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1. Habitat Considerations for Mussel Re-establishments and Translocations Brett J. K. Ostby
Department of Fisheries and Wildlife Sciences
Virginia Tech
2. Translocation Woes Stress to mussels in collection and transportation
No or limited consideration for habitat
3. Overview Background
Literature review
Basic concepts
Terms
Applying that knowledge
Framework for selecting suitable destination sites
What to measure
5. Why microhabitat? Understanding habitat at this scale may explain behavior and survival of individuals
Intuitive
Important for fish, why not mussels?
Focus on this scale may be a consequence of fragmentation
6. Microhabitats Strayer (1981)
Species that coexisted in a site had similar microhabitat associations
Species had broad distributions within a site
Microhabitats occupied by a species varied among sites
7. Microhabitat Other studies found subtle differences among microhabitat use by species
But many others have failed to detect patterns at small scales
10. Generation of new hypotheses Measuring the wrong components of habitat
Patterns concealed by processes and events at greater temporal and spatial scales which shape habitat at smaller scales and may directly effect abundance and richness
Other biological processes explain abundance and richness
Host fish distribution and abundance (Haag & Warren 1998)
11. Measuring the Wrong Components of Habitat?
12. Hydraulic Stream Ecology Layzer and Madison (1995) use simple and complex hydraulic parameters to measure a reach below a dam with consideration for temporal context
Found low predictive power for simple parameters; however, shear stress was negatively correlated with mussel abundance at a higher discharge
13. Several recent studies have since applied this approach at the microhabitat and greater scales and have seen patterns, however these patterns differ by stream
Myers-Kinzie (1998)
Hardison and Layzer (2001)
Krstolic (2001)
Gangloff (2003)
Stone et al. (2004)
Ostby (2005)
Adair (2005)
14. Fliesswasserstammtisch (FST) hemispheres used to measure local shear stress near bed flow
15. Measuring the Wrong Components of Habitat? Adair (2005) study in the Duck River
Adult and juveniles densities within a reach related to
shear stress (FST)
interstitial water temperature
Substrate permeability also a predictor of juvenile occurrence
17. Spatial and Temporal Scale
18. Stream Systems Events and Processes that form and alter stream systems influence habitat at finer scales and affect assemblage patterns and species distributions
Several studies have observe that mussels occupying certain microhabitats were absent in systems where similar microhabitat exist
Strayer (1983) suggested that macrohabitat factors controlled velocity, turbidity, water chemistry, and timing an character of organic input
19. One step further . . . Stayer (1983) suggested variation in discharge patterns where the most important limiting factor Stream Systems
20. Flow Regime Magnitude of discharge describes the volume of water passing a fixed location per unit time
Gangloff (2003) observed that increases in magnitude of flow over the recent past were associate with declines in some streams of the Upper Alabama River basin
21. Flow Regime Frequency is how often a flow above a give magnitude recurs and is inversely related to flow magnitude
Hastie et al. (2001) documented the effect of a 100 yr flood on mussel populations in the River Kerry
Found that some mussel beds untouched while other buried or dislodged as channels were scoured and reformed
Refuges?
22. Flow Regime Duration or timing of flow events have never been explicitly studied
Nevertheless, the timing or predictability of flows has often been cited as a culprit in the decline of musses below dams
May affect reproductive success, fish assemblages
23. Flow Regime Rate of change (flashiness or hydrological variability) appears to have profound effects on species distributions
Di Maio and Corkum (1995) found different assemblage patterns in flashy than in stable streams
Arbuckle (2000) found flashy streams in Iowa had reduced density
Both studies noted that these patterns were related to land use (landscape scale)
24. Stream Systems Stream systems can have very different flow regimes controlled by basin topography, climate, and land use
These factors can determine long-term stability of habitat patches used by mussels and obscure patterns at finer scales
Clinch River (Virginia and Tennessee) vs. Eel (Northern California)
25. Eel High discharges constrain distribution in the Eel River
Mussels are almost exclusively found in pools, near channel banks in sedge mats where shear stress and flow velocities are considerably lower
26. Clinch Mussels less abundant in pools and deeper runs
Riffles and Shoals more stable habitats?
27. Stream Systems Geology, soils, and land use differences among streams also have affects on assemblages via changes to
Flow regime
Sediment regime
Water quality
28. Stream Segments Physico-chemical differences among stream segments
Input from tribs
Progression from first-order streams to large rivers
River Continuum Concept
May be complicated by anthropogenic impacts
29. Stream Segments Riparian Vegetation Density has been correlated with riparian vegetation type (Leff et al. 1990)
Vegetation type indicative of hydrological variation?
Morris and Corkum (1996, 1999) observed that riparian zones affected growth and species distribution
Forest = species with slow growth
Grasses = species fast growth
Transplants confirmed these patterns
Iowa Streams with forested riparian had higher richness (Arbuckle 2000)
30. Stream SegmentsLithology and Valley Shape Church (1997) observed that large continuous areas of alluvium (gravel shoals) with little or no bedrock supported mussel beds
Shoals occurred in reaches with braided channels; however, the structures that created these conditions changed with channel lithology and valley morphology (segments)
Of 26 braided reaches, 24 occurred on shale formations, while only two on limestone-dolomite
31. Stream SegmentsLithology and Valley Shape Greatest number of high quality braided reaches occurred over the thicker of two shale formations
32. Reaches Krstolic (2001) compared hydraulic parameters of riffle complexes among reaches in the Clinch River
33. Reaches Stone et al. 2004 saw a contrasting pattern in a southwestern Washington stream, as did Gangloff (2003) in Alabama
Mussel populations higher in low shear stress habitats
34. Current Paradigms Flow Regime
Spatial and Temporal Scale
Limiting factors at all scales
Refugia
35. So many things to consider where do we start? Water quality?
Substrate?
Flow?
Geomorphology?
Landscape?
Microhabitat?
36. Translocation Habitat Framework
37. Landscape Risk Assessment (Zimmerman 2003, Guyot 2006)
Some variables used
# of mines
Distance to road
% urban land use
Hydrological models
38. Reaches Stability
Refuges (Shear stress and channel morphology)
Riparian vegetation
Bank Stability
Visual habitat assessment (McRae et al. 2004)
39. Within Reaches Are low flow conditions relevant?
Most of the time streams experience low flow conditions
41. Within Reaches Are low flow conditions relevant?
Flow for biological needs most of the time streams experience low flow condition
Some species have specific habitat needs (Ostby 2005)
43. Within Reaches Are low flow conditions relevant?
Most of the time streams experience low flow conditions
Some species have specific habitat needs (Ostby 2005)
Juvenile habitat?
Interstitial flow
Embeddedness
Fewer clogging fines
45. Within Reaches Are low flow conditions relevant?
Most of the time streams experience low flow conditions
Some species have specific habitat needs (Ostby 2005)
Juvenile habitat?
Interstitial flow
Embeddedness
Fewer clogging fines
Small Scale Refugia (Strayer 1999)
Fish Habitat
46. Within Reaches Limitations:
Data is limited (Ostby 2005, Adair 2005, Boden & Brown 2002)
Transferability of criteria
Currently testing transferability of criteria to Duck River and assessing value to guide translocation in French Broad
47. Some Sensible suggestions Include money for habitat evaluation in projects!
Develop risk assessments
Empirically derived bankfull Shear Stress
Monitor low flow conditions in selected reaches
Faux mussels?
48. Faux Mussels Place in potential destination sites to identify locations where suitable low flow conditions and refuges are coincident
Could be a rock with the same density (specific gravity) or buoyant weight
49. Translocation Habitat Framework
50. Discussion