Acoustic classification of seabed habitats using the QTC VIEW™ system

Abstract

Ellingsen, K. E., Gray, J. S., and Bjornbom, E. 2002. Acoustic classification of seabedhabitats using the QTC VIEW system. – ICES Journal of Marine Science, 59:825–835.The QTC VIEW acoustic seabed classification system was used in Fraenfjorden,western Norway (62 N, 7 E), to map the spatial scales and variability of benthichabitats, and to evaluate its performance. Position and water depth were loggedcontinuously along with the acoustic data. Water depth in the survey area ranged from5 to 72 m over a spatial scale of ca. 1.5 8 km and there was considerable variation insediment characteristics at 20 ground-truth sites. Six acoustically-distinct seabed typeswere identified and the QTC system defined their spatial scales and variability.Generally, the acoustic classifications were consistent at track crossings. The classifi-cation was generally in accordance with the sediment grain size and was most likelyinfluenced by the softness of the substrate. However, these sediment characteristicscould not alone explain the diversity of acoustic classes and the classes were probablyalso related to other physical or biotic seabed characteristics. The QTC systemprovides new insights but the usefulness of the acoustic classification depends upon theamount and quality of ground-truth data, which is the key aspect when relatingacoustic class to seabed type. The acoustic system collects continuous data from largeareas relatively quickly, and defines seabeds that would be missed by traditional coreor grab point samples and will therefore be highly relevant to both geological- andbenthic-diversity studies.