Download Alternative conceptual approaches for assessing ecological impact

WHAT CONCEPTUAL APPROACH FOR
ASSESSING ECOLOGICAL IMPACT OF
RADIATION
Biocentric versus ecocentric view
F. Bréchignac, C. Bradshaw
François Bréchignac
(IRSN & IUR)
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Today’s radiation protection framework
for environment protection
 Legislation, existing or upcoming, requires environment protection
measures for all stressors, with no exception for radioactivity
 Will to be able to demonstrate that the environment is indeed
protected
 Reconsidering the anthropocentric ICRP paradigm « Human
protection indirectly ensures adequate protection of the
F. Bréchignac, C. Bradshaw
environment »
Today’s radiation protection framework is based
upon « reference organisms »
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
« Reference organism » approach: biocentric
ENVIRONMENT
Sources
Targets
Air
Soil
Sediment
Sources
Environment
CROP
PLANTS
WILDLIFE
PLANTS
ANIMALS
Meat, milk
Man
ANIMALS
F. Bréchignac, C. Bradshaw
Water
Anthropocentric
concept
Biocentric
concept
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
What is the reference organisms’ approach ?
 A drastic simplification of the very large number of biota species, in
order to settle an operational assessment methodology
 Concept inspired from « reference man » used in human radiation
protection. ICRP selected 12 RAPs to be used as reference for
comparison purposes
 Concept also aligned with conventional eco-toxicology methods
where dose-responses are documented for individual organisms
(man/surrogate, eco-test species)
F. Bréchignac, C. Bradshaw
« Reference organisms » approach entirely built upon effect
responses of individual organisms
Restricts the scope of risk assessments to individual organisms
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Individual organism/species‐based
frameworks do not address ecosystems
 Interactions between species and indirect effects not considered
 Non‐linear responses, emergent properties, resilience, etc…, not
addressed
 Effects at ecosystem level cannot be predicted/extrapolated from
effects at individual organism/species level
F. Bréchignac, C. Bradshaw
 Adequate to address biological effects, but may over‐ or
underestimate ecological effects / risk
 May explain why in situ population/ecosystem level studies
exhibit different/conflicting effects results …
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Why an “ecosystem approach” is needed ?
 Because objectives of protection are most usually set at
population/ecosystem levels
 Because all organisms can only survive in the context of an
ecosystem featuring obligatory interactions
– Interactions between species, populations, biotic/abiotic
– Emergent properties
– Resilience,
F. …Bréchignac, C. Bradshaw
Bradshaw et al (2014) Fig 2.
C = competition, P =
predation,
H = herbivory , Sy = symbiosis ,
Sh = shelter
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Ecosystem approach is needed to meet
the objectives of protection
Biological impact of radiation
(ICRP)
Imbricated system
(homeostatic stability)
Ecological impact of radiation
(IUR-CERAD)
Network of species interactions
(submitted to abiotic variability)
Producers
Molecules
Organs
Individual
Organisms
Pop. 1
External abiotic environment
(air – water - soil/sediment)
Consumers
Objectives
of
Pop. A
protection
are here
Pop. a
Decomposers
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Mismatch
Protection
target
Methods
to
achieve
protection
goals
Individuals of
endangered species
Reference
organism
approach
Populations / communities
Structure and functions of ecosystems
Ecosystem approach
Population level endpoints: Community-level endpoints:
• Population growth rate Structural
• Biodiversity
• Population density
• Taxonomic composition
• Population
size
Bréchignac,
C. Bradshaw
• Trait distribution
(numbers, biomass)
• Food web structure
• Population age/size
Functional
structure
• Primary production
• Net reproduction rate
• Probability of extinction • Biomass/energy flow
• mineralization
Individual organism
level endpoints:
F.
• Early mobidity
• Mortality
• Reproductive
success
• Chromosome
damage
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
« Ecosystem approach » enlarges the
framework to an ecocentric vision
Environment including man
Oxygen
Biomass
Water

PRODUCERS
CONSUMERS
Man
Minerals
Water
CO2
DECOMPOSERS
Biomass
Waste
CO2
Ecosystem = Biotope + biocenose
Air
Water
Soil
Sedim.
Animals
(man)
Plants
Microbes
 Services (waste recycling, provision of
ressources, …)
 Life support (water recycling, air
bioregeneration, biomass production, …)
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Interpretation of differences between
laboratory experiments and in situ studies
(From Garnier-Laplace J. et al. (2013) JER 121: 12-21)
In situ Chernobyl observations
Controlled laboratory
experimental data
Potential confounding factors:
- Total accumulated dose
- g + a,b radiation
- In situ organisms are within
their ecosystem (interactions)
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Workshop of the 2d IUR « Ecosystem approach » Task group, Stockholm University, Sweden, 18-20 December 2013
Ecosystem resilience
 Emergent property linked to complexity
 Ecosystem capacity to « buffer » a perturbation pressure without
apparent damage
a
c
F. Bréchignac, C. Bradshaw
Highly resilient ecosystem
Poorly resilient ecosyst.
Explanation why various in situ studies have yielded contrasted
effect results ?
Different critical thresholds of perturbation without effect ?
Are universal standards possible at all ?
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Integrated conceptual model
External irradiation
Air
Surface
water
Herbicides
Soil
Sediment
Pelagic
aquatic biota
Soil
microfauna
Fish
Terrestrial
plants
Crops
F. Bréchignac,
C. Bradshaw
Soil microfauna
Benthic
aquatic biota
Herbivorous
mammals
feeders
Cows…
Inhalation
Herbivorous
insects
Insectivorous
wildlife
Ingestion
Predators
Insecticides
Homo
sapiens
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Birds
Comparative summary
Biocentric view
Ecocentric view
Biological effects
Ecological effects
based upon population and
ecosystem level related
F. Bréchignac, C. Bradshaw
endpoints
based upon individual
organism endpoints
Reference organism
approach
Ecosystem approach
Laboratory experiments in
controlled conditions
In situ studies and experiments
in real conditions
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
CONCLUSION
Ecosystem approach value
 Complements the « reference organisms » approach
and compensates for its shortcomings
 Adresses both radiation and other hazards on the same
grounds
 Yields a more convincing demonstration of protection
more directly aligned with protection
F.because
Bréchignac,
C. Bradshaw
obectives
 Sets the appropriate conceptual grounds for exploring
if integration of human beings and populations of
other species and their ecosystems within the
radiation protection system is sensible and feasible
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015
Thank you
F. Bréchignac, C. Bradshaw
IUR International Consensus Symposium - Miami, Florida, USA, 17-19 November 2015