Tubificoides benedii (Tubificidae, Oligochaeta) — a pioneer in hypoxic and sulfidic environments. An overview of adaptive pathways

Abstract

Eutrophic tidal flats and polluted coastal sites are the predominant habitat of the marine oligochaete Tubificoides benedii. The worms live in dense populations in these stressed habitats which are often characterized by high levels of hydrogen sulfide. This indicates that they have a high capacity to tolerate anoxic (and sulfidic) conditions. Respiration rates of T. benedii measured at various oxygen concentrations showed that aerobic respiration is maintained even at very low oxygen concentrations. This ability is combined with a high regulatory capacity of oxygen uptake. Addition of sulfide considerably reduced this capacity of maintaining aerobic metabolic pathways at low oxygen concentrations. The present work in relation to earlier physiological and structural studies (Giere et al, 1988; Dubilier et al., 1994, 1995, 1997) suggests adaptive strategies that make T. benedii one of the most successful inhabitants of ecologically stressed, sulfidic benthic environments. This is corroborated by comparison with other typical’ sulfide annelids’ such as the polychaetes Capitella capitata and Arenicola marina.