Quarterly Report of Investigations of Suspected Exotic Marine And

MARINE AND FRESHWATER Quarterly report of investigations of suspected exotic marine and freshwater pests and diseases Marine snails investigated A member of the public noticed a large Exotic pest and disease investigations are managed and reported by the number of large black snails while MPI Diagnostic & Surveillance Directorate, Wallaceville. The following is collecting shellfish from a local beach. He a summary of investigations of suspected exotic marine and freshwater was concerned they might be elephant diseases and pests during the period from October to December 2020. snails (Scutus antipodes), which are native to Australia, and wanted to know if they were common in New Zealand. From the images and description, it was near to any significant waterway likely cleaned. Samples were sent to MITS, determined that the snails were most to contain native crabs of this size. No where they were identified as mainly likely the endemic ducks-bill limpet recently imported containers had arrived Papenfussiella lutea, but there were (Scutus breviculus). at the store. Photos of the crabs were also two small plants of Scytosiphon sent to the Marine Invasives Taxonomic lomentaria. Both these species are native New to New Zealand Service (MITS) at NIWA, where they to New Zealand. were identified as purple rock crabs or ascidian Botrylloides swift-footed shore crabs (Leptograpsus Oyster mortality diegensis detected variegatus). This is a common indigenous investigated species found on New Zealand rocky Staff of the National Institute of An employee of a biosecurity service shores. It is unclear how the crabs came Water and Atmospheric Research provider reported an unusual mortality to be in the store, though human- (NIWA) notified MPI that they had of farmed Pacific oysters (Crassostrea mediated transport cannot be excluded. identified a new to New Zealand gigas), and an investigation was initiated ascidian species, Botrylloides diegensis. to rule out any exotic disease. Samples The ascidian was initially believed to Growths of mussel shell were sent to MPI’s Animal Health be B. listerianum, a species already investigated Laboratory for testing, and the Vibrio established in New Zealand, but after A factory employee working on a mussel splendidus clade of bacteria was isolated further taxonomic research it was processing line found a mussel shell from all oysters submitted. Bacterial confirmed to be B. diegensis. Specimens with a large number of unusual growths invasion of body tissues was also noted have been collected from both Bluff on it. Photos of the shell and growths on three oysters. Vibrio splendidus is and New Plymouth, suggesting it may were sent to MITS for identification, common in New Zealand, is a known be widespread. NIWA will conduct and it was confirmed that the growths opportunistic pathogen of shellfish, and molecular analysis to further clarify were the egg casings of an indigenous is considered likely to have played a the identification and distribution of gastropod, either Dicathais orbita or role in the oyster mortalities observed, this species. Haustrum haustorium. which resolved over the course of the investigation. New to New Zealand Fanworm investigated ascidian Lissoclinum sp. A member of the public observed a detected marine worm in a rock pool at Campbells Rissa Williams Senior Incursion Investigator During the Marine High Risk Site Bay, Auckland. He was concerned it Aquatic & Environment Health Team Surveillance Programme, at New might be an exotic species, and wanted Biosecurity New Zealand Plymouth, NIWA detected a new to to know if the worms were common in Ministry for Primary Industries New Zealand ascidian. The ascidian New Zealand. Photos of the fan worm [email protected] belongs to the genus Lissoclinum but it were sent to MITS, where they were could not be determined whether the identified as the Mediterranean fanworm species was new to science or non- (Sabella spallanzanii). This is native to indigenous. NIWA will undertake further the Mediterranean and Atlantic coasts of research to identify the species. Europe but is now present in a number of New Zealand harbours, including the Crabs in hardware store location of this detection. investigated Brown seaweeds on a vessel An employee of a large hardware store reported finding two live crabs in the investigated store. The crabs were roughly 50 mm in A marine biosecurity scientist reported carapace width. The store is not located finding unusual brown seaweeds on a recreational vessel as it was being 36 Surveillance 48 (1) 2021.

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