A field method for the concurrent measurement of fine sediment content and embryo survival in artificial salmonid redds

Abstract

The infiltration cube method presented in this paper allows concurrent field measurement of fine sediment content and embryo survival in an incubating environment reproducing, as closely as possible, the morphology and grain size composition of a natural salmonid redd. An infiltration cube is made up of a rectangular (30 cm square and 20 cm high) steel frame with no walls, which has a folded plastic bag attached to its base. Each infiltration cube is buried in the substrate using a procedure aimed at reproducing, as closely as possible, the construction and morpho-sedimentological structure of a natural salmonid redd. Using a tripod installed on the river bed or at the surface of the ice, the infiltration cube method provides a quick, easy and robust way to pull relatively large samples (approximately 65 kg) out of underwater substrate even during tough winter field conditions. The absence of walls on the cube also precludes bias in infiltration rates by both allowing lateral sediment transport within substrate and preventing loss of fine particles during retrieval from underwater.

Effects of silt and very fine sand dynamics in Atlantic salmon (Salmo salar) redds on embryo hatching success

“…Using the method described in Levasseur et al (2006), each artificial redd consisted of an infiltration cube containing a known amount of fertilized eggs and buried in a morpho-sedimentological unit resembling a salmon redd. The infiltration cube method is a modification of the infiltration bag sampling method described by Lisle and Eads (1991).…”