a primer to site-level monitoring activities for volunteer coordinators

This publication is part of a Monitoring Your Wetland series available online in pdf format at:wetlandmonitoring.uwex.edu

yourMonitoring

Wetland

. . . . . . . . . .Macroinvertebrates

Macroinvertebrates may be small and spineless, but when it comes to the cycling of wetland nutrients there’s

nary a niche where you won’t find them. Some, like snails, graze peacefully on aquatic plants, while others, like dragonfly nymphs, voraciously prey on other invertebrates. Sowbugs, caddisfly larvae, clams and other janitorial macroinver­

tebrates recycle decomposing and particulate matter. Finally, all macroinvertebrates provide food for other wetland animals.

Most macroinvertebrates are too small to noticeably stir the water’s surface, but are large enough to see with the naked eye. They include

small worms, mollusks, leeches, crustaceans, insects and insect larvae. Besides playing a star role in many important wetland functions, macroinvertebrates are sometimes employed as a tool for characteriz­ing aquatic habitats and learning about aquatic habitat water quality. Macroinvertebrates are sensitive to physical, chemical and biological environmental stressors. And because of their limited mobility, they cannot easily avoid pollution, low oxygen levels or other unfavorable conditions.

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About Macroinvertebrate Surveys

Macroinvertebrate monitoring can help characterize wetlands, but as a water

quality indicator, wetland macroinvertebrate monitoring has not yet matured. In other aquatic habitats, and particularly streams, macroinvertebrate monitoring has a long history as a tool for assessing water quality. Volunteers who monitor macroinvertebrates in streams look for the presence, absence or dominance of sensitive or tolerant species and then use a biotic index of health to interpret what they indicate about the quality of the stream.

Unfortunately, macroinvertebrate monitor­ing in wetlands is much more challenging than in streams. The macroinvertebrate community found in a wetland will differ considerably from

the communities in other wetland types. And, because there is a great deal of variation among wetland types, it is difficult to standardize protocol for collecting repre sen tative macroinver­

tebrate samples or identifying a healthy or unhealthy macro invertebrate community.

Consequently, it is also difficult to determine when variations in sampled macroinvertebrate

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About Macroinvertebrate Surveys – continued from front page communities are due to wetland degradation or natural wetland characteristics.

Differences in wetland characteristics that have nothing to do with degradation can influence the presence or absence of various species of macroinvertebrates. In contrast to shallow, land­locked wetlands, for example, wetlands connect­ed to lakes or rivers typically have fish, which tend to reduce macroinverte brate abundance and species diversity. Addition­ally, naturally high levels of acidity in bogs can also reduce macroinvertebrate diver sity, but don’t necessarily indicate poor wetland quality.

Macroinvertebrate monitor­ing is one of the more difficult and costly moni­toring efforts a wetland volunteer monitoring group can engage in. Wetland monitoring groups often become frustrated trying to achieve satisfactory results if they are determined to develop a complete inventory of wetland macroinvertebrate species or monitor macroin­vertebrates as an indicator of wetland quality. When trying to monitor macroinvertebrates as indicators, sampling, picking and especially specimen identification can be difficult.

All of this having been said, macroinver­tebrate monitoring may be a great activity to

engage your volunteers in if your primary goals are to raise awareness and characterize the wetland. Macroinvertebrate monitoring is a good way to teach volunteers about wetland ecology. And identifying some of the types of macro­invertebrates living in your wetland contributes

to what you know about it. This publication outlines some basic macroinverte brate survey methods that can be applied to a broad range of wetland types.

These are methods designed to help maximize volunteers’ ability to produce an inventory of species that will help characterize a wetland. We will not explain

what sampling results indicate about wetland health, since methods for doing so are nascent even for professional biologists. But for those of you interested in experimenting with prelim­inary methods for mon itoring macroinvertebrates as wetland health indicators, we will briefly describe and provide references to projects testing such methods in Midwestern wetland areas (see Informational Resources on the back page).

Macroinvertebrate monitoring may be a great activity to engage your volunteers in if your primary goals are to raise awareness and characterize the wetland.”

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Monitoring Your Wetland – Benthic Macroinvertebrates

2

Costs for the equipment, supplies

and possibly laboratory services

needed to support macroinverte­

brate monitoring can range from

moderate to high depending on

the rigor of the identification

standards used. Monitoring will,

at minimum, require equipment

for collecting samples. Depending

on how you structure your volun­

teer group’s monitoring activities,

they may also need equipment

and supplies for separating

specimens from organic matter,

identification and preserving

specimens.

For Collecting Samples

Volunteers need at least three

basic pieces of equipment to

gather macroinvertebrate

samples. First, they need D-frame macroinvertebrate sampling dip nets and basins or pails for

holding samples. Recommended

mesh sizes for the sampling

nets ranges from 600­1,200

microns. Finer mesh nets will

capture more macroinvertebrates,

but will also clog easily and can

collect an unnecessarily large,

debris­laden sample. Finally,

because volunteers need to leave

dry land to collect samples, they

will also need hip boots or waders and possibly a canoe.

For Picking Specimens

When volunteers sample macro­

invertebrates from a wetland

they will almost definitely gather

a great deal of organic matter

and need to pick macroinverte­

brate specimens from a mat of

duckweed, plant fragments and

muck. White invertebrate counting trays made out of fiber­

glass or plastic will help volunteers

sort through the mess. Trays

used to hold collect ed samples

while volunteers pick specimens

out of organic matter should be

light­weight, flat­bottomed and

shouldn’t twist or easily spill.

Macroinvertebrate picking trays

can come in a variety of sizes, but

a typical tray might measure 25

cm wide, by 30 cm long and 5 cm

deep. Some volunteer groups use

dish pans, which are affordable

and easy to find.

To assist in separating organic

matter from macroinvertebrate

specimens you may also want to

provide each volunteer with a

framed screen. The screen

frame can be made out of wood

and the screen can be made out

of chicken wire, hardware cloth

or other wire mesh with holes big

enough for large macroinverte­

brates to fall through, but small

enough to hold back a large

quantity of vegetative matter.

The screen frame should just fit

within the perimeter of a tray and

suspend the screen below the lip

of the tray and above the tray

bottom. You will also need tools

for grabbing and removing

specimens from organic matter,

such as forceps and eyedroppers.

Volunteers may prefer different

tools for picking and you may

want to experiment with a

number of tools, such as plastic spoons, basting brushes or

turkey basters.

For Identification and Preserving

After picking, you will need

additional supplies and possibly

laboratory services to complete

the identification process. For

rudimentary identification that

can be conducted in the field,

volunteers will need a few

basic supplies including

macroinvertebrate taxonomic keys, ice cube trays for sorting

picked macroinvertebrates into

families, hand-held magnifying glasses and data recording sheets. For more rigorous

identification, volunteers will

need access to a laboratory supplied with microscopes.

If they are not identifying in the

field, they will also need supplies

for preserving specimens

including vials or bottles to hold

macroinvertebrates and a

preservative, such as alcohol or

glycerin. To obtain the most

rigorous identification of sample

specimens, volunteer groups will

need professional laboratory

services. Unfortunately,

laboratory services can cost

hundreds of dollars and often

exceed the resources available

to many volunteer monitoring

groups.

Supplies and Equipment

Monitoring Your Wetland – Benthic Macroinvertebrates

3

Volunteers empty a D-frame sampling dip net into containers.

A wetland macroinvertebrate monitoring team will require a highly skilled team

leader and moderate­to­high skill levels among other volunteers, depending on the design of the monitoring effort. Three tasks must be completed to determine the types and species of macroinvertebrates present in a wetland. Samples must be collected, macro invertebrates must be picked from the organic matter mixed in the sample and the macroinvertebrates must be identified.

Samples must be collected using consistent methods, but volunteers can learn these methods

Survey Participants relatively easily when taught by an experienced instructor. As little as two to three hours of field training may be sufficient to train volunteers to collect samples. However, picking, and particularly identifying macroinvertebrates, can be very dif­ficult and requires a high level of skill that cannot be taught over a short period of time.

If you ask volunteers to pick and identify specimens, you will need a highly experienced team leader to ensure volunteers are properly picking and to double check identifications. Generally, volunteers are said to struggle with identifying down to the family level.

“As little as two to three hours of field training may be sufficient to train volunteers to collect samples. However, picking, and particularly identifying macroinvertebrates, can be very difficult and requires a high level of skill that cannot be taught over a short period of time.”

Monitoring Your Wetland – Benthic Macroinvertebrates

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To get the most representative macroin­vertebrate sample possible, volunteers

need to sample at the right time and in the right locations. Volunteers don’t need to wake up before dawn or limit monitoring to days with low wind speeds, but they do need to take samples at the right time of year. The best time to sample macroinvertebrates is roughly from early June through July or mid­August. Samples collected earlier could contain large numbers of under­developed organ isms, which will be difficult to identify. Sampling is typically completed before August, since by late summer the macroinvertebrate community is more likely to include macroinvertebrates that have migrated in from connected water bodies and will be less representative of the wetland. Also, in late summer many wetlands can become dry.

Volunteers can determine where to sample by examining wetland vegetative composition and water depths. Volunteers should sample macroinvertebrates from both emergent herbaceous plant communities (the underwater portion) and submerged and floating aquatic communities when both are present. They should also take samples that represent a range of water

Surveying – When, Where & How to Sample depths. Depending on how dense the vegetation is, volunteers should sample in water depths ranging from no deeper than hip level down to ankle level. In deep water volunteers may find sowbugs, midges and worms, but macroinvertebrate diversity will be low compared with shallow water areas surrounded by emergent vegetation.

When taking a sample, volunteers should sweep the net through the entire water column with a vigorous jabbing motion, starting near the sediment surface. With each jab of the net, the volunteer reaches outward and then rapidly pulls toward their body with the net, dislodging macroin vertebrates

from emergent and floating vegetation. When a volunteer reaches the water’s surface with their sample, they should deposit it in a pail. To ensure the pail contains a robust collection of macro invertebrates, the volunteer should dipnet one to two more additional samples in the same general area and combine them in the

pail with the first. These two to three samples will be treated as one sample when picking and identifying.

Depending on how dense the vegetation is, volunteers should sample in water depths ranging from no deeper than hip level down to ankle level.”

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D-frame dip net, macroinvertebrate key, containers and tools.

Monitoring Your Wetland – Benthic Macroinvertebrates

5

Unless you send unpicked samples to a lab for identification, volunteers will need to

learn how to pick macroinvertebrates from the organic matter scooped up in their dip nets. Even if your volunteers will be sending sampled specimens to a lab for professional identification, your group will likely want to pick the samples first since laboratory fees for unpicked samples are very high.

Volunteers should process samples right away while the macroinvertebrates are still moving and easy to see. To pick, volunteers should spread their sample over screens placed inside white picking trays. The macroinverte­brates will squirm down toward the bottom of the tray to escape the light and fall through the screen into the tray. Volunteers should let the sample sit for about five to ten minutes while the macroinvertebrates move down.

Physical features examined to identify macroinvertebrates include overall body

shape, number and location of legs, presence and location of gills and tails, the shape of the head capsule and unusual appendages. Macroinvertebrate casings and mode of locomotion can also be used to identify macroinvertebrates. Some crawl, swim side to side or swim up­down. And among

Surveying – Picking & Preserving

Identification

After allowing the sample to settle for five to ten minutes, the screen and organic matter caught by it can be removed. Before removing the screen, volunteers should inspect it for invertebrates that did not move down into the tray. After removing the tray, volunteers can begin picking. Volunteers should continue to pick either until they have picked 150 specimens from their sample or have been picking for 30 minutes. To avoid picking bias, volunteers should resist the urge to ignore macroinvertebrates that are difficult to pick because they are fast or very small. Volunteers should pick big, small, slow and fast macroinvertebrates. Volunteers should use tweezers or an eye dropper to grab specimens, then drop them into a jar or bottle of water for temporary storage until they can be sorted and/or preserved.

those that have casings, some have a case of sticks and others a case of stone. Even with all

of these possible distinguishing features, macroinvertebrate identification is incredi­bly difficult.

Unless your volunteers are retired entomologists, they will probably only be able to identify most macroinvertebrates down to the order or family taxonomic levels. Non­expert entomologists will Sorted macroinvertebrates and identification notes.

Monitoring Your Wetland – Benthic Macroinvertebrates

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Tubifex worm

The Key to Life in the Wetlands flow chart

MACROINVERTEBRATES

Scud or sideswimmer Black fly larva Mayfly

typically not be able to identify macroinverte­brates down to the species or even the genus level. If it is important to you to have a large proportion of sampled macroinvertebrates identified down to the genus or species level and you have substantial resources to support the monitoring project, you might consider sending samples to a professional lab for identification.

Laboratories in Stevens Point and at UW­Superior offer identification services. A monitoring project can expect to pay approxi­mately $150 in laboratory fees to have a single pre­sorted sample of macroinvertebrate

specimens identified down to the lowest practical taxonomic level, usually genus or species. 

If you plan to have volunteers identify macroinvertebrates in the field, they’ll need ice cube trays for separating macroinvertebrates into families and macroinvertebrate identifica­tion informational resources. Two online identification resources are listed among the Informational Resources on the back page – a guide to macroinvertebrates of the Upper Midwest and a flow chart for identifying common macroin vertebrates found in Wisconsin wetlands.

Tubifex worm: Jason Neuswanger, troutnut.com; scud and black fly: Missouri Dept. of Conservation; mayfly: Dr. Stanley Szczytko, UW­Stevens Point

Monitoring Your Wetland – Benthic Macroinvertebrates

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a primer to site-level monitoring activities for volunteer coordinatorsyourMonitoring

Wetland

. . . . . . . . . . . . . . . . . . . . . . . . . . .Macroinvertebrates INFORMATIONAL RESOURCES

Minnesota Pollution Control Agency Macroinvertebrate Community Sampling Protocol for Depressional Wetland Monitoring Sites This document outlines protocol developed for expert­led volunteer monitoring of depressional wetlands in Minnesota. The methods are designed to use macroinvertebrate monitoring as a means of assessing water quality and require identification of macroinvertebrates down to the genus or species level using microscopes. (see website link on wetland monitoring site)

Field Testing the Wisconsin Depressional Wetland Macroinvertebrate and Plant Indices of Biological Integrity for Application by Trained VolunteersThis report documents the effectiveness of Wisconsin Department of Natural Resources developed macroinvertebrate and plant biotic index for assessment of isolated depressional wetlands in Wisconsin, when used by DNR biologists not trained in aquatic entomology. (see website link on wetland monitoring site)

Great Lakes Coastal Wetlands Consortium Great Lakes Coastal Wetlands Monitoring PlanThe fourth chapter of this plan outlines protocol for monitoring macroinvertebrates in Great Lakes coastal wetlands. Requires laboratory identification of macroinvertebrates down to species and genus level. http://www.glc.org/wetlands/final-report.html

Water Action Volunteers Biotic IndexThis Web page and linked documents are designed to help volunteers monitor macroinvertebrates in streams as part of the Water Action Volunteers program. These guidelines cannot be used to monitor macroinvertebrates in wetlands, but can be used when wetland volunteers monitoring a wetland in which there is a stream would like to monitor the stream.

http://watermonitoring.uwex.edu/wav/monitoring/biotic.html

University of Minnesota, Guide to the Aquatic Invertebrates of the Upper Midwest This guide provides an identification key for common aquatic invertebrates found in the Upper Midwest, based on mature larvae or adults.

http://wrc.umn.edu/pubs/watersqq/guidetoaquaticinverts

Wisconsin Department of Natural Resources and University of Wisconsin Extension Key to Life in the WetlandsThis is a flow chart for identifying common macroinvertebrates found in many Wisconsin wetlands. This chart is handy for identification of macroinvertebrates in the field.

http://watermonitoring.uwex.edu/pdf/level3/WEPP/WEPPLifeinWetland.pdf

University of Wisconsin-Superior and University of Wisconsin-Stevens Point Laboratory Identification ServicesFor macroinvertebrate identification contact either UW­Superior Aquatic Entomology Assistant Professor Kurt Schmude, kschmude@uwsuper.edu (715)394­8421 or UW­Stevens Point Aquatic Entomology Laboratory Supervisor & Research Specialist Jeff Dimick, jdimick@uwsp.edu (715)346­3868

March 2011

Project coordination by the Rock River Coalition and Suzanne Wade, UW­Extension Basin Education Initiative.

Researched and written by Patrice Kohl

With editorial contributions from Kurt Schmude University of Wisconsin­Superior assistant professor, aquatic entomology; and Dick Lillie, biologist. Editorial assistance by Marie Martinelle and graphic design by Jeffrey J. Strobel, UW­Extension Environmental Resources Center. Photography by Kris Stepenuck/Citizen Monitoring except where otherwise noted.

Project funded through a DNR Citizen­Based Monitoring Partnership Program Grant with support from University of Wisconsin­Extension.

University of Wisconsin, U.S. Department of Agriculture and Wisconsin counties cooperating. An EEO/AA employer, University of Wisconsin Extension provides equal opportunities in employment and programming, including Title IX and American with Disabilities (ADA) requirements.

The Monitoring Your Wetland series includes 9 sections:

•IntroductiontoWetland Monitoring

•Birds

•SmallMammals

•Dragonflies&Damselflies (Odonata)

•FrogsandToads(Anurans)

•Butterflies(Lepidoptera)

•InvasivePlants

•WaterQuality

Macroinvertebrates

Available online in pdf format at:

wetlandmonitoring.uwex.edu

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