Settlement, post-settlement mortality and growth of the damselfish Chromisfumea (Pisces : Pomacentridae) on two artificial reefs in New Caledonia (south-west Pacific ocean)

Density and size of Chromis fumea (Pisces: Pomacentridae) were regularly mo nitored during 13 months (from August 1996 to August 1997), on two artifici al reefs in New Caledonia (south-west Pacific ocean): a ship-wreck (CT2) ju st after scuttling, and an assemblage of iron boxes (Caissons) sunk more th an 50 years ago. The settlement of C. fumea was first observed 20 August 19 96 and lasted 20 days. At the beginning the recruits were 1 cm size-class f ish and at the end 2 cm size-class. This major settlement phase was again o bserved one year later (September 1997). A second minor settlement phase oc curred in December 1996 on CT2. Significant immigration of adults was also observed between November 1996 (6 cm) and April 1997 (7 cm), indicating tha t this species is capable of medium range migration (>50 m). Population siz e decreased by 87.8% between the settlement of juveniles and the first immi gration phase of adults. The final density of the 1996 cohort was 10.5% of the initial input of recruits on CT2 and 19.3% on Caissons. Initial density of recruits was 3.4 times higher on CT2 than on Caissons, whereas density of juveniles was similar at the end of the survey, indicating that post-set tlement mortality was greater on CT2. Chromis fumea von Bertalanffy growth models were similar on CT2 and Caissons. This short-lived species is charac terized by an initial rapid growth phase (K > 3.36 y(-1)), with the fish re aching 68.5% of L-infinity in three months, and a second slower growth phas e (1 cm in ten months).