Environmental studies on natural halogen compounds. I Estimation of biomass of the acorn wormPtychodera flava Eschscholtz (Hemichordata: Enteropneusta) and excretion rate of metabolites at Kattore Bay, Kohama Island, Okinawa.

In order to study the environmental significance of the acorn wormPtychodera flava, which excretes a copious amount of halogenated metabolites, the biomass and the excretion rate were estimated at Kattore Bay, Kohama Island, Okinawa. The habitat, which extends over 1 km(2), could be divided into two areas: zone A, 3.0 × 10(5)m(2), density 95.6/m(2); and zone B, 7.2 × 10(5) m(2), density 48.8/m(2), according to the densities. The total population was estimated to be 6.4 × 10(7) ± 2.0 × 10(7) individuals or 93.0 ± 28.9 tons. These worms daily excrete about 480 tons of fecal sand which was estimated to contain 43 kg of the material extractable with organic solvents. The material contained halogenated metabolites which showed antimicrobial activity.