Small-scale turbulence can reduce parasite infectivity to dinoflagellates

• Published in: Marine ecology. Progress series (Halstenbek) 2010-08, Vol.412, p.45-56
• Main Authors: Llaveria, Gisela, Garcés, Esther, Ross, Oliver N., Figueroa, Rosa Isabel, Sampedro, Nagore, Berdalet, Elisa
• Format: Article
• Language: English
• Subjects: Alexandrium minutum; Flasks; Infections; Marine; Modeling; Parasite hosts; Parasites; Phytoplankton; Plankton; Prorocentrum micans; Scrippsiella trochoidea; Sporangia; Turbulence; Turbulence models
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps08663

Small-scale turbulence and parasite infection are 2 important factors that govern the dynamics and fate of phytoplankton populations. We experimentally investigated the influence of turbulent mixing on the infectivity of the parasiteParvilucifera sineraeto dinoflagellates. Natural phytoplankton communities were collected during 3 stages of a bloom event in Arenys de Mar Harbour (NW Mediterranean). The 15 to 60 μm size fraction was used as the inoculum and distributed into spherical flasks. Half of the recipients were exposed to turbulence while the rest were kept still. In the experiments, the dinoflagellate assemblage was mainly composed ofProrocentrum micans,Scrippsiella trochoideaandAlexandrium minutum. We observed a collapse ofA. minutumandS. trochoideapopulations in the unshaken flasks, which coincided with an increase in parasite infectivity. After a short exposure to turbulence, the development of the dinoflagellate populations slowed down and stabilised as expected. In the shaken treatments, the infectivity was lower and the decay in the host cells numbers was delayed compared to the still treatments. The degree of interference of the turbulence with infectivity varied among the experiments, due to differences in cell abundances and possibly their physiological state. Results from a numerical model suggest that turbulence could lead to a 25 to 30% decrease in the maximum infection rate, which could be due to host population dispersion and/or reduced host–parasite contact times. Turbulence may thus be effective in delaying the initial infection, but not in preventing it.