Differences Found in the Macroinvertebrate Community Composition in the Presence or Absence of the Invasive Alien Crayfish, Orconectes hylas.

Introductions of alien species into aquatic ecosystems have been well documented, including invasions of crayfish species; however, little is known about the effects of these introductions on macroinvertebrate communities. The woodland crayfish (Orconectes hylas (Faxon)) has been introduced into the St. Francis River watershed in southeast Missouri and has displaced populations of native crayfish. The effects of O. hylas on macroinvertebrate community composition were investigated in a fourth-order Ozark stream at two locations, one with the presence of O. hylas and one without. Significant differences between sites and across four sampling periods and two habitats were found in five categories of benthic macroinvertebrate metrics: species richness, percent/composition, dominance/diversity, functional feeding groups, and biotic indices. In most seasons and habitat combinations, the invaded site had significantly higher relative abundance of riffle beetles (Coleoptera: Elmidae), and significantly lower Missouri biotic index values, total taxa richness, and both richness and relative abundance of midges (Diptera: Chironomidae). Overall study results indicate that some macroinvertebrate community differences due to the O. hylas invasion were not consistent between seasons and habitats, suggesting that further research on spatial and temporal habitat use and feeding ecology of Ozark crayfish species is needed to improve our understanding of the effects of these invasions on aquatic communities

Statistical significance (Pr > F values) for interaction terms from analysis of site differences in metric values (non-parametric nested ANOVA, α = 0.05) for Crane Pond Creek, Iron County, Missouri, USA.

<p>Macroinvertebrates sampled in two habitats during four time periods in 2011. Metric abbreviations are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150199#pone.0150199.t001" target="_blank">Table 1</a>. NS = not significant, P = Sampling Period (season), H = Habitat, S = Site.</p

Sampling locations on Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Sampling locations on Crane Pond Creek, Iron County, Missouri, USA in 2011.</p

Percent (%) Chironomidae of macroinvertebrate communities sampled during four periods in two habitats at Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Bars represent mean and range of n = 3 samples, with ± 1 S.E. Habitats: CS = coarse substrate, NF = non-flow, HP = both habitats pooled. * = significant differences detected between sites.</p

Missouri Biotic Index of macroinvertebrate communities sampled during four periods in two habitats at Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Bars represent mean and range of n = 3 samples, with ± 1 S.E. Habitats: CS = coarse substrate, NF = non-flow, HP = both habitats pooled. * = significant differences detected between sites.</p

Statistical significance (Pr> │+│from ANOVA, α = 0.05) in macroinvertebrate metrics between Site 1 (invaded) and Site 2 (control) in two habitats sampled from Crane Pond Creek, Iron County, Missouri, USA in Summer 2011.

<p>Metric abbreviations are defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150199#pone.0150199.t001" target="_blank">Table 1</a>. NS = Not Significant.</p

List of macroinvertebrate metrics, references, abbreviations, metric categories and predicted responses to increasing perturbation at biological sampling sites in 2011 at Crane Pond Creek, Iron County, Missouri, USA.

<p>List of macroinvertebrate metrics, references, abbreviations, metric categories and predicted responses to increasing perturbation at biological sampling sites in 2011 at Crane Pond Creek, Iron County, Missouri, USA.</p

Statistical significance (Pr> │+│from ANOVA, α = 0.05) in macroinvertebrate metrics between Site 1 (invaded) and Site 2 (control) in two habitats sampled from Crane Pond Creek, Iron County, Missouri, USA in Late Summer 2011.

<p>Metric abbreviations are defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0150199#pone.0150199.t001" target="_blank">Table 1</a>. NS = Not Significant.</p

Total Taxa Richness of macroinvertebrate communities sampled during four periods in two habitats at Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Bars represent mean and range of n = 3 samples, with ± 1 S.E. Habitats: CS = coarse substrate, NF = non-flow, HP = both habitats pooled. * = significant differences detected between sites.</p

Percent (%) EPT (Ephemeroptera; Plecoptera; Trichoptera) of macroinvertebrate communities sampled during four periods in two habitats at Crane Pond Creek, Iron County, Missouri, USA in 2011.

<p>Bars represent mean and range of n = 3 samples, with ± 1 S.E. Habitats: CS = coarse substrate, NF = non-flow, HP = both habitats pooled. * = significant differences detected between sites.</p