Summary:

The Myxozoa infecting the European seabass and seabream cause serious growing delays, with great economic losses. There are in Portugal at least 4 species reported (Sphaerospora dicentrachi, Ceratomyxa labracis, C. diplodae and Myxobilatus sp.) so far, which are quite frequent and who life cycle is unknown. For seabream we do not have systematic parasitological surveys in Portugal and none of the recorded Myxozoa species abroad has known life cycle. The new approach of this project is to determine the life cycle of Myxozoa, whose knowledge will allow in a near future to propose measures to control those infections.

 

We intend under this project to characterize the life cycle of the species of Myxozoa known in seabass and seabream: adding important information on their ultrastructure; performing the molecular characterization of the forms actinosporean and myxosporean in order to match them and, that way, close their life cycles, and to provide a efficient tool of diagnose for each parasitosis; and also to describe the development stages of Actinoporea in Annelida and test some infection conditions.

In first place we will sample seabass and seabream, and other occasional fish, in aquaculture that produces fish in a semi-intensive way, in Algarve, in order to obtain infected tissues by species of Myxozoa (Myxosporean form) and thus to study its ultrastructure and perform its molecular characterization.
In the same locality and in the same fish pounds, we will perform periodical samples of Annelida, where it will be surveyed the actinosporean forms, characterize its morphology (namely its ultrastructure) and genotype, and studied its development
in this host. At the same time we will do experimental infections of Annelida, with myxosporean spores.
At last, and using the molecular information, which will be send to the GenBank, we will try to match the species found, either in the form of Actinosporea and Myxosporea, with other genotypes available in order to find pairs and thus close the life cycle of some species.

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Main Objectives Achieved:

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The main objectives of the present project were the following:

 

We intend under this project to characterize the life cycle of the species of Myxozoa known in seabass (Dicentrarchus labrax) and seabream (Sparus aurata), what we did for Sphaerospora dicentrarchi, Ortholinea labracis and Ortholinea aurate. Some more species still need work, but this was a very nice beginning once the difficulty of closing marine life cycles is huge.

 

We intend to add information on their ultrastructure; performing the molecular characterization what we did for the new species described: Zschokkella auratis sp.n., Ceratomyxa auratae sp.n., Ortholinea auratae sp.n., and Ortholinea labracis.

 

We intend to describe a new species of Myxobilatus, but we could not find it in Alvor estuary, where we made the sampling, but instead we describe 4 new species, previously mentioned, most of them from seabream.

 

We intend to provide an efficient tool of diagnose for each parasitosis, and we made the molecular characterization of all myxosporea found in seabass and seabream, and also for one species of white seabream, which is a good tool for diagnose.

 

As a conclusion we may say that the project proposal objectives were almost all meet, and even overlapped.