Ms. Jenny Ann Sweatman1, A/Prof. J. David Aguirre1, Dr Adam N. H. Smith1, A/Prof. Libby Liggins1
1Massey University, Auckland, Aotearoa New Zealand
In contrast to the east coast of Australia, where the Long-spined sea urchin (Centrostephanus rodgersii) underwent a rapid, poleward range extension with dramatic ecosystem impacts, shifts in the range of C. rodgersii have not been recorded in Aotearoa New Zealand (NZ). Owing to NZ’s complex geography and oceanography however, range shifts in response to climate change may not be strictly polewards. Moreover, demographic changes within established populations that might be indicative of climatic responses have not been adequately monitored. We surveyed the sizes of individuals (population size structure) and used population genomic analyses to infer the population history and demography of C. rodgersii in NZ. Population size structure analyses revealed a likely poleward range extension from North Cape to the Coromandel, but indicated that offshore islands to the east and as far south as Whakaari (White Island) were colonised earlier and have more regular recruitment than coastal, northern populations. Population genomic analysis revealed that populations of Rangitāhua (Kermadec Islands) are genetically differentiated from mainland populations, but there is ongoing migration from Rangitāhua to NZ, particularly to offshore southern locations. Importantly, patterns of population genetic (co)variance differed across size classes (corresponding to urchins less than 15 years old, and urchins over 15 years old), indicating that the metapopulation dynamics of C. rodgersii in NZ have changed over recent decades. Our results suggest that monitoring C. rodgersii populations, and their impacts on local biodiversity, should be prioritised to inform actions to mitigate widespread damage to NZ’s ecosystems and fisheries.
Biography:
Libby is a New Zealand Rutherford Discovery Fellow based at Massey University Auckland and a Research Associate of the Auckland Museum Tāmaki Paenga Hira. Her research is interested in the generation and changing nature of biogeographic, ecological and demographic patterns in the ocean. She specialises in using genetic and genomic data, in combination with ecological data and modelling approaches. Alongside her research she is an active participant in science outreach and community engagement and she collaborates in several international research consortia and scientific committees, advocating open data, knowledge transfer, and appropriate data stewardship.
