|dc.description.abstract||Non-indigenous marine species are a major concern worldwide. For some species, insufficient historical and biogeographical data can leave their origin and patterns of dispersal difficult to determine. Among such species are marine wood borers. This thesis uses an interdisciplinary approach, combining both historical and biological methods, to address marine borer impacts, management attempts, and their status in New Zealand.
This research had two key components. Firstly, a historical review sought to improve the understanding and awareness of the historic impacts and responses to borers, with particular reference to New Zealand between 1850 and 1930. Marine wood borers have had profound impacts throughout history, responsible for significant structural and economic damage to wooden ships and marine infrastructure globally. In New Zealand, trade and economy played an important role in providing both the transportation vectors and infrastructure for marine wood borers to inhabit. Ongoing trialling of timber alternatives and chemicals for the preservation of infrastructure followed, with little success until the introduction of ferro-concrete in the early 1900s. When considered in a global context, the New Zealand case study of borer impacts and management attempts highlights their significant role in environmental history.
Mitochondrial DNA (COI) sequence analyses were used to examine the questionable invasion histories and status of common marine wood borers in New Zealand. It has been assumed that many marine wood borers invaded New Zealand via wooden ships. However, these purported introductions are historic, and the specific origins of many species are unclear. Species from three families and two phyla were collected around the North Island, New Zealand; Teredinidae (Bivalvia: Mollusca), Sphaeromatidae and Limnoriidae (Isopoda: Arthropoda). Low levels of genetic divergence (0-2%) were found among the New Zealand populations of two species, Limnoria quadripunctata and Sphaeroma quoianum, suggesting a non-indigenous status. Limnoria quadripunctata also showed a close genetic affinity to populations in Chile, supporting a non-indigenous status, with its widespread distribution in New Zealand explained by multiple introductions. For Lyrodus pedicellatus, a lack of genetic affinity to conspecifics sequenced elsewhere (France), greater genetic diversity compared to the native Bankia australis, and evidence of population structuring among New Zealand locations, suggested L. pedicellatus may be native to New Zealand. Lyrodus pedicellatus from New Zealand was highly divergent (>20%) from global L. pedicellatus populations, suggesting that either identifications of specimens on global databases are incorrect, or the New Zealand species represents a morphologically undescribed cryptic congener. In conclusion, COI sequences provided a useful tool in elucidating the status of marine wood borers in New Zealand, and highlighted a need for taxonomic resolution of some species.
Collectively the two chapters illustrate the knowledge gaps and lack of recognition surrounding marine wood borers, globally and in New Zealand. This research provides an extensive understanding of their significant historical role in marine environmental history and assists in re-evaluation of their current native or non-indigenous status in New Zealand.||