An evaluation of alternative procedures using the Bou-Rouch method for sampling hyporheic invertebrates

This study assesses the influence of well design, pumping rate, and sample volume on hyporheic invertebrate density and richness estimates in three st reams differing in sediment composition. A comparison of five well designs, i.e., temporary wells with no pores and with 4-, 6-, and 8-mm pores along the lower 15 cm and permanent wells with 6-mm pores, revealed no significan t differences in either total invertebrate densities or taxon richness. Pum ping rates, i.e., 1.5 versus 4 L.min(-1), significantly affected density es timates at two streams and taxon richness at one of the three streams, show n by higher values at the faster pumping rate. A comparison of five sample volume sizes, i.e., 0.5, 1.0, 1.5, 2.0, and 2.5 L, indicated that smaller s ample volumes produced significantly higher estimates of density, while lar ger sample volumes gave significantly higher estimates of taxon richness. T hese results underscore the importance of maintaining consistent pumping ra tes and sample volume sizes throughout the course of a study.