COMPARATIVE-STUDIES OF INTEGUMENTARY UPTAKE OF SHORT-CHAIN CARBOXYLIC-ACIDS BY FRESH-WATER OLIGOCHAETES

1. Freshwater oligochaetes can take up considerable amounts of acetate and propionate (short-chain, volatile fatty acids, VFA) from artificial tap water at concentrations of 50-3000 muM. 2. Four species of oligochaetes which are studied in this paper, Tubifex tubifex, Limnodrilus hoffmeisteri, Iliodrilus templetoni (Tubificidae) and Lumbriculus variegatus (Lumbriculidae) differ considerably in their mechanisms of VFA uptake as well as in the absolute amounts absorbed. 3. In T. tubifex, acetate and propionate uptake results from a combination of saturable (mediated) and nonsaturable (diffusional) transport, Both, L. hoffmeisteri and I. templetoni take up acetate by a mediated transport system, whereas propionate is absorbed passively, In L. variegatus, no evidence for a mediated transport system is found. 4. The relevance of the results to the biochemical ecology of the freshwater oligochaetes is discussed.