Bight 08 Benthic Infauna Abundance Harmonized

This report describes the benthic macrofaunal studies of the Southern California Bight (SCB) Regional Marine Monitoring Program (Bight'08), the fourth SCB regional survey conducted in 2008. The Southern California Bight is a 100,000-square-mile body of water and submerged continental shelf extending from Point Conception, California in the north to Cabo Colnett, Baja California, Mexico in the south. Benthic macrofauna were successfully collected and processed from 382 sites between Point Conception and the United States-Mexican border using a random tessellation stratified (RTS) study design. Sites ranging in depth from 0.3 to 1,023 m were stratified into 10 habitats including inner, middle, and outer continental shelf; Channel Island continental shelf; upper continental slope; lower continental slope and basins; estuaries, ports, marinas, and other bays. Samples were collected with a 0.1-m2 Van Veen grab, sieved through a 1-mm mesh screen, and processed using standard laboratory methods. A total of 179,338 organisms from 1,734 taxa were identified and counted. Two assessment tools were applied: the Benthic Response Index (BRI) for mainland and island shelf habitats, and the Sediment Quality Objectives Benthic Line of Evidence (BLOE) for marine bays and estuaries. Overall, the SCB benthos were in good condition during 2008, with 99.7% of the SCB in reference condition or deviating only marginally from reference. No evidence of disturbance was found on the island shelf or the mainland shelf. Macrofaunal communities in embayments were more frequently disturbed, with slightly over 12% of embayment area containing clearly disturbed benthos. Benthic communities in poor condition occupied more than half the area (59.0%) of southern California estuaries and more than a third (37.4%) of marinas. Regional benthic community condition showed no dramatic change between 1994 and 2008, with disturbed benthic community remaining less than 4% of the SCB for the last 15 years. A special study on gear size effects found that none of the tested sample areas were clearly preferable to the existing standard 0.1 m2 method.