Nest site selection of sergeant majors (Abudefduf saxatilis): artificial vs. natural reef structures

Nesting animals select sites for reproduction based on adaptive behaviors that have evolved to improve reproductive success and the survival rates of offspring. Abudefduf saxatilis, commonly known as the sergeant major, is a pomacentrid fish that exhibits nesting and nest-guarding behaviors. This study in the coastal waters of Bonaire, Dutch Caribbean, evaluates whether A. saxatilis selects rough or smooth substrates for nesting, and whether there is a vertical relief requirement for the nesting site using a reef survey and a field experiment. Nests on the reef were surveyed to determine if trends exist in the number and area of nests as height and rugosity of substrates increase, and a field experiment was designed to present the fish with a choice between rough or smooth surfaces and between units of varying heights. It was hypothesized that A. saxatilis would lay more and larger nests on smooth substrates with a vertical relief >20cm in both the experimental and reef environments. A trend towards more nests on smoother surfaces was observed in both the block experiment and in the reef survey, but no trends in number or area of nests were consistent between the experiment and the reef survey. Understanding the patterns of nest selection of A. saxatilis will provide important insight into the reproductive success of this highly abundant species, and because availability of nesting sites is a bottom-up control that can influence coral reef trophic structures.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 12-19 from CIEE Bonaire.

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