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Development and validation of a habitat suitability model for the non-indigenous seagrass Zostera japonica in North America
Citation:
Shafer, D., T. Swannack, C. Saltus, Jim Kaldy, AND A. Davis. Development and validation of a habitat suitability model for the non-indigenous seagrass Zostera japonica in North America. Management of Biological Invasions. Regional Euro-Asian Biological Invasions Centre, Helsinki, Finland, 7(2):141-155, (2016).
Impact/Purpose:
We developed a habitat suitability model that will allow resource managers to identify estuarine areas at risk for future invasion by Zostera japonica. Having a predictive model also allows managers to develop proactive plans for limiting the opportunities for further introduction and spread in areas where it does not currently occur. The model uses simple environmental parameters (depth, nearshore slope, and salinity) to quantitatively describe habitat suitable for Z. japonica colonization based on ecology and physiology from the primary literature. The model was applied to Yaquina Bay, Oregon, USA, an area that has well documented Z. japonica expansion over the last two decades. The model was validated by comparison to a multi-year time series of Z. japonica maps, revealing a strong predictive capacity. Sensitivity analysis performed to evaluate the contribution of each parameter to the model prediction revealed that depth was the most important factor. In general, shallow sloping intertidal soft-bottom sediments appear to provide optimum habitat for this species.
Description:
We developed a spatially-explicit, flexible 3-parameter habitat suitability model that can be used to identify and predict areas at higher risk for non-native dwarf eelgrass (Zostera japonica) invasion. The model uses simple environmental parameters (depth, nearshore slope, and salinity) to quantitatively describe habitat suitable for Z. japonica invasion based on ecology and physiology from the primary literature. Habitat suitability is defined with values ranging from zero to one, where one denotes areas most conducive to Z. japonica and zero denotes areas not likely to support Z. japonica growth. The model was applied to Yaquina Bay, Oregon, USA, an area that has well documented Z. japonica expansion over the last two decades. The highest suitability values for Z. japonica occurred in the mid to upper portions of the intertidal zone, with larger expanses occurring in the lower estuary. While the upper estuary did contain suitable habitat, most areas were not as large as in the lower estuary, due to inappropriate depth, a steeply sloping intertidal zone, and lower salinity. The lowest suitability values occurred below the lower intertidal zone, within the Yaquina River channel. The model was validated by comparison to a multi-year time series of Z. japonica maps, revealing a strong predictive capacity. Sensitivity analysis performed to evaluate the contribution of each parameter to the model prediction revealed that depth was the most important factor. Shallow sloping intertidal soft-bottom sediments appear to provide optimum habitat for this species. This model would allow resource managers to identify those areas at risk for future invasion, and develop proactive plans for limiting the opportunities for further introduction and spread in areas where it does not currently occur.
