Pelagic dispersal and population connectivity of the green-lipped mussel (Perna canaliculus) in the Bay of Plenty

An understanding of the pelagic dispersal and connectivity in wild mussel populations is important for their sustainable management and for guiding the harvesting of wild seed for the mussel aquaculture industry. However, due to the complexity of the larval dispersal process, most studies have been unable to determine their detailed dispersal pathways; rather only their coarse directions of travel have been estimated. Microchemical methods can leverage the variation in deposition of trace metals in the shells of dispersal stages and further infer their locations during dispersal. In this study the natal sources and detailed pelagic pathways for recently settled green-lipped mussels, Perna canaliculus, within the Bay of Plenty (BoP) in northern New Zealand, including an offshore mussel farm, were estimated using their time-series of shell microchemical signatures. The feasibility of applying microchemical methods to mussels in this study area was firstly verified by evaluating the spatial and temporal resolution of shell microchemical signatures obtained from reference mussels cultured in situ across BoP. Subsequently, the remotely-sensed ocean environmental parameters were confirmed to correlate with the shell microchemistry and have the potential to improve the performance of the microchemical methods. In addition, the pathways of mussels traveling to the offshore mussel farm were specifically cross-validated by two biophysical particle modelling methods, with highly consistent results further independently confirming the effectiveness of the microchemical methods. This study found most mussels (~61%) arriving in the entire study area in BoP (~110 km) were concentrated within a short length (~25 km) of coastline from Whakatāne to Matata, and these mussels were predominantly plantigrades (~84% larger than 0.8 mm), undergoing secondary pelagic migration. Further microchemistry analyses indicated the majority (~80%) of them originated from the same source near Ōhiwa Harbour and Whakatāne. A significant proportion of these mussels remained in this same area for approximately 25 days post-natal to complete their larval development and primary settlement. More extensive secondary dispersal as plantigrades occurs only after 25-37.5 days post-natal. These results highlight the significance of the pelagic dispersal of juveniles versus larvae in mussels, and provide direct field evidence for extensive pelagic dispersal of juvenile mussels following initial larval settlement, which had rarely been documented before.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Marine Science

Grantor dc:publisher

ResearchSpace@Auckland

Year dc:date.issued

2024

Author dc:creator

• Wu, Wenjie

Advisors dc:contributor.advisor

• Jeffs, Andrew G
• Lundquist, Carolyn J

Statement dc:rights

• Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Licence dc:rights.uri

• https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm

Handle dc:identifier.uri

https://hdl.handle.net/2292/69702

OAI identifier oai:identifier

oai:researchspace.auckland.ac.nz:2292/69702