Modeling Sea-Level Rise in Rocky Intertidal Zone

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Intertidal ecosystems are valued for their biodiversity, traditional foods, cultural significance, and recreational and educational opportunities. To protect and manage the intertidal zone’s multiple values, Tribes, land managers, and coastal communities need to be able to anticipate the effects of sea-level rise on these complex systems. In the Pacific Northwest, rocky intertidal systems are characterized by high structural complexity and diverse invertebrate communities structured largely by fine-scale differences in elevation relative to tidal range. Modeling the potential effects of sea-level rise in these systems requires cost-effective and logistically feasible methods for developing high-resolution elevation models of the intertidal zone. USGS scientists are testing the utility of Terrestrial Laser Scanning (TLS), also known as ground-based lidar, for developing elevation models at scales useful for ecological research. In this pilot study, TLS-derived topographic surface models are being used to estimate current and future potential foraging habitat for the black oystercatcher on Rabbit Rock, an approximately 0.72-hectare area along the central Oregon coast. Black oystercatchers are intertidal-obligate birds that influence intertidal community structure through predation and link rocky intertidal habitat patches through their movements throughout the annual cycle.  Intertidal-obligates are species that are dependent on living off the intertidal zone and the other creatures that inhabit it. Based on the TLS-derived models, researchers are developing a model of oystercatcher prey (limpets) distribution based on tidal elevation and topography, estimating the area of potential foraging habitat for black oystercatchers, and estimating changes in potential foraging habitat with sea level rise up to 2 m. Preliminary results generally show trends toward reduction in foraging habitat with substantially higher sea level, with the surprising exception of an increase in foraging habitat with a modest increase in sea level as a result of the specific topography at the study site. This project also demonstrates that TLS can be an important source of timely, efficient, and scale-appropriate topographic information where most alternate methods are inadequate or infeasible, reinforcing its utility for ecological research in structurally complex systems like the intertidal zone.


Author Name
Susan Haig
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