Occurrence of Perkinsus olseni and other parasites in New Zealand black-footed abalone (Haliotis iris)

The culture of endemic New Zealand black-footed abalone (Haliotis iris) represents a growing aquaculture industry, which is potentially threatened by pathogens and parasites. To identify and characterise health risks, a targeted sampling event was conducted of healthy- and unhealthy-looking abalone (shell deformities, tissue damage and brown creamy substance/fluid in tissues) at a land-based farm. Histological analysis showed signs of ill health, including disrupted and swollen gills with haemocytosis, ceroid material and parasites, and muscle tissues with focal haemocytosis with parasites. For the first time in H. iris, detailed histological observations, followed by confirmatory in situ hybridisation (ISH) resulted in the identification of Perkinsus olseni (5% prevalence). Scyphidia-like ciliates (56%), Sphenophrya-like ciliates (5%), unidentified disintegrated ciliates (26%), intracellular bacterial microcolonies (IMCs) (9%), apicomplexan-like cells (1%) and bacteria (2%) were also identified across organs. There was a significant association between the presence of P. olseni and IMCs. Immunological tissue responses (haemocytosis and ceroid material) and gill pathology were evaluated semi-quantitatively and were significantly associated with P. olseni. Gross abalone appearance was also significantly associated with P. olseni and unidentified disintegrated ciliates. These findings indicate the types of pathogens and parasites found in cultured H. iris for future health assessment studies of this important aquaculture species.

Automated summary

This study identified and characterized pathogens and parasites in cultured New Zealand black-footed abalone, including Perkinsus olseni, which is important for future health assessment studies of this aquaculture species.