Dataset: Substrate Coverage

The Kelp Forest Monitoring data record span surveys across 28 years from 1971 through 2023 at 20 locations on the Sonoma-Mendocino Coast, Northern California, and span the major marine heatwave of 2014-2016. Years without data, inclusive: 1972-1985, 1987, 1988, 1993-1998, 2002, 2020, 2021. These surveys are ongoing and are conducted by the California Department of Fish and Wildlife dive team with participation from dive program partners at UC Davis, UC Santa Cruz, Cal Poly Humboldt, Sonoma State and other dive programs and volunteers. Not all sites were surveyed in all years. Surveys prior to 2003 were not conducted by the same teams or with the same methods except that all surveys were done using Scuba along 30 x 2m transects randomly placed in the subtidal zone in rocky habitats dominated by bull kelp, Nereocystis luetkeana, forests. These randomly placed band transects surveys were stratified by depth (A=0-15, B=16-30, C=31-45, D=46-60 ft) as we know sea urchin and abalone populations differ by depth. Data collected include the number of live, dying (in some years during the mass mortality events), and sea urchins (red-Mesocentrotus franciscanus and purple-Strongylocentrotus purpuratus), red abalone (Haliotis rufescens), pinto abalone (H. kamtschatkana), flat abalone (H. walallensis), as well as empty abalone shells (again in some years). Additional data collected (if scuba bottom time and/or air allowed): red abalone size, numbers or presence of associated species such as sea stars and predators, algal group quantification, and presence of bull kelp, substrate type. Data on algae and associated species differed depending on the year and the focus of the studies in response to ecosystem conditions but all years quantified sea urchins and abalones. This dataset provides in situ estimates of the coverage of the substrate along each survey transect as a percentage of four substrate types: reef, boulder, cobble, and sand.