Benthic Macroinvertebrates

Benthic Macroinvertebrates Benthic – bottom-dwelling Macro – can be seen with the unaided eye Invertebrates – without a backbone or spinal column Examples: clams, snails, worms, crustaceans, insects

Question How do we know whether a stream is “healthy” or polluted?

Qualitative Sampling (finding as many as you can) D net Kick the stream bed vigorously upstream Collect in different habitats Sand, silt, gravel, mud, rub large stones, overhanging banks, under overhanging brush, etc.

Benthic Macroinvertebrates as Indicators of Water Quality Every species has a range of conditions in which it can survive “Tolerant” species - can survive in a wide range of conditions “Intolerant” species - are sensitive to pollution A large number of intolerant species indicates unpolluted water

Examples - Snails Gilled Snail (right-handed) – pollution intolerant Lunged or Pouch Snail (left-handed) – pollution tolerant

Examples - Crustaceans Scuds (Amphipods) Crayfish

Aquatic Worms Tubifex Worms Aquatic Earthworm

Examples – Insects Life Cycles EGG LARVA ADULT PUPA

Examples – Insects Life Cycles EGG NYMPHS ADULT

Insects – Mayflies Nymphs 1-2 years, Adults 1-2 days

Insects – Stoneflies Nymphs 1-4 years, Adults a few weeks

Insects – Caddisflies Use silk to make nets and cases Adults 1-2 weeks, Complete life cycle 1 year

Insects – Dobsonflies Larvae: a few years, Adults: 7 days Adult Female – can bite! Up to 5” long Larva: “Hellgrammite” Adult Male

Insects – Craneflies Look like large mosquitoes, but do not bite

Insects – Blackflies Complete Life Cycle: 6-15 weeks Larvae attach to rocks and catch food with “fans” Females feed on blood

Some Larva known as “blood worms” Insects – Midges Larvae are “C” shaped, includes biting midges or “no-see-ums” Complete Life Cycle: Can be 2-3 weeks Some Larva known as “blood worms”

Insects – Dragonflies Predators of mosquitoes Larvae 1-4 years, Adults a few months

Insects – Damselflies Complete Life Cycle: 1-2 years

Using an Identification Key

Question Which of these is the most reliable indicator of whether a stream is “healthy” or polluted? Water color and cloudiness Chemical tests Litter and trash Benthic macroinvertebrates

Importance for Recreation

The Adams Fly: Invented in 1922 by guide Leonard Halladay for Judge Charles B. Adams, Mayfield Twp.

Benthic Macroinvertebrates