A Preliminary Study on Improving The Quality Of Aquatic Insect Data Collected By Students

and Volunteers

Patrick Edwards

Portland State University

Center for Science Education

Best Education Practices (BEPs) for Water Outreach ProfessionalsJune 2-4

Purpose:

• Examine the factors that affect both identification accuracy and taxonomic precision.

• Report findings from a research project to improve the accuracy of student identifications of live insects in the field while advancing the taxonomic scope of students’ biomonitoring projects to the family level

Biomonitoring is the use of living organisms as indicators of environmental pollution.

Aquatic Macroinvertebrate (insects) Biomonitoring:

Advantages• Engaging• Inexpensive• Educationally Appropriate• Scientifically Relevant

Disadvantages• Identification is Difficult• Resources for Educators are Limited• Course Measure• Accuracy of Student Data is Suspect

Increasing Precision

Difficulty in Identifying

Order Family Genus Species

As the taxonomic focus moves towards the genus and species level, a biomonitoring study gains precision, while insect identification becomes more difficult

Taxonomy and Precision:

Scientific Research and Policy

Proposed Current

Order Family Genus Species

Too Difficult for Ed-Based Studies

Current and proposed taxonomic alignment of education-based biomonitoring. At the family level, education-based biomonitoring data are more precise and accurate than order level, and better aligned to inform science and policy.

Advancing the Taxonomic Scope:

Limitations of Resources for Educators

Guides and Keys

• Taxonomically unaligned with the goals of education.• Photographs of preserved insects• No reference for scale• No comparison views• Wide geographic scope• Either too broad (Order) or too narrow (Genus)

Redesigned Guide• Limited Scope (EPT&D)• Scale Photos• Organized by Family• Live Insects• Scale and Comparison views

Small Minnow Mayfly

Flat-Head

Yellow Stonefly

Golden Stonefly

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Image 19: Magnified gills of a Flat Head Mayfly

Image 18: Live Flat Head

Identification: Flat-head Mayflies are identified by their flat-broad bodies and wide oval-shaped head (A). They range in color from light brown to black, with a prominent row of gills along the side of the abdomen. The gills are oval and flat with a mass of fibers (B) that can be seen with a magnifying glass (image 19). Heptageniidae have two (C) or three (D) long tails (image 20).

ID Tips: The most recognizable characteristics of the this family is their flattened bodies and large heads, which are the widest part of the body. Nymphs are much wider flatter than other mayflies, such as small minnow (image 22). Flat-Headed Mayflies are generally crawlers, but they can swim, and do so with an odd flopping motion. Similar looking families: Small-Minnow Mayfly (pg. 18) and the Spiny-Crawler Mayfly (pg. 19).

Image 20: Scale view showing 3 specimens of the Flat Head Mayflies. Notice the varying number of tails and the wide range of coloration.

Flat-Head Mayflies

A

B

C D

C

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Image 24: Two-Tailed Flat Head Mayfly

Image 22: Scale view comparing Flat Head to Small Minnow

Image 23: Flat-Head Mayfly. Note the wide, oval-shaped head.

Image 21: Three-tailed Flat Head

Flat-Head Mayfly (Heptageniidae)

Ecology: Flat Head Mayflies cling to the surface of rocks and woody debris where they scrape algae and collect detritus (8). Their flattened, streamlined bodies are well adapted to life along the bottom of fast-moving streams. Their wide mouths with a row of thick hairs are used to collect algae by scraping the surface of rocks and other substrates.

Tolerance: Flat Head Mayfly represents a wide range of tolerance to pollution. Some genera are are quite sensitive to pollution, while other are

more tolerant. FBI Value: 4

Family Overview: In the Willamette Valley, the Flat Head is one of the more abundant and widespread Mayflies families. There are at least nine genera of Heptageniidae in streams and rivers of the Northwest (1).

Small Minnow Mayfly

Flat-Head

Methods

Participants: Upper Division college students enrolled in a 10 week water quality course for non-science majors.

• Experiment 1: Guide Only - Compared redesigned guide to standard guides.

• Experiment 2: Key ID Characteristics - Students learned the Key ID features of 15 families of aquatic insects through photographic slides and discussion

• Experiment 3 - Students were given a tray of insects to use a reference

Methods

Determining in Accuracy: Students data were compared to the verified sample

Jar # Students ID’s Instructor Verification Correct?

1 5 Baetidae 3 Baetidae, 2 Heptageniidae

Yes

2 5 Ephemerillidae

1 Ephemerillidae, 4 Baetidae

No

3 75 Heptageniidae

70 Heptageniidae, 4 Baeitade

Yes

MethodsData Analysis: Two approaches were used to calculate Accuracy - Percent Correct and Percent Total Difference (PTD)

• Percent Correct – Is the total number of correctly identified (>50% of the organisms correct)

• PTD - Represents the percent difference between the students’ identifications and the verified sample (cite). Lower PTD indicates higher accuracy.

PTD = [ 1- (comppos / N] X 100

Limitations•The Percent Correct tend to overestimate accuracy • The PTD tends to underestimate accuracy in samples with high numbers of individuals from one family

Results: Guide Only Study

Results of the accuracy tests on the guides only. * p >.025

Major Findings: • Redesigned guide likely resulted in improved accuracy, but not at a sufficient level of certainty. • Confounding variables influenced the outcome of the study.• Students felt that the scale shots, comparison views, and descriptions were helpful.• Not a good way to teach students how to identify aquatic insects.

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Results: Interventions

Results of the intervention experiments. p >.25

Major Findings: • Key ID characteristics improved identification accuracy • Reference tray improved identification to better than the recommended PTD of 15%• Does not represent an effective cognitive model for learning.• Further statistical tests are required to detect any statistical differences.

12109

Percent Correct

Graph 1: Percent Correct for all interventions.

PTD

Graph 2: Percent Taxonomical Difference for all interventions. A small PTD value indicates higher accuracy. Line represents suggested max PTD

Conclusions

• Guides designed with photos of live insects, scale photos, comparison views, and good key ID descriptions will likely result in more accurate field identifications.

•Students report less frustration using redesigned guides

• Providing a reference tray of insects will result in data that is of sufficient accuracy for volunteer-based biomonitoring programs and official reports.

• Reference tray approach is not a good way to teach how to identify aquatic insects.

Future Directions• Redesign and re-test guide• Study the accuracy of student’s ability to biomonitor• Create a PNW index for major families

Considerations

• This study only represents how well students can identify insects, not how well they can conduct a biomonitoring project

• Study not randomized (both in student selections and insect selections)

• Experience and practice identifying insects likely played a role in the results

Patrick Edwards

Portland State Universtiy

Center for Science Education

503.725.8303

psu22536@pdx.edu