Basics of Aquatic Macroinvertebrate Identification

1. Basics of Aquatic Macroinvertebrate Identification Wetland Ecology and Management

2. What are aquatic macroinvertebrates? • Definition (PA Code, Chapter 93): • Spend a “living portion of their life cycle” in an aquatic environment • Can be seen without the aid of a microscope • Animals without a backbone • Examples: crayfish, snails, insect larvae http://www.dec.ny.gov/animals/35772.html

3. Why study macroinvertebrates in wetlands? • Like plants, macroinvertebrates can serve as indicators of water quality. • Sensitive to a variety of chemical and physical stressors: • Nutrient loading • Unstable hydrology • Habitat destruction Minnesota Pollution Control Agency staff evaluating invertebrate samples http://www.pca.state.mn.us/

4. How is macroinvertebrate data used by wetland managers? • Macroinvertebrate community data can be used to: • Monitor the condition of a wetland • Determine the effectiveness of wetland mitigation • Make decisions regarding permit issuance

5. Aquatic Macroinvertebrate Phyla • Aquatic macroinvertebrates fall mainly into 3 different phyla: • Phylum Mollusca • Phylum Annelida • Phylum Arthropoda Scientific Classification: Kingdom Phylum Class Order Family Genus Species

6. Phylum Mollusca • Clams and snails R L Helisoma sp. Stagnicola elodes Physa sp. http://spinner.cofc.edu

7. Phylum Annelida • Aquatic earthworms and leeches • Aquatic earthworms are very similar to terrestrial earthworms – eat mud and small bits of organic bottom as they move through substrate.

8. Phylum Arthropoda • Class Malacostraca: Crayfish and Amphipods • Characteristics: • Large diversity in this class • 20-segmented body • Two pairs of antennae • Two pairs of maxillae http://www.dec.ny.gov/animals/35772.html; http://iz.carnegiemnh.org/crayfish/

9. Phylum Arthropoda • Class: Insecta • 3 distinct body regions • Head • Thorax • Abdomen • 2 pairs of wings • 3 pairs of jointed legs http://www.snh.org.uk/

10. How can we identify insects? • 1 pair of antennae • Compound eyes • Mouthparts consisting of: • 1 pair of mandibles • 1 pair of maxillae • 1 labrum • 1 labium http://bugs.bio.usyd.edu.au/

11. The insect body plan Merritt and Cummins 1996

12. 10 most common aquatic insect orders

13. Order Ephemeroptera • Common name: Mayflies • Nymph characteristics: • Possess 2-3 tails at end of abdomen • Gills arise from side of abdomen http://www.dec.ny.gov/animals/7470.html

14. Order Ephemeroptera • Adult characteristics: • VERY short-lived • Do not feed – just reproduce, then die • Occur in large swarms • Swarms are so large that they can be detected on radar!

15. Order Plecoptera • Common name: Stoneflies • Larval characteristics: • Each leg ends in 2 claws • Possess 2 cerci at the end of abdomen • Antennae typically 4-6 times the width of the head http://www.dec.ny.gov/animals/7450.html

16. Order Trichoptera • Common name: Caddisflies • Larval characteristics: • Often possess 2 prolegs with hooks at tip of abdomen • Can free-living or build complex casings • Often have thread-like gills on abdomen http://www.dec.ny.gov/animals/35772.html

17. Order Trichoptera Tube Case makers

18. Order Odonata • Common name: Dragonflies, Damselflies • Larval characteristics: • Damselflies: • Delicate looking • 3 caudal leaf or paddle-shaped gills at tip of abdomen • Dragon flies: • Stout body, gills located inside abdomen tip http://www.dec.ny.gov/animals/35772.html

19. Order Odonata • Larvae have a HUGE, hinged lower jaw that can be extended to capture prey as large as fish!

20. Order Odonata • Adult characteristics: • Dragonflies: • Wings are held out to the side when at rest • Rear wings have a broader base than front pair • Damselflies: • Wings are held above the body when at rest • Wing pairs of similar shape and size http://www.ucmp.berkeley.edu/arthropoda/uniramia/odonatoida.html

21. Order Hemiptera • Common name: True bugs • Characteristics: • Mouthparts are modified into a beak called a rostrum • May be found with air bubble in the water • 1st pair of wings are modified into leathery coverings for hindwings (hemelytra) http://www.dec.ny.gov/animals/35772.html

22. Order Hemiptera Interesting facts: • Watch out in the water! Also known as toe-biters, these bugs will take a stab at unsuspecting humans swimming in ponds or lakes. • Rostrum operates by piercing the prey, ejecting digestive enzymes into the prey, and then sucking out the digested remains. • Allows the bugs to feed on large prey, including snakes and small turtles.

23. Order Diptera • Common names: Mosquitoes, Blackflies, Craneflies, Chironomids • Larval characteristics: • HUGE diversity, difficult to id any farther than family • Lack jointed legs on the thorax • Often have tubercules – small, fleshy appendages http://www.dec.ny.gov/animals/35772.html

24. How to classify macroinvertebrates • Many different “metrics” are used to describe macroinvertebrate communities. • Most common metric: • Taxa richness: # of taxa in a community • Prediction: As water quality ↓, taxa richness ↓ • Related metric: • EPT richness: # of Ephemeroptera, Plecoptera, and Trichoptera taxa in a community • Thought to be more pollution sensitive

25. Other metrics • Functional feeding groups • Measures functioning rather than structure of the community • Types of groups: • Scrapers - remove attached algae • Shredders – utilize large pieces of organic matter • Collectors – utilize small particles of organic matter, either by filtering or gathering them. • Predators – capture prey

26. Functional feeding groups http://www.epa.gov

27. Additional metrics • Habitat and Behavior measures • Tolerance/Intolerance measures

28. Sampling methods • “Crawdad Dance” • Sweeping