Blooms of Pyrodinium bahamense var. compressum and rock oyster toxicity in Costa Chica, Guerrero, Mexico

Abstract

Blooms of Pyrodinium bahamense var. compressum were detected from July to December 2010 in Costa Chica, Guerrero. To estimate the cell abundance of this dinoflagellate, phytoplankton samples were collected from 7 July to 9 December 2010 at five sampling sites. Wild rock oysters and specimens from fishing cooperatives were only collected during November-December 2010. Abundance of P. bahamense var. compressum ranged from < 1000 to 194000 cells L–1 in the first three samplings performed in July. Low densities (< 9000 cells L–1) were observed at the end of November and December. Rock oyster toxicity from the fishing areas ranged from 46.24 to 788.85 μg STXeq 100 g–1. Rock oyster samples collected in the fishing cooperatives had toxicity from 52.2 to 440.88 μg STXeq 100 g–1. Although rock oysters were collected at the end of the blooms, their toxicity could be associated to this dinoflagellate both during this period and during previous blooms thatoccurred from on July-August in the study area.