. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Density (# ha ') • 0-10 11-20 21-30 31 + 25 50 75 100 Km o O o o O O Figure 1. Balhymetric map of the Mendocino Ridge and Gorda Escarpment, showing all dive sites. Depths are in meters. One hundred and fourteen hours of video from ROV bottom time was recorded, annotated, and analyzed. Annotations of all occurrences of discernible animals and geologic features were stored in a searchable database with corresponding environmental (CTDO), observational (time, position), and system (camera zoom) data. Bathymetry is derived from
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Density (# ha ') • 0-10 11-20 21-30 31 + 25 50 75 100 Km o O o o O O Figure 1. Balhymetric map of the Mendocino Ridge and Gorda Escarpment, showing all dive sites. Depths are in meters. One hundred and fourteen hours of video from ROV bottom time was recorded, annotated, and analyzed. Annotations of all occurrences of discernible animals and geologic features were stored in a searchable database with corresponding environmental (CTDO), observational (time, position), and system (camera zoom) data. Bathymetry is derived from a hull-mounted EM300 sonar system with 20-m pixel resolution. Ultrashort baseline Transponders (Sonardyne. Houston. TX) mounted on the ROV and the ship determine position. Tracklines are derived in a real-time ArcView-based (Environmental Systems Research Institute) navigation system. Closed circles, open circles, and hatched circles are densities (# ha~'l of blob sculpin (yellow) and octopus (red) from dives in 2000, 2001. and 2002 respectively. For each dive the densities reflect the number of animals observed over the surveyed area of seafloor. Areas for density estimates were calculated using the navigation to determine track length and assuming an average observational width of 4 m. Overlap of the dive track was accounted for in the calculations. characterized by small rocky cliffs and bouldered slopes that shoaled to a sloping talus field in which the gravel and boulders were interspersed with sediment. Site 2 (depth 1534-1583 m; dive T351; Fig. 1) was on a shallowly sloping mud and sand bottom interspersed by boulders, talus, and small rock outcrops. Diffuse cold seeps at the base of several bouldered slopes at both sites were evident by the presence of small patches of vestimentiferan tube worms and vesicomyid clams (10). Sites 1 and 2 were characterized by an average bottom water temperature of °C (range = - °C) and very low oxygen con- centration (mean
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
