Vertical distribution of gymnamoebae (rhizopoda, lobosea) in the top layer of brackish-water sediments.

The paper reports on the distribution of amoebae in a vertical slice of sandy sediment from the brackish-water Nivå Bay (Baltic Sea, The Sound). The 24 x 20 mm slice 2 mm in thickness was gently cut from the top of sediment to a depth of 20 mm using coverslips, and further sectioned into 2 x 2 x 2 mm cubes. Each cube was inoculated into enrichment media to reveal the biodiversity of amoebae. The map of amoebae species distribution in the slice was drawn and analyzed. The results show patchy distributions of many amoebae species. Amoebae tend to form a band of maximum diversity within the depth interval 2-16 mm. Two mini-cores of sediment located close to the butt-ends of the slice were collected using cut 1 ml syringes. They were sliced and inoculated to reveal the biodiversity of amoebae at different depths. The distribution patterns of amoebae in the mini-cores were similar to the ones obtained in the slice, and show evident patchiness of some species. It seems that abundant species mostly form irregular patches 1-2 cm across, whereas many species are rare and appear in few number of specimens or in patches smaller than 2 mm.