[Skip Navigation]
Benthic Habitat Mapping
Spatial Data
Mapping Information
Project Planning
Mapping Techniques
Satellites and Aerial Photos
Acoustics
Light and Imaging
Sediment Sampling
Analyzing Benthic Data
Applying Benthic Data
Resources
Funding / Partnership Information
Active Projects
Classification Standards
Benthic Habitat Mapping

Search Benthic Site:
Mapping Techniques: Light and Imaging

Sediment Profile Imaging

Click here to view a video of a SPI camera penetrating the seafloor.
Courtesy: Science Applications International Corporation

The sediment profile imaging (SPI) system is designed to photograph the sediment-water interface without creating disturbance. A sharp-edged prism cuts cleanly into the sediment to a depth of 15 to 20 cm. The camera is mounted in the top of the prism, and a mirror is used to reflect the sediment image to the camera from the vertical faceplate. Since the sediment is right up against the faceplate, lack of water clarity is never a limitation on this optical method.

Advantages and Limitations

Sediment profile imaging is a useful tool for rapidly collecting data and analyzing a suite of seafloor parameters. These include: sediment grain size, camera prism penetration depth (an indirect measure of sediment density), roughness of the sediment-water interface, transition between oxygenated surface sediments and underlying sediments with little or no oxygen (called the apparent redox potential discontinuity layer), biological successional stage, and presence of methane gas bubbles, burrows, fauna, and dredged material.

SPI Examples

Typical sediment-profile images showing a variety of physical and biological characteristics at the sediment-water interface.
Courtesy: Science Applications International Corporation

The small sample "footprint" is the main limitation of this technique. It is difficult to relate the sample footprint to an entire habitat, so SPI is often used in combination with other techniques.

How do the images relate to habitat maps? View Image

Uses

Scientists have developed indices, such as the Organism-Sediment Index and the Benthic Habitat Quality Index, to characterize overall benthic habitat quality based on SPI analysis. More details are given in the Applying Benthic Data section of this website, but, in general, these indices define a scale for assessing habitat quality based on biogeochemical indicators of benthic condition. The lowest possible index values (highly disturbed/degraded benthic habitat quality) denote black sediments that lack oxygen and have no sign of any active benthic life. The highest possible index values (undisturbed or non-degraded benthic habitat quality) denote well-oxidized sediments having evidence of a mature and well-developed benthic community.

In addition to general habitat mapping and quality assessment, SPI can also be used to

  • designate and monitor sites for disposal of dredged material
  • monitor the seafloor for oxygen deficiency
  • conduct impact studies for pollutants, aquaculture, and oil platforms
  • verify data collected by acoustical sensors, such as side-scan or acoustic seafloor classification systems

Recently, scientists have used SPI to create time-lapse movies of the sediment-water interface. Time-lapse SPI (tSPI) provides additional insights about the way benthic organisms interact with each other and their sedimentary environment over relatively short time scales (that is, minutes to hours).

Click to view a time-lapse SPI movie. View Image

The Benthic Habitats of NY/NJ Harbor project used SPI to map benthic habitats in New York/New Jersey Harbor. This project was conducted to address a need for better management of dredged material. Part of that management strategy involved open-water disposal of sediments and upland restoration using dredged material. In order to develop a strategy for these disposal options, a thorough assessment of the Harbor's benthic habitats was needed. SPI was used in conjunction with grab sampling in this project.

Other Sites of Interest:

Site Map : Acknowledgments : Terms of Use