Metabolism of an Antarctic solitary coral, Flabellum impensum

Few physiological or behavioral studies have been undertaken on the genus Flabellum, particularly on Antarctic species. The present study characterizes the metabolism of the endemic Antarctic coral F. impensum, one of the world's largest solitary corals, with measurements of oxygen consumption rate and metabolic enzyme activity. F. impensum had a low rate of oxygen consumption at 0 °C, ranging from 0.06 to 0.64 μmol O2 g− 1 h− 1 and averaging 0.31 μmol O2 g− 1 h− 1, calculated using tissue wet mass. Ammonium excretion averaged 4.21 nmol NH4+ gwm− 1 h− 1 (range: 0.54-13.99 nmol NH4+ gwm− 1 h− 1). The activity values of the metabolic enzymes citrate synthase (CS), malate dehydrogenase (MDH), and lactate dehydrogenase (LDH) fell within the normal range expected for a cnidarian, averaging 0.13 (range: 0.04-0.32), 1.01(range: 0-3.51), and 0.42 (range: 0.18-0.99) activity units (U) gwm− 1, respectively. Skeletal density averaged 22% more than the density of pure aragonite and a count of the growth bands on the calyx suggests that this species has a linear extension rate of approximately 1 mm per year. F. impensum is a long-lived, slow-growing coral, with a low metabolic rate.