Deep water vegetations of Lobophora variegata (Phaeophycae) in the coral reef of Curagao: population dynamics in relation to mass mortality of the sea urchin Diadema antillarum

Abstract

Cover, blade size, growth rate, longevity and reproduction of the foliose brown macroalga Lobophora variegata (Lamouroux) Womersley were recorded in 2 deep-water populations (25 to 35 m) in the coral reef of Curaqao (Netherlands Anhlles) for over a year. No seasonal effects were observed. Although mean cover was relatively constant, turnover rates were very high with half-life of blades being, on average, only ca 20d. During ths study the herbivorous sea urchin Diadema a n t i l l a m Philippi suffered mass mortality. The effect of the disappearance of this grazer was evident at one of the 2 locations, where D. antillam densities had been highest, L. vanegata cover lowest and blade sizes smallest. At this station, following D. antillarum mortality, cover and blade size increased significantly and reached a new equilibrium after ca 6 mo.