Stream Animals & the Heterotrophic Food Chain

Processing of Organic Matter• In fall, leaf debris from

overhanging deciduous trees accumulates in the stream

• Flowing water leaches the leaves soluble organic matter as dissolved organic matter (DOM) or fine particulate organic matter (FPOM)

• The leaves remain as coarse particulate organic matter (CPOM)

Microbial Processing

• The remaining leaf surface is colonized by bacteria (on FPOM) and fungi (on CPOM)

• These microorganisms convert the cellulose and lignin into forms useable by invertebrates

Invertebrate Processing:1) Shredders

• The shredders feed on the leaves and their resident microbes, and convert the CPOM into FPOM

Common Shredders

• Craneflies(Diptera)

• Caddisflies (Trichoptera)

• Stone-Fly Nymphs (Plecoptera)

• Crayfish

2) Filtering and Gathering Collectors

• FPOM carried down stream is acquired by the Filtering and Gathering Collectors, processed, and turned into DOM

Common Collectors

• Blackflies(Diptera)

• Fan and net spinning Caddisflies (Trichoptera)

• Midges

3) Scrapers, Piercers, & Gougers

• Algae and mosses coating the surface or rocks is processed too

• Scapers and Piercers feed on algae, while Gougers feed by burrowing into the trunks of fallen trees

Common Scrapers, Piercers, & Gougers

Scrapers• Beetle Larvae

(Coleoptera)• Mobile Caddisflies• Snails

Piercers• Microcaddisflies

Gougers• Fly Larvae (Diptera)

Invertebrate Predators

• All the invertebrate organisms that process the leaves, algae, and wood are potential food for invertebrate predators

• One common predator is the Hellgramite or Dobsonfly Larvae (Megaloptera)