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School of Environment and Natural Resources


Discovering Macroinvertebrates - One ENR experience at a time

Oct. 19, 2021
Two students sampling for macroinvertebrates.

On a recent beautiful late summer day at The Ohio State University, students in ENR 4345 - Methods in Aquatic Ecology led by instructors Dr. Lauren Pintor and Krystal Pocock had the opportunity to learn first-hand about aquatic macroinvertebrates and sample for them. The School of Environment and Natural Resources (SENR) caught up with Dr. Pintor and Ms. Pocock to find out more about what students discovered and how these in-field class experiences make a difference.

What are macroinvertebrates and why study them?

SENR:  What are aquatic macroinvertebrates and what are their significance in the study of aquatic ecosystems? 

Ms. Pocock:  Aquatic macroinvertebrates are insects that are in their nymph and larval stages that are found in rivers, lakes, and streams. They are visible to the naked eye, but small enough that you may not have noticed them before!  These nymphs and larvae later develop into dragonflies, beetles, flies, and more.

These organisms are often used as indicators of water quality because of their known tolerance or intolerance to pollution and certain stream conditions (e.g., sedimentation, water velocity, etc.). Thus, the presence or absence of particular species can tell us a lot about water quality and ecosystem processes. Additionally, macroinvertebrates are a critical component of aquatic food webs because they are a primary food source for larger, predatory macroinvertebrates and insectivorous and omnivorous fishes.

Mayfly nymph. Photo: AdobeStockNymph of dragonfly. Photo: AdobeStock

Sampling for aquatic macroinvertebrates

SENR:  What is involved in sampling for aquatic macroinvertebrates? Can you share a bit about the opportunity and what students discovered? 

Ms. Pocock:  During class, we show students several techniques for sampling macroinvertebrates. First, we begin by demonstrating three pieces of commonly used sampling equipment: a Hess sampler, a surber sampler, and a d-frame net. Students collect samples and count the number of macroinvertebrates present. Later, we have students perform a statistical analysis to compare the abundance of macroinvertebrates found in each sampling method and have them visualize the data on a bar graph. We also teach students how sample for and calculate an ICI, or Invertebrate Community Index. This is an index commonly used by the EPA and in research that assigns an overall “score” to a stream based on the composition of species present.

SENR:  What are some of the sampling techniques students learn and practice in your course? 

Ms. Pocock:  Dr. Pintor has designed the course so that students gain hands-on experience in both biotic and abiotic sampling techniques. In addition to the macroinvertebrate sampling techniques, students also learn how to sample fishes using seines, a backpack electroshocker, and a longline electroshocker and crayfish using seines and minnow traps. We also teach students how to measure stream velocity and discharge, mark and tag fishes and macroinvertebrates, age fishes using otoliths and scales, and analyze water samples for a variety of different parameters (e.g., turbidity, total suspended solids, algae via chlorophyll-a and ash-free dry mass, phosphorus, and nitrate).

We’re looking forward to partnering back up with OEPA and ODNR next year to provide students with an opportunity to learn fish sampling and aging techniques from professionals in the field. This also helps facilitate networking connections between the students and agency professionals.   

ENR 4345 students engaged in a lab.

A toolbox of skills

SENR:  What do you hope students walk-away with or gain from these hands-on class experiences you offer? 

Ms. Pocock:  The sampling techniques that we expose students to in the course are used daily by agency and research professionals, as well as individuals working in the private sector. Our main goal of the course is for students to walk away with an understanding of aquatic sampling methods, including when and why to use particular techniques as well as how to collect and analyze the data. Additionally, students come away with a toolbox of skills that make them marketable to employers in a competitive job market.

About ENR 4345:  Methods in Aquatic Ecology

ENR 4345 introduces students to experimental designs, field and laboratory techniques, and statistical methods commonly used to study aquatic ecosystems. The hybrid course is offered autumn semester with a number of in-person labs designed to prepare students with a toolbox of knowledge and skills needed to study, monitor and manage biological, chemical and physical components of aquatic ecosystems.

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