Mapping seaweed forests with IKONOS image based on bottom surface reflectance

Tatsuyuki Sagawa, Atsuko Mikami, Masakazu N. Aoki, Teruhisa Komatsu

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    14 Citations (Scopus)


    Seaweed forests are important habitats for many fishery species. However, decrease in seaweed forests is reported in all over Japan. Mapping and monitoring seaweed forest distribution is necessary for understanding their present status and taking measures for their conservation. Since traditional diving visual observation is not efficient for large scale mapping, alternative method is required. Although satellite remote sensing is one of the noteworthy methods, only a few studies have been conducted probably due to two main problems about mapping seaweed forests by remote sensing. The first one is a difficulty to collect field truth data. The second one is a light attenuation effect in water column which makes analysis more difficult. We applied an efficient method to overcome these two problems. We selected the seaweed beds off Shimoda in Izu Peninsula, Japan, as a study area. An IKONOS satellite image was used for analysis because its high spatial and radiometric resolutions are practical for seaweed mapping. We measured spectral reflectance profiles of seaweed and substrates in the study area. The result revealed effective wavelength bands for distinguishing seaweeds from other substrates. Truth data for satellite image analysis and evaluation were collected in the field using the boat and an aquatic video camera. This method allowed us to collect many truth data in short time. Satellite image analysis was conducted using radiometric correction for water column and maximum likelihood classification. The overall accuracy using error matrix reached 97.9%. The results indicate usefulness of the method for seaweed forest mapping..

    Original languageEnglish
    Title of host publicationRemote Sensing of the Marine Environment II
    ISBN (Print)9780819492647
    Publication statusPublished - 2012 Jan 1
    EventRemote Sensing of the Marine Environment II - Kyoto, Japan
    Duration: 2012 Oct 312012 Nov 1

    Publication series

    NameProceedings of SPIE - The International Society for Optical Engineering
    ISSN (Print)0277-786X
    ISSN (Electronic)1996-756X


    OtherRemote Sensing of the Marine Environment II


    • IKONOS
    • bottom surface reflectance
    • mapping
    • seaweed forest

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Computer Science Applications
    • Applied Mathematics
    • Electrical and Electronic Engineering


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