MEPS 163:225-233 (1998)  -  doi:10.3354/meps163225

Short-distance dispersal of black coral larvae: inference from spatial analysis of colony genotypes

K. J. Miller*

National Institute of Water and Atmosphere Ltd, PO 14-901, Kilbirnie, Wellington, New Zealand

Antipathes fiordensis is a black coral species endemic to the south-western region of New Zealand. Restricted larval dispersal has been demonstrated to occur in A. fiordensis, although the exact scale of larval dispersal is unknown. This study examines the fine-scale (<50 m) pattern of relatedness between black coral colonies at 3 sites in Doubtful Sound, Fiordland, to infer dispersal distance and gain a better understanding of patch size in this species. At each of the 3 sites the position of all black coral colonies was mapped and allozyme electrophoresis was used to determine the 10-locus genotype of each colony. Two statistical methods were used to examine the association between colony genotype and distance at each of the 3 plots; spatial autocorrelation of individual loci and Mantel's Test which examines the relationship between multi-locus genotypes. At 1 of the 3 sites (Tricky Cove) there was a significant positive association among colonies separated by <5 m for 4 of the 6 loci tested. Similarly, Mantel's Test showed a significant positive correlation between genetic distance and Euclidean distance at the Tricky Cove site (r = 0.2, p = 0.007). These results suggest dispersal of black coral larvae is highly philopatric and that larvae settle very close to parent colonies. However at the other 2 sites there was no spatial association detected among genotypes, indicating either that gametes or larvae are more widely dispersed at these 2 sites (>50 m) or that other ecological and evolutionary factors are operating that have influenced the observed genetic structure of the populations. Genetic studies suggest that gene flow in A. fiordensis populations will be restricted and that patch size in this species may be relatively small. These findings will have important implications for the conservation and management of the rare and unique shallow water populations of black corals in New Zealand's fiords.

Black coral · Larval dispersal · Philopatry

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