Form, function and physics: the ecology of biogenic stabilisation

Abstract

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 Becosystem engineers^and associated discussion of Bniche 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.

The role of microphytobenthos in soft‐sediment ecological networks and their contribution to the delivery of multiple ecosystem services

“…MPB also play a central role in water purification, by influencing the removal, transformation, and retention of pollutants (Kowalski et al, ; Snelgrove et al, ; Tolhurst, Gust, & Paterson, ). MPB mediate sediment dynamics by providing protection against erosion (Paterson, Hope, Kenworthy, Biles, & Gerbersdorf, ), which in turn reduces the resuspension of fine sediments (Tolhurst et al, ) and enhances water clarity. Coastal soft‐sediments also provide important recreational and cultural services, attracting bird watchers, tourists and supporting culturally significant species and habitats that rely on the benthic food web.…”

“…In the 19th century, the naturalist Ernst Haeckel, presented some of the first amazing images of microscopic algae but suggested these organisms, although beautiful, played no significant role within the ecosystem. Perspectives have changed considerably over recent years and it is well recognized that MPB and biofilms contribute substantially to the functioning of coastal soft‐sediments (Miller, Geider, & MacIntyre, ; O'Meara, Hillman, & Thrush, ; Paterson et al, ; Pinckney, ). The functionally important roles of MPB were addressed in two key articles by MacIntyre et al () and Miller et al () who appropriately called MPB biofilms in soft‐sediments ‘The secret garden’.…”

Interactions between sediment microbial ecology and physical dynamics drive heterogeneity in contextually similar depositional systems

“…While MPB community succession can be revealed through the microscopic identification of cells, this is time‐consuming and could be complimented by next generation sequencing of the prokaryote and eukaryote communities for longer‐term studies (Hicks et al 2018). This would provide a more comprehensive microbial community analysis in relation to biostabilization (Paterson et al 2018) as the diversity of prokaryotes has been linked to hydrodynamic regimes (Besemer et al 2009). Such an approach would be incredibly useful for capturing the transformation of sites that are frequently disturbed and dynamic in nature, into more stable muddy habitats over longer timescales.…”

“…These pioneers promote the rapid recolonization of the sediment bed after physical disturbance, instigating a biological succession, which promotes greater biodiversity and heterogeneity in the biofilm and among higher organisms (Balvanera et al 2006). This can pave the way for a more heterogeneous community of microorganisms and a complex habitat that can increase biostabilization (Paterson et al 2018).…”

Assessing Risk of E. coli Resuspension from Intertidal Estuarine Sediments: Implications for Water Quality

“…Biogenic impacts on sediment stability can be sizeable, for example the influence of Nereis diversicolor , a burrowing polychaete which has been reported to both stabilize and destabilize sediments in different environments [48]. Many examinations of the biogenic impacts on sediment stability have been made [17,49], but the accurate determination and modelling of these effects remain hugely challenging due to variation in the relative diversity, abundance and activity of fauna present in intertidal systems, and their wide-ranging and context-dependent burrowing and feeding regimes.…”