The fine sediment conundrum; quantifying, mitigating and managing the issues

Abstract

Excess fine sediment is a global cause of lotic ecosystem degradation. Despite historic interest in identifying sediment sources and quantifying instream dynamics, tackling fine sediment problems remains a key challenge for river managers and a continued focus of international research. Accordingly, a national meeting of the British Hydrological Society brought together those working on fine sediment issues at the interface of hydrology, geomorphology, and ecology. The resulting collection of papers illustrates the range of research being undertaken in this interdisciplinary research arena, by academic researchers, environmental regulators, landowners, and consultants. More specifically, the contributions highlight key methodological advancements in the identification of fine sediment sources, discuss the complexities surrounding the accurate quantification of riverbed fine sediment content, demonstrate the potential utility of faunal traits as a biological monitoring tool, and recognize the need for improved mechanistic understanding of the functional responses of riverine organisms to excess fine sediment. Understanding and mitigating the effects of fine sediment pressures remains an important and multifaceted problem that requires interdisciplinary collaborative research to deliver novel and robust management tools and sustainable solutions.

Phenotypic plasticity of a Baetid mayfly larvae (Baetis rhodani) at sites with high levels of deposited fine sediment

“…It is, therefore, important that our understanding and management of this pressure is advanced. To achieve this, the mechanisms driving responses from the organism to the community level need to be understood (Mathers et al, 2017).…”

“…It is, therefore, important that our understanding and management of this pressure is advanced. To achieve this, the mechanisms driving responses from the organism to the community level need to be understood (Mathers et al, 2017). While research at the community level is important for monitoring and management approaches, only at the organism level can the specific cause and effects be isolated.…”

Do legacy effects of deposited fine sediment influence the ecological response of drifting invertebrates to a fine sediment pulse?

“…At a global scale, many freshwater ecosystems experience increased fine sediment loadings that impact their ecological functioning and biodiversity (Ormerod et al 2010). Fine sediments (generally defined as inorganic and organic particles < 2 mm in size: Wood and Armitage 1997;Jones et al 2012) can infiltrate into bed substrates and cause streambed colmation/clogging (Mathers et al 2017a;Wilkes et al 2019;McKenzie et al 2020), which can alter macroinvertebrate community structure and functioning (Jones et al 2012;Descloux et al 2013;Wood et al 2016;Mathers et al 2017b). The ecological impacts of fine sediment on macroinvertebrates depends on the magnitude, frequency and duration of fine sediment supply and transport (Evans and Wilcox 2014).…”

Using Continuous Turbidity and Seismic Measurements to Unravel Sediment Provenance and Interaction Between Suspended and Bedload Transport in an Alpine Catchment

“…However, in the past decades, flume experiments (Diplas, 1994; Drummond et al., 2017; Hill et al., 2017; Mooneyham & Strom, 2018) and field observations (Cook et al., 2018; Meunier et al., 2006; Misset, et al., 2019; Misset, Recking, Navratil, et al., 2019; Navratil et al., 2010; Park & Hunt, 2018) have questioned on the consistency of these thresholds for suspended load partitioning. It therefore remains an open scientific question to which extent suspended load interacts with the river bed (Mathers et al., 2017; Vercruysse et al., 2017).…”