Reconstructing long-term trajectories of fish assemblages using historical data: the Seine River basin (France) during the last two centuries

Abstract

We used historical sources from the end of the nineteenth to the mid-twentieth century and current data to retrace fish assemblage trajectories for the past 150 years on 29 river stretches distributed throughout the Seine River basin. We based our analyses on species presence/absence, occurrence of amphidromous and non-native species, and species ecological traits related to habitat preference, oxygen and temperature requirements, and diet. In accordance with general trends observed for Western Europe, we detected a general decline of amphidromous species and an increase in non-native species, even if, at some sites, several non-native species were extirpated. These changes affecting amphidromous and non-native species led to a weak increase in beta-diversity in fish assemblages. Independently of amphidromous and non-native species, for a reduced set of sites, we noted that changes in the balance of ecological traits over time, trace, in a consistent way, the major steps that affected watercourses like waterway development, increasing pollution, dam construction, or, locally, the recent wastewater treatment improvement. Despite local variations, we found contrasted trends between, on one hand, large rivers and/or catchments which had experienced strong expansion in human population, where fish assemblages had deteriorated, and, on the other hand, upstream catchments, with a declining human population, where fish assemblages showed signs of improvement. Because our results suggested that long-term changes affecting fish assemblages cannot be summarized as an unequivocal gradual degradation, we questioned the use of historical data to define ecological reference conditions for river assessment and management purposes.

Monitoring freshwater fish communities in large rivers using environmental DNA metabarcoding and a long‐term electrofishing survey

“…This change has been attributed to recent achievements in wastewater treatment in the greater Paris area, and that has considerately improved the water quality, especially dissolved oxygen, organic matter and ammonia nitrogen in the Seine River (Azimi & Rocher, 2016). At a larger spatial and temporal scale, a recent study showed that amphidromous species declined in the past 150 years on 29 river sections of the Seine River basin, where non-native species colonized (Belliard et al, 2018). (Azimi & Rocher, 2016).…”

Historical cartographic and topo-bathymetric database on the French Rhône River (17th–20th century)

“…The Beaucaire-Tarascon station (KP 269.5) records flows of the whole basin and is the oldest hydrometric station on the Rhône. Daily water level measurements started in 1816 and daily estimates of discharge started in 1920 (Billy et al, 2018). These chronicles are part of the HISTRHONE database, which contains a large volume of archives related to hydroclimatic events in the lower Rhône over a period between the 14th and 20th century (Pichard and Roucaute, 2014).…”

“…For example, historical maps can help to better contextualize sediment core samples and geophysical surveys when investigating floodplain evolution (Salvador and Berger, 2014) and delta evolution during the Holocene (Vella et al, 2005). Historical cartographic and topo-bathymetric datasets are also of interest to hydrologists analysing flood frequency based on historical geometries (Billy et al, 2018). They are also key resources in historical ecology, allowing the formulation of hypothesis on fish habitat-species relationships since the industrial revolution, especially given the lack of old quantitative data in terms of species number, abundance, and distributions (Carrel, 2002;Frimpong et al, 2016;Belliard et al, 2018).…”

Trajectories of the Seine River Basin

“…6. We have also reconstructed the evolution of the fish population, a key integrative ecological indicator within the basin, from historical and archaeological archives collected over more than two centuries [65,66].…”