Amyloodinium ocellatum (Chromalveolata: Dinoflagellata) in farmed turbot
2011
Saraiva, Aurélia | Jerónimo, Daniel | Cruz Mínguez, Cristina
Turbot Scophthalmus maximus (Linnaeus, 1758) referred many times as Psetta maxima junior synonym is a Pleuronectiformes fish that has been produced in aquaculture since the last quarter of XX century. One decisive factor to the maintenance and development of this economically important production is the increase of the knowledge of the most important diseases affecting turbot. The most deleterious infections on turbot culture in Iberian Peninsula are caused by bacteria and parasites. During a survey conducted during a 10month period (September 2009 to June 2010) in a Portuguese turbot intensive fish farm the cosmopolitan ectoparasite dinoflagellate Amyloodinium ocellatum was detected in 87.2% of turbot when water temperatures ranged from 18.2 to 19.7°C (temperate season) and 44.4% when water temperature ranged from 16 to 18.1°C (cold season). In both seasons infections levels were light and did not cause abnormal mortality. Histological sections revealed the occurrence of few scattered trophonts that insert the attaching disc into host cells causing vacuolar degeneration, focal hyperplasia and necrosis on gill epithelium. In this study it was stated that A. ocellatum was present and can multiply along all year around in temperate regions without causing epizootic problems when infection levels is low. However surveillance should be performed in spring and summer time in order to avoid proliferation of parasites and associated fish mortalities. This is the first report of the occurrence of A. ocellatum in a turbot fish farm.
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