Louisiana Waterthrush and Benthic Macroinvertebrate Response to Shale Gas Development

Abstract

Because shale gas development is occurring over large landscapes and consequently is affecting many headwater streams, an understanding of its effects on headwater-stream faunal communities is needed. We examined effects of shale gas development (well pads and associated infrastructure) on Louisiana waterthrush Parkesia motacilla and benthic macroinvertebrate communities in 12 West Virginia headwater streams in 2011. Streams were classed as impacted (n = 6) or unimpacted (n = 6) by shale gas development. We quantified waterthrush demography (nest success, clutch size, number of fledglings, territory density), a waterthrush Habitat Suitability Index, a Rapid Bioassessment Protocol habitat index, and benthic macroinvertebrate metrics including a genus-level stream-quality index for each stream. We compared each benthic metric between impacted and unimpacted streams with a Student's t-test that incorporated adjustments for normalizing data. Impacted streams had lower genus-level stream-quality index scores; lower overall and Ephemeroptera, Plecoptera, and Trichoptera richness; fewer intolerant taxa, more tolerant taxa, and greater density of 0–3-mm individuals (P ≤ 0.10). We then used Pearson correlation to relate waterthrush metrics to benthic metrics across the 12 streams. Territory density (no. of territories/km of stream) was greater on streams with higher genus-level stream-quality index scores; greater density of all taxa and Ephemeroptera, Plecoptera, and Trichoptera taxa; and greater biomass. Clutch size was greater on streams with higher genus-level stream-quality index scores. Nest survival analyses (n = 43 nests) completed with Program MARK suggested minimal influence of benthic metrics compared with nest stage and Habitat Suitability Index score. Although our study spanned only one season, our results suggest that shale gas development affected waterthrush and benthic communities in the headwater streams we studied. Thus, these ecological effects of shale gas development warrant closer examination.

Molecular analysis of nestling diet in a long-distance Neotropical migrant, the Louisiana Waterthrush (Parkesia motacilla)

“…Despite the frequent detection of Lepidoptera in nestling diet, previous studies have convincingly demonstrated that Louisiana Waterthrush respond negatively to reductions in EPT availability (Mattsson and Cooper 2006, Mulvihill et al 2008, Wood et al 2016. EPT taxa are also reliable indicators of overall riparian quality (Hilsenhoff 1977, Barbour et al 1999) and reflect several factors that impact the suitability of waterthrush breeding territories (e.g., bank erosion, anthropogenic land use, and stream order; Brooks et al 1998, Prosser and Brooks 1998, Mattsson and Cooper 2006.…”

“…Regardless, the frequency of occurrence of a single family of Ephemeroptera (Heptageniidae) in waterthrush nestling fecal samples (60%) is particularly interesting because it contains several of the most pollution-sensitive aquatic insects in eastern North America (Barbour et al 1999). Reliance on Heptageniidae raises considerable conservation concern as anthropogenic impacts to water quality continue throughout the Louisiana Waterthrush breeding range (Drohan et al 2012, Wood et al 2016.…”

“…Waterthrush that nest along degraded streams with suboptimal water quality must establish larger territories to acquire sufficient prey resources (Mulvihill et al 2008), and they lay smaller, delayed clutches (Mulvihill et al 2008) and rarely attempt a second brood ). These negative impacts on Louisiana Waterthrush are believed to be the result of reductions in the availability of 3 orders of pollution-sensitive aquatic insects used as biological indicators for stream quality: Ephemeroptera, Plecoptera, and Trichoptera (EPT; Mattsson and Cooper 2006, Mulvihill et al 2008, Wood et al 2016. Previous studies have suggested that EPT taxa are important prey for Louisiana Waterthrush (Mattsson et al 2009) because they were found in the gut contents of 15 individuals in the only published description of waterthrush diet (Eaton 1958).…”

Demographic, Spatial, and Epigenetic Response of the Louisiana Waterthrush (Parkesia Motacilla) to Shale Gas Development

“…We developed a set of 7 a priori candidate models [58] that we hypothesized might influence DSR of waterthrush nests based on the results of Wood et al [29] and Frantz et al [28]. All covariates are defined in Appendix Table 2.…”

“…Our follow-up study was able to establish how shale gas alterations to riparian habitat quality and the food web can lead to potential effects at a higher trophic level in an apex predator. By also documenting waterthrush demography decline (Table 1, [28]) and shifts in aquatic prey community structure ( [29]; G.…”