LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

GROUP 1, SESSION A: ANIMAL PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
27. A multi-scale method for assessing ecological intensification in
aquaculture systems
Aurélie Wilfart 1,2,* , Jéhane Prudhomme 1,2,3 , Jean-Paul Blancheton 3 , Joël Aubin 1,2
1 INRA, UMR1069 Sol Agro et hydrosystème Spatialisation, F-35000 Rennes, France, 2 AGROCAMPUS
OUEST, F-35000 Rennes, France, 3 IFREMER, Laboratoire de Recherche Piscicole de Méditerranée,
Chemin de Maguelone, 34250 Palavas-les-Flots, France, Corresponding author. E-mail: aurelie.wilfart@rennes.inra.fr
To meet the challenges of producing more while lowering impacts on ecosystems, new farming systems have
to be designed. To define development strategies, a multi-scale assessment method that estimates the tradeoff
between human demand and natural services, as well generates consistent performance indicators on utilisation
of natural resources and environmental emission levels based on the same set of input data is needed.
LCA estimates resource use and potential environmental impacts throughout a product’s life cycle at global
and regional scales (ISO, 2006) but does not consider the provision of ecosystem services or products (Ulgiati
et al., 2006). Emergy accounting (EA) is an ecology-based tool developed to integrate all system inputs
(environmental and economic values) using a common unit, solar emergy joule (Odum, 1996). EA inserts the
productive cycle into a local environmental context and quantifies the energy flows between the environment
and the production system. Through three contrasting fish-farming systems, we attempted to demonstrate the
interest of a combination of LCA and EA to define the major components of environmental sustainability
and ecological intensification of fish farming and more globally of agricultural systems.
The first system is a recirculating system (RSF) of Atlantic salmon depending highly on external inputs (feed
and energy). The second one is extensive fish polyculture in a pond (PF1) with few external inputs. The last
one is a small pond farm with use of external feeds. These systems were assessed according the ISO standards
for attributional LCA during one production year. The assessment covered farm operations and transportation
at all stages. Local emissions of nutrients were estimated using nutrient balance modeling and pond
emissions were refined to include nitrogen-fate factors. LCA results are presented as traditional midpoint
indicators according CML 2 baseline 2001and are expressed by tonne of fish produced. Emergy accounting
[3] is based on LCA system definition but includes also the contributions of natural systems (sun, rain,
groundwater, etc.) and provide indicators to evaluate the efficiency of energy use and its quality during the
lifecycle. The chosen Emergy indicators are: Percentage of renewability (%R); the Emergy Yield Ratio
(EYR, ability to rely on local resources; Environmental Loading Ratio (ELR, level of exploitation of nonrenewable
resources compared to renewable ones).
For 1 tonne of living fish, RSF had higher potential impacts for NPPU and all the Emergy indicators (Fig. 1).
PF2 had higher potential impacts in comparison with PF1 except for water dependence. However, RSF had
lower potential impacts for climate change, eutrophication, land competition and water dependence than
ponds, which reflects the level of intensification of the systems. The consumption of energy (calculated by
LCA, Figure 2) was similar for RSF and PF1 and higher for PF2. But, the contributors to this impact differed
among the systems (direct energy use for ponds and feeds and direct energy used for RSF). The difference
in%R between systems was due to water origin: for RSF water was pumped whereas for ponds it came essentially
from rain and water run-off. PF1 has a higher EYR, which means that it depends less on market
resources than RSF. The RSF higher value of ELR (7.98) indicates a moderate environmental impact.
The combination of LCA and Emergy accounting on contrasting systems provides a perspective of what
ecological intensification could mean in aquaculture: a decrease in potential impacts per unit mass of final
products, especially for global warming, eutrophication and acidification; a decrease in dependence on market-based
and external resources; and an increase in the use of renewable natural resources and input efficiency.
This is particularly true for choices regarding feed ingredients and the origin of energy sources.
References
ISO, 2006. Environmental Management -Life Cycle Assessment- Principles and Framework. ISO 14040.
Odum HT. Environmental Accounting: Emergy and Environmental Decision Making. New York: Wiley;
1996.
Ulgiati S, Raugei M, Bargigli S., 2006. Overcoming the inadequacy of single-criterion approaches to Life
Cycle Assessment. Ecol. Modell., 190:432-42.
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