Recognition of Patterns of Benthic Diatom Assemblages within a River System to Aid Bioassessment

Shuxin Mao,Hongbing Deng,Shuhan Guo,Zhicai Xie,Tao Tang

doi:10.3390/w10111559

Abstract

Benthic algae, especially diatoms, are commonly used to assess water quality in rivers. However, algal-based assessments are challenging at the river system scale because longitudinal variation in physical habitat conditions may obscure algal responses to changes in water quality. In the present study, we surveyed benthic diatoms and environmental variables from a mountainous Chinese river system. Hierarchical clustering, discrimination analysis, and indicator species analysis were used together to explore associations between distribution patterns of diatom assemblages and water quality variables. Study sites were clustered into five groups based on their diatom community composition, with sites grouped by the sampling months. Chemical oxygen demand (COD), elevation, and total nitrogen (TN) were the most important predictors for site classification. Site groups with higher elevations had higher TN concentrations; however, COD concentrations were higher in lower elevation groups. Moreover, COD concentrations significantly differed between temporally separated groups. In total, 49 indicator species were identified for individual groups, with most taxa indicating the eutrophic condition. Additionally, we found that European diatom indices are not closely associated with water quality variables. We conclude that the identification of algal patterns and their driving forces can provide valuable information to aid bioassessment at the river system scale.

Highlights

IntroductionSpatio-temporal patterns of lotic assemblages change substantially along anthropogenic stressor gradients (e.g., water quality pollution, hydrological alteration, and sediment erosion).understanding biological patterns and their driving forces can aid in the identification of the stressors affecting them [1]
Spatio-temporal patterns of lotic assemblages change substantially along anthropogenic stressor gradients.understanding biological patterns and their driving forces can aid in the identification of the stressors affecting them [1]
We found that benthic diatom assemblages in the Chishui river system could be classified into two or three groups depending on the sampling month

Summary

Introduction

Spatio-temporal patterns of lotic assemblages change substantially along anthropogenic stressor gradients (e.g., water quality pollution, hydrological alteration, and sediment erosion).understanding biological patterns and their driving forces can aid in the identification of the stressors affecting them [1]. Spatio-temporal patterns of lotic assemblages change substantially along anthropogenic stressor gradients (e.g., water quality pollution, hydrological alteration, and sediment erosion). For a given river system, the assessment of changes in lotic assemblage structures/patterns and functions responding to stressors, namely bioassessments, could indicate the causes of degradation in the biological condition, and guide proper watershed management practices [2,3,4]. In recent decades, lotic bioassessments have been increasingly included as foundational components of watershed management plans [5,6]. Performing lotic bioassessments at the river system scale pose many challenges [7], especially for relatively small rivers of hundreds of kilometers in length and thousands of km in watershed size. When bioassessments are performed at large scales, e.g., at regional or national scales [8,9], both natural environmental factors

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Conclusion