Comparison of beachgrass species.

Comparison of beachgrass species including new hybrid.

CoastWatch volunteers are helping researchers at Oregon State University map the range of the new hybrid, the offspring of two invasive beachgrass species. You can help map hybrid beachgrass on the Oregon coast using iNaturalist.

In the Pacific Northwest, two invasive beachgrasses, European beachgrass (Ammophila arenaria) and American beachgrass (A. breviligulata) were introduced beginning in the early 20 th century and dramatically transformed the coastline by building dunes. Today, they are widespread across the coast and, where they overlap in their ranges in northern Oregon and southern Washington, we have detected that hybridization is occurring. Through a citizen science project in partnership with CoastWatch, community members have uploaded over 1,200 observations of the Ammophila parents and their hybrid since the beginning of the project in 2020. Additionally, we have searched over 26 miles of dune and discovered nearly 300 hybrid occurrences across the hybrid’s range, a 155-mile stretch from Pacific City, Oregon to Ocean Grove, Washington, although other opportunities for hybridization are possible beyond this range.

Research first led by Dr. Rebecca Mostow in 2020 and 2021, suggested that the hybrid may exceed its parents in traits important for dune-building, such as stem height and stem density, which may lead to greater sand capture and produce taller and perhaps wider dunes. This means that the hybrid has the potential to influence dune shape and coastal protection from extreme storms and sea level rise, and may affect snowy plover habitat and other aspects of beach and dune ecology. Many more hybrid beachgrass patches are likely to be found if searches continue in coastal dune areas, especially on the north Oregon coast in Clatsop county. Dr. Mostow provided background on beachgrass and the efforts to trace the new hybrid in an information-packed webinar for CoastWatch, available on the CoastWatch YouTube channel. Further research in 2022 and 2023 by Risa Askerooth found that the hybrid shows substantial growth, exceeds its parents in certain traits important for dune building, and is found near and within threatened bird habitat. Overall, the high abundance of this new beachgrass, as well as its likelihood to spread further in future, indicate that the hybrid is an important consideration for dune management and conservation planning. Risa’s talk, Research Insights into Hybrid Beachgrass Ecology With Help From Citizen Science, can be also found on our YouTube channel

As a result of dune surveys led by researchers and community scientists, 117 patches of the hybrid have currently been found–much more than previously realized just a year ago! On iNaturalist alone, the hybrid beachgrass mapping project has nearly 1,000 observations, including 33 of the hybrid, from 599 different people. These hybrid beachgrass patches, which range in size from just a few square meters to patches that run along the foredune for nearly a kilometer, are located across a 155-mile stretch from Pacific City, Oregon to Ocean Grove, Washington. 

For any questions about where to hunt for the hybrid grass or if you need help with iNaturalist, please contact CoastWatch Programs Manager Jesse Jones, Happy hunting!