Habitat Considerations for Mussel Re-establishments and Translocations

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