Cysts of potentially harmful dinoflagellates, with emphasis on the genus Alexandrium, in Sepetiba Bay (Brazil) during a port survey of GloBallast

Abstract

Sepetiba Bay in south-eastern Brazil has been selected as a pilot demonstration site within the Global Ballast Water Management Programme (GloBallast; IMO/PNUD/GEF). As part of the port baseline survey, a series of 43 sediment cores was taken in triplicate in the bay in November 2001, by SCUBA divers, using PVC tubes. The top 60mm of each core was processed for dinoflagellate cyst analysis. Cysts of the potentially toxic Alexandrium cf. minutum were identified in 41% of the samples, but the highest density (22 cysts cm⁻³) was found in the port area, at the Iron Ore Terminal. Other Alexandrium-type cysts were observed in 37% of the samples and their highest density (26 cysts cm⁻³) was also associated with the port area. These results indicate that the northern area of the bay is unsuitable for the intake by ships of ballast water. This investigation highlights the importance of cyst surveys to the management of ballasting and deballasting in port areas.