Application of side-scan sonar in marine biology

Side-scan sonar provides an acoustic picture of the sea floor which can be viewed as if it were an unrectified, aerial photograph. Resolution is such that both sediment and faunal facies boundaries can be mapped on the basis of their varying acoustical response. Tracks left by commercial fishery dredges are often clearly visible on the bottom because of the contrast in bottom roughness between the dredged path and the surrounding, undisturbed sediment. The boards of otter trawls leave true furrows in the bottom, which can frequently be followed on side-scan imagery. Terraces built of dead roots of Posidonia oceanica L. plus entrapped sediment could be delineated over a large area of the North Adriatic Sea. Reefs and areas of secondary hard bottom — of interest to biologists and geologists alike — have been effectively mapped using side-scan sonar.