Using natural landscape and instream habitat to identify stream reference groups for bioassessment

Area of Science:

• Ecology
• Environmental Science
• Biomonitoring

Background:

• Grouping streams is essential for evaluating biotic integrity using multi-metric indices.
• Traditional ecoregion-based grouping in Oklahoma is complex due to high diversity.
• This study simplifies reference groups by analyzing natural drivers of species distribution.

Purpose of the Study:

• To simplify Oklahoma's complex stream reference groups.
• To develop a hierarchical system of stream groups and archetypes based on natural drivers.
• To improve the application of biotic integrity assessments in Oklahoma.

Main Methods:

• Employed two K-means clustering algorithms for hierarchical stream grouping.
• Tier I clustering used climatic and geologic features; Tier II used water chemistry and habitat.
• Classification trees and multivariate analyses validated and defined 'stream archetypes'.

Main Results:

• Identified six hierarchical stream groups representing regional and geomorphological differences.
• Established two primary regions (East and West) and four subtypes (Plains, Valley, Hills, Highlands).
• The six groups effectively explained habitat and water chemistry variability, outperforming 13 ecoregions.

Conclusions:

• Developed six hierarchical stream groups and three archetypes (Plains, Valley, Rocky) for Oklahoma.
• These archetypes simplify complex stream classifications and are based on natural drivers.
• The new system is expected to enhance biotic community evaluations in Oklahoma.