Benthic Biological Interpretation for California Seafloor Mapping Program

Final Report State Coastal Conservancy Grant Agreement No. 11-002

Investigators: Mary Yoklavich and Lisa Krigsman, NOAA National Marine Fisheries Service, Southwest Fisheries Science Center

31 December 2012

Visual surveys of the seafloor have been conducted during 2007-2012 using a towed camera sled to groundtruth maps produced during the CA Seafloor Mapping Project. The camera sled (approximately 1 m x 1 m x 2 m in size) was equipped with an altimeter and a pair of scaling lasers set 15 cm apart. The sled had multiple digital video cameras and a digital still camera. The camera sled was towed above the seafloor at a speed of approximately one knot along transects roughly one nautical mile in length. A biologist (Lisa Krigsman) annotated video footage at sea from some (but not all) of these ocean cruises, assisting the staff from USGS to ground-truth seafloor maps along the California coast. Data acquisition in the field (Task 1) has been completed for this project.

Video analysis and data development in the laboratory (Task 2) were underway until funding was exhausted for this project (December 2012). During the last quarter of this project (October to December 2012), Lisa Krigsman reviewed video footage from the August 2012 cruise (C01202SC). Observations were made during 10-second intervals at the top of every minute. The 2012 cruise covered an area offshore from Ano Nuevo to Point Conception. During the video review process, benthic macro-organisms were identified to the lowest possible taxa. Components of benthic habitats, including primary (>50% coverage within the viewed area during the 10-second sample) and secondary (>20% coverage) substratum types (e.g., rock, sand, etc., based on Tissot et al. 2006), biotic coverage, and biotic-complexity (organisms with complex structure, height greater than a meter, or in high numbers), also were evaluated and recorded in each 10-second interval. Data acquired directly from the cruises were used to populate the fields for abiotic complexity based on small-scale variations in height of the seafloor surface and abiotic slope (measured as low, medium, or high degree of complexity). Still photographs taken along each camera sled line also were used to help identify the benthic macro-organisms.

Observations were recorded into a spreadsheet using the video program MediaMapper (Red Hen Systems, Inc.), and held in digital data files. During the October-December quarter, observations from 1,308 10-second samples were recorded from part of the 166 camera lines associated with the 2012 cruise (see accompanying comma delimited text file). Data were recorded on cruise name, time, latitude, longitude, and camera-line number, in addition to the variables mentioned above (i.e., primary and secondary habitat, abiotic slope, abiotic complexity, biotic coverage, biotic complexity, and associated benthic macro-organisms).

The project data set now includes a total of 6,677 records related to benthic organisms and associated components of habitat off California (see accompanying comma delimited text file). Video footage from 253 survey lines remains to be reviewed, including lines from the 2011 survey (Santa Monica Bay to U.S.-Mexico border) and the 2012 survey (Monterey Bay to Piedras Blancas, and Point Conception). We estimate that an additional 650 hours will be required to complete Task 2 (video analysis and data development) for these remaining survey lines.