Peat-forming mosses grow from their tips and have no roots, removing preservation problems due to bioturbation
that may be found in forests or areas with woody or herbaceous vegetation.
However, modeling of bioturbation
(the mixing of sediment by action of the macrobiota--worms, clams, etc.
The extent of bioturbation
by benthic invertebrates in freshwater is typically found to be 2-5 cm (McCall and Tevesz 1982, Cohen et al.
After 1,000 years of tropical bioturbation
, we can only speculate on the size and efficacy of the original structures.
Echols (1972) noted evidence of enrichment by winnowing, cessation of sedimentation, and washing together of scattered material by water movements, as well as bioturbation
as possible causes of the fossil concentration.
Their dark colour, general absence of bioturbation
and organic content are evidence of oxygen deficient water conditions during deposition (Kauffman and Sageman, 1990; Flugel, 2004).
possible role of particulate shuttles, position and stability of the chemocline in the enrichment environment, influence of microbial mediation, bioturbation
, ripple marks and mudcracks are observed in Mianwali Formation, while cross bedding is dominant in the overlying Tredian Formation.
Fragmentation is generally due to shrink-swell behaviour or bioturbation
, and in some cases to salt crystallisation (Kuhn et al.
Restoration efforts may be hindered by resource competition and bioturbation
from native crustaceans such as burrowing shrimp (Neotrypaea californiensis and Upogebia pugettensis), which have been shown to have an indirect negative effect on oyster survival and growth (Feldman et al.
We conclude that the Taukihepa result is unaffected by bioturbation
According to Bromley (1990), an assemblage is the basic objective term that embraces all the trace fossils occurring within a single rock unit (single bed, bed couplet, or recurrent interbeds) irrespective of whether of not the traces were produced simultaneously or as temporally separate bioturbation