Silicoflagellate Fluxes in Cuenca Alfonso, Mexico During the 2002-2003 El Niño Event
Abstract
Changes in the circulation and water mass patterns in the Gulf of California are closely associated with changes in atmospheric circulation. At the interannual scale, such changes are associated with events like El Niño, which in the Gulf are characterized by greater penetration of tropical-equatorial water. Subsamples of sediment trap material, collected between January 2002 and February 2004 were examined with the aim of inferring average oceanographic conditions in Cuenca Alfonso, Bahia de La Paz and those during the relatively mild 2002- 03 El Niño. Analysis of the silicoflagellate data series reveals seasonal and interannual relationships between the silicoflagellate fluxes and the dynamics of the water column. Comparison of silicoflagellate fluxes with those of the diatom group indicate that the former represent 0-52% of their combined flux. Both silicate groups generally co-vary but show differences in intensity. Thirteen taxa made up the silicoflagellate species composition. The simultaneous occurrence of Dictyocha epiodon and Distephanus speculum with Dictyocha calida and Dictyocha californica during August 2002 to May 2003, indicated the presence of both California Current Water and Equatorial Surface Water in the area close to Cuenca Alfonso. This favored the increase, mainly in November-December, in the flux of the dominant species, Octactis pulchra (as high as 7 x 106 skeletons m-2 day-1). Spring, on the other hand, was notable for a drop in the total silicoflagellate flux, probably due to the influence of the El Niño event. The subsequent increase in species typical of warm water and the replacement of the dominant species (O. pulchra) by Dictyocha messanensis var messanensis, suggest that the effects of El Niño extended to the fall of 2003.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2007
- Bibcode:
- 2007AGUSMOS32A..04A
- Keywords:
-
- 4200 OCEANOGRAPHY: GENERAL;
- 4227 Diurnal;
- seasonal;
- and annual cycles (0438);
- 4262 Ocean observing systems;
- 4800 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL (0460);
- 4806 Carbon cycling (0428)