What Is Sediment Profile Imaging (SPI)?

Sediment Profile Imaging (SPI)

One of the Sediment Profile Imaging (SPI) camera’s most powerful attributes is its ability to convey ecological information in a format that most people can understand quite easily: a picture.


Sediment Profile Imaging (SPI) technology has been used extensively throughout the United States and internationally.  For the past 40 years, SPI has been used to monitor the environmental impacts of dredged material disposal, characterize sediment quality, monitor the impact of construction activity on the seafloor, and look for pollution “hot spots”.  This optical coring device works like an upside-down periscope and takes cross-sectional images of the upper 20 cm of the seafloor.

As one of the developers of the technology, we had the privilege of introducing it to the government of Hong Kong in 1993, and it became a key component of the 4-year, territory-wide monitoring program associated with the massive dredging/land reclamation that was a key part of the new Chep Lap Kok airport construction. We introduced the technology in many areas outside the United States (Canada, Ireland, Italy, New Zealand, China, Azerbaijan).  SPI is a powerful technology that provides an innovative and cost-effective solution to many marine environmental monitoring programs.

A schematic view of the Sediment Profile Imaging and Plan view camera in action.
A schematic view of the Sediment Profile Imaging and Plan view camera in action.

What Sediment Profile Imaging can Measure

Sediment Profile Imaging allows rapid data acquisition during field sampling (the camera is literally “pogo-sticked” across the seafloor). A wide variety of physical and biological parameters can be measured from each image.

  • Grain-size major mode and range (gravel, sand, silt, clay).
  • Small-scale surface boundary roughness.
  • Evidence of erosional or depositional environments, allowing identification of high and low kinetic energy areas.
  • Subsurface methane gas pockets (evidence of high Sediment Oxygen Demand).
  • Depth of the apparent RPD (Redox Potential Discontinuity).
  • Calculation of the Organism-Sediment Index, allowing rapid identification and mapping of disturbance gradients in surveyed areas.
  • Presence of epifauna.
  • Surface microbial aggregations.
  • Infaunal Successional Stage.
  • Evidence of excess organic loading and high sediment oxygen demand.


Benefits of using Sediment Profile Imaging:

Because traditional seafloor sampling techniques are expensive and time-consuming, an efficient sampling strategy for surveys can be an enormous aid to an efficient survey.   SPI aids in determining the location of traditional sampling stations by rapidly characterizing the variation in benthic sedimentary and community conditions.  Limited sampling resources can be allocated to the optimum sampling locations to accurately characterize the variance that exists in a particular area. All too often the results of monitoring programs show that a particular parameter of interest has either been over- or under-sampled as a result of “flying blind” initially and then sticking with the initial station locations that were chosen arbitrarily from a nautical chart.

INSPIRE scientists deploying a Sediment Profile Imaging Camera SPI on the deck of one of our survey vessels.
INSPIRE scientists deploying a Sediment Profile Imaging Camera SPI on the deck of one of a survey vessel.


Rapid and cost-effective data collection and analysis

SPI can survey large areas of seafloor quickly and efficiently. For many monitoring objectives, SPI technology can provide the necessary answers without the need to collect grab samples or repeatedly enumerate and identify individual invertebrates and assemble long species lists each time a sampling study is performed.

Gradient delineation between sampling locations accurately

Because the camera can obtain pictures rapidly and efficiently, it can supplement traditional sampling methods.  SPI achieves this by “filling in the gaps” between traditional chemical and biological sampling locations. The camera can accurately delineate gradients in biological community type, organic loading, or sediment grain-size between fixed station locations.

Bioturbation depth can be measured with a Sediment Profile Imaging camera and plotted on a map.
Sediment Profile Imaging can measure bioturbation depth which can then be mapped.


Results that are easily understandable by a non-scientific audience;

Many environmental programs have suffered because of their inability to convey results to regulators or a public audience who may not have a marine science background. One of the camera’s most powerful attributes is its ability to convey ecological information in an easily understandable format: a picture.

Over the past 10 years, we have come to realize that the technology’s most powerful asset is this last item.  SPI was able to provide the decisive evidence in several environmental litigation cases concerning ocean disposal impacts.  SPI technology proved that impacts were transitory and a full ecosystem recovery had taken place.

Learn more about SPI by visiting our downloads library:

Downloads Library


Three Sediment Profile Image (SPI) examples showing the benthic environment from the cameras point of view.
Three Sediment Profile Image, SPI, examples. Taken by INSPIRE Environmental


  • December 14, 2016

    Arnfinn Skadsheim

    I am Project leader for capping projects in the municipality of Stavanger, Norway. We plan as a first step to place fine grained sand, 0-2 fraction possibly, on polluted sediments. Standard procedure is to use split bottom barges to portion out the sand. Depths for sand to sink to the seabed may be 20-30 m at most. I fear considerable losses of the smallest sized sand grains and drifting of be weak currents.

    How precisely can the SPI measure the sand grain sizes in the capping layer?

    We aim at a 0.5 m final sand layer before larger gravel to stone fractions are put on top to prevent erosion. The sand will be distributed in two rounds each at ca 25 cm.

    Is the SPI only able to record the upper ca. 25 cm?

    With the best wishes
    Dr. Arnfinn Skadsheim

    • December 14, 2016

      Steven Sabo

      Hello Dr. Skadsheim,

      Thank you very much for your comment.

      Your project seems like something that INSPIRE would be interested in learning more about. One of our scientists will be in touch via email shortly.

      – INSPIRE Environmental


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