Tide-related changes of volatile fatty acids in the blood of the lugworm, Arenicola marina (L.)

Abstract

The intertidal lugworm, Arenicola marina, develops a respiratory and metabolic blood acidosis when the oxygen availability is reduced during emersion time at low tide. Measurement of volatile fatty acids in prebranchial blood sampled in the field showed that blood acetate and propionate concentrations increased with length of emersion time. Experimentally confined lugworms excreted acid by-products into the medium when water oxygen tension dropped below 50 Torr (1 Torr = 133.322 Pa) or when oxyhemoglobin concentration fell below 0.45 mmol L⁻¹. A metabolism oriented toward easily excreted end-products may be considered as adaptive in view of the energy yield and the possibility of minimizing metabolic acidosis.