A Horizontal Intragravel Pipe for Sampling Water Quality in Salmonid Spawning Gravel

Abstract

A new sampler, the horizontal intragravel pipe, was developed for collecting samples ofintragravel water in salmonid spawning gravel. The device is a 2.54 x 76.2-cm length of slotted polyvinyl chloride pipe that is buried perpendicular to flow in the streambed. The slots (about 320/pipe) through which the intragravel water flows were cut perpendicular to the long axis of the pipe. Each slot is 1.9 cm long by 0.15 mm wide. A rigid plastic tube (0.64 cm inside diameter) centered axially within the intragravel pipe is perforated with three 3.2-mm holes equally spaced along its length to distribute equally the effect of pumping. The interior tube is connected by Tygon tubing to a peristaltic pump on a platform above the water surface. Intragravel water is pumped to containers for on-site measurement of dissolved oxygen, pH, and specific conductance, and for determination of other constituents in the laboratory. The principal advantages of a horizontal intragravel pipe are that a substantial quantity of water can be withdrawn for analysis, and samples of water may be integrated across an artificial redd.

Habitat quality of historic Snake River fall Chinook salmon spawning locations and implications for incubation survival. Part 2: intra-gravel water quality

“…At each sampling location we constructed groups of four redds in close proximity to each other, and referred to them as redd clusters (Figure 3). During construction of the simulated redds, an intra-gravel water sampling probe, similar to that described by Hoffman (1986), Burton et al (1990), Maret et al (1993), andSoulsby et al (2001), was buried horizontally in the redds, within the area associated with the egg pocket, at approximately 0.25 m depth relative to normal river bed level (Figure 4). At each redd cluster, at least one piezometer was placed in nearby undisturbed substrate.…”

Field Testing of New Monitoring Protocols to Assess Brown Trout Spawning Habitat in an Idaho Stream

“…Intragravel dissolved oxygen was monitored with a sampling device similar to that described by Hoffman (1986). In this study, IGDO was defined as the oxygen concentration in the interstitial water collected from 10-20 cm below the streambed surface, the approximate depth of the buried eggs.…”

“…Bjornn and Reiser (1991), in their comprehensive summary of the literature, indicated the lack of data available for the egg pocket or spawning redd. The intragravel technique used by Hoffman (1986) appears to be an effective method to measure IGDO in the natural incubation environment. Burton et al (1990) developed measures of salmonid egg incubation success in relation to fine sediment accumulation in artificial redds.…”

“…Their technique has been tested by Burton et al (1990) and King and Thurow (1991), who indicated that although the exact morphology of natural redds is difficult to mimic, IGDO concentrations, temperatures, and fine sediments in artificial redds were not significantly different from those in nearby natural redds. This paper describes a comprehensive field procedure that integrates the methods of Hoffman (1986) and Burton et al (1990) to assess and monitor the effects of sediment on salmonid spawning. We measured the survival of brown trout embryos in relation to the proportion of fine sediment in the substrate and IGDO.…”

The sedimentation of salmonid spawning gravels in the Hampshire Avon catchment, UK: implications for the dissolved oxygen content of intragravel water and embryo survival

“…Samples of intragravel water were extracted from the artificial redds, using a modified version of the intragravel water sampling technique described by Hoffman (1986). The technique involved installing a horizontal sampling pipe ( Figure 3) at a depth of approximately 25 cm in the centre of an artificial redd tailspill and perpendicular to the direction of flow, so that only the top of the vertical access tube remained above the redd surface.…”