Abstract
The sea pen Pteroeides sp. shows variability in size frequency distributions and density between areas of a population, suggestive of spatially unpredictable and patchy recruitment. The spatial distribution of colonies does not differ significantly from a random distribution. The calcareous axial style contains growth rings, though it was not established whether rings are annual. Colonies are able to successfully reanchor within the substratum following diver removal, but exposure of colonies may increase chances of possible predatory damage. Movement of colonies across the substratum occurs, but is not significant over the population as a whole. The nudibranch Tritonia sp. is identified as the only known predator of Pteroeides sp. in New Zealand fiords to date. Ten to twenty percent of Pteroeides sp. colonies in the study area contain an endosymbiotic filamentous brown alga. Pteroeides sp. is gonochoric with a sex ratio of 1:1. Gametogenesis is synchronous among all polyps in a colony. Both sexes show the same annual pattern of gamete maturity with an annual spawning event. The presense of immature oocytes throughout the year indicates oogenesis may take more than one year to complete. Mature oocytes are large (c. 500-550μm in diameter) and broadcast spawning occurs in late summer.