Settlement and growth of Antipathes pennacea on a shipwreck

A large population of the black coral Antipathes pennacea (Pallas) was studied underwater on a 37 year old shipwreck in Jamaican waters. The occurrence of A. pennacea at depths of 30–32 m supports previous observations that the minimum depth for black corals is reduced in turbid waters. Specimens of A. pennacea were found only on the underside of overhangs and 96 were measured. This pattern of occurrence suggests that the angle of inclination of the substrate is assesed prior to larval settlement. A. pennacea morphology was density dependent; isolated individuals grew three dimentionally in the form of a bush, the major stem being circular in cross section. Crowded individuals however, were tall with thin, oval or hourglass shaped stems and had a vertically orientated fan shape. The largest crowded individuals averaged growth rates of 57 mm height/year while the largest isolated individuals averaged 0.92 mm stem diameter/year.