Resumo

LOPEZ-CORTES, David Javier et al. Co-ocurrence of Chattonella marina and Gymnodinium catenatum in Bahía de La Paz, Gulf of California (Spring 2009). Hidrobiológica [online]. 2011, vol.21, n.2, pp.185-196. ISSN 0188-8897.

During the period of 24 March to 14 May 2009, water and net samples were obtained for phytoplankton analyses; one aliquot was fixed in Lugol's solution for species quantification and identification. Net samples were used for the identification of live phytoplankton species. Additionally, temperature in situ, chlorophyll a and inorganic nutrients were measured weekly in three stations. Two species were identified: Chattonella marina (Subrahmanyan) Y. Hara et Chihara and Gymnodinium catenatum Graham. Chattonella marina was the most abundant species with a density at subsurface level of 14 × 10³ to 36 × 10³ cell L^-1. Gymnodinium catenatum had densities were of 1 × 10³ to 19 × 10³ cell L^-1. Water column temperature was quasi homogeneous from surface to 20 m in depth, with an interval of 19.5 to 22.0 °C and 20.0 to 21.5 °C from March to April respectively. In the middle of May stratification of the water column initiated with a slight temperature difference of 5.0 °C recorded from surface to 20 m in depth. Nitrates varied from 0.5 to 11.0 μM and orthophosphates from 0.4 to 2.6 μM. Chlorophyll a showed a value at surface level of 7.5 mg m^-3 and 3.5 mg m^-3 at 20 m in March; in May chlorophyll a values ranged between 2.0 to 7.0 mg m^-3. We conclude that the presence of these two species during this study period was associated to the relaxation of the mixing processes in the zone.

Palavras-chave : Chatonella marina; Gymnodinium catenatum; Bahía of La Paz; Gulf of California; marine phytoplankton.