Chapter 9- Habitat fragmentation Principles in Conservation Biology
Assessing impacts of habitat fragmentation on fish ......Assessing impacts of habitat fragmentation...
Transcript of Assessing impacts of habitat fragmentation on fish ......Assessing impacts of habitat fragmentation...
Assessing impacts of habitat
fragmentation on fish
populations, and prioritisation
of restoration actions
Paul Kemp
International Centre for Ecohydraulics Research
Presentation plan
• Introduction to Fish Research at the University of Southampton
• History – river development in Europe
• Implications of EU Legislation - Water Framework Directive
• Assessing impacts of barriers to fish migration
• Developing inventories of barriers
• Prioritisation of restoration (or development) of rivers
Introduction – Fish Research at the
University of Southampton
University of Southampton
International Centre for
Ecohydraulics Research
• Research in Fish Ecology and Fisheries Engineering –
International
• Fish passage, screening, compensation flows
• Experimental and field based research
• Multiple species
• Behaviour and locomotory performance
• Fish response to hydrodynamics and acoustics
Facilities
• 1 Open channel external flume facility
- Trapezoidal concrete channel
- 60 m long and 2 m wide
Large channel swimming
performance tests
Trajectory of a migrating adult eel
using acoustic telemetry
Developing fish passage criteria for large
hydropower dams in China
………and United States
……. and Sweden (and other European
countries)
Fish Behaviour in response to turbulence
and other hydrodynamic factors
Developing screening
criteria for downstream
migrating adult eel
0.0 0.5 1.0 1.5 2.0 2.5
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120 = 10%
approaches
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80%
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Distance upstream of bypass (m)
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me w
idth
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me w
idth
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Turbulence
intensity (K)
Infrasound
Infrasound induces an avoidance
response in migrating European eels
River Imsa, Norway Sand et al. 2000
Acoustic bubble screen River Frome, Dorset
A novel smolt counting system, developed by CEH, incorporating
acoustic bubble screens (Fish Guidance Systems Ltd) to divert fish
through counters (Welton et al., 2002).
Screening water intakes at power stations
Key message from research
• Need to consider fish behaviour when
developing fish passage and screening criteria
• Need to consider multiple species
• Need to develop realistic measures of swimming
performance
• Need to develop behavioural devices that deter
fish (e.g. using acoustics or hydraulics)
History – River Development in
Europe
“All kydells for the future shall
be removed altogether from
Thames and Medway, and
throughout all England, except
upon the sea shore”.
Kydells = fish weirs
The Magna Carta
England and Wales:
Area = 151,000 km2
(Minas Gerais = 586,528 km2)
Approx. 26,000 dams and weirs
that disrupt connectivity of ecological
processes
Majority = small
• UK and Europe = long historic legacy
of river development
• Negative impacts have been recognized
for a long time
• Structures are often relatively small
• High density of infrastructure
What’s the problem?
Disrupts connectivity
(longitudinal and
lateral) of ecological
processes and
fragments habitat
Year
An
nu
al c
atch
(sa
lmo
n a
nd
gri
lse)
0
20000
40000
60000
80000
100000
120000 1
95
2
19
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2000
Tay District Salmon Catch Statistics (1952-2001)
American eels – St Lawrence Freshwater fish extinctions: graph to show known
species extinctions by decade
Implications of EU legislation
Water Framework Directive
Conflict or Counterbalance?
Renewable Energy
Obligations
Water Framework
Directive
Requirements of EU Water
Framework Directive
• To maintain "good ecological status" in terms of the
quality of the biological community, the hydrological characteristics and the chemical characteristics.
• The controls are specified as allowing only a slight departure from the biological community which would be expected in conditions of minimal anthropogenic impact.
• Habitat fragmentation prevents rivers attaining good ecological status independent of water quality and availability of suitable physical habitat
Repair or removal of barriers is the
easiest and quickest way to maximize
benefits of restoration actions
The removal or mitigation of barriers that block fish dispersal have led to some
of the largest increases in fish production (Roni et al. 2002).
Scully et al. (1990) observed that 70% of increases in fish production in
rehabilitated Idaho streams were due to barrier removal versus in-stream
and other restoration techniques.
Europe - the challenge is to:
1. Develop methodologies to survey river infrastructure
2. Assess the impact of river infrastructure
on ecology (often fish) – what is the porosity to fish movements?
3. Construct inventories of river infrastructure and map networks of barriers
4. Efficiently prioritise restoration action
Assessing the impact of barriers to
fish migration
Locate the barrier
Record the location and
ownership information
Determine if the stream
is fish bearing No
Collect basic
barrier
measurements
Yes or unknown
Level A
Barrier Assessment Not a
barrier Stop
Conduct Level B
Barrier Assessment Not a barrier
or unknown Stop
Barrier
Prioritize the
Barrier for correction
Conduct Habitat
Assessment
unknown
Barrier
Barrier assessment protocol
Aerial surveys
Methodologies to quantify porosity of
barriers to fish migration
1. Direct observation and filming
2. Hydroacoustic sonar
3. Telemetry
4. Fish surveys
5. Presence/absence data
6. Genetic structure of populations
7. Rule-based simulation
8. Statistical models
9. Expert opinion
• Fine-scale
• Detailed information on behaviour and passage.
• Limited application
(e.g. low turbidity,
shallow depth)
1. Direct observation and filming
2. Hydroacoustic sonar
• Fine-scale.
• Detailed information on behaviour and passage.
• Expensive.
• Limited application.
• High data processing.
3. Telemetry
• e.g. Passive Integrated Transponder (PIT), Radio, Acoustic, combined.
• Fine-scale.
• Detailed information on timing, rates, and routes of migration, facilitating accurate estimates of fish passage, attraction, and guidance efficiency.
• Relatively expensive and resource intensive.
• Not viable at watershed, regional, or national scales.
PIT Telemetry
Radio
telemetry
From Brown et al. 2009
Downstream passage
(American eel) – Hydroacoustic Telemetry
4. Fish surveys
• Abundance and density estimation (e.g. electrofishing, redd counts netting, mark-recapture, catch depletion, trapping).
• Intermediate-scale.
• Provides spatial and temporal information on distribution, abundance, and density of populations and community composition in relation to river infrastructure and associated habitat fragmentation.
• Limited information on barrier passability associated with individual
structures.
5. Presence/absence data
• Coarse-scale.
• Low cost.
• Data collected rapidly through surveys or by canvassing local knowledge.
• Limited information on barrier passability associated with individual structures.
• Can be misleading if infrastructures are considered independently (e.g. absence of fish may be related to other factors or the presence of impassable barriers elsewhere in the watershed)
6. Genetic structure of
populations
• Coarse-scale
• Provides information on genetic isolation of populations that may indicate potential compromise of long-term population persistence which may be used to make conservation decisions.
• Highlights the impacts of lost
connectivity over the longer term.
• Potential high cost.
• Need for specialist expertise.
• Of limited value for diadromous
fish species.
7. Rule-based simulation
• e.g. FishXing.
• Multiple scale
• Low cost.
• Can be employed across scales.
• Requires detailed hydrological data.
• Information about multiple species of fish is often incomplete or lacking.
• Validation using fine-resolution fish data is rare.
FishXing –
helps design and evaluation of culverts for
fish passage based on estimates of swimming
capabilities of fish
8. Statistical models
• (e.g. multivariate regression)
• Multiple scale
• Low cost.
• Can be employed across scales.
• Identifies factors that influence passability.
• Transferability of predictions to barriers with similar physical and hydraulic conditions.
• Requires basic input data which must usually be obtained using fine-scaled approaches.
9. Expert opinion
• Multiple scales.
• Low cost.
• Can be employed across scales.
• Validation using fine-resolution fish data is
rare.
Developing Inventories of Barriers
Database
of barriers
- California Database of barriers
- England and Wales
The development of inventories
• Inventories of barriers tend to be GIS
based geospatial databases
• Problems - data quality
- obtained from multiple
sources
- ownership and
management
The development of inventories
Prioritisation of restoration actions
Prioritisation of restoration actions
Barrier removal or repair
• Scoring-and-ranking
• Network analysis
• Optimisation
Optimization modelling
Precedents in transport
system modelling
Network analysis can also be used to plan
river development in a way that minimises
environmental impacts
Conclusions • Europe – long historic legacy of river development
so high density of barriers to fish migration
• Extensive habitat fragmentation due to barriers
• Water Framework Directive – legislative framework for restoration
• Multiple methods for barrier porosity assessment
• Inventories of barriers based largely on GIS
• Prioritisation (of restoration or development) should use optimisation and network analysis and avoid scoring and ranking
Thank you