Introduction to Stream Macroinvertebrates

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Introduction to Stream Macroinvertebrates
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Benthic Macroinvertebrates

• Benthic bottom of stream (abiotic)
• Macroinvertebrates
• no backbone
• large enough to see
• Retained in a 500 ?m (250 ?m) sieve
• Benthos community (biotic)

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Benthic Macroinvertebrates

• Many different phyla
• Arthropoda dominant phylum
• Crustaceans
• Crayfish, amphipods, isopods, shrimp
• Arachnids
• water mites, aquatic spiders
• Insects dominant arthropod (Insecta)

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Aquatic Insects

• 10 orders
• Larval stage is aquatic
• Nymphs
• Naiads
• Some adults are aquatic

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Collembola

• Not true insects

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Ephemeroptera (Mayflies)

• Diverse in well oxygenated, unpolluted stream
• Baetidae
• Ephemerellidae
• Heptageniidae

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Odonata (dragonflies and damselflies)

• Predators
• Gomphidae
• Cordulogasteridae

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Plecoptera (stoneflies)

• Fish food
• Leaf shredders
• Clean, well oxygenated waters
• Chloroperlidae
• Leuctridae/Capniidae
• Perlidae
• Perlodidae
• Peltoperlidae
• Pteronarcyidae

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Trichoptera (caddisflies)

• Build cases, retreats, or silk nets
• Some are free-living
• Indicate good WQ
• Brachycentridae
• Glossosomatidae
• Hydropsychidae
• Rhyacophilidae

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Megaloptera (fishflies, dobsonflies, alderflies,
hellgrammites)

• Predators
• Variety of habitats
• Corydalidae
• Sialidae

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Hemiptera (true bugs)

• Piercing mouth parts
• Gerridae

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Lepidoptera (moths)

• Rare
• Grazers

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Coleoptera (beetles)

• Diverse
• Elmidae
• Psephenidae

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Diptera (True flies)

• 40 of all aquatic insects
• Nuisance species, vectors of disease
• Tolerant
• Chironomidae dominate
• Simuliidae
• Tipulidae

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Aquatic Insect Life History Strategies

• Holometabolus
• Complete change
• Eggs ? Larvae ? Pupa ? Adult
• Diptera, Trichoptera
• Hemimetabolous
• Incomplete change
• Eggs ? Early instar ? Late instar ? Adult
• Plecoptera, Ephemeroptera

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Aquatic Insect Life History Strategies

• Duration of Life Cycle
• Univoltine 1 generation / year
• Mayflies, stoneflies
• Biovoltine 2 generations / year
• Multivoltine gt 2 generations / year
• Dipterans (Chironomids) stoneflies
• Semivoltine 1 generation / 2 years
• Merovoltine 1 generation / gt 2 years
• Dragonflies

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Macroinvertebrate Functional Feeding Groups

• Describe the functional role of organisms in
  aquatic food webs

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Macroinvertebrate Functional Feeding Groups

• Shedders CPOM (leaves, sticks)
• Scrapers periphyton (attached algae, biofilm)
• Collector-gatherers FPOM
• Collector-filterers FPOM
• Predators fish, insects