Project

Parasites infecting imported ornamental fish

Goal: The ornamental fish trade is one of the largest commodity sectors in the world, with over 100 countries involved in the export and import of over one billion live fish globally. Fish are either wild caught or farmed, and exported following stringent quarantine and biosecurity conditions. Nonetheless, parasites can be highly cryptic, infections can be asymptomatic, and despite strict quarantine practices, some parasites infecting ornamental fish are not detected at quarantine and have been subsequently introduced into native ecosystems. The aim of my research is to determine which high risk parasites infect ornamental fish imported into Australia and to evaluate new border security methods using molecular techniques.

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Alejandro Trujillo González
added a research item
Context Biological resource use represents the most common direct threat to biodiversity. Despite this, there is a paucity of comprehensive and overarching data relating to the biological resource use. The global aquarium trade encompasses millions of individual live fishes representing thousands of marine and freshwater species traded on an annual basis. The lack of specific data systems for recording information where fish are exported or imported has resulted in limited accessible trade data. An evaluation of the data-reporting frameworks presently employed by countries engaged in the aquarium trade is warranted to better understand the means by which comprehensive data on the aquarium trade can be made more accessible. Aims This study examines the data-reporting framework of The Australian Government Department of Agriculture and Water Resources (DAWR) used to collate aquarium fish import data, and its capacity to inform on the aquarium trade biodiversity imported to Australia. Methods Aquarium import records from 2010–16 were provided by DAWR and used to determine the quantity of individual fishes and consignments imported to Australia. The potential biodiversity of imports was determined from the Australian Government’s List of Permitted Live Freshwater/Marine Fish Suitable for Import 2018 (Number 69, F2017C00079), the legislative document identifying species permitted import to Australia for the aquarium trade. Species permitted import were cross-referenced with the International Union for Conservation of Nature (IUCN) Red List to address whether the Australian aquarium trade is importing threatened species. Key results A total of 10320 consignments encompassing more than 78.6 million aquarium fishes were imported to Australia between 2010 and 2016. A total of 4628 species of fishes were permitted import to Australia for the aquarium trade with 73 of the marine species (2.0%) and 81 of the freshwater species (7.5%) found to be threatened with some degree of extinction risk. The data-reporting framework for aquarium fish imports offered limited capacity to taxonomically differentiate imports and only 12.5% of all aquarium fishes imported could be identified to species. Conclusions The aquarium fish import records provided by DAWR had limited taxonomic resolution and, consequently, limited capacity to contribute to an improved understanding of the biodiversity imported to Australia for the aquarium fish trade. While more detailed information is available than is presently collated by DAWR, the availability of this information is constrained by the laws around protected information and the resources available to DAWR. Implications Accessible, detailed information on aquarium fish imports is necessary to support comprehensive research capable of addressing threats to biodiversity loss from the aquarium trade. To this end, the means by which Australian aquarium import data can be reported at greater taxonomic resolution under the existing legislative and resource restraints should be explored further.
Alejandro Trujillo González
added an update
Efective border control relies on stringent biosecurity protocols to detect and prevent introductions of exotic pests and diseases. Detection of pathogens and parasites in the live ornamental fish trade using environmental DNA (eDNA) techniques has the potential to improve current biosecurity practices. We examined water samples from 11 target consignments (cyprinids susceptible to Dactylogyrus spp. infections) and seven non-target fish consignments (non-cyprinids, not susceptible to Dactylogyrus spp. infections) imported from Southeast Asia to Australia for the presence of eDNA from five Dactylogyrus species (Monogenea: Dactylogyridae). A four-step predictive framework was used to predict putative positive and putative negative detections from quantitative PCR assays. Both target and non-target consignments were positive for Dactylogyrus spp. eDNA as confrmed by Sanger sequencing. Positive detections for Dactylogyrus spp. eDNA in non-target fish consignments demonstrates the possibility of source water contamination, limiting the applicability of eDNA screening methods at border control. This study suggests that screening for parasite eDNA within ornamental fish consignments should be tested during pre-export quarantine periods to avoid false positive detections at border control. Lastly, the proposed predictive framework has a broad utility for minimizing false positive and false negative eDNA detections of aquatic organisms.
 
Alejandro Trujillo González
added 2 research items
The phylogenetic tree (Figure 7) in the published document has incorrect Bayesian analysis posterior probabilities. This error prevents accurate analysis by future research in parasitology. The figure is therefore replaced by the corrected figure below.
Effective border control relies on stringent biosecurity protocols to detect and prevent introductions of exotic pests and diseases. Detection of pathogens and parasites in the live ornamental fish trade using environmental DNA (eDNA) techniques has the potential to improve current biosecurity practices. We examined water samples from 11 target consignments (cyprinids susceptible to Dactylogyrus spp. infections) and seven non-target fish consignments (non-cyprinids, not susceptible to Dactylogyrus spp. infections) imported from Southeast Asia to Australia for the presence of eDNA from five Dactylogyrus species (Monogenea: Dactylogyridae). A four-step predictive framework was used to predict putative positive and putative negative detections from quantitative PCR assays. Both target and non-target consignments were positive for Dactylogyrus spp. eDNA as confirmed by Sanger sequencing. Positive detections for Dactylogyrus spp. eDNA in non-target fish consignments demonstrates the possibility of source water contamination, limiting the applicability of eDNA screening methods at border control. This study suggests that screening for parasite eDNA within ornamental fish consignments should be tested during pre-export quarantine periods to avoid false positive detections at border control. Lastly, the proposed predictive framework has a broad utility for minimizing false positive and false negative eDNA detections of aquatic organisms.
Alejandro Trujillo González
added an update
For more than 500 years, human translocation has facilitated the spread of goldfish globally, which has enabled numerous and repeated introductions of parasite taxa that infect them. The parasite fauna assemblage of goldfish is generally well documented, but few studies provide evidence of parasite coinvasion following the release of goldfish. This review provides a comprehensive synopsis of parasites that infect goldfish in farmed, aquarium-held, native, and invasive populations globally and summarises evidence for the cointroduction and coinvasion of goldfish parasites. More than 113 species infect goldfish in their native range, of which 26 species have probably coinvaded with the international trade of goldfish. Of these, Schyzocotyle acheilognathi (Cestoda: Bothriocephalidae), Ichthyophthirius multifiliis (Ciliophora: Ichthyophthiriidae), Argulus japonicus (Crustacea: Argulidae), Lernaea cyprinacea (Crustacea: Ergasilidae), Dactylogyrus anchoratus, Dactylogyrus vastator and Dactylogyrus formosus (Monogenea: Dactylogyridae) are common to invasive goldfish populations in more than four countries and are considered a high risk of continued spread. Coinvasive parasites include species with direct and complex life cycles, which have successfully colonised new environments through utilisation of either new native hosts or suitable invasive hosts. Specifically, I. multifiliis, A. japonicus and L. cyprinacea can cause harm to farmed freshwater fish species and are important parasites to consider for biosecurity. These species may threaten other aquatic animal industries given their low host specificity and adaptable life histories. Future attention to biosecurity, management and border detection methods could limit the continued spread of exotic parasites from the ornamental trade of goldfish.
 
Alejandro Trujillo González
added a research item
Goldfish, Carassius auratus Linnaeus, 1758, are immensely popular ornamental cyprinid fish, traded in more than 100 countries. For more than 500 years, human translocation has facilitated the spread of goldfish globally, which has enabled numerous and repeated introductions of parasite taxa that infect them. The parasite fauna assemblage of goldfish is generally well documented, but few studies provide evidence of parasite coinvasion following the release of goldfish. This review provides a comprehensive synopsis of parasites that infect goldfish in farmed, aquarium-held, native, and invasive populations globally and summarises evidence for the cointroduction and coinvasion of goldfish parasites. More than 113 species infect goldfish in their native range, of which 26 species have probably coinvaded with the international trade of goldfish. Of these, Schyzocotyle acheilognathi (Cestoda: Bothriocephalidae), Ichthyophthirius multifiliis (Ciliophora: Ichthyophthiriidae), Argulus japonicus (Crustacea: Argulidae), Lernaea cyprinacea (Crustacea: Ergasilidae), Dactylogyrus anchoratus, Dactylogyrus vastator and Dactylogyrus formosus (Monogenea: Dactylogyridae) are common to invasive goldfish populations in more than four countries and are considered a high risk of continued spread. Coinvasive parasites include species with direct and complex life cycles, which have successfully colonised new environments through utilisation of either new native hosts or suitable invasive hosts. Specifically, I. multifiliis, A. japonicus and L. cyprinacea can cause harm to farmed freshwater fish species and are important parasites to consider for biosecurity. These species may threaten other aquatic animal industries given their low host specificity and adaptable life histories. Future attention to biosecurity, management and border detection methods could limit the continued spread of exotic parasites from the ornamental trade of goldfish.
Alejandro Trujillo González
added 2 research items
The ornamental fish trade is a known pathway for the global translocation of aquatic parasites. Australian import conditions require all ornamental fish to be inspected seven days prior to importation to be free of parasites and diseases, however only goldfish consignments are required to be treated with parasiticides for the presence of Dactylogyrus extensus (Mueller and Van Cleave, 1932) and Dactylogyrus vastator Nybelin, 1924. We examined 37 ornamental fish consignments imported from Singapore, Malaysia, Thailand, and Sri Lanka to Australia (including freshwater and marine fish species) for monogenean parasites following inspection at Australian border control. Parasite species were identified based on haptoral and copulatory organ morphology, and representative samples of each species were used to amplify the ITS1 gene region for comparison. More than 950 monogenean parasites were collected from 15 consignments, representing a total of 14 species from five freshwater ornamental fishes. Seven Dactylogyrus spp. (including Dactylogyrus vastator Nybelin, 1924), and three Gyrodactylus spp. infected goldfish, Carassius auratus Linnaeus, 1758, from Malaysia, Singapore and Thailand; Dactylogyrus ostraviensis Řehulka, 1988, infected rosy barb, Pethia conchonius Hamilton, 1822, from Singapore, Sri Lanka and Thailand; two Trianchoratus spp. infected three spot gourami, Trichopodus trichopterus Pallas, 1970 and pearl gourami T. leeri Bleeker, 1852, from Sri Lanka and; Urocleidoides reticulatus Mizelle and Price, 1964, infected guppy, Poecilia reticulata Peters, 1859, from Sri Lanka. The discovery of D. vastator in goldfish consignments from Malaysia and Thailand suggests that the requirements of import health certificates for goldfish consignments prior to exportation to Australia are not being met. It is particularly concerning that other freshwater fish species require no prior treatment for parasites, as U. reticulatus and D. ostraviensis displayed high prevalence and mean infection intensities (prevalence=86.6% with mean intensity ± S.E.=18.30 ± 3.57, and 73.3% with 6.05 ± 0.74, respectively). The outcome of this study suggests that pre-export conditions and visual inspection at border control were insufficient to detect monogenean parasites infecting ornamental fish. Inspection of fish consignments prior to exportation and at border control must consider how highly cryptic in nature monogenean parasites can be, and consider alternative detection methods to visual inspection.
The ornamental fish trade provides a pathway for the global translocation of aquatic parasites. We examined a total of 1020 fish imported from Singapore, Malaysia, Thailand, or Sri Lanka to Australia (including freshwater and marine fish species) for monogenean ectoparasites. Fish were received following veterinary certification that they showed no clinical signs of pests and diseases from the exporting country and visual inspection at Australian border control. Australian import conditions require mandatory treatment for goldfish with parasiticides (e.g. trichlorfon, formaldehyde, sodium chloride) for the presence of gill flukes (Dactylogyrus vastator Nybelin, 1924 and Dactylogyrus extensus Mueller and Van Cleave, 1932) prior to export. Over 950 individual parasites were detected in five imported fish species, representing 14 monogenean species. Seven Dactylogyrus spp. including D. vastator and three Gyrodactylus spp. infected goldfish, Carassius auratus Linnaeus, 1758, from Malaysia, Singapore, and Thailand. Dactylogyrus ostraviensis Řehulka, 1988, infected rosy barb, Pethia conchonius Hamilton, 1822, from Singapore, Sri Lanka, and Thailand while two Trianchoratus spp. infected three spot gourami, Trichopodus trichopterus Pallas, 1970 and pearl gourami Trichopodus leerii Bleeker, 1852, from Sri Lanka. Urocleidoides reticulatus Mizelle & Price, 1964, infected guppy, Poecilia reticulata Peters, 1859, from Sri Lanka. The discovery of D. vastator in goldfish, as well as 13 other monogenean species, shows that pre-export health requirements, which include chemical treatment of goldfish, and inspection of all ornamental fish species did not prevent infection by monogeneans. Inspection prior to exportation and at border control must account for the highly cryptic nature of monogenean parasites and consider alternatives to current pre-export conditions and visual inspection at border control.
Alejandro Trujillo González
added a project goal
The ornamental fish trade is one of the largest commodity sectors in the world, with over 100 countries involved in the export and import of over one billion live fish globally. Fish are either wild caught or farmed, and exported following stringent quarantine and biosecurity conditions. Nonetheless, parasites can be highly cryptic, infections can be asymptomatic, and despite strict quarantine practices, some parasites infecting ornamental fish are not detected at quarantine and have been subsequently introduced into native ecosystems. The aim of my research is to determine which high risk parasites infect ornamental fish imported into Australia and to evaluate new border security methods using molecular techniques.