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Abstract:
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This study was conducted to model the extent of eelgrass habitat in Humboldt Bay, California through physical surveys of the maximum depths and upper limits of growth in conjunction with recently acquired high-resolution bathymetry data and supplemental imagery. A combination of chronic turbidity, frequent coastal stratus, and wind-waves, make Humboldt Bay a challenging environment to assess subtidal eelgrass (Zostera marina) habitat from remotely-sensed imagery. Additionally, eelgrass and green algae overlap extensively in shallow intertidal areas, confounding efforts to distinguish between habitat types from imagery alone. A relative exposure index (REI) was developed to identify areas of eelgrass habitat that may be prone to disturbance from wind-waves. Approximately 2200 hectares of eelgrass habitat were identified. Accuracy was assessed at 91% for modeled eelgrass habitat in South Humboldt Bay based on a comparison with hyperspectral imagery captured in October, 2004. Modeling the extent of eelgrass habitat represents an important step towards understanding the extent to which future restoration or mitigation may be possible in Humboldt Bay. |
