination capacities of seeds in invasive populations of I. pseudacorus, allowing colonization of new sites following potentially long-distance dispersal of buoyant seeds with tidal currents. These results will help managers improve risk assessments on the invasive spread of I. pseudacorus in freshwater and saline tidal environments.

1 - 1055 W Blaine Street Apt 129, Riverside, CA, 92507, United States
2 - Universidad de Sevilla, Departamento de Biología Vegetal y Ecología, Biology, Apartado 1095, CP 41080, Seville, SPAIN
3 - University of California, Davis, Plant Sciences , Dept of Plant Sciences Mail Stop 4, One Shields Avenue, Davis, CA, 95616, USA
4 - USDA ARS Invasive Species & Pollinator Health Research Unit, Dept of Plant Sciences, UC Davis, Plant Sci MS-4, One Shields Avenue, Davis, CA, 95616, USA
5 - USDA-ARS, U. California Davis, USDA-ARS Invasive Species Research, One Shields Avenue, Dept Plant Sciences MS-4, Davis, CA, 95616, United States

Invasive species
Sea level rise

Presentation Type: Poster
Session: P, Ecology Posters
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 5:00 PM Time and date to be determined
Number: PEC021
Abstract ID:114
Candidate for Awards:None

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