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Azizan A, Alfaro AC, Venter L, Jaramillo D, Bestbier M, Bennett P, Foxwell J, Young T. Quantification of Photobacterium swingsii and characterisation of disease progression in the New Zealand Greenshell™ mussel, Perna canaliculus. J Invertebr Pathol 2024; 203:108065. [PMID: 38246322 DOI: 10.1016/j.jip.2024.108065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 01/23/2024]
Abstract
Greenshell™ mussels (Perna canaliculus) are endemic to New Zealand and support the largest aquaculture industry in the country. Photobacterium swingsii was isolated and identified from moribund P. canaliculus mussels following a mass mortality event. In this study, a challenge experiment was used to characterise, detect, and quantify P. swingsii in adult P. canaliculus following pathogen exposure via injection into the adductor muscle. A positive control (heat-killed P. swingsii injection) was included to account for the effects of injection and inactive bacterial exposure. Survival of control and infected mussels remained 100% during 72-hour monitoring period. Haemolymph was sampled for bacterial colony counts and haemocyte flow cytometry analyses; histology sections were obtained and processed for histopathological assessments; and adductor muscle, gill, digestive gland were sampled for quantitative polymerase chain reaction (PCR) analyses, all conducted at 12, 24, 48 h post-challenge (hpc). The most profound effects of bacterial injection on mussels were seen at 48 hpc, where mussel mortality, haemocyte counts and haemolymph bacterial colony forming were the highest. The quantification of P. swingsii via qPCR showed highest levels of bacterial DNA at 12 hpc in the adductor muscle, gill, and digestive gland. Histopathological observations suggested a non-specific inflammatory response in all mussels associated with a general stress response. This study highlights the physiological effects of P. swingsii infection in P. canaliculus mussels and provides histopathological insight into the tissue injury caused by the action of injection into the adductor muscle. The multi-technique methods used in this study can be applied for use in early surveillance programs of bacterial infection on mussel farms.
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Affiliation(s)
- Awanis Azizan
- Aquaculture Biotechnology Research Group, Department of Environmental Sciences, School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand
| | - Andrea C Alfaro
- Aquaculture Biotechnology Research Group, Department of Environmental Sciences, School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand.
| | - Leonie Venter
- Aquaculture Biotechnology Research Group, Department of Environmental Sciences, School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand
| | - Diana Jaramillo
- Animal Health Laboratory, Ministry for Primary Industries, PO Box 2526, Wellington 6140, New Zealand
| | - Mark Bestbier
- Animal Health Laboratory, Ministry for Primary Industries, PO Box 2526, Wellington 6140, New Zealand
| | - Peter Bennett
- Animal Health Laboratory, Ministry for Primary Industries, PO Box 2526, Wellington 6140, New Zealand
| | - Jonathan Foxwell
- Animal Health Laboratory, Ministry for Primary Industries, PO Box 2526, Wellington 6140, New Zealand
| | - Tim Young
- Aquaculture Biotechnology Research Group, Department of Environmental Sciences, School of Science, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand; Centre for Biomedical & Chemical Sciences, School of Science, Auckland University of Technology, Auckland, New Zealand
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French AD, Ragg NLC, Ericson JA, Goodwin E, McDougall DR, Mohammadi A, Vignier J. Balancing essential and non-essential metal bioavailability during hatchery rearing of Greenshell mussel (Perna canaliculus) larvae. Ecotoxicol Environ Saf 2021; 216:112194. [PMID: 33862436 DOI: 10.1016/j.ecoenv.2021.112194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 03/20/2021] [Accepted: 03/24/2021] [Indexed: 06/12/2023]
Abstract
The use of ethylenediaminetetraacetic acid (EDTA) during bivalve hatchery production is thought to improve larval yields due to the reduced exposure to toxic metals (such as Cu); however, few studies have focused on the bioavailability of metals during the rearing process. Greenshell™ mussels (Perna canaliculus) were reared for 48 h with and without EDTA (12 µM) exposure and larvae were subsequently raised to 21 days post-fertilisation with and without EDTA exposure. Survival, shell length, algal ingestion rate, swimming activity, total metal concentration in water, bioavailable metal concentrations and larval metal accumulation were monitored for the 21 day period. Larval fitness (specifically D-yields) was improved on day 2 in the EDTA treatment, whereas an overall negative effect of EDTA treatment on fitness was observed on day 10 and 21. During the first 48 h, increased survival in the EDTA treatment is believed to be due to the reduction of bioavailable Zn concentrations in the rearing seawater. No other metal (essential or non-essential) displayed a consistent trend when comparing metal bioavailability to any of the fitness parameters measured throughout the experiment. Though the measured metal bioavailability was not clearly linked to fitness, the uptake of Al, P, Cr, Fe, Co, Ni, Zn, As, Cd, and Hg by P. canaliculus was reduced during the first 48 h, suggesting that the biological regulation of these elements is just as important as the bioavailability. Overall, treatment of the rearing seawater with 12 µM EDTA is effective for improving Greenshell™ mussel larval yields by decreasing metal bioavailability during the first two days of development but has minimal benefit between day 2 and 21.
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Affiliation(s)
| | - Norman L C Ragg
- Cawthron Institute, 98 Halifax Street East, Nelson, New Zealand
| | | | - Eric Goodwin
- Cawthron Institute, 98 Halifax Street East, Nelson, New Zealand
| | - Daniel R McDougall
- Institute of Marine Science, University of Auckland, Private Bag, 92019 Auckland, New Zealand
| | - Amir Mohammadi
- University of Waikato, Hillcrest Rd, Hamilton, New Zealand
| | - Julien Vignier
- Cawthron Institute, 98 Halifax Street East, Nelson, New Zealand
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