Form, function and physics: The ecology of biogenic stabilization

The effect of biological cohesion on the behaviour of sediments is gaining increasing notice. This is partly supported by ecological theory in terms of the role of organisms as “ecosystem engineers” and the associated discussion of “niche construction”, suggesting an evolutionary role for habitat modification by biological action. In addition there is a strong societal and policy drive toward the “ecosystem approach” supporting an integrated examination of the functional roles of biota in selected habitats. In this context the increasing recognition of the importance of biological activity in the mediation the erosion, transport, deposition and consolidation (ETDC) cycle of sediments is important and advances in technology will improve our ability to examine these effect under their natural settings. This will shortly be combined with vastly enhanced molecular tools that will allowthe discrimination of microbial biodiversity and examination of their metabolism contribution to ecosystem function. This may lead to a step-change in our ability to research the influence of microbiota on natural sediment dynamics and opens an exciting era for new interdisciplinary research

Form, function and physics:the ecology of biogenic stabilisation

Purpose:  The objective of this work is to better understand the role that biological mediation plays in the behaviour of fine sediments. This research is supported by developments in ecological theory recognising organisms as “ecosystem engineers” and associated discussion of “niche construction”, suggesting an evolutionary role for habitat modification by biological action. In addition, there is acknowledgement from engineering disciplines that something is missing from fine sediment transport predictions.Materials and methods:  Advances in technology continue to improve our ability to examine the small-scale 2D processes with large-scale effects in natural environments. Advanced molecular tools can be combined with state-of-the-art field and laboratory techniques to allow the discrimination of microbial biodiversity and the examination of their metabolic contribution to ecosystem function. This in turn can be related to highly resolved measurements and visualisation of flow dynamics.Results and discussion:  Recent laboratory and field work have led to a paradigm shift whereby hydraulic research has to embrace biology and biogeochemistry to unravel the highly complex issues around on fine sediment dynamics. Examples are provided illustrating traditional and more recent approaches including using multiple stressors in fully factorial designs in both the laboratory and the field to highlight the complexity of the interaction between biology and sediment dynamics in time and space. The next phase is likely to rely on advances in molecular analysis, metagenomics and metabolomics, to assess the functional role of microbial assemblages in sediment behaviour, including the nature and rate of polymer production by bacteria, the mechanism of their influence on sediment behaviour.Conclusions:  To fully understand how aquatic habitats will adjust to environmental change and to support the provision of various ecosystem services, we require a holistic approach. We must consider all aspects that control the distribution of sediment and the erosion-transport-deposition-consolidation cycle including biological and chemical processes, not just the physical. In particular, the role of microbial assemblages is now recognised as a significant factor deserving greater attention across disciplines