Effect of substrate size on sympatric sand darter benthic habitat preferences

Figures & data

Figure 1. Map of the lower 190 rkm of the Elk River watershed shaded by elevation below the dam (black rectangle) in Sutton, WV, USA. Western sand darters have been detected from Mink Shoals to Clendenin and eastern sand darters have been detected from Mink Shoals to Frametown. The black circles represent the three sand darter collection locations.

Table 1. Substrate selection ratio estimates and the Bonferroni confidence intervals for the western sand darter only aquaria and combined species aquaria. Selection ratio values > 1 indicate selection, while values < 1 indicate avoidance. An asterisk * indicates significant selection or avoidance.

Substrate type	Selection ratio	Lower CI	Upper CI
Western sand darter (single species aquaria)
Fine sand	0.81	0.532	1.078
Medium sand	1.10	0.798	1.408
Coarse sand	1.31	0.992	1.628
Very coarse sand	0.78	0.513	1.051
Western sand darter (sympatric aquaria)
Fine sand	0.64	0.287	0.985*
Medium sand	1.27	0.827	1.719
Coarse sand	1.55	1.079	2.011*
Very coarse sand	0.55	0.218	0.872*
Eastern sand darter (sympatric aquaria)
Fine sand	1.33	0.872	1.794
Medium sand	1.38	0.915	1.847
Coarse sand	1.05	0.618	1.478
Very coarse sand	0.24	0.007	0.469*

Table 2. Pairwise comparison with Bonferroni confidence intervals for the western sand darter only and combined species aquaria. An asterisk * indicates significant selection. The substrate categories used for the study included fine sand (FS), medium sand (MS), coarse sand (CS), and very coarse sand (VCS).

Substrate comparison	Lower CI	Upper CI	p Value
Western sand darter (single species aquaria)
CS vs. FS	−0.039	1.032	0.080
CS vs. MS	−0.349	0.722	1.000
FS vs. MS	−0.846	0.226	0.710
CS vs. VCS	−0.002	1.069	0.051
FS vs. VCS	−0.498	0.573	1.000
MS vs. VCS	−0.188	0.883	0.489
Western sand darter (sympatric aquaria)
CS vs. FS	0.263	1.496	0.002*
CS vs. MS	0.275	0.892	1.000
FS vs. MS	−0.504	0.012	0.058
CS vs. VCS	0.978	1.594	<0.01*
FS vs. VCS	0.098	0.714	1.000
MS vs. VCS	0.702	1.318	0.017*
Eastern sand darter (sympatric aquaria)
CS vs. FS	−0.948	0.565	1.000
CS vs. MS	−1.043	0.470	1.000
FS vs. MS	−0.852	0.661	1.000
CS vs. VCS	0.135	1.647	0.013*
FS vs. VCS	0.226	1.838	0.001*
MS vs. VCS	0.421	1.934	<0.01*

Figure 2. Western sand darter only experiment (A), western sand darters from the combined aquarium (B), eastern sand darters from the combined aquaria (C), and combined selection results (D). Values above the dashed line at 1 indicate selection and values below indicate avoidance. Bonferroni 95% confidence intervals that do not contain the value of 1 are statistically significant.