Parasitism as a biological control agent of dinoflagellate blooms in the California Current System

• Published in: Harmful algae 2011-09, Vol.10 (6), p.763-773
• Main Authors: Mazzillo, Fernanda F.M., Ryan, John P., Silver, Mary W.
• Format: Article
• Language: English
• Subjects: Akashiwo sanguinea; Algae; algal blooms; Amoebophrya; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; biological control agents; community structure; Dinophyceae; Fundamental and applied biological sciences. Psychology; Monterey Bay; parasites; Parasitism; physicochemical properties; phytoplankton; Plant cytology, morphology, systematics, chorology and evolution; Plants and fungi; Red tides; species diversity; surface temperature; surface water; Thallophyta; Upwelling; wind
• ISSN: 1568-9883; 1878-1470
• DOI: 10.1016/j.hal.2011.06.009

► Epidemic infection outbreaks contributed to the end and prevention of the occurrence of red tides. ► Absence of parasitism was associated with an extreme A. sanguinea red tide. ► Parasitism mat strongly influence red tide dynamics in upwelling systems. ► Parasitism may indirectly influence net phytoplankton species composition. Amoebophrya is a marine parasite recently found to infect and kill bloom-forming dinoflagellates in the California Current System (CCS). However, it is unknown whether parasitism by Amoebophrya can control dinoflagellate blooms in major eastern boundary upwelling systems, such as the CCS. We quantified the abundance of a common bloom-forming species Akashiwo sanguinea and prevalence of its parasite (i.e., % infected cells) in surface water samples collected weekly from August 2005 to December 2008 at the Santa Cruz Wharf (SCW), Monterey Bay, CA. Additionally, we measured physical and chemical properties at the SCW and examined regional patterns of wind forcing and sea surface temperature. Relative abundance of the net phytoplankton species was also analyzed to discern whether or not parasitism influences net phytoplankton community composition. Epidemic infection outbreaks (>20% parasite prevalence in the host species) may have contributed to the end or prevented the occurrence of A. sanguinea blooms, whereas low parasite prevalence was associated with short-term (≤2 weeks) A. sanguinea blooms. The complete absence of parasitism in 2007 was associated with an extreme A. sanguinea bloom. Anomalously strong upwelling conditions were detected in 2007, suggesting that A. sanguinea was able to outgrow Amoebophrya and ‘escape’ parasitism. We conclude that parasitism can strongly influence dinoflagellate bloom dynamics in upwelling systems. Moreover, Amoebophrya may indirectly influence net phytoplankton species composition, as species that dominated the net phytoplankton and developed algal blooms never appeared to be infected.