How Healthy is Jackson Creek at Crescent Valley High?

• Describe the term macro-invertebrate • Describe general insect life cycles • Explain how and why macroinvertebrates can be used as

biological indicators of water quality• Use observation skills to identify three or more

macroinvertebrates from photos and from live specimens • Be able to name some things that pollute streams and

ideas to prevent those pollutants from going into streams• Connect the results of this study to the installation of the

CV Arboretum

Macroinvertebrates as Indicators of Stream Health

Aquatic Snail

Stonefly

What is a macroinvertebrate?• An animal• Large enough to be seen with the naked eye• In = no, vertebrate = backbone• No backbone

Sow Bug

Mayfly Nymph

Insect Life Cycles• What do you know about the basic life cycle of an insect?• What is metamorphosis?

– biological process involving a conspicuous and relatively abrupt change in the insect's body structure through cell growth and differentiation.

• Complete metamorphosis is egg > larva (nymph) > pupa > adult

Incomplete metamorphosis

Insect Life Cycles• Many (but not all) of the aquatic macroinvertebrates we are

studying will be in the larval, or nymph stage and will eventually leave the water when they are adults that can fly.

• Insects often have very short life spans, maybe only 24 hours or a few days. The insects being collected may not live very long once removed from their stream habitat.

Why are macroinvertebrates biological indicators

of stream health?• Spend up to one year in the

stream• Have little mobility• Generally abundant• Primary food source for many

fish• Good indicators of local

conditions• Diversity = healthy stream• Easy to sample

Caddis Fly

Threats to Macroinvertebrates

• Sedimentation• Chemical pollution• Habitat loss

Black Fly NymphsFresh water crayfish

Collection and Identification of Macroinvertebrates

In order to judge if our stream is healthy or not, first we have to be able to identify the macroinvertebrates that we find

Collecting Macroinvertebrates• Use kick nets or leaf packs on bricks• Collect as many individuals as possible (50-100)• Identify and count• Complete data form

Three Categories of Aquatic Macroinvertebrates

• Group 1: Pollution Sensitive– Need high DO (dissolved oxygen level of 5 ppm), neutral

pH (7), cold water– Mayflies, stoneflies and caddis flies

• Group 2: Somewhat Pollution Tolerant– Black flies, sow bugs, and crayfish

• Group 3: Pollution Tolerant– Can tolerate lower oxygen levels in the water (less than 5

ppm), higher and lower pH (1-14), warm water– Aquatic worms, aquatic snails

Examples of Macroinvertebrates

Photos from Michigan Technical University

Abiotic Indicators

• In addition to biotic indicators of stream health, there are also abiotic ones

• The levels of oxygen, phosphates and nitrates• The pH (how acidic or basic)• The turbidity (cloudiness or haziness of a fluid

caused by individual particles (suspended solids) that are generally invisible to the naked eye

• The temperature• We will be measuring and recording these as well

Review• What is a macroinvertebrate?• What is a biological/biotic indicator?• Why do macroinvertebrates make good biological

indicators?• What are the three most common threats to aquatic

macroinvertebrates?• If you see stoneflies, mayflies and caddis flies only,

what does that mean about the water? • If you see worms, black flies and snails only, what

does that mean about the water • What if you see all of them?• What are some abiotic indicators?

Lab Report Preview• Introduction

– Background (after answering the questions about macroinvertebrates and biological and abiotic indicators from the previous slide, rewrite your answers in paragraph form)

– Purpose (what is the purpose of the lab)– Hypothesis (what is your hypothesis)

• Materials • Procedure

– You’ll need to write this down on Wednesday• Data

– Observations– 2 tables (biotic indicators in one, abiotic indicators in the other)

• Conclusions– What does the data tell you about the health of Jackson Creek?– Was your hypothesis supported? Explain.