Gravelometer

All individual samplers selected similar-sized substrates (+/- one size class of the gravelometer) at three predetermined locations along a transect (location 1 (chi-sq = 0.72, df = 3, P = 0.87), location 2 (chi-sq = 1.31, df = 3, P = 0.73), location 3 (chi-sq = 7.25, df = 3, P = 0.06); Kruskal-Wallis test, α = 0.016 with Bonferroni correction; Fig 3A ).