Download Contribution de la FRE BioMéa aux études - Umr

MSEAS - Brest
Dynamic simulations of the Seine
estuary food web:
Towards a holistic and integrated
approach of management scenarios on
ecosystem functioning
Samuele Tecchio, Jean-Claude Dauvin,
Pascal Galichon, Nathalie Niquil
Université de Caen Normandie
funded by Le Havre Port Authority (GPMH)
and Agence de l’Eau Seine-Normandie (AESN)
MSEAS - Brest
The Seine estuary:
MSEAS - Brest
The estuary before Port2000
MSEAS - Brest
Port2000 (building 2002-2003)
MSEAS - Brest
The estuary in 2006
MSEAS - Brest
The new dune system
MSEAS - Brest
Seabirds repository isle
MSEAS - Brest
A multitude of actors
MSEAS - Brest
Studying impacts…
•
•
New container terminal, dredging,
Positive efforts of mitigation
•
Changing hydrography at the same time:
Before/after study was unable to
discriminate impacts
•
Temporal-dynamic ecosystem model:
direct contact with managers
MSEAS - Brest
• Ecopath : snapshot of the food web (1996)
• Base structure for dynamic simulations
MSEAS - Brest
Time-dynamic simulation
Equations :
Forcing data:
Reference series:
- Foraging (e.g.
search rates)
- Mediation (indirect
effects)
- Primary production
- Organic matter input
- Landings and fishing
effort
Biomasses obtained
with scientific sampling
MSEAS - Brest
FORCING TIME SERIES
Primary production :
conc. ChlA (µg/l) -> tC/km2
Organic matter input :
Seine flow (m3/y)
×
conc. C (g/m3)
×
surface of model (1/m2)
=
Detritus import flow
MSEAS - Brest
Model fitting
MSEAS - Brest
Scenarios
•
Absence of mitigation measures
•
How would species change in the case of loss of intertidal flat?
•
Expert knowledge for species responses
(other scientists)
•
The modeller synthesises their ideas
MSEAS - Brest
MIXED TROPHIC IMPACT:
Low impact of fishing relative to biotic relations
MSEAS - Brest
TST
• ENA indices:
related to
system stress
and resilience
SOI
• Trophic
specialisation,
stable recycling,
reduction in link
redundancy:
system
maturation
FCI
R/DC
MSEAS - Brest
Conclusions
•
Network analysis: a set of methods to study
changes in ecosystem functioning
•
•
•
Time-dynamic simulations follow ecological
indicators over the years
•
•
•
Complexity: contradictions due to non-monotonous responses
Link with resilience and ecosystem stress
Surveillance tool
Scenario testing to deconvolute effects
Bringing experts and managers together to
synthesize their ideas into a scenario simulation
MSEAS - Brest