Validation of soft bottom benthic habitats identified by single-beam acoustics

Abstract

Acoustic diversity charts were produced for a Portuguese soft bottom mid-shelf area, depth from 30 to 90 m, using a single-beam echo sounder coupled to the acoustic systems QTC VIEW™ Series IV and V. A similar acoustic pattern was identified by both systems, which, after ground-truth interpretation based in available sediment and biological data, established a preliminary spatial distribution model of the benthic habitats in this coastal area. However, some of the acoustic areas were interpreted using one or very few sediment and benthic samples. A specific validation survey was conducted a posteriori, in which the positioning of the sediment and benthic community sampling sites was based on the acoustic diversity previously identified. The results clearly confirm the benthic habitats distribution model suggested by the acoustic method, indicating a high potential for the use of such approach in the identification and mapping of large-scale soft bottom coastal shelf habitat diversity.