Relationships between habitat and recruitment of three species of damselfish (Pomacentridae) at Heron Reef, Great Barrier Reef

Abstract

Recruitment of coral-reef fish species varies widely on a range of spatial scales, but the extent to which this variation is related to variability in habitat structure is unclear. We examined relationships between the recruitment of three species of damselfish (Pomacentrus moluccensis Bleeker, P. wardi Whitley and P. amboinensis Bleeker) and microhabitat structure (composition of the substrata) across six broad habitat zones at Heron Reef. Comparison of the distribution of recruits with the availability of substratum types along 10x2-m belt transects indicated that recruits of all three species utilised the substrata non-randomly. However, despite the distinct patterns of microhabitat use exhibited by each species, relationships between the density of recruits and the availability of preferred substrata were poor. We suggest that spatial stochasticity in larval supply and/or post-settlement mortality weakens relationships between recruitment and microhabitat availability. Univariate and multivariate analyses indicated significant differences in the recruitment of each species and in overall recruitment among habitat zones, and these differences may reflect large-scale variation in larval supply and/or rates of post-settlement mortality. Based on combined recruitment data, there was little evidence to suggest that areas of patchy coral reef received more or less recruitment than comparable areas of contiguous reef. Furthermore, recruitment to lagoonal patch reefs did not differ from recruitment to nearby sections of the reef slope offering a similar habitat with respect to depth and characteristics of the substratum.