Assemblages of dinoflagellate resistance cysts and copepod eggs in superficial sediments at the upper Gulf of California

Abstract

The diversity, abundance, and geographic distribution of dinoflagellate cysts in recent sediments serve as bioindicators to specific regions' environmental conditions and productivity. We present dinoflagellate cysts assemblages from 53 superficial sediment samples from the upper Gulf of California (uGC) obtained in July 2016 and February 2017. Forty-seven species were identified, of which twenty-seven are considered heterotrophic (Het) and twenty autotrophic (Aut). Ten species of this last group are potentially toxin producers (PTxS). The total concentration (Tot) of cysts in all the samples was 3481 cysts/g in 2016 and 4223 cysts/g in 2017. Aut represented 59%, Het 41%, while the PTxS represented ∼36.5% of the Tot cysts. The higher abundance of the Aut is likely to manifest the local high sea surface temperature and salinity. The increase in the Tot of cysts in the 2017 set was related to a Gymnodinium catenatum harmful algal bloom. Copepod eggs abundance was 7137 eggs/g in 2016 and 6555 eggs/g in 2017. The Aut Gymnodinium spp., Spiniferites spp., Operculodinium spp, and the Het Protoperidinium americanum, Quinquecuspis concreta, Selenopemphix nephroides, Brigantedinium spp., and Echinidinium spp., were typical in both seasons but differed on their concentrations between each season. The cysts distribution between both sampling periods reflects local currents and the sediment dynamics of the uGC, and the high species diversity in this area reflects the elevated primary productivity in this area.