Seasonal and annual variability in particle fluxes in the Gulf of California: A response to climate forcing

A six-year time series of sediment trap samples is used to document seasona l and interannual changes in particle fluxes in Guaymas Basin, Gulf of Cali fornia. Sedimentation in this region of the Gulf of California is dominated by two seasonally varying components: biogenic silica during the late fall -spring and lithogenic material during the summer. This variability in sedi ment fluxes is a direct response to the seasonally reversing monsoon climat e in this region. In addition, this seasonal variability in particle flux t o the seafloor combined with the lack of bioturbation results in the format ion of sediment laminae or varves in Guaymas Basin. Observed interannual di fferences in the magnitude of sediment fluxes appear to be related to ENSO. These findings indicate that biogenic sediment fluxes, and hence primary p roductivity, are higher during non-ENSO years in the central Gulf of Califo rnia. A decrease in the carbonate: opal flux ratio from 1991 to 1996 indica tes that diatoms became an increasingly important component of the plankton during this period and further supports our findings that productivity in Guaymas Basin is higher during non-ENSO years. (C) 1998 Elsevier Science Lt d. All rights reserved.