Modern mangrove monitoring technique

Mangroves are one of the many ecosystems in Western Australia that strongly support a number of the Australian recreational lifestyles (e.g. sailing, mud-crabbing, fishing) and Australia’s biggest industry-Tourism.

Most mangrove habitats around the world have experienced significant adverse change in recent years due to human and natural environmental causes. In Australia though, vast mangrove areas are generally undisturbed and remain in pristine state.

To maintain the status of these mangrove areas requires monitoring. This can be an easy or difficult task. Large mangrove areas and widely dispersed mangroves require extensive amounts of time, money and energy to monitor them frequently.

A study on the mangroves of Barrow and Montebello Islands, Western Australia, showed that high resolution images (aerial photographs and Digital Multi-Spectral Video (DMSV)) in conjunction with the cooperation of the organizations and visitors to the area is the most cost-effective monitoring method. The high resolution images better the low resolution images (Landsat Thematic Mapper (Landsat TM)) in identifying most mangrove patches, small change, and discriminating different mangrove types (Figure 1). The size of the identified large mangrove areas though of the high and low resolution images was similar.

Since high resolution images are expensive, they are less frequently acquired compared to low resolution images (Table 1). Adequate monitoring though requires constant information. Therefore, to monitor the large mangroves areas in Australia would be most cost-effective through the use of Landsat TM. For the small mangrove areas that cannot be resolved by Landsat TM, visitors and organizations impacting/visiting these mangrove areas should report any observed adverse change to CALM and follow the regulations for the area. For the mangroves in the Montebello and Barrow Islands, for example, visitors to the area must follow and help meet the management objectives mentioned in the Proposed Montebello/Barrow Islands Marine Conservation Reserves 2004.

Image Type	Cost in Australian Dollars
DMSV (with a 0.64m2 resolution covering only the Montebello and Barrow Islands, Western Australia, 519 km2.	87,190
Landsat TM (625 m2 resolution, covering the Montebello, Barrow, Lowendal Islands and part of the Pilbarra region)	1,200

Table 1: A comparison of the cost for acquiring DMSV and Landsat TM images over the Montebello and Barrow Islands

Reference:

Tarin, J. (2005) A suggested cost-effective monitoring methodology for the mangroves at the proposed Montebello/ Barrow Islands Marine Conservation Resrves, Western Australia, Honours Dissertation, University of Notre Dame Australia.