Decision tree references

There are many survey techniques available and comprehensive decision trees for the many mapping techniques are available for the survey systems described in the technical section. The range and resolution of the acoustic systems used are dependant on frequency, so there is always a trade off between the two. The success in using satellite imagery, aerial photography or Lasers (LIDAR) is dependant on water clarity as this effects the ability to use light instead of sound. The decision trees available range from basic to the being extremely complex. Due to the complexity of the habitat mapping process decision trees are useful as a guide but the final conclusions are needed to be made based on the trade off in the availability of survey funds, site locality, weather conditions and what survey resources are at hand. The experience of the consulting professionals with their specialist local knowledge often dictate what can and what cannot reasonably be done.

The benthic habitat mapping flowchart below illustrates the main stages and considerations taken in to account in the work done by the University of Western Australia in their Marine Parks Mapping projects. (Courtesy: Karen W Holmes, School of Plant Biology, University of Western Australia.)

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The main steps to Habitat Mapping are summarised as follows:

The experiences gained by the Coastal CRC and its Partners has allowed for the identification of several clear and distinct steps to be undertaken for the assessment of shallow marine systems.

  1. Decide Where to Survey
    Although this sounds like a simple issue, the Australian coastline is very large, multiple stakeholders desire different areas to be mapped for equally valid reasons, but budgets are always limited.
  2. Design the Survey
    Conducting the survey within budgetary constraints is always a priority. The use of robust survey estimation software permits the fine tuning of the survey plan, resulting in an accepted survey area, which can be surveyed within financial constraints.
  3. Carry out the Hydro Acoustic Survey (field work)
    Using multibeam systems, together with state-of-the-art inertial motion and navigation system, conduct a full cover survey in a rapid, 24 hours/day operation. Rapid data processing offshore ensures data is gathered to the required standards, and no data holidays are apparent. Derivatives from the seafloor such as slope, aspect, rugosity are generated, and presented as GIS layers for fast analysis of potential habitats. Backscatter processing of the Multibeam data generates a raster file of seafloor texture, which can be used to identify variations in seafloor bottom types.
  4. Carry out the Ground-truthing Survey (field work)
    Using results from the hydro acoustic survey, design and conduct a ground-truthing video sampling plan. This usually implies a smaller vessel, daylight operations, and a maximum survey speed of 1 knot.
  5. Carry out Biodiversity Survey (field work)
  6. Create the Habitat Maps in a GIS
  7. Report on the Resource and its Condition
  8. Establish Targets for the Resource
  9. Establish monitoring frameworks

There are also a number of excellent examples of Benthic Habitat Mapping Flow Charts in the Case Study section of this website as well as in international publications which are available and published on the internet.

Designs (258 KB PDF) for marine remote sampling: a review and discussion of sampling methods, layout, and scaling issues. For a review and discussion on the various different approaches to designing and undertaking benthic habitat mapping see Task 2.1 Milestone Report, May 2004. Researchers: Karen W. Holmes1,2, Kimberly Van Niel2, and Katrina Baxter1,2 Sub-project Leader: Gary Kendrick1.1School of Plant Biology.2School of Earth and Geographical Sciences. University of Western Australia.

"Practical guide to acoustic techniques for benthic habitat classification"
COASTAL ZONE CRC – COASTAL WATER HABITAT MAPPING – SHALLOW WATER ASSESSMENT TECHNOLOGIES. MILESTONES CA: 5.02 (5 MB PDF) Robert D. McCauley, Justy Paulus Siwabessey. Centre for Marine Science and Technology (CMST), Curtin University of Technology. November 2005.

BROAD SCALE REMOTE SURVEY AND MAPPING OF SUBLITTORAL HABITATS AND BIOTA (11 MB PDF) 1999, RL Foster-Smith, J Davies & I Sotheran, SeaMap Research Group, Department of Marine Sciences and Coastal Management, University of Newcastle-upon-Tyne, UK NE1 7RU, that discuss and report in detail the various traditional approaches to undertaking broad scale mapping of sublittoral habitats and biota (biotopes) based on acoustic remote sensing mapping methodology known as the BMAP project, a project supported by the European Commission under the Life programme. The Part 2 of this publication, " Planning a broad scale survey and analysis of results" , gives useful and comprehensive technical guidance to surveyors wanting to make use of the many traditional acoustic survey systems available, such as single beam echosounders and side scan sonar.

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