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In vitro production of the fish parasite Amyloodinium ocellatum – Possible applications and future perspectives

Márcio Moreira1, 2*, José I. Navas3, Pedro Pousão-Ferreira1 and Florbela Soares1
  • 1 Aquaculture Research Station, Portuguese Institute for the Sea and Atmosphere, Portugal
  • 2 Centro de Ciências do Mar (CCMAR), Portugal
  • 3 IFAPA Centro Agua del Pino, Spain

Fish diseases are one of the main problems in aquaculture, especially in intensive fish farming where they represent severe annual costs to producers (Murray and Peeler, 2005). Amongst them, parasitic diseases caused by obligate or opportunistic organisms can have a major impact in aquaculture, representing a constraint to production, sustainability and economic viability of aquaculture (Shinn et al., 2015). Amyloodiniosis is a parasitic disease caused by the dinoflagellate Amyloodinium ocellatum, that provokes fast and asymptomatic outbreaks, with acute morbidity and mortality in brackish and marine warm water fish on different aquaculture facilities worldwide (Noga et al., 2011). It also represents a major threat for semi-intensive aquaculture, especially in Southern Europe (Soares et al., 2012). There are some treatments already available for amyloodiniosis, but they are very ineffective in earthen ponds. There is also scarce information available at some levels (genetic, metabolic) about this parasite (Moreira et al., 2017). This could be due to the difficulty in the isolation and production of the three life stages of A. ocellatum (tomont – resting phase, dinospore – free-living phase, trophont – parasitic phase) and the fact that the more available form of the parasite, the tomont, is very difficult to work with. There is some work already available on the production of the three phases of A. ocellatum. Most of them were made in gill cellular lines, that are expensive and have various problems with parasite inhibition or survival (Noga, 1987, Noga, 1989, Noga and Bower, 1987), or via an uncontrolled methodology to produce dinospores and trophonts (Masson et al., 2013). So, to address this problem, we are developing at Aquaculture Research Station, Portuguese Institute for the Sea and Atmosphere (EPPO-IPMA) a low-cost system to improve the production of the three life phases of A. ocellatum in vitro. White seabreams were reared in contamination tanks according to the methodology described by Moreira et al. (2018). To obtain the tomonts we used the methodology described by Picón-Camacho et al. (2013). For the dinospore or infective phase, we incubated the obtained tomonts according to the methodology described by Masson et al. (2011). For the obtention of trophont or parasitic phase, we try to develop a low-cost alternative by different substrates that could allow dinospores fixation and their transformation in trophonts. We obtained easily the tomont phase from the gills of infected fish from the contamination tanks. As for the dinospore phase, the methodology described by Masson et al. (2011) not only lead to a low rate of sporulated A. ocellatum tomonts, but also to a low quantity of dinospores after 72h of incubation. To overcome this problem, we tested several conditions in vitro with tomonts cultivated in 25 cm3 chambers at 22ºC for 72h in different solutions. The results showed better results with sterilized water supplemented with fish gill, with high quantity of infective dinospores in suspension. For the obtention of the trophont phase, we have tested until now several matrixes, with mixed result in terms of parasite fixation. A system for in vitro production of all the life phases of the parasite A. ocellatum has an enormous potential as a tool for development of more effective treatments for amyloodiniosis, but also to improve the overall knowledge of this parasite.

Acknowledgements

This work was financed by DIVERSIAQUA (MAR202016-02-01-FMP-0066) project. Márcio Moreira has a PhD grant from FCT (SFRH/ BD/118601/ 2016).

References

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Keywords: Amyloodiniosis, Tomont, Dinospore, Trophont, production systems

Conference: IMMR'18 | International Meeting on Marine Research 2018, Peniche, Portugal, 5 Jul - 6 Jul, 2018.

Presentation Type: Oral Presentation

Topic: Aquaculture

Citation: Moreira M, Navas JI, Pousão-Ferreira P and Soares F (2019). In vitro production of the fish parasite Amyloodinium ocellatum – Possible applications and future perspectives. Front. Mar. Sci. Conference Abstract: IMMR'18 | International Meeting on Marine Research 2018. doi: 10.3389/conf.FMARS.2018.06.00109

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Received: 27 Apr 2018; Published Online: 07 Jan 2019.

* Correspondence: Mr. Márcio Moreira, Aquaculture Research Station, Portuguese Institute for the Sea and Atmosphere, Olhão, Portugal, marciojvmoreira@gmail.com