Metabolism of two dominant epibenthic echinoderms measured at bathyal depths in the Santa Catalina Basin

Abstract

Metabolism of two abundant echinoderm species constituting 99.6% of the epibenthic megafauna in the Santa Catalina Basin, off southern California, USA was measured at 1 300 m during the 1979 “Bathyal Expedition”. Specimens of the ophiuroid Ophiophthalmus normani and the holothurian Scotoplanes globosa, collected by the submersible “Alvin”, were individually placed in respirometers, and measured in situ for O2 consumption and ammonium excretion rates. For O. normani, weight-specific O2 consumption rates decreased with increasing weight and were of comparable magnitude to rates of deep-sea and shallow-water ophiuroids; excretion rates were highly variable. Population O2 consumption and excretion rates for O. normani (estimated from size-frequency distribution, abundance, and rate regression equations) were 1 129.28 μl O2 m-2 h-1 and 27.30 nmol NH 4 + m-2 h-1. Weight-specific O2 consumption and ammonium excretion rates of S. globosa decreased with increasing weight and were of comparable magnitude to rases of shallow-water holothurians. Population O2 constimption and excretion rates of S. globosa were 1.38 μl O2 m-2 h-1 and 4.86 nmol NH 4 + m-2 h-1. Combined population O2 consumption rates for O. normani and S. globosa are of comparable magnitude to that of the sediment community and plankton in the benthic boundary layer (sediment and overlying 50 m water column) of the Santa Catalina Basin.