fish community recovery process was not complete, probably because of the irreversible morphological alteration of the river (Fig. 5).
6 The Seine River Axis During the Past Four Decades
The existence of numerous electrofishing data since the early 1980s makes it
possible to address in some detail the changes in fish communities along the Seine
River axis over the past four decades, a pivotal period for a better understanding of
the ongoing recovery processes. For this purpose, we focused our analysis on the
Seine River course, from its confluence with the Aube River, about 200 km upstream
from Paris, to the estuary. Variations of the French fish index (IPR) values and its
metrics over time were examined.
The IPR (Indice Poissons Rivière, i.e. Fish River Index) [32] was developed to
measure the state of river fish communities. It is composed of seven metrics, based
on the number of species or fish abundance, reflecting the community’s functional
or structural features. A score is assigned to each metric measuring the deviation
1980
1870
18801940 1930
2000
1990
1870
1880
1940
1930
1990
1980
1980
1870
1880
1940
1930
2000
1990
Habitat
requirement
0.3
2000
Tolerance to
oxygen depletion
Diet
0.2 0.5
0
0.7
0.8
0
0.5
0.2
0.3
0.8
0.5
0.5
0.5
0.2
0.8
0
0 . 3
P
is
c
iv
o
r
o
u
s
Eurytopic
L im
n o p h il ic
Invertivorous
Intermediate
T o le r a n t
Fig. 5 Long-term changes in the proportion of ecological traits of species in the fish assemblage of
the Seine River around Paris
312
J. Belliard et al.