Influence of conspecifics on choice of settlement sites by larvae of two pomacentrid fishes (Dascyllus aruanus and D. reticulatus) on coral reefs
- Cite this article as:
- Sweatman, H.P.A. Mar. Biol. (1983) 75: 225. doi:10.1007/BF00406006
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Field experiments investigating interactions between recruits and resident Dascyllus aruanus and D. reticulatus were carried out between 1978 and 1980 at Lizard Island, Great Barrier Reef, Australia. Standard Coral Units (SCUs) were constructed on a sandy substrate at a low tide depth of about 2 m. Each SCU was composed of living colonies of Pocillopora damicornis, measuring 60 cm in diameter by 40 cm in height. A grid of 12 SCUs was laid out such that adjacent SCUs were 20 m apart and at least 40 m from the nearest natural patch reef. Established SCUs were defaunated, and subsequently each was repopulated with a group of either D. aruanus or D. reticulatus. The fishes on each SCU were then censused over a 6 mo period spanning the recruitment season of these species. Over this period the net increase in numbers of D. aruanus was significantly greater on those SCUs predominantly inhabited by established D. aruanus than on SCUs where established D. reticulatus predominated. Conversely, the net increase in numbers of D. reticulatus was significantly greater on those SCUs predominantly inhabited by established D. reticulatus than on SCUs where established D. aruanus predominated. Although the results did not categorically rule out the possibility of differential survival after recruitment, they are most readily interpreted in terms of enhanced settlement of larvae on coral heads where conspecific fish predominate. Thus competition is not the only way in which resident reef fish may influence larval recruitment.