Non-native, habitat-forming species have the potential to have either positive or negative effects on ecosystems, which need to be considered in management. Eelgrass (Z. marina) is a marine habitat-forming species that is native to all northern hemisphere coastlines. Found in shallow, coastal and estuarine waters, it is internationally protected due to its ability to provide ecosystem services, such as stabilizing coastlines, cycling nutrients, and providing habitat for economically important fish and other species. Consequences of anthropogenic activities, such as warmer temperatures and increased disturbances are threatening eelgrass.   

From Northern California to British Columbia, there is also a non-native eelgrass (Zostera japonica) that grows in the same area as the native eelgrass. Throughout the invaded range, management of this non-native species depends on the jurisdiction. In Washington state, where this study will occur, Z. japonica is a class C noxious weed, allowing for the spraying of Z. japonica with herbicide. However, since Z. japonica can better withstand rising air and water temperatures, and is already filling in unvegetated habitat (i.e., bare mudflats), there is the possibility that as climate change stressors reduce Z. marina, Z. japonica may provide substitute habitat for the many species that depend on eelgrass. Currently, there is a lack of understanding about whether non-native eelgrass can fulfill the same role as the native eelgrass in the ecosystem, a question that has important management implications as the climate changes. 

To help fill this knowledge gap, Maria will collaborate with partners at the Washington Department of Natural Resources and the Washington Department of Ecology to understand the role of the non-native eelgrass in its ability to provide habitat for other organisms in Willapa Bay, Washington. Prior to the invasion of Z. japonica, there were larger areas of unvegetated habitat. Since non-native Z. japonica is more tolerant of warmer temperatures and desiccation, or drying that can occur at low tide, it is able to exist in a niche where Z. marina cannot. Prior to the invasion of Z. japonica, the area that it occupies was unvegetated. To identify the role of Z. japonica as a habitat provider, Maria will collect data about nekton — aquatic organisms able to swim freely, like fish, crab and shrimp —, as well as epifaunal invertebrates —, invertebrates that live either attached to a surface, like that of eelgrass, or move on the surface of bottom sediments. She will then compare the abundance of nekton and epifauna communities in unvegetated, native vegetative, and non-native vegetative habitat. Her project partners will use this information to inform management of the non-native species through the creation of a fact sheet.