1 Introduction
The interest in studying the long-term ecological functioning of rivers grew in the
1980s in an attempt to provide a better understanding of the current ecological status
of water bodies [1, 2]. These historical approaches have been boosted since the
2000s with the implementation of the Water Framework Directive, which imposes
the assessment of ecological status of water bodies relative to a former reference
status. The question of defining ecological reference conditions was raised, and
reconstructing trajectories of temporal changes of fish communities was a way
of addressing this issue. European rivers and particularly the Seine River have
been heavily modified by human activities. The period around 1850 is considered
as a milestone with the beginning of channelisation for navigation purposes [3],
although mills already greatly impacted streams as early as the Middle Ages, making
historical data necessary to reconstructing long-term changes. Historical written
documents are a valuable source of information, particularly for reconstructing
long-term changes in fish communities, although their exploitation requires a critical
assessment [4].
Given the many human impacts on rivers and their fish communities over the
Seine basin, temporal trajectories may differ depending on the time period considered but also the geographical context (e.g. demographic impact, land use changes,
stream size, etc.). In this chapter, we examined fish communities and their response
to human impacts, over the past 150 years and more recent time periods, and at
different spatial scales, from local river stretches to the whole Seine basin.
2 Various and Complementary Data to Address Time
Trajectories
One of the main challenges in investigating long-term changes in fish communities is
the availability of reliable data. The electrofishing approach, which is used widely
nowadays to sample river fish communities, began to be applied in the basin in
the 1960s. Unfortunately, the data collected at that time were rarely archived. Some
of these data were nevertheless used to elaborate maps of the distribution and
abundance of species in several areas of the Seine basin around the 1970s. From
the 1980s onwards, electrofishing sampling methods began to be standardised, their
application became more widespread and the data collected were better stored.
Annual monitoring was implemented on the Seine River in the Paris region as
from 1990 [5] and then extended to numerous rivers in the whole basin beginning
in 1995 [6]. As a result, changes in fish communities over the past three or four
decades can be analysed in detail.
To go back further in time, it is necessary to use other data sources such as
historical written sources. These historical written sources are of multiple types
(early scientific and naturalist literature, fishery laws, administrative surveys on
302
J. Belliard et al.
The interest in studying the long-term ecological functioning of rivers grew in the
1980s in an attempt to provide a better understanding of the current ecological status
of water bodies [1, 2]. These historical approaches have been boosted since the
2000s with the implementation of the Water Framework Directive, which imposes
the assessment of ecological status of water bodies relative to a former reference
status. The question of defining ecological reference conditions was raised, and
reconstructing trajectories of temporal changes of fish communities was a way
of addressing this issue. European rivers and particularly the Seine River have
been heavily modified by human activities. The period around 1850 is considered
as a milestone with the beginning of channelisation for navigation purposes [3],
although mills already greatly impacted streams as early as the Middle Ages, making
historical data necessary to reconstructing long-term changes. Historical written
documents are a valuable source of information, particularly for reconstructing
long-term changes in fish communities, although their exploitation requires a critical
assessment [4].
Given the many human impacts on rivers and their fish communities over the
Seine basin, temporal trajectories may differ depending on the time period considered but also the geographical context (e.g. demographic impact, land use changes,
stream size, etc.). In this chapter, we examined fish communities and their response
to human impacts, over the past 150 years and more recent time periods, and at
different spatial scales, from local river stretches to the whole Seine basin.
2 Various and Complementary Data to Address Time
Trajectories
One of the main challenges in investigating long-term changes in fish communities is
the availability of reliable data. The electrofishing approach, which is used widely
nowadays to sample river fish communities, began to be applied in the basin in
the 1960s. Unfortunately, the data collected at that time were rarely archived. Some
of these data were nevertheless used to elaborate maps of the distribution and
abundance of species in several areas of the Seine basin around the 1970s. From
the 1980s onwards, electrofishing sampling methods began to be standardised, their
application became more widespread and the data collected were better stored.
Annual monitoring was implemented on the Seine River in the Paris region as
from 1990 [5] and then extended to numerous rivers in the whole basin beginning
in 1995 [6]. As a result, changes in fish communities over the past three or four
decades can be analysed in detail.
To go back further in time, it is necessary to use other data sources such as
historical written sources. These historical written sources are of multiple types
(early scientific and naturalist literature, fishery laws, administrative surveys on
302
J. Belliard et al.