MacroinverteWHATS? Macroinvertebrates!

What are macroinvertebrates? Macroinvertebrates are small animals that lack backbones and are visible to the naked eye. They live in streams and other bodies of water where they shred decaying plant matter. Macroinvertebrates include mayflies, beetles, dragonflies, crayfish, and snails. Many of these organisms leave their aquatic environments when they become adults.

What do macroinvertebrates look like?

Why are macroinvertebrates important to science? Macroinvertebrates are indicators of the water quality of a stream. They are sensitive to changes in their surroundings. They migrate only short distances. They live in water for extended periods of time. Macroinvertebrates are important components of the food chain.

How can I capture macroinvertebrates?

How can I identify macroinvertebrates? Use a hand lens or microscope. Observe distinguishing characteristics, both physical and behavioral. Consult a field guide or a key.

That are sensitive to pollution Introducing Three Important Macroinvertebrates That are sensitive to pollution

Caddisflies Dark, hardened head External case Prolegs With claws Hooked legs

Stoneflies Wing pads Long antennae Two tail filaments Hooks on legs

Mayflies Gills on abdominal segments Usually three tail filaments

Macroinvertebrate Classes that are somewhat sensitive to pollution

Damselfly Nymph Dragonfly Nymph 3 oar-shaped tails Large Eyes Wide to round abdomen

Helgrammite (Dobsonfly larva) Crane fly larva Plump body Large pinching jaws 8 pairs feelers

Crustaceans Scud (Amphipod) Sowbug (Isopod) > 6 legs

Data interpretation Single vs. Multiple samples Seasonal changes Yearly changes EPT index % Abundance One day’s data vs combining many days. Combining data gives better picture of community composition Seasonal Changes—Since many of animals are in larval form, their metamorphosis to terrestrial adults leaves fewer animals in streams in some seasons Yearly changes: Drought, flood, and temperature changes Ephemeroptera, Plecoptera, Tricoptera Mayfly, Stonefly, Caddisfly % Abundance—Determines relative contribution of one species to community. If one or two species dominate—especially pollution tolerant ones—there may be an imbalance or problem in the stream.

Macroinvertebrate Metrics Index of Biotic Integrity Number of families EPT families Ephemeroptera families Diptera families % Ephemeroptera (individuals) Intolerant families Beck’s Biotic Index (weighted sum of intolerant taxa)

Important to look at diversity Important to look at diversity. When a Community is dominated by a few species, it may indicate pollution or less than healthy conditions. Data from Sampling dates in diff seasons over 6 years indicate GOOD to FAIR quality, with generally 9 – 24 families present. Again, some species not present in summer due to life cycle. Other factors: Weather Flooding

Two-run Creek Ephemeroptera (mayflies) very sensitive to pollution. Abundance indicates good stream quality, while scarcity indicates poor stream quality. Ephemeral nature of mayflies: metamorphose in May, live one day, mate, and die. Slide illustrates why important to sample in different seasons. No mayflies collected in Summer except in 1998—because most had become adults. Numbers in fall were also fairly low because mayflies are extremely small in that season. Notice winter best season for finding ephem in stream Data from many sampling dates indicated GOOD stream quality; Some indicated FAIR quality—however, summer data for mayflies are not good indicator Important to give weight to Spring 2002—emergence may have occurred before sampling took place

GOOD FAIR POOR

Now let’s go into the field to capture and identify some macroinvertebrates.