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Instream Cover or Stucture

Instream Cover or Stucture. Not “tree cover,” but instream physical structure. Newer Cover Scoring Procedure. Previous threshold for check box for a given cover type was low (~5%)

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Instream Cover or Stucture

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  1. Instream Cover or Stucture Not “tree cover,” but instream physical structure

  2. Newer Cover Scoring Procedure • Previous threshold for check box for a given cover type was low (~5%) • Overall cover metric and number of cover types correlated with IBI, but individual cover type quality not rated well • Each cover type scored from 0-3 points based on standard definition • Still scoring based on old method also, will phase out next year; need to calibrate new method to old data

  3. New Cover Metric • Instructions for scoring the alternate cover metric: Each cover type should receive a score of between 0 and 3, Where: • 0 - Cover type absent; • 1 - Cover type present in very small amounts or if more common of marginal quality; • 2 - Cover type present in moderate amounts, but not of highest quality or in small amounts of highest quality; • 3 - Cover type of highest quality in moderate or greater amounts. Examples of highest quality include very large boulders in deep or fast water, large diameter logs that are stable, well developed rootwads in deep/fast water, or deep, well-defined, functional pools.

  4. Amount of Cover

  5. Rootwads/Logs

  6. High Quality Rootwad • Sycamore among the best quality • Large diameter roots • Best when in deep water • Best when in or adjacent to fast water

  7. Aquatic Macrophytes • Only macrophytes, not algae or diatoms • Emergent or submergent • Great nursery areas • Improve riffle quality by making riffles narrower and deeper

  8. Boulders • Examine all cover types to determine whether they are functional! Functional Boulder: In Deep Fast Water Non-Functional Boulder: In Shallow Water & Embedded

  9. Undercut Banks • Needs to be in deep enough water and undercut enough to provide function as cover • If undercut is part of rootwad count as rootwad, not as undercut

  10. Rootmats • Fine fibrous roots of willows and other plants • Small fish may use these as cover or feed on invertebrates that colonize them

  11. Logs and Woody Debris • Habitat forming functions • Fish cover • Macroinvertebrate production, especially in big rivers • Bank protection

  12. Overhanging Vegetation • Shading • Refuge from avian predators (e.g., kingfishers, herons) • Terrestrial food • Does not include high canopy

  13. Oxbow Backwater Oxbows, Backwaters, & Side Channels • Oxbows, backwaters, and side channels are excellent nursery habitat • Sequester/transform nutrients • Spawning areas (e.g., northern pike, muskie)

  14. Shallows in Slow Water • Y-O-Y fish use margin areas to feed and escape predators

  15. Cover vs IBI

  16. Benefits of New Scoring Approach Spotted Bass

  17. Habitat Generalist: Green Sunfish

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