Dinoflagellate cysts and ENSO-PDO climate forcing in the southern Gulf of California

Abstract

This paper presents a high-resolution analysis of dinoflagellate cyst groups (1959 to 2009), in the southern Gulf of California (GoC). We analyzed 100 samples of laminated sediments with an effective sampling resolution of ~7 months. Our primary goal is to clarify the relation between changes in these groups and the climate forcing defined by the El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) indices. Principal component analysis indicates three groups (A1, A2, and A3). A1 and A3 are mostly constituted by dinoflagellate cysts of heterotrophic taxa, while A2 is composed mainly of autotrophic taxa. Strong El Niño events decrease the contribution of all dinoflagellate cyst groups, while extreme La Niña events increase the contribution of the A2 and A3 groups. Also, the PDO modulates the marine productivity in the southern GoC, with cold phases increasing productivity, while the warm stages decrease productivity. As with climatic events in the southern GoC, autotrophic and heterotrophic taxa of dinoflagellate cysts respond clearly, when PDO and ENSO are in phase. Finally, dinoflagellate cyst concentrations in laminated sediments can be used regionally, as a chronostratigraphic tool in the last 50 years.