Welcome to Rhithron

Rhithron Associates, Inc. specializes in quality-assured taxonomy of freshwater invertebrates and freshwater and marine algae (diatoms and non-diatom algae). Our expertise includes the fauna and flora of streams, rivers, wetlands, and lakes of all ecological regions of North America. In addition, Rhithron provides biological metric calculation, statistical data analysis and ecological interpretation, and other laboratory services such as chlorophyll measurements, and biomass analysis for both macroinvertebrates and algae. Our exacting quality assurance protocols distinguish our work: internal QA/QC systems include evaluation of accuracy and precision of taxonomic determinations and enumerations, measuring and assuring the efficiency of macroinvertebrate sample sorting, and assessing the accuracy of data handling and metric calculation.

For over 23 years, Rhithron Associates has delivered high quality services: this has allowed us to grow from a single provider in 1991 to a staff that includes professional taxonomists, ecologists, research scientists, technicians, and support and management personnel. Our invertebrate taxonomists collectively hold 29 Level-II certifications from the Society for Freshwater Science, more than any other provider of similar services in the world. Rhithron’s phycologists are among the most experienced in North America, providing species-level determinations for diatoms consistent with the most current nomenclature.

We have developed strong relationships with our clients as a result of our integrity and our ability to provide consistent, cost-effective, quality-assured services for projects both big and small. We are large enough to carry out exacting quality assurance protocols and to offer fast turnaround, and yet small enough to regard each client and each project with the most responsive attention. Rhithron provides the right mix of qualified and skilled staff, experienced leadership, and company structure, support, and depth to insure reliability and timely project completion.

Rhithron’s services include:

  • Aquatic macroinvertebrate taxonomy, including Chironomidae and Oligochaeta
  • Freshwater periphyton taxonomy, including diatoms and non-diatom algae
  • Statistical and interpretational data analysis
  • Research and development of bioassessment tools
  • Ecological research
  • Biomass measurements, including morphometry-based analysis with regressions and ash free dry weight (AFDW)
  • Chlorophyll analysis
  • Fish diet analysis, otolith and scale aging
  • Marine diatom taxonomy
  • Paleoecological research


GSA contract