Comparative population genetic study of an important marine parasite from New Zealand flat oysters
The comparative genetic structure of hosts and parasites can reveal constraints acting on parasite dispersal among host populations and the evolution of local adaptation. We sampled New Zealand flat oysters Ostrea chilensis from 12 sites throughout New Zealand to (1) determine the distribution and prevalence of the haplosporidian parasites Bonamia exitiosa and B. ostreae, and (2) test for congruent patterns of host and parasite genetic structure. B. exitiosa was detected at three sites: Hauraki Gulf (5% prevalence), Marlborough Sounds (30%), and Foveaux Strait (7%), whereas B. ostreae was only detected in the Marlborough Sounds (37%). Using nuclear internal transcribed spacer (ITS) rDNA sequences of B. exitiosa, as well as mitochondrial cytochrome c oxidase subunit 1 gene (CO1) sequences of O. chilensis from the same sites plus other key O. chilensis growing areas (Tasman Bay and Chatham Islands), we compared the genetic structure of host and parasite. B. exitiosa displayed genetic structure across all three sites which were reflected in populations of O. chilensis except for gene flow between Tasman Bay-Marlborough Sounds-Chatham Islands. The observed patterns reflect the host specificity of Bonamia parasites and the limited dispersal capability of oysters. O. chilensis may experience long distance dispersal which is likely influenced by oceanographic factors. Nonetheless, a failure to detect Bonamia parasites among genetically connected O. chilensis populations suggests natural long distance co-dispersal of Bonamia parasites with O. chilensis is unlikely. Instead, the dispersal of Bonamia parasites is likely influenced by anthropogenic factors.
We thank New Zealand’s Ministry for Primary Industries (MPI), NIWA, and Kono Seafoods for the efforts in sample collection. The Animal Health Laboratory, Wallaceville, (MPI) provided laboratory resources during the course of this study which was carried out as part of a Ph.D. project at the University of Otago, within Prof. Robert Poulin’s laboratory group. Finally, we thank the anonymous reviewers, whose input greatly improved this manuscript.
Compliance with ethical standards
Conflict of interest
All authors declare that they have no conflicts of interests.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.
- Diggles BK, Hine PM (2002) Bonamia exitiosus epidemiology in Foveaux Strait oysters. National Institute of Water and Atmospheric Research, 2002. Ministry of Fisheries Research Project OYS1999/01AGoogle Scholar
- Flannery G (2014) Aspects of the biology of the parasite Bonamia ostreae with a view to gaining a greater understanding of how to alleviate its impact on the European flat oyster, Ostrea edulis. Dissertation, University College Cork, CorkGoogle Scholar
- Hine PM (1997) Health status of commercially important molluscs in New Zealand. Surveillance 24:25–28Google Scholar
- Jeffs AG, Creese RG (1996) Overview and bibliography of research on the Chilean oyster Tiostrea chilensis (Philippi, 1845) from New Zealand waters. J Shell Res 15:305–311Google Scholar
- Lane HS (2017) Studies on Bonamia parasites (Haplosporidia) in the New Zealand flat oyster Ostrea chilensis. Unpublished Dissertation, University of Otago, DunedinGoogle Scholar
- Michael KP, Fu D, Forman J, Hulston D (2013) The Foveaux Strait oyster (Ostrea chilensis, OYU5) stock assessment survey and status of Bonamia infection and mortality, February 2012. New Zealand Fisheries Assessment Report 2013/09Google Scholar
- Michael KP, Forman J, Hulston D (2015) A survey of the Foveaux Strait oyster (Ostrea chilensis) population (OYU5) commercial fishery areas and the status of Bonamia (Bonamia exitiosa) in February 2015. New Zealand Fisheries Assessment Report 2015/73, p 88Google Scholar
- Ross PM, Hogg ID, Pilditch CA et al (2012) Population genetic structure of the New Zealand estuarine clam Austrovenus stutchburyi (Bivalve: Veneridae) reveals populations subdivision and partial congruence with biogeographic boundaries. Estuar Coasts 35:143. https://doi.org/10.1007/s12237-011-9429-z CrossRefGoogle Scholar
- Tajima F (1989) Statistical method for testing the neutral mutation hypothesis by DNA polymorphism. Genetics 123:585–595Google Scholar
- Thomas LJ (2015) A molecular and population genetics study of the Bluff oyster (Ostrea chilensis). Dissertation, Victoria University of Wellington, WellingtonGoogle Scholar