Ephemeral parasitism on blooming diatoms in a temperate estuary

GUINDER, VALERIA A.; CARCEDO, M. CECILIA; BUZZI, NATALIA; MOLINERO, JUAN CARLOS; ABBATE, CELESTE LÓPEZ; MELISA, FERNÁNDEZ SEVERINI; FLORENCIA, BIANCALANA; KÜHN, STEFANIE

MARINE AND FRESHWATER RESEARCH

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2017 vol. 69

1323-1650

Parasites of phytoplankton influence phytoplankton bloom dynamics and may severely affect the type of foodavailable for higher trophic levels. The incidence of parasitic infections generally is expected to increase acrossecosystems worldwide under the scenario of global change. Herein we report on a massive parasite infection on twodominant diatoms of the austral winter bloom, namely Thalassiosira pacifica and Chaetoceros diadema, recorded duringan extreme precipitation period in the Bahı´a Blanca Estuary, Argentina. The parasite infection was concomitant with amarked drop in water salinity and affected more than 40% of host cells. Although the parasite on C. diadema was notidentified, the parasite on T. pacifica was most likely Pirsonia sp., a nanoflagellate with high host specificity. After theintense rainy period and the parasitic infection, the phytoplankton biomass dropped (by more than 80%) and thecommunity structure shifted to one with smaller species (i.e. Thalassiosira curviseriata, T. hibernalis and T. minima).We discuss the implications that these modifications may have on the food web dynamics and the potential relationshipbetween precipitation-driven modifications in water properties and the emergence of parasitism in coastal eutrophicenvironments.