High-resolution ocean color remote sensing of benthic habitats: a case study at the Roatan island, Honduras

Abstract

Abstract-Natural resource managers clamor for detailed reef habitat maps for monitoring smaller scale disturbances in reef communities. Coastal ocean color remote sensing techniques permit benthic habitats to be explored with higher resolution than ever before. The objective of this research was to develop an accurate benthic habitat map for an area off the northwest coast of Roatan Island, Honduras, using high-resolution multispectral IKONOS data. Atmospheric (Rayleigh and aerosol path radiance) and water column corrections (water depth and water column attenuation) were applied to the imagery, making it a robust method for mapping benthic habitats. Water depth for each pixel was calculated based on a site-specific polynomial model. A mechanistic radiative transfer approach was developed that removed the confound effect of the water column (absorption and scattering) from the imagery to retrieve an estimate of the bottom reflectance (albedo). Albedos were 12% for seagrass benthos, 12% to 24% for coral areas, and 24% for sand-dominated areas. The retrieved bottom albedos were then used to classify the benthos, generating a detailed map of benthic habitats, followed by accuracy assessment.

Benthic Habitat Mapping from Seabed Images using Ensemble of Color, Texture, and Edge Features

“…This approach is suitable for that. Most of the works that approach this problem are from remote satellite images [2]- [5]. Only one study was undertaken so far on the same set of images in [6].…”

“…A number of works are observed in the literature [2]- [14] that automates the habitat map production process from aerial imagery, underwater photos, acoustic surveys, and data gathered from sediment samples. Depending on the area under consideration the segmentation algorithm, feature extraction process and the classification process varies.…”

Remote Sensing of Submerged Aquatic Vegetation

“…Remote sensing is a valuable tool for monitoring benthic habitats such as SAV, benthic algae, and coral-reef ecosystems, and several researchers have tested airborne and spaceborne sensor systems for such studies (e.g., Mishra et al, 2005). Spatial resolutions of these systems range from 30 m for the Landsat Thematic Mapper (TM) to 2.44 m for QuickBird multispectral data and 1 m or less for airborne hyperspectral data.…”

“…Spatial resolutions of these systems range from 30 m for the Landsat Thematic Mapper (TM) to 2.44 m for QuickBird multispectral data and 1 m or less for airborne hyperspectral data. Those evaluating the utility of TM have mapped subtidal coastal habitats (Khan et al, 1992), delineated sand bottoms (Michalek et al, 1993), classified coral reef zones (Mishra et al, 2005(Mishra et al, , 2006, evaluated the benthos (Matsunaga & Kayanne, 1997), and performed time series analyses (Dobson & Dustan, 2000). Similarly, researchers have used IKONOS (4 m) and QuickBird (2.44 m) imagery with radiative transfer models to map benthic habitats (Mishra et al, 2005(Mishra et al, , 2006 and apply a similar model to Airborne Imaging Spectroradiometer for Applications (AISA) hyperspectral data to identify benthic habitats (Mishra et al, 2007).…”

“…In the case of aquatic remote sensing, the total signal received at satellite altitude is dominated by radiance contributed by atmospheric scattering, and only 8-10% of the signal corresponds to the water reflectance and reflectance from benthic features (Kirk, 1994, Mishra et al, 2005. Therefore, it is advisable to correct for atmospheric effects to retrieve any quantitative information for surface waters or benthic habitats from satellite images.…”