Distribution and recruitment patterns of Evechinus chloroticus and other New Zealand echinoderms: The role of pre- and post-settlement events

Numerous environmental and biological processes are responsible for shaping community structure in temperate rocky reefs. Replenishment of most marine invertebrate populations is largely determined by recruitment success, but it can be highly variable at different spatial and temporal scales. Recruitment is a complex process that involves larval supply, settlement (attachment to a suitable substrate and metamorphosis) and survival and growth of settled juveniles. However, factors controlling recruitment of mobile invertebrates, such as sea urchins, remain largely unknown. This study examines the major biotic and abiotic processes affecting early life stages of the sea urchin Evechinus chloroticus, and to what extent these events control the size and distribution of adult populations. This thesis contributes to a better understanding of the processes shaping population structure of E. chloroticus and other echinoderm species. In Chapter 2, I investigated the spatial and temporal variation in settlement of E. chloroticus, during the austral summer, at five sites in two locations of the Wellington region (Harbour and South coast) that differ in population structure and environmental conditions. The highest mean seawater temperature and lowest salinity were observed in the Harbour, while the South coast displayed higher chlorophyll and turbidity values. Density of adult sea urchins was significantly higher in the Harbour compared to the South coast and was significantly correlated to the predominant habitat type (shells). The mean size of urchins was larger in the South coast sites and juveniles (