Habitat Use by the Eastern Sand Darter, <em>Ammocrypta pellucida</em>, in Two Lake Champlain Tributaries

Abstract

O'Brien, Shannon M., and Douglas E. Facey. 2008. Habitat use by the Eastern Sand Darter, Ammocrypta pellucida, in two Lake Champlain tributaries. Canadian Field-Naturalist 122(3): 239-246.The Eastern Sand Darter (Ammocrypta pellucida) is endangered or threatened throughout much of its range, which includes the St. Lawrence-Lake Ontario drainage of southern Ontario and Quebec and several Vermont tributaries of Lake Champlain. The species is known for its tendency to burrow, and field observations have suggested that habitat use may depend on substrate particle size. To determine whether Eastern Sand Darter densities were correlated with substrate particle size, fish and substrates were sampled in 156 plots in two Vermont rivers during the summers of 2001 and 2002. The Eastern Sand Darter occurred mainly in areas in which substrate composition was over 45% fine to medium sand (0.24-0.54 mm); they were much less abundant in areas in which substrate composition exceeded 25% particles greater than 1.9 mm. Substrate preference was tested by allowing 49 fish kept in aquaria to choose among four different substrates. The fish showed a significant preference (P<0.005) for the finer substrate categories (0.24-0.54 mm, 0.55-1.0 mm), and mostly avoided the coarser substrates (1.0-1.9 mm, 2.0-4.1 mm). This suggests that the Eastern Sand Darter is selective regarding substrate composition, and therefore might be affected by fluctuations or changes in substrate composition within its habitat, such as those caused by changes in flow.

Effect of substrate size on sympatric sand darter benthic habitat preferences

“…In general, western sand darters selected for a narrower range of substrate sizes compared to the eastern sand darter, and habitat use overlap occurred most often in the medium sand category. This study was contingent upon five designated substrate types that were similar to previous sand darter habitat use studies (Daniels 1993;O'Brien & Facey 2008) and represented a range of benthic habitats both species may encounter (Welsh & Perry 1998;Facey & O'Brien 2004;Tessler et al 2012). Habitat use in the field could vary compared to the aquaria-based study, but our results demonstrated that each sand darter species exhibited nonrandom selection of substrate types, indicating that a certain benthic habitat was preferred compared to the other available sizes.…”

“…The western and eastern sand darters mean total length was 52.7 mm (SD 2.30 mm) and 56.9 mm (3.24 mm), respectively. For collection, a straight 1.5 £ 3 m seine with 3 mm mesh was used in wadable areas of the river, including upstream and downstream parallel seine hauls and perpendicular hauls pulled into shore (O'Brien & Facey 2008;Driver & Adams 2013). Sampling for the sand darters occurred during the fall because the Elk River experiences lower flows (i.e.…”

“…The sand for the substrate trials was sifted using a Gilson 20.3 cm (8 in) sieve Shaker (115 V/60 Hz) with US Standard brass sieves. Finer substrate was not used since particles smaller than fine sand may not remain settled due to fish activity and current from the water filter (O'Brien & Facey 2008).…”

“…In the field and laboratory setting, eastern sand darters exclusively associated with sand substrates, while water velocity, depth, and distance from the bank had little to no effect on the distribution of individuals (Daniels 1993). Laboratory studies that investigated eastern sand darter substrate use reported that individuals generally used medium (0.25-0.5 mm) sized particles (Daniels 1993;O'Brien & Facey 2008). Furthermore, field surveys revealed that the species was commonly detected in sand comprised of fine to medium (0.12-0.5 mm) particles, while few individuals were detected in areas where the particle size was larger than 1.0 mm (Facey & O'Brien 2004;Tessler et al 2012;Dextrase et al 2014).…”

“…Sand darters are habitat specialists and thus sensitive to habitat alterations, which is why both species are often valued as indicators of ecosystem integrity (Grandmaison et al 2004;Drake et al 2008). Habitat use and sand grain size preference is well documented for the eastern sand darter (Daniels 1993;Facey & O'Brien 2004;Drake et al 2008;O'Brien & Facey 2008;Tessler et al 2012;Dextrase et al 2014), but literature pertaining to the western sand darter is sparse, and little information is available from areas where the two species are sympatric.…”