• Linking
  hydromorphology
  to ecology
• Network Contacts
• Resources
• Physical Habitat Assessment Methods in Rivers
• 2009 AGU Session
• 2008 AGU Session
• Ballater Workshop
• Relevant Literature
• Ongoing progress
• Contact
• South Korean 4-rivers project
• Catchment Management Homepage

Break-out session 2. Linking hydromorphology to ecology (covering topic 5)

Group A

Group B

Group C

Group D

Group A:

What approaches are available to link ecology to hydromorphology (e.g., focal species, multi-metric indicators) in order to assess the ecological health of fluvial systems? How can reference states be assessed?

Reference state: physical, chemical and biological?
Policy approach: classification and/or reference reach

• Reference state – a set of natural circumstances
• Regulate against potential for impact (e.g., sedimentation)
  • Standards?
  • Thresholds?
• Historical, analogue, analytical

Parameterisation: easy with water quality, hydrology

Expert judgment – parameters?

General principal: process – form/function – habitat – biology (decreasing spatial and temporal scale, action to response). Most HM knowledge of physical process and form/function, ecology most knowledge of habitat and biology – linking middle area missing – communication! Benefit of conceptual model identifying links between process – form – habitat – biology.

General problems: HM often deterministic, dynamic, stratified sampling; ecology often stochastic, static and random sampling – need to communicate and allow compatibility.

Approach:

• P-F-H-B
• Identifying pressures (mechanisms)
• Monitor parameters

Requires:

• Surveys
• Experiments
• Existing literature
• models

Existing monitoring data not ideal or useless but how do we supplement for added value? Need to beging to collect data that is fit for purpose.
Then:

• watershed analysis :
  • what was?
  • what is?
  • how did change occur?
  • what do we want?
• Risk assessment/ standards – e.g., abstraction – flow reduction – biotic impact
• Absence of pressures for reference reach with historical impacts assessed (thro historical or analytical approaches) – form ~ natural unmodified

 

Group B:

What aspects of hydromorphology and spatial/temporal scales are most effectively linked to ecology to understand physical and biological relationships?

Ecology = ecosystem (structure? Or process?)
Scientific vs prescriptive outlook

• cf. practitioners, i.e., not starting with constraints
• Context dependent

Most important HM variables

• Flow regime (Magnitude, timing, variability)
• Sediment reimge (volume, texture)
• Channel morphology/ relative stability
• Wood flux (LWD organic debris)

Some key process concepts

• Competence, aggrading/degrading/lateral stability
  • Morphological resilience
• Constraints
• Primary productivity
• Dispersal
  • Migration (upstream, downstream, lateral, vertical
• Resilience/refugia
• Food web dynamics

Catchment diagram illustrates

• 1. Space – need holistic view
  • Catchment, segment, reach, pool-riffle
  • “Where” is as important as ‘at what scale”
• 2. Hydromorphology: sections where water/sed/wood regime is internally consistent
• 3. Resolution /timing
  • Need to capture
    • Annual, seasonal, monthly, weekly, days
    • Events (biological and physical),
    • Critical ecological windows (e.g., emergence)
  • Doerthe: metabolism is an integrated measure which allows higher temporal resolution
• Integrative measures of ecosystem health
  • Woody debris flush
    • Communities
  • Metabolism (measure of respiration and productivity)
    • Oxygen drawdown at night (high resolution in time)

 

Group C:

What are the legislative requirements for ecological assessment and how does this impact the practicality and scale of different methodologies?

• Classification of rivers
• Ideally good ecological status – compliance
• Restoration success
• Diagnostic
• Habitats directive
• WFD – scale –
• Catchment size?
• Fish – mostly negative response in Sweden and Germany
• Management units
• Typologies

WFD

• Diatoms, macrophyte, macroinvertebrate, fish
• Standard methods
• Intercalibration of metrics

Scale issues

• Source analysis – catchment overview
• Catchment, reach, patch

Biological clarification reflective of hydromorphological pressures

• Hypotheses (mechanisms)
• Metric response
• RHMI, life scores species, traits are better
• Link pressures to process

What do we need better from ecological assessment to identify hydromorphological pressures

• Functional metrics
• Trait based metrics
• Conceptual models (resistance, resilience)
• Better understanding of process-function

Conceptual models

• Shifting habitat mosaic
• Value in different river types

Habitat sampled?

• Multi-habitat
• Semi-terrestrial habitats
• Gravel bars
• Better indicators

Barriers

• – structure of agency
• public participation
• Stakeholder buy-in to regulation

Temporal scale

• NAO – Big Drivers
• Lag time between restoration and improvement
• Recalibration of models
• Natural variation and climate change invalidating static reference conditions

 

Group D:

Why are some data sets not showing links between hydromorphology and ecology?

• Disagree with the statement – there are links, but not always
• Lacking from RHS data sets at times
  • Hasn’t always been the aim; originally for WQ
  • Possibly confounded with WQ
• What scales and level of origin? All H-M vs all biota?
• Are biology samples sampling the right array of HG categories?
• Food web effects modify physical-biological relations
• Dispersal and other biological traits may confound relationships
• Alpha, beta, gamma diversity at different scales
• Adequacy of WQ monitoring
  • Some classes of contaminants not included
  • May miss ‘episodes’
• May be limited gradients of physical variables – may not overcome residual variance
• Inadequate characterization of hydrological time series
  • Data gaps (in time and kind)
• Some biological processes may be more robust than appreciated
• Some species may occur in unexpected/ “inappropriate” places
• Communities may be biased by common/robust/ubiquitous spp
  • Could overwhelm subtle community level or spp level changes
• Some WQ reflects natural catchment HM variation, others more anthropogenic
• Integration of antecedent conditions could be inadequate
• Sample may be inadequate
• Explanations to be found in demographic/behavioral responses
• Additional taxa, processes, and structures that are included may show stronger responses
• Lack of attention to meiofauna (hyporheos, groundwater)
• Consideration of connected habitats – eg. For plants in lateral habitats
• Absence of monitoring restoration as a test of relations
• Learning opportunities from regulated rivers
• Training of suffuicuent numbers of HM practioners
• Inadequate background (historical geomorph)
• Limited view of HM processes from a few cross sections
• Need for well defined mechanistic (and alternative) hypotheses
• Non-linearities, lags, thresholds

 

We can group these into four categories

1. Limits to what we measure
2. Taxonomy issues (both biological and physical)
3. Links
4. Interpretation
   1. Expertise, stats, scale, models

Future – better hypotheses, mechanistic Incorporating sample error rates, calibration and others, confidence intervals

Break-out session 3. Restoring ecology through hydromorphology (covering topic 6)