Direct and indirect effects of sediment pulse duration on stream invertebrate assemblages and rainbow trout (Oncorhynchus mykiss) growth and survival

• Published in: Canadian journal of fisheries and aquatic sciences 2001-11, Vol.58 (11), p.2213-2221
• Main Authors: Shaw, E Al, Richardson, John S
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Creeks & streams; Fish; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; Invertebrates; Oncorhynchus mykiss; Physical growth; Salmon; Sediments; Synecology; Trout
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f01-160

Elevated concentrations of inorganic sediment supply in streams may impair many biological functions. However, the contribution of exposure duration to the observed impacts has not been previously considered. We evaluated the effects of sediment pulse duration using 14 streamside flow-through experimental channels, each of which contained a naturally colonised invertebrate assemblage and 10 rainbow trout (Oncorhynchus mykiss) fry. Channels were exposed to fine sediment pulses of constant concentration but varied pulse duration (ranging from 0 to 6 h) every second day over 19 days. Total abundance of benthic invertebrate and family richness declined as sediment pulse duration increased. Invertebrate drift total abundance increased as pulse duration increased; however, family richness of drift decreased. Trout length and mass gain over the 19-day period was negatively correlated with pulse duration. Path analysis suggests that the direct effects of fine sediment on trout (impaired vision leading to reduced prey capture success and (or) increased metabolic costs from physiological stress) are more important to trout growth than indirect effects (decreased drift and benthic invertebrate richness and drift abundance).