Effect of nutrient concentration and salinity on diel vertical migration of Chattonella marina (Raphidophyceae)

Abstract

Vertical migration plays an important role in the development of Chattonella populations in the natural environment; however, this behaviour has remained largely undescribed. In the present study, the diel vertical migration of Chattonella marina in the Ariake Sea was examined along with nutrient concentrations and salinity at four sampling sites during the bloom in the summers of 2008, 2009 and 2010. Cells of Chattonella were abundant at the surface (0 m depth) in the daytime in most cases. However, when surface salinity was 9, which is the lower limit for growth, the population accumulated at a depth of 2 m, where salinity was 15, suggesting that Chattonella moves to avoid water with low salinity. Chattonella cells actively migrated, even under nutrient-replete conditions (mean DIN concentration, 12.73 µM). The present study demonstrates that Chattonella cell migration is independent of nutrient availability. In addition, Chattonella cells stop upward migration when the surface salinity is low (< 15). These insights are important for making predictions of Chattonella population dynamics after heavy rains.

Key words:

• Chattonella
• diel vertical migration
• harmful algal blooms

Acknowledgements

We are grateful to Dr Sakurada and Mr Shibahara for granting access to laboratory facilities during the sampling.

Funding

This study was supported by a Grant-in-Aid for Scientific Research (C) (20589002) from the Japan Society for the Promotion of Science.

Editorial responsibility: David Montagnes

Additional information

Funding

Funding: This study was supported by a Grant-in-Aid for Scientific Research (C) (20589002) from the Japan Society for the Promotion of Science.