Defining the Reference Condition for Wadeable Streams in the Sand Hills Subdivision of the Southeastern Plains Ecoregion, USA

Abstract

The Sand Hills subdivision of the Southeastern Plains ecoregion has been impacted by historical land uses over the past two centuries and, with the additive effects of contemporary land use, determining reference condition for streams in this region is a challenge. We identified reference condition based on the combined use of 3 independent selection methods. Method 1 involved use of a multivariate disturbance gradient derived from several stressors, method 2 was based on variation in channel morphology, and method 3 was based on passing 6 of 7 environmental criteria. Sites selected as reference from all 3 methods were considered primary reference, whereas those selected by 2 or 1 methods were considered secondary or tertiary reference, respectively. Sites not selected by any of the methods were considered non-reference. In addition, best professional judgment (BPJ) was used to exclude some sites from any reference class, and comparisons were made to examine the utility of BPJ. Non-metric multidimensional scaling indicated that use of BPJ may help designate non-reference sites when unidentified stressors are present. The macroinvertebrate community measures Ephemeroptera, Plecoptera, Trichoptera richness and North Carolina Biotic Index showed no differences between primary and secondary reference sites when BPJ was ignored. However, there was no significant difference among primary, secondary, and tertiary reference sites when BPJ was used. We underscore the importance of classifying reference conditions, especially in regions that have endured significant anthropogenic activity. We suggest that the use of secondary reference sites may enable construction of models that target a broader set of management interests.

Benthic diatom and macroinvertebrate assemblages, a key for evaluation of river health and pollution in the Shahrood River, Iran

“…Therefore, we defined our reference stations as those with the least disturbed conditions (Sánchez-Montoya et al 2009;Kosnicki et al 2014). Our preliminary investigations showed that the reference stations (R1 and R2) tended to have low concentrations of nutrients and low levels of disturbance (Tables 1, 3).…”

Macrophyte and macroinvertebrate patterns in unimpacted mountain rivers of two European ecoregions

“…Therefore, precise and efficient monitoring requires the correct identification of biological communities in reference conditions for each existing river type (Moss, 2008;Nõges et al, 2009;Demars et al, 2012;Mao & Richards, 2012). Ecological assessment based on reference conditions is used to measure streams' health, to identify degraded conditions and to monitor human impact or determine restoration effectiveness; it is also applied outside the European Union member states (Pond, 2012;Gerth et al, 2013;Kosnicki et al, 2014). Unfortunately, biological recognition of pristine rivers is not sufficient especially in mountains.…”

Hydrogeomorphic Reference Condition and Its Relationship with Macroinvertebrate Assemblages in Southeastern U.S. Sand Hills Streams

“…We quantified channel geometry following the method of Kosnicki et al. (). Briefly, we estimated channel cross‐sectional dimension by surveying equidistant channel cross‐sectional transects within four to six runs of each stream reach.…”

“…; Kosnicki et al. ). We preserved samples in 95% ethanol in the field and transported them to the laboratory.…”

“…Stream biota in the SE Plains strongly differ compositionally from that in upland ecoregions, likely reflecting contrasting instream habitat conditions (Feminella ; Kosnicki et al. ). In addition to these unique features of sand‐bed streams of this ecoregion, increases in human population growth are predicted (reviewed in Nagy et al.…”