The flat oyster Ostrea edulis L. is widespread along the Italian coasts. In particular, the Manfredonia Gulf (Adriatic Sea) represents an important site where natural beds subsist. Previous monitoring conducted in 1990 by light microscopy and ultrastructural studies revealed the presence of Bonamia-like microcell parasites in some flat oysters: following this observation, a new sampling of O. edulis was carried out at this location in 2007. Of 750 oysters collected, 3 showed the presence of uninucleated microcells (2 to 3 µm diameter) free or inside the haemocyte cytoplasm by cytology and histopathology. Molecular analysis confirmed that the microcells in 2 oysters were B. exitiosa, whereas in the third oyster the microcells were B. ostreae. Moreover, molecular studies were carried out to confirm the existence of Bonamia sp. in archived samples, confirming the presence of B. ostreae in the Manfredonia Gulf since 1990. KEY WORDS: Bonamia spp. · Ostrea edulis · Molecular analysis · Electron microscopy Resale or republication not permitted without written consent of the publisherDis Aquat Org 89: [79][80][81][82][83][84][85] 2010 Bonamia exitiosa infects Ostrea chilensis in New Zealand (Hine et al. 2001) and O. angasi in Australia (Corbeil et al. 2006) and has been recently reported in O. edulis in Spain (Abollo et al. 2008). B. roughleyi, previously called Mikrocytos roughleyi, infects Saccostrea glomerata in southeast Australia (Farley et al. 1988). B. perspora is a newly described protozoan species found in Ostreola equestris (North Carolina, USA) and represents the first Bonamia species producing a typical haplosporidian spore (Carnegie et al. 2006). Other B. exitiosa-like organisms have been described in O. chilensis from Chile (Kern 1993, Campalans et al. 2000, O. puelchana from Argentina (Kroeck & Montes 2005), and Crassostrea ariakensis from North Carolina ); these organisms have been subsequently declared B. exitiosa (Lopez-Flores et al. 2007).Previous studies have reported by microscopic and ultrastrustural means the occurrence in Italy of small parasites similar to Bonamia sp. in flat oysters collected from the southern (Tiscar et al. 1991) and northern Adriatic Sea (Tiscar et al. 2002). A small number of molluscs appeared infected by the parasites (1/161 from the southern and 8/600 from the northern Adriatic Sea, respectively). Nevertheless all the infected oysters showed high infection level of the haemocytes with the presence of numerous protozoans per cell (Tiscar et al. 1991(Tiscar et al. , 2002.Taking into account these previous reports, the aim of the present study was to investigate by cytology and histology the occurrence of microcell parasites in flat oysters Ostrea edulis newly collected from natural beds in the southern Adriatic Sea and to characterize the recovered parasites by molecular and ultrastructural analyses as well as to confirm and characterize the presence of Bonamia sp. in one positive sample collected during 1990 from the Manfredonia Gulf (Tiscar et al. 1991). MAT...

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Crayfish plague, caused by the oomycete Aphanomyces astaci, is a serious disease of European freshwater crayfish and has eliminated entire populations in several European countries. In September 2011, mortality was observed among the Austropotamobius pallipes population of a river basin in the Abruzzi region (central Italy), and A. astaci DNA was detected by PCR in dead crayfish. A systematic survey was carried out to evaluate the spread and the effects of the plague in the river basin. The source of the outbreak remained unknown since North American crayfish species, which frequently act as subclinical carriers of the infection, were not detected in the area. The A. pallipes population disappeared from a river stretch of ~1 km, where A. astaci infection was detected in dead crayfish. However, apparently unaffected crayfish were still present upstream of that area as well as in a tributary that joined the brook in the apparently depopulated stretch. A. astaci infection was not detected in dead individuals collected in the upstream area and tributary. A follow-up visit conducted in the following season showed the presence of A. pallipes in the river stretch hit by the plague. In this outbreak, the spread of the infection could have been limited by a low density of the crayfish population and by the geographic conformation of the river basin, which includes a dense network of small tributaries, characterized by high flow velocity and low water temperature. In this particular setting, crayfish plague outbreaks can remain undetected. This underlines the importance of active monitoring programs aimed at the prompt recognition of both episodes of mortality and the presence of non-indigenous crayfish species.

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