Water transport, respiration and energetics of three tropical marine sponges

Abstract

The rates of water transport and respiration of three tropical marine demosponges Mycale sp., Tethya crypta (de Laubenfels), and Verongia gigantea (Hyatt), have been determined in natural field populations. Mycale maintains high rate of transport (0.27-0.21 cm 3 water/cm 3 sponge/sec), high transport efficiency (19.6 1/cm 3 O 2), high metabolic rate, but low ecological impact due to its relatively low population density. This species conforms to the definition of an opportunistic eurytopic generalist in all of its characteristics. Tethya crypta exhibits a moderate transport rate (0.18 cm 3 water/cm 3 sponge/sec), but because of behavioural complexity and narrow adaptations to a sporadically unstable habitat its mean effective rate over the year is only 0.044 cm 3 water/cm 3 sponge/sec. The species shows high transport efficiency 22.8 1/cm 3 O 2, low metabolic rate, and high ecological importance within its special shallow-water habitat. Tethya is characterized as a stenotopic specialist in its population attributes. Verongia gigantea consists of a tripartite community: sponge-bacteria-polychaete. It shows a low transport rate (0.100.05 cm 3 water/cm 3 sponge/sec), low efficiency, low metabolic rate but high ecological importance due to large, persistant standing crop within its narrow deepwater habitat, and the complex is also characterized as a stenotopic specialist. Energy budgets indicate that the two ‘pure’ sponges have no requirement for a dissolved food source. The Verongia complex must obtain at least 70 % of its food requirements from nonparticulate materials. The total activity of the rich sponge fauna of the deep Jamaican reefs is estimated in relation to coral/zooxanthellae production of organic matter.