Seabed habitat mapping techniques: an overview of the performance of various systems

Seabed mapping has become vital for effective management of marine resources. An important role in moving towards ecosystem based management is played by the defining and understanding of the relationships among marine habitat characteristics, species distribution and human activities. Mapping seabed characteristics by means of remote acoustic sensing, using seabed seismic profiling, sidescan sonar, or echo-sounder based classification systems, is becoming of increasing importance. This paper gives a brief overview, of existing marine habitat mapping technologies and their recent developments. In single-beam echo-sounders, using multiple frequencies will be useful in classifying the seabed. It must be observed that the resolution of a sidescan sonar with narrower along-track beam width and higher range sampling rates will be better than a multi-beam echo-sounder, although the specifications of the newer systems are much improved. Airborne LIDAR bathymetry is very useful for shallow water seabed mapping, particularly in challenging rocky areas vulnerable for ship-based mapping operations. Seabed maps are essential in any case for siting of bottom mounted energy devices. The utmost care should be taken at all stages of the classification process, such as input data, control of interfering factors, seabed acoustic attributes, classification methods and ground-truth observations. The results of seabed mapping depend mostly on instrument stability, settings, algorithms adopted, environmental factors and survey methods. It is essential that seabed maps undergo frequent updation and improvement over time due to technological advances.