Dr. Kasey Barton, School of Life Sciences, UH-Manoa

Coastal plants experience extreme conditions –high temperatures and solar intensity, limited rainfall, physical disturbances caused by humans and wave action, and salinity exposure to their roots and leaves. Although we expect that coastal plants have evolved to tolerate high salinity, this has rarely been tested. Moreover, sea level rise and an increase in storm frequency and severity mean that coastal plants are experiencing increasing salinity now and into the future.

Using an experimental approach, we have examined salinity tolerance in two widespread Hawaiian plant species, Jacquemontia sandwicensis (pāʻūohiʻiaka) and Sida fallax (ʻilima). Surprisingly, neither species was fully tolerant of high salinity, and they were particularly vulnerable during young stages (seeds and seedlings). Susceptibility during seed germination and seedling establishment could limit population persistence under future climate change, leading to declines and possible extirpation of these native plants. To investigate whether coastal plants are generally vulnerable to salinity, our current work expands this experimental approach to include 20 additional species and field trials. Our results will provide new insights into the evolution of these endemic plants as well as provide information to coastal land managers working to restore and conserve native coastal plant communities.

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