Investigation of phagotrophy in natural assemblages of the benthic dinoflagellates Ostreopsis, Prorocentrum and Coolia

Abstract

Almada et al.: Phagotrophy assessment in benthic dinoflagellates 392 Investigation of phagotrophy in natural assemblages of the benthic dinoflagellates Ostreopsis, Prorocentrum and CooliaMixotrophy has been shown to be a common trait among dinoflagellates and its importance in the nutritional ecology of harmful algae has been hypothesized. Benthic harmful species have not been extensively investigated as their planktonic counterparts and there are major gaps in the knowledge of their nutritional strategies. In this study the occurrence of phagotrophy was investigated in natural assemblages of benthic dinoflagellates using epi-fluorescence microscopy with DAPI and LysoSensor staining. The study was conducted at five sites along the coast of Rio de Janeiro that were visited in January, August and December 2010. In total, 1659 dinoflagellate cells were observed. From these, only 0.4% of 1195 Ostreopsis cf. ovata and 2.2% of 134 Coolia spp. cells presented evidence of phagotrophy with vacuoles stained by LysoSensor or a DAPI (4',6-diamidino-2-phenylindole) stained inclusion. Stained vacuoles were not registered in the 330 Prorocentrum spp. cells observed. Few O. cf. ovata cells contained round red inclusions ("red spots") that were not stained either by DAPI or LysoSensor, suggesting that these structures are not ingested prey. The results showed that phagotrophy was not a frequent nutritional strategy in benthic dinoflagellates during the study period. AbstrAct Descriptors:Dinoflagellates, LysoSensor, Mixotrophy, Phagotrophy.A mixotrofia tem se mostrado uma característica comum entre dinoflagelados e a sua importância na ecologia nutricional de algas nocivas vem sendo investigada. Espé-cies bentônicas nocivas não foram tão estudadas quanto as planctônicas, e existem grandes lacunas no conhecimento de suas estratégias nutricionais. A ocorrência de fagotrofia em comunidades naturais de dinoflagelados bentônicos foi investigada usando microscopia de epi--fluorescência e marcação por DAPI e LysoSensor. O estudo foi realizado em cinco locais ao longo da costa do Rio de Janeiro nos meses de janeiro, agosto e dezembro de 2010. No total, foram observadas 1659 cé-lulas de dinoflagelados. Destas, apenas 0,4% das 1195 células de Ostreopsis cf. ovata e 2,2% das 134 células de Coolia spp. observadas apresentaram evidências de fagotrofia com vacúolos marcados por LysoSensor ou inclusão celular marcada por DAPI (4', 6-diamidino-2--phenylindole). Não foram observados vacúolos marcados nas 330 células de Prorocentrum spp. observadas. Células de O. cf. ovata apresentaram inclusões esféricas avermelhadas ("red spots") que não foram coradas por DAPI e LysoSensor, sugerindo que estas estruturas não correspondem a presas ou a vacúolos digestivos. Os resultados mostraram que a fagotrofia não foi uma estraté-gia nutricional frequente nas espécies de dinoflagelados bentônicos observadas durante o período de estudo. resumoDescritores: Dinoflagelados, LysoSensor, Mixotrofia, Fagotrofia.

Abiotic Changes Driving Microphytoplankton Functional Diversity in Admiralty Bay, King George Island (Antarctica)

“…When compared to heterotrophic competitors, mixotrophy confers the ability to compete and overcome both strictly autotrophic and heterotrophic organisms by using nutrients more efficiently (Leles et al, 2018). In addition, the presence of vacuoles, associated mainly with mixotrophic dinoflagellates, may be indicative of a digestive function for these organelles and the consequent occurrence of phagotrophy by these organisms (Onuma and Horiguchi, 2013;Almada et al, 2017). Another selected trait was the production of resistance stages, which is a survival strategy among dinoflagellates that favors the reintroduction of species into the water column and eventually HAB formation (McQuoid et al, 2002;Ellegaard and Ribeiro, 2018).…”

Genetic Analyses of the rbcL and psaA Genes From Single Cells Demonstrate a Rhodophyte Origin of the Prey in the Toxic Benthic Dinoflagellate Ostreopsis

“…Faust (1998) reported that the abundance of Ostreopsis species with prey ranged from 7 to 55% of all specimens examined from Belize. Very recently, Almada et al (2017) reported only a small percentage (0.4%) of O. cf. ovata containing prey from Brazil.…”

“…Since then, some studies (e.g., Aligizaki and Nikolaidis, 2006;Selina and Orlova, 2010;Accoroni et al, 2014) also observed the presence of red bodies in Ostreopsis cells collected in field samples, and Fraga et al (2012) suggested that the presence of these red bodies might be related to the mixotrophic behavior of Ostreopsis species. Very recently, Almada et al (2017) also reported that only a small percentage (0.4%) of O. cf. ovata cells in Brazil showed evidence of phagotrophy by using epifluorescence microscopy with DAPI and LysoSensor staining, although the prey inside the cells were not discernible.…”

Chemical Ecology of the Benthic Dinoflagellate Genus Ostreopsis: Review of Progress and Future Directions

“…In 2012, Fraga et al (2012) linked the presence of reddish round inclusions inside Ostreopsis cells (detected through light microscopy) to the mixotrophic behavior. Almada et al (2017) showed evidence of phagotrophy using LysoSensor staining even if the prey inside the cells were not discernable. More recently, using molecular approaches, Lee and Park (2018) defined the red bodies as digestive vacuoles containing ingested red macroalgae (Class Florideophyceae).…”