Trophic relationships Feeding roles in streams

Aquatic insects categorized: Food type and how food is obtained Feeding guilds = functional groups

Base of trophic relationship Productivity from? Microbial loop: –Fungi, bacteria –Use dissolved organic carbon (DOC) –Passed to protozoans, etc.

Invertebrate consumers Food resources: –Periphyton –Macrophytes –Detritus –Animals

Feeding roles Shredders –Leaves, associated microbiota (CPOM) –Chewing –Trichoptera, Plecoptera, Diptera CPOM = > 1 mm

Feeding Roles Suspension feeder / filterer-collector –FPOM and microbiota –Sloughed periphyton –Use setae, nets, etc. –Net-spinning Trichoptera, Simuliidae, Ephemeroptera

Feeding Roles Deposit feeder / collector-gatherer –FPOM and microbiota –Browse, collect on surface, burrow –Ephemeroptera, Chironomidae, Ceratopogonidae FPOM = < 0.5 mm

Feeding Roles Grazer –Periphyton (mostly diatoms) by scraping –Macrophytes by piercing –Ephemeroptera, Trichoptera, Diptera, Lepidoptera, Coleoptera

Feeding Roles Predator –Animals –Biting, piercing –Odonata, Megaloptera, Plecoptera, Trichoptera, Diptera, Coleoptera

Terrestrial Stream CPOM DOM Leaching Microbes Shredders Feces FPOM

FPOM consumers Suspension and deposit feeders –Many adaptations for filtering –Philopotamidae caddisfly spins net

FPOM consumers Suspension feeder –Black fly larvae = Simulidae

FPOM consumers Deposit feeder = collector-gatherer –Some in sediments, some forage

Consumers of autotrophs Grazers, piercers –Graze periphyton –Scraping mouthpart adaptations –Water penny beetle larva Psephenus

Consumers of autotrophs Another grazer –Mayfly Stenonema –Brush algae, then collect it

Predators Most engulf prey entire or in pieces; others have piercing mouthparts

Problems with trophic classification Diet shifts with age and size Many very young invertebrates feed on fine detritus, then change