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Heterotrophy

Heterotrophy. Input of CPOM (>1mm) occurs throughout the year. Fall Winter Spring Summer. Leaves Needles 54% of total litter input to Bear Brook, NH. Flowers Seeds. Flowers Fruit Seeds Frass. Litterfall

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Heterotrophy

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  1. Heterotrophy Input of CPOM (>1mm) occurs throughout the year Fall Winter Spring Summer • Leaves • Needles • 54% of total litter input to Bear Brook, NH • Flowers • Seeds • Flowers • Fruit • Seeds • Frass

  2. Litterfall composition, Glenwild Lake, NJ Sebetich & Horner-Newfeld (2000)

  3. Fate of allochthonous material once it enters a stream: • Breakdown - Function of: • Physical • Chemical • Biological actions • Transport – Function of: • Discharge • Streambed composition

  4. From: Webster et al. (1999)

  5. Effect of discharge on organic matter concentration in streams

  6. CPOM trapped more efficiently by: • Channel roughness • Backwaters • Debris dams • Trapping efficiency can be determined experimentally • Leaves & small wood may travel <10 meters downstream • (about 100m during spate) • FPOM travels about 200m downstream

  7. Fate of CPOM • Leaching • Microbe colonization • Fragmentation (Allan 1995)

  8. Microbes • Decompose leaves and other o.m. • Make leaves more palatable & nutritious to shredders • e.g., Cummins’ cracker & peanut butter example Fragmentation • By invertebrates • About 25% of leaf degradation is due to • invertebrate animals

  9. FPOM (0.45-1000 μm) • examples: fragments, fine terrestrial particles, algae, feces of invertebrates • More easily transported due to the small size • Availability to consumers influenced by discharge and instream obstructions • FPOM travel in stream ~ 200m • FPOM feeders ingest >4x their weight/day • Total standing crop of FPOM in Sycamore Creek, AR injested and egested every 2-3 days

  10. DOM • Sources: • Soil o.m. & shallow groundwater (2-30 mg/L) • Precipitation (1 mg/L) • Below canopy (2-3 mg/L) • Canopy drip (25 mg/L) • Extracellular releases from algae • Leaf leachate of DOC • Fate: • Taken up rapidly (within 48-72 hrs) • Adsorption onto clays • Complexation reactions w/Al & Fe • Flocculation • Photochemical destruction

  11. Annual Energy Budget for Bear Brook, NH

  12. Food (energy) Processing • Major Food Resource Pools in Lotic Systems • Detritus – CPOM & FPOM • Periphyton • Macrophytes • Prey • What processes these and how? • Shredders • Collectors • Scrapers Grazers • Piercers • Predators

  13. Role of Microbes Fully conditioned Conditioning Time 3-4 weeks

  14. The influence of conditioning time of discs of hickory leaves on utilization by Tipula abdominalis. (From: Allan, 1995)

  15. What is the Fate of Microbial Biomass? • microbes metazoans macroinverts fish • - major energy losses with each trophic level • microbes • mineralization Microbe Loop “link” vs. “sink” debate

  16. What Consumes CPOM? • amphipods (Gammarus) • isopods • crayfish • freshwater shrimp • snails • Tipulidae (crane fly larvae) • trichopterans (wood consumers: midges, elmids, caddisfly, cranefly)

  17. FPOM Processors • Captured from: • Suspension collectors-gatherers • Substrate grazers & scrapers • Suspension Feeding Capture Mechanisms • Setae on mouthparts or forelegs Source: Hynes (1972)

  18. Use of structures on the head Source: Hynes (1972)

  19. Catch Nets (esp. Trichoptera, some Chironomids) Source: Hynes (1972)

  20. Production of current through tubes

  21. FPOM Processors (continued) • Deposit Feeding (grazers/scrapers) • Feeding while burrowing • - e.g., annelids • Feeding on surface deposited particles • - snails, stonefly (Brachyptera)

  22. Is temporal and spatial variability in substrate food sources • Some species are capable of: - differential ingestion: usually select higher % of small particles - differential digestion e.g., high quality foods = rapid absorption high feeding rates & short GRT e.g., low quality foods = slow absorption low feeding rates & long GRT

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