Ephemeral parasitism on blooming diatoms in a temperate estuary

GUINDER VALERIA ANA; CARCEDO MARIA CECILIA; BUZZI NATALIA SOL; MOLINERO JUAN CARLOS; LOPEZ ABBATE MARÍA CELESTE; FERNÁNDEZ SEVERINI MELISA DAIANA; BIANCALANA FLORENCIA; KÜHN STEFANIE

MARINE AND FRESHWATER RESEARCH

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2017 vol. 68 p. 128 - 133

1323-1650

Parasites of phytoplankton influence phytoplankton bloom dynamics and may severely affect the type of food available for higher trophic levels. The incidence of such infections is expected to increase across ecosystems worldwide under the scenario of global change. Herein we report on a massive parasite infection on two dominant diatoms of the austral winter bloom, namely Thalassiosira pacifica and Chaetoceros diadema, recorded during an extreme precipitation period in the Bahía Blanca Estuary, Argentina. The parasite infection was concomitant with a marked drop in water salinity and affected more than 40% of host cells. Although the parasite on C. diadema was not identified, the parasite on T. pacifica was most likely Pirsonia sp., a nanoflagellate with high host specificity. After the intense rainy period and the parasitic infection, the phytoplankton biomass dropped (by more than 80%) and the community structure shifted to a one with in which smaller species (i.e. Thalassiosira curviseriata, Thalassiosira hibernalis and Thalassiosira minima) were dominant. We discuss the implications that these modifications may have on the food web dynamics and the potential relationship between precipitation-driven modifications in water properties and the emergence of parasitism in coastal eutrophic environments.