Biological Effects of Fine Sediment in the Lotic Environment

Abstract

/ Although sedimentation is a naturally occurring phenomenon inrivers, land-use changes have resulted in an increase in anthropogenicallyinduced fine sediment deposition. Poorly managed agricultural practices,mineral extraction, and construction can result in an increase in suspendedsolids and sedimentation in rivers and streams, leading to a decline inhabitat quality. The nature and origins of fine sediments in the loticenvironment are reviewed in relation to channel and nonchannel sources andthe impact of human activity. Fine sediment transport and deposition areoutlined in relation to variations in streamflow and particle sizecharacteristics. A holistic approach to the problems associated with finesediment is outlined to aid in the identification of sediment sources,transport, and deposition processes in the river catchment. The multiplecauses and deleterious impacts associated with fine sediments on riverinehabitats, primary producers, macroinvertebrates, and fisheries are identifiedand reviewed to provide river managers with a guide to source material. Therestoration of rivers with fine sediment problems are discussed in relationto a holistic management framework to aid in the planning and undertaking ofmitigation measures within both the river channel and surrounding catchmentarea.KEY WORDS: Sedimentation; Fine sediment; Holistic approach; Ecologicalimpact; River restoration

Changing climate and nutrient transfers: Evidence from high temporal resolution concentration-flow dynamics in headwater catchments

“…Phytobenthos (an ecological indicator under WFD) demonstrates that these periods of lower phosphorus standards are associated with lower ecological status (Snell et al, 2014). Under the WFD, there are no accepted targets for turbidity or suspended sediment in rivers, although the need for targets which consider the relationship between sediment pressures and ecological condition (Wood and Armitage, 1997) has been identified Collins et al, 2011). The annual mean SS concentration was 9.5 mg L −1 , with a concentration of 25 mg L −1 exceeded for 6% of the year, during storm events.…”

Diversidad de insectos acuáticos en quebradas impactadas por agricultura y minería, Caldas, Colombia

“…Estos resultados concuerdan con lo reportado por varios autores, donde se reiteran los efectos adversos de la agricultura sobre los ecosistemas acuáticos y la diversidad (Maloney & Weller, 2011;Piggott et al, 2012;Chará-Serna et al, 2015), y de la importancia de la vegetación ribereña CUADRO 1 Morfoespecies dominantes entre tipos de impacto para el mantenimiento de una mayor diversidad al interior de los ecosistemas acuáticos (Subramanian, Sivaramakrishnan, & Gadgil, 2005). La diversidad de insectos acuáticos puede estar determinada por la disponibilidad de recursos al interior del cauce, las caracterís-ticas fisicoquímicas e hidrológicas (Ramírez & Viña, 1998) y el tiempo de exposición al impacto (Wood & Armitage, 1997). La presencia de vegetación ribereña provee mejores condiciones al interior de las quebradas, proporcionando mayor disponibilidad de recurso (refugio y alimento) para los insectos acuáticos (Subramanian et al, 2005), ya que ofrece alimento para muchos organismos y las raíces protegen al suelo de la erosión, y mantienen la integridad del cauce (Naiman, Décamps, & McClain, 2005), lo cual explicaría que las quebradas impactadas por minería (con presencia de vegetación ribereña) sustentan una mayor diversidad y composición de insectos acuáticos, similar a las quebradas de referencia, con respecto a las de la zona agrícola.…”

“…Adicionalmente, el efecto del impacto sobre las comunidades puede estar determinado por el tiempo de uso del suelo y de recuperación del impacto (Wood & Armitage, 1997). En este estudio, la agricultura se ha llevado a cabo por ~90 años y la minería ~50 años (com.…”

“…Todos estos factores pueden incrementar el pH, la conductividad eléctrica y los sólidos disueltos totales (Palmer et al, 2010) al interior de los ríos y quebradas. Por otro lado, el tiempo de uso del suelo y la ubicación con respecto al impacto en cada localidad, hace que la perturbación tenga un nivel de impacto variable (Wood & Armitage, 1997).…”

Influence of environmental variables on stream fish fauna at multiple spatial scales

“…Land use changes, such as agriculture, remove riparian vegetation and decreases bank stabilization thereby increasing sedimentation. Sedimentation reduces stream depth heterogeneity, leading to decreased species diversity (Wood & Armitage, 1997;Sutherland et al, 2002). Therefore, those patterns and processes operating at local and regional scales play an important role in determining stream fish assemblage structure and complexity (Matthews, 1998), and both are affected by human activities.…”