BOMB-PRODUCED RADIOCARBON ACROSS THE SOUTH PACIFIC GYRE-A NEW RECORD FROM AMERICAN SAMOA WITH UTILITY FOR FISHERIES SCIENCE

Coral skeletal structures can provide a robust record of nuclear bomb produced C-14 with valuable insight into air-sea exchange processes and water movement with applications to fisheries science. To expand these records in the South Pacific, a coral core from Tutuila Island, American Samoa was dated with density band counting covering a 59-yr period (1953-2012). Seasonal signals in elemental ratios (Sr/Ca and Ba/Ca) and stable carbon (delta C-13) values across the coral core corroborated the well-defined annual band structure and highlighted an ocean climate shift from the 1997-1998 El Nino. The American Samoa coral C-14 measurements were consistent with other regional records but included some notable differences across the South Pacific Gyre (SPG) at Fiji, Rarotonga, and Easter Island that can be attributed to decadal ocean climate cycles, surface residence times and proximity to the South Equatorial Current. An analysis of the post-peak C-14 decline associated with each coral record indicated C-14 levels are beginning to merge for the SPG. This observation, coupled with otolith measurements from American Samoa, reinforces the perspective that bomb C-14 dating can be performed on fishes and other marine organisms of the region using the post-peak C-14 decline to properly inform fisheries management in the South Pacific.