Burrows of marine nematodes as centres for microbial growth

Six free-living marine nematode species (Diplolaimella ocellata, Diplolaimelloides deconincki, Geomonhystera disjuncta, Daptonema riemanni, Sabatieria pulchra and Enoplus communis) have been isolated from different localities and microhabitats. They all make sinusoidal burrows when moving in agar. In laboratory experiments, at normal and low (ca. 5% atm. sat.) oxygen tensions, bacteria and the ciliate Uronema subsequently colonized the burrows. The addition of nematodes to a patch of agar with bacteria stimulated bacterial growth and burrows made by nematodes expanded the available space for a microbial colonization in an otherwise sterile agar. The observations are discussed in relation to bioturbative effects caused by interstitial nematodes affecting pore water chemistry and decomposition of organic matter in the sea bed.