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Algal Attributes: An Autecological Classification of Algal Taxa Collected by the National Water-Quality Assessment Program

By Stephen D. Porter

Abstract

Algae are excellent indicators of water-quality conditions, notably nutrient and organic enrichment, and also are indicators of major ion, dissolved oxygen, and pH concentrations and stream microhabitat conditions. The autecology, or physiological optima and tolerance, of algal species for various water-quality contaminants and conditions is relatively well understood for certain groups of freshwater algae, notably diatoms. However, applications of autecological information for water-quality assessments have been limited because of challenges associated with compiling autecological literature from disparate sources, tracking name changes for a large number of algal species, and creating an autecological data base from which algal-indicator metrics can be calculated. A comprehensive summary of algal autecological attributes for North American streams and rivers does not exist. This report describes a large, digital data file containing 28,182 records for 5,939 algal taxa, generally species or variety, collected by the U.S. Geological Survey’s National Water-Quality Assessment (NAWQA) Program. The data file includes 37 algal attributes classified by over 100 algal-indicator codes or metrics that can be calculated easily with readily available software. Algal attributes include qualitative classifications based on European and North American autecological literature, and semi-quantitative, weighted-average regression approaches for estimating optima using regional and national NAWQA data. Applications of algal metrics in water-quality assessments are discussed and national quartile distributions of metric scores are shown for selected indicator metrics.

Table of Contents

Abstract

Introduction

Nutrient and Organic Enrichment

Major Ions and pH

Microhabitat Traits

Semi-Quantitative Approaches for Evaluating Algal Species Autecology

Tolerant and Sensitive Species

Objectives and Scope

Acknowledgments

Methods

Indicators of Nutrient Concentrations and Trophic Condition

Indicators of Organic Enrichment

Indicators of pH, Salinity, Specific Conductance, and Chloride Concentrations

Indicators of Microhabitat Traits, Suspended Sediment, and Calcium Concentrations

Calculating Algal Metrics

Discussion

Summary

References Cited

Data Files

Tables

1. National algal-metric indicators of nutrient concentrations and trophic condition.

2. Regional algal-metric indicators of nutrient concentrations and trophic condition.

3. Algal-metric indicators of organic enrichment.

4. Algal-metric indicators of pH, salinity, specific conductance, and chloride concentrations.

5. Algal-metric indicators of microhabitat traits, suspended-sediment, and calcium concentrations.

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