Infection dynamics of Amoebophryidae parasitoids on harmful dinoflagellates in a southern Chilean fjord dominated by diatoms

Abstract

Parasitoids belonging to Amoebophryidae (Marine ALVeolate Group II or MALV II) infecting dinoflagellates were investigated in Reloncaví Fjord (southern Chile) in the austral summer 2009. Of the 12 dinoflagellate species recorded during monthly sampling, Prorocentrum micans, Dinophysis acuminata, and Phalacroma rotundata were infected by Amoebophrya spp. To assess parasitoid control of host populations, the short-term dynamics of Amoebophrya spp. were followed for 21 d during a bloom of P. micans. Host mortality induced by Amoebophrya spp. (% hosts killed per day) was estimated by dividing prevalence by the generation time of these parasitoids. Parasitism by Amoebophrya spp. was responsible for ~10% of P. micans mortality between 8 and 17 March. The small subunit rDNA genes of individual parasitoids infecting different host cells were sequenced, and like most environmental sequences retrieved from this ecosystem in January and February, all belonged to the MALV II Clade 4. However, as soon as the P. micans bloom was detected, the MALV II genetic composition changed drastically, with the detection of Clades 1, 4 (a different sub-cluster than before), 5, 6, and 12. Our results suggest that different types of parasitoids belonging to Amoebophryidae likely infect dinoflagellates in Reloncaví Fjord, offering the first demonstration of the presence of important genetic diversity in MALV II inhabiting an ecosystem where dinoflagellate hosts are not the usual dominant phytoplanktonic organisms.

A Quantitative Assessment of the Role of the Parasite Amoebophrya in the Termination of Alexandrium fundyense Blooms within a Small Coastal Embayment

“…in other systems [11], [26], [32]. Peaks in A. fundyense cell concentrations were followed by increased infection levels and subsequently, by release of dinospores 4–5 days later.…”

Characterization of Dinophysis spp. (Dinophyceae, Dinophysiales) from the mid‐Atlantic region of the United States1

“…, Alves‐de‐Souza et al. ). The relationship between the mid‐Atlantic Dinophysis population and nutrients, prey, and species‐specificity between host and parasite will be the focus of future studies.…”

Characterization of the Parasitic Dinoflagellate Amoebophrya sp. Infecting Akashiwo sanguinea in Coastal Waters of China

“…Amoebophrya infection is a widespread interspecific interaction among planktonic dinoflagellates in coastal and oceanic ecosystems around the world (Alves‐de‐Souza et al. ; Elbrächter and Schnepf ; Erard‐Le Denn et al. ; Siano et al.…”

“…The estimated maximum level of infection (I max ) was 92.22 AE 5.43%, and the initial slope of the fitted curve (a) was 21.21 AE 1.24 (r 2 = 0.9518; P < 0.0001). oceanic ecosystems around the world (Alves- de-Souza et al 2012;Elbr€ achter and Schnepf 1998;Erard-Le Denn et al 2000;Siano et al 2011). Recent studies have revealed its enormous diversity Guillou et al 2008;Li et al 2014;Lima-Mendez et al 2015) and resulted in further investigation of its ecological role in marine ecosystems.…”