Bonamia ostreae
Encyclopedia
Bonamia ostreae is a parasitic protist
in the phylum Haplosporidia that can cause lethal infections in shellfish, particularly the European flat oyster, Ostrea edulis. Infection in oysters rarely results in clinical signs of disease and often the only indication of the infection is increased mortality. The Australian flat oyster, Ostrea angasi
, has also been infected with Bonamia parasites.
of the oyster. Lesions occur with focal infiltration of the haemocytes within the connective tissue of the mantle and gills, and in the vascular sinuses near the digestive gland, intestine and stomach. Infection seems to be correlated to haemocyte destruction and diapedesis.
of the epidemiology of European flat oysters, Ostrea edulis, infected with Bonamia ostreae showed that the parasite was present throughout the year and was detected in all oyster weight classes. The study analyzed the prevalence relative to O. edulis density, biomass and a range of environmental parameters. Prevalence was greatest in the largest oysters and was higher in spring than in the autumn, perhaps because of the mortality of these shellfish
during the summer. Mortality seemed to be correlated with higher water temperatures and oysters seemed to be more susceptible to infection after seasons with lower food availability or lower salinity levels.
Another study was made in 2004 into the incidence of infection by Bonamia ostrea in different populations of Ostrea edulis.
A study made in 2010 aimed to evaluate the Bonamia spp. infection status of Ostrea stentina in the Mediterranean Sea.
A further study made in 2010 investigated whether the Pacific oyster
, Crassostrea gigas, could act as a carrier or a reservoir of Bonamia ostreae and transmit the infection to Ostrea edulis.
Protist
Protists are a diverse group of eukaryotic microorganisms. Historically, protists were treated as the kingdom Protista, which includes mostly unicellular organisms that do not fit into the other kingdoms, but this group is contested in modern taxonomy...
in the phylum Haplosporidia that can cause lethal infections in shellfish, particularly the European flat oyster, Ostrea edulis. Infection in oysters rarely results in clinical signs of disease and often the only indication of the infection is increased mortality. The Australian flat oyster, Ostrea angasi
Ostrea angasi
The southern mud oyster or native flat oyster, Ostrea angasi, is endemic to southern Australia, ranging from Western Australia to southeast New South Wales and around Tasmania.-Diet:...
, has also been infected with Bonamia parasites.
Pathology
The cells of Bonamia ostreae measure 2-3 µm in diameter and are found within the haemocytesHemocyte
A hemocyte is a cell that plays a role in the immune system of invertebrates. It is found within the hemolymph.Hemocytes are phagocytes of invertebrates....
of the oyster. Lesions occur with focal infiltration of the haemocytes within the connective tissue of the mantle and gills, and in the vascular sinuses near the digestive gland, intestine and stomach. Infection seems to be correlated to haemocyte destruction and diapedesis.
Epidemiology
A study in the NetherlandsNetherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
of the epidemiology of European flat oysters, Ostrea edulis, infected with Bonamia ostreae showed that the parasite was present throughout the year and was detected in all oyster weight classes. The study analyzed the prevalence relative to O. edulis density, biomass and a range of environmental parameters. Prevalence was greatest in the largest oysters and was higher in spring than in the autumn, perhaps because of the mortality of these shellfish
Shellfish
Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...
during the summer. Mortality seemed to be correlated with higher water temperatures and oysters seemed to be more susceptible to infection after seasons with lower food availability or lower salinity levels.
Distribution
In Europe, distribution of the parasite is along the Atlantic coast from Spain to Denmark. In the USA it is found on the Atlantic coast in Maine and the Pacific coast from California to Washington.Research
A study was made in 2001 into the relative susceptibility of different strains of Ostrea edulis to the parasite Bonamia ostreae.Another study was made in 2004 into the incidence of infection by Bonamia ostrea in different populations of Ostrea edulis.
A study made in 2010 aimed to evaluate the Bonamia spp. infection status of Ostrea stentina in the Mediterranean Sea.
A further study made in 2010 investigated whether the Pacific oyster
Pacific oyster
The Pacific oyster, Japanese oyster or Miyagi oyster , is an oyster native to the Pacific coast of Asia. It has become an introduced species in North America, Australia, Europe, and New Zealand.- Etymology :...
, Crassostrea gigas, could act as a carrier or a reservoir of Bonamia ostreae and transmit the infection to Ostrea edulis.
