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OR&R Examines Physical Drivers of Seagrass Landscape Configuration

NOVEMBER 16, 2018 — A recent OR&R publication in the journal Landscape Ecology examined how hydrodynamic drivers and physical setting influence seagrass landscape composition and configuration.

Graphic showing presence or absence of sea grass.
Binary maps generated from classified aerial imagery indicate the presence (black) or absence (white) of seagrass for 5 of the 62 seagrass landscapes examined in the study. The sequence of emerging spatial pattern in response to increasing wave energy is apparent. Image credit: NOAA.

The Marine Debris Program’s Chief Scientist, Amy V. Uhrin, together with a colleague at the University of Wisconsin-Madison, used landscape metrics to quantify the spatial configuration of seagrass and then modeled the response of these metrics to wave energy, tidal current speed, and water depth at 62 estuarine sites in North Carolina.

The study identified change points in wave energy (between 675–774 J m−1) beyond which seagrass spatial configuration changed dramatically. In addition, seagrass percent cover, patch size, and number of patches all declined with increasing wave energy. With weather extremes on the rise, much of this estuarine seagrass will be exposed to increased wave energy. Where seagrass exists just below the wave energy change points, increases in wave energy could tip those habitats into a new stable state of lower cover resulting in less cover overall in the estuary.

Having this information can help address seagrass resilience in future climate change scenarios and altered hurricane regimes, as patchy seagrass areas (typically found in wave energy environments above change point) are known to be more susceptible to storms than continuous meadows (typically found in areas below the change point). The research highlights that efforts to restore seagrass habitat should aim for restoring not just cover but also the original spatial arrangement of the beds. 

For more information, please contact Amy.Uhrin@noaa.gov.

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