Use of a Remote Operated Vehicle and Sonar to Characterize and Estimate the Distribution of Benthic Vegetation in Waldo Lake, Oregon

Abstract

ABSTRACT Bryophytes that occur in Waldo Lake, Oregon were video-documented and their distribution estimated with sonar. In August 1990, the in situ growth form of the plants was directly observed for the first time using a remote operated vehicle (ROV). Specific growth form of the plants ranged from relatively uniform stand heights (0.25 to 1.0 m) within patches to moderately isolated forms best described as twisted “windrows” or “whorls.” The diameter of the whorls ranged from approximately 0.25 to 0.75 m in diameter and from 5 to 15 m in length. The whorl form was typically in association with patch edges. Plants were found at depths of 128 m (the maximum depth of the lake) and to an upper depth limit of approximately 40 m. The maximum distribution of plants was estimated at 48.9% of the lake area. The use of direct ROV video observation, combined with the sonar, proved to be an acceptable first step in qualitatively describing plant growth and estimating benthic vegetation distribution within the lake.