# Presentation: 221895

## Habitat Considerations for Mussel Re-establishments and Translocations 

- Brett J. K. Ostby
- Department of Fisheries and Wildlife Sciences
- Virginia Tech

## Translocation Woes

- Stress to mussels in collection and transportation
- No or limited consideration for habitat

## Overview

- Background
- Literature review
- Basic concepts
- Terms
- Applying that knowledge
- Framework for selecting suitable destination sites
- What to measure

## Quantifying habitat 

-   Flow depth and velocity
-   Substrate particle size

- And many studies to this day quantify habitat by velocity, depth, and substrate size during low flow conditions with varying success

- Quantifying habitat

## 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

## 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

## Microhabitat

- Other studies found subtle differences among microhabitat use by species
- But many others have failed to detect patterns at small scales

##   Patterns are rarely clear

-   Patterns are rarely clear

-   The same species appeared to occupy different habitats in different streams

- Species appear to have broad overlapping habitat use

## Slide 9

## 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)

## Measuring the Wrong Components of Habitat?

- Reynolds number
- Turbulence
- Froude number
- Gravity vs. inertial force
- Shear stress
- Force on bed
- Stream Power
- Describes the erosive capacity of a stream

- Hydraulic stream ecology approach proposed by Statzner et al. (1988)

## 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

## 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)

- Myers-Kinzie (1998)
- Hardison and Layzer (2001)
- Krstolic (2001)
- Gangloff (2003)
- Stone et al. (2004)
- Ostby (2005)
- Adair (2005)

- Hydraulic Stream Ecology

## Fliesswasserstammtisch (FST) hemispheres used to measure local shear stress near bed flow

- Hardison and Layzer (2001)

## 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

## Spatial and temporal context

- Nested Habitat Hierarchy

## Spatial and Temporal Scale

## 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

## One step further . . . Stayer (1983) suggested variation in discharge patterns where the most important limiting factor  

- One step further . . . Stayer (1983) suggested variation in discharge patterns where the most important limiting factor

- Stream Systems

## 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

## 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?

## 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

## 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)

## 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)

## 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

## Clinch

- Mussels less abundant in pools and deeper runs
- Riffles and Shoals more stable habitats?

- Mussels beds found in riffles and shoals often in the middle of the river
- These habitats have the highest velocities and shear stress  values during low flows

## Stream Systems

- Geology, soils, and land use differences among streams also have affects on assemblages via changes to
- Flow regime
- Sediment regime
- Water quality

## 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

## 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)

## Stream SegmentsLithology 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

## Stream SegmentsLithology and Valley Shape

- Greatest number of high quality braided reaches occurred over the thicker of two shale formations

- The segment of river that flowed through this formation also had a greater valley floor width and the lowest gradient of all formations in the river

- But . . .high quality reaches also existed in the limestone dolomite segments where the stream flowed perpendicular to the underlying bedrock ledges

## Reaches

- Krstolic (2001) compared hydraulic parameters of riffle complexes among reaches in the Clinch River

- She found simple hydraulic measurements varied little among reaches

- However, she observed different patterns between high and low quality reaches for shear stress and stream power

- High quality were high in spring, moderate in late summer

## 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

## Current Paradigms

- Flow Regime
- Spatial and Temporal Scale
- Limiting factors at all scales
- Refugia

## So many things to consider where do we start?

- Water quality?
- Substrate?
- Flow?
- Geomorphology?
- Landscape?
- Microhabitat?

## Translocation Habitat Framework

- Landscape

- Reach

- Within Reach

## Landscape	 

- Risk Assessment (Zimmerman 2003, Guyot 2006)
- Some variables used
- # of mines
- Distance to road
- % urban land use
- Hydrological models

## Reaches

- Stability
- Refuges (Shear stress and channel morphology)
- Riparian vegetation
- Bank Stability
- Visual habitat assessment (McRae et al. 2004)

## Within Reaches

- Are low flow conditions relevant?
- Most of the time streams experience low flow conditions

## Slide 40

## 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)

## Upper

- Lower

## 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

## Within Reaches : Embeddedness, interstitial flow, %fines

- Within Reaches : Embeddedness, interstitial flow, %fines

## 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

## 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

## 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?

## 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

## Translocation Habitat Framework

- Landscape

- Reach

- Within Reach

- Risk Assessment & Prediction models

- Stability

- Specific and juvenile needs coincident with stability

## Discussion