Coastal Restoration Trust of New Zealand

Coastal Dune Ecosystem Reference Database

A literary review on the Poor Knights Islands Marine Reserve

Sim-Smith, C., Kelly, M.
National Institute of Water & Atmospheric Research Ltd
Publisher / Organisation
Department of Conservation, Northland Conservancy
Poor Knights, Marine Reserve
The Poor Knights Islands Marine Reserve is renowned for its unique assemblage of marine flora and fauna, its rich diversity of marine life, and unusual subtidal habitats, and consequently has been the focus of a number of scientific research studies. The last comprehensive literature review of the Poor Knights Islands Marine Reserve was by Kelly (1983). Over the last 25 years significant new information has been generated on the habitats of the Poor Knights Islands and the marine flora and fauna that inhabit them. The aim of this project is to collate and review scientific information that has been generated on the Poor Knights Islands Marine Reserve since 1983 to increase our overall understanding of the Poor Knights Islands ecosystem. The Poor Knights Islands (Tawhiti Rahi Island and Aorangi Island) are extremely steep, with rocky cliffs extending over 100 m below sea level. Seven subtidal habitat types have been defined at the Poor Knights Islands; vertical reef walls and caves, macroalgal reef habitats, coralline flats/Evechinus chloroticus-dominated reefs, broken rock, sand, encrusting corallines, and Centro (Centrostephenus rodgersii) barrens. The vertical reef wall and macroalgal reef habitats have been well described in the literature, but there is currently a paucity of available information on the other habitat types. The National Institute of Water and Atmospheric Research is currently conducting a subtidal habitat mapping study of the Poor Knights Islands, to be published in 2009, that will provide us with detailed information on the other subtidal habitats within the reserve. The Poor Knights Islands lie slightly west of the East Auckland Current, and thus are influenced by waters of higher temperature, salinity, and clarity than the waters around the mainland or at other islands on the northeastern coastline. Larvae of numerous subtropical and tropical species are transported to the Poor Knights Islands from northern regions, and consequently there is a rich diversity of subtropical flora and fauna within the reserve. A number of these subtropical species are transient visitors that settle at the Poor Knights Islands in mid summer but are unable to survive over winter. Other subtropical species fail to establish successful breeding populations in New Zealand, relying on the continual transport of larvae from outside New Zealand to sustain populations at the Poor Knights Islands. Thus, the population size of these non-breeding species at the Poor Knights Islands varies greatly over time. An updated species inventory shows a large increase in the number of protozoans (110 new species records), molluscs (153 new species records) and fish (70 new species records) recorded from the Poor Knights Islands Marine Reserve. Macroalgae, cnidarians, and arthropods showed a moderate increase (10–25 new species records), while poriferans, bryozoans, ascidians, annelids, echinoderms, brachiopods, seabirds, reptiles, and marine mammals increased by less than 10 species per phylum. The species diversity of marine invertebrate taxa, at the Poor Knights Islands is most likely to be underestimated, given that there has been no significant research collection of marine invertebrates undertaken at the Poor Knights Islands in the last 20 years.