Seine River ecosystem
The Seine River, one of France's major rivers, flows approximately 482 miles (776 kilometers) from the Langres Plateau in eastern France through Paris, eventually reaching the North Atlantic Ocean. Its gentle current and extensive tributaries, including the Aube, Yonne, Oise, and Marne rivers, contribute to the region's fertile agricultural land, particularly in Île-de-France, where crops like barley, wheat, and vineyards thrive. Historically, the Seine supported a rich biodiversity, but pollution from industrial, agricultural, and urban sources has severely impacted its ecosystem, leading to fish die-offs and the decline of many species.
Efforts to restore the Seine have seen a resurgence of certain fish, such as salmon, although they remain endangered. The river now hosts around 32 fish species, although the prevalent hardy species include roach, carp, and bream. The surrounding fauna includes various mammals and birds, while its flora supports chestnut trees and linden. Despite restoration initiatives, challenges remain, including high pollution levels, habitat loss due to human modifications, and the effects of climate change. Significant wastewater treatment efforts are underway, including a major facility capable of processing millions of cubic yards of water daily, aiming to improve the river's health for both wildlife and the communities that depend on it.
Subject Terms
Seine River Ecosystem
Category: Inland Aquatic Biomes.
Geographic Location: Europe.
Summary: One of France’s major rivers, the heavily polluted Seine is at last seeing concentrated efforts to return its ecological health to previous habitat-supporting levels.
One of the five major rivers of France, the Seine flows through the capital, Paris, winds across northern plains, and joins ultimately with the waters of the North Atlantic Ocean. The Seine runs generally east-west, beginning as a stream on the Langres Plateau, passing through the Burgundy and Champagne regions, then Paris and the estuary segment, and empties into Baie de Seine, an extension of the English Channel. While the river is 482 miles (776 kilometers) long, it repeatedly loops back on itself, traveling only 250 miles (402 kilometers) by straight measure.
The Seine has a very gentle current. The river begins 1,545 feet (471 meters) above sea level and drops to 800 feet (244 meters) approximately 30 miles (48 kilometers) from its source. By the time it reaches Paris, the Seine is just 80 feet (24 meters) above sea level, and still more than 125 miles (200 kilometers) from the Channel.
The Seine River biome includes such main tributaries as the Aube, Yonne, Oise, and Marne Rivers. The Seine flows through a large farming region referred to as the Île-de-France, which has extremely fertile soil, intensively used for crops such as barley, wheat, corn, and many produce types, as well as vineyards. The river also provides the city of Paris with half of its drinking water.
Biodiversity
Efforts to clean the Seine have resulted in a return of salmon to the river after decades of absence resulting from river pollution that began in the late 1800s and killed off the once-large population. Today, Atlantic salmon are on the European Union’s endangered species list. The cleaner water has resulted in a rebirth of lively fish habitat in the river, which now includes some 32 species. However, because the river remains polluted, only hardy fish species are here in abundance; these include roach, carp, chub, and bream. Trout and ombre also are native to the Seine, but can live only in the cleaner waters of the upper river.
Terrestrial fauna of the Seine River area include beavers, gray squirrel (Sciurus carolinensis), red squirrel (Sciurus vulgaris), least weasel, long-tailed weasel (Mustela nivalis), mink, skunk, raccoon, and muskrat. Avian species are represented here by duck, heron, cormorant, Merlin (Falco columbarius), killdeer (Charadrius vociferus), spotted sandpiper (Actitis macularius and A. macularia), Franklin’s gull (Leucophaeus pipixcan), herring gull (Larus argentatus), and mourning dove (Zenaida macroura).
The characteristic flora of the Seine, rendered artistically in the 19th century by renowned Impressionist painters such as Claude Monet, Edouard Manet, Auguste Renoir, and Vincent van Gogh, include chestnut trees (Castanea spp.), linden (Tilia spp.), and balsam poplar (Populus balsamifera), mixed with dense clusters of European mistletoe (Viscum album).
Impact of River Modifications
While there have been several positive effects of human involvement, especially through modern restoration efforts, the negative impact includes high pollution levels from industrial discharge, agricultural runoff, and sewage dumping. Mass fish die-offs have sometimes resulted. Parisian officials and other governmental agencies are working together to lower the pollution levels and restore the Seine, making the river safer for fish and people.
Paris is near the point of convergence of several of the Seine’s tributaries, and a system of canals, locks, and dams were built to control water flow and improve navigation. Reservoirs were added for storage of drinking water, as well as flood protection. In the past, floods caused the river to overflow from heavy rainfall; much of this seasonal flooding has been lost, with concomitant effects on floodplain vegetation and fauna. Deforestation and marshland drainage to maximize space for farming also have adversely affected the wetlands. The redirecting of the natural flood zone, in conjunction with the canal-and-dam system, is seen as a culprit in decreased diversity of fish species, harshly affecting populations of eel, sturgeon, and salmon here.
More than 50 types of pollution are monitored in the Seine; some areas have recorded over 100 times the European Union safe-swimming limit for certain strains of bacteria. Toxic algae blooms are a periodic concern, as is sewage overflow during heavy rains. From time to time, government agencies have resorted to pumping bubbles directly into the Seine to counteract low-oxygen zones and attempt to save fish. Some efforts are questionable: About 20 species of nonnative fish were introduced into the Seine, in a gesture to support species diversity, but the long-term effects on habitat and native species is unknown.
Climate change could complicate the river clean-up programs. Warmer temperatures foster algal spread and tend to augment riverine and groundwater nitrate concentrations. Warming also alters the suitability of various river habitats for certain species. Gudgeon, minnow, and stone loach have prospered in recent years, while grayling, brown trout, nase, and dace populations have been undercut; some of this change is allayed to damming, however, and it is not clear how much is due directly to temperature, precipitation, and runoff changes. Also, many individuals of some fish species have suffered from average size reduction, as harsh conditions multiply.
The Syndicat Interdepartemental pour l’Assainissement de l’Agglomeration Parisienne (SIAAP) has been working since the 1970s to clean up the Seine by creating ways to treat wastewater and permanently raise the oxygen levels to prevent further mass fish die-offs. SIAAP recently installed a massive station to treat wastewater by removing excess ammoniacal nitrogen. The facility, on the riverbank at Acheres, is one of the largest wastewater treatment sites in the world, capable of processing 2.2 million cubic yards (1.7 million cubic meters) of wastewater per day from the metropolitan Paris area.
Bibliography
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Bendjoudi, H., et al. “Riparian Wetlands of the Middle Reach of the Seine River (France): Historical Development, Investigation and Present Hydrologic Functioning. A Case Study.” Journal of Hydrology 263 (2002).
Billen, Giles, et al. “The Seine System: Introduction to a Multidisciplinary Approach of the Functioning of a Regional River System.” Science of the Total Environment 375 (2007).
Boët, Philippe, et al. “Multiple Human Impacts by the City of Paris on Fish Communities in the Seine River Basin, France.” Hydrobiologia 410 (1999).
Lafite, Robert and Louis-Alexandre Romana. “A Man-Altered Macrotidal Estuary: The Seine Estuary (France): Introduction to the Special Issue.” Estuaries and Coasts 24, no. 6 (2001).
Mauch, Christof and Thomas Zeller. Rivers in History: Perspectives on Waterways in Europe and North America. Pittsburgh, PA: University of Pittsburgh Press, 2008.
Rosenblum, Mort. The Secret Life of the Seine. Reading, MA: Addison-Wesley, 1994.