Red List habitat classification > RLC - Freshwater habitats > RLC2.4 Tidal river, upstream from the estuary

Tidal river, upstream from the estuary

Quick facts

Red List habitat type code RLC2.4
Threat status
Europe Endangered
EU Endangered
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)

Summary

This habitat includes portions of large rivers subject to the tide, upstream from the estuary. The water level is subject to tidal influence, but the water is mainly freshwater or slightly brackish (1-2 psu).  Several aquatic macrophytes and helophytes are characteristic of this habitat, and some of them are endemic to specific river floodplains. In this habitat, the submerged aquatic vegetation is especially developed in shallow parts of the river system, where the water level is only about 20 cm at low tide. Here, submerged macrophytes can form extensive beds. The banks are covered by extensive helophyte vegetation, usually dominated by Phragmites australis that is tolerant to periodical water table fluctuations. More characteristic for the lower zones are Schoenoplectus triqueter and Bolboschoenus maritimus. The helophyte dominated vegetation growing on the permanently flooded part of the beds is included in this habitat, however the emergent vegetation growing on the periodically flooded banks, with characteristic species like Leucojum aestivum and Senecio fluviatilis, is included in the habitat type C5.1.Some endemic species occur in tidal freshwater areas, like Oenanthe conioides and Deschampsia wibeliana in the Elbe floodplain, and Caltha palustris ssp. araneosa  in the Scheldt, Rhine-Meuse and Elbe floodplains.

Vegetation zonation is highly dependent on flooding frequency. In sheltered parts of the tidal creeks, which almost never dry completely, Nuphar lutea, Potamageton pusillus and Potamageton perfoliatus may locally dominate. Potamogeton pectinatus, Zannichellia palustris ssp. palustris, Sagittaria sagittifolia, Veronica anagallis-aquatica, Veronica catenata and Sparganium emersum sometimes also occur in or near the gullies. Special (semi)aquatic species that occur in tidal freshwater habitats are those of the genus Elatine. Although extreme rare and not completely associated with tidal freshwater habitats, Elatine hydropiper and Elatine triandra occur in this system in The Netherlands.

Tidal freshwater wetlands have become scarce in Europe because of drastic human alterations of estuarine geomorphology. The habitat is restricted to the Atlantic and North Sea coast of Europe, where tidal fluctuation is relatively large. In the current situation, the main tidal freshwater wetlands are distributed directly upstream from the estuaries of the Thames, Trent (UK), Weser (DE), Elbe (DE/NL), Rhine-Meuse (NL), Scheldt (B), Garonne, Loire, Seine, Charente (FR) and Mondego (PT).

Indicators of good quality:

  • Submerged, open fields of sediment-rooted aquatic macrophytes
  • Absence of or only limited alterations of estuarine hydromorphology
  • Tidal amplitude unchanged
  • Freshwater to slightly brackish water
  • Good water quality in terms of nutrient content and water clarity supporting submerged macrophyte growth

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

A full quantitative assessment of the decline in abiotic and biotic quality and quantity was not possible due to data deficiency. However, based on a combination of assumptions and reported data from the main countries, trends have been calculated, The degradation in quality is very high, leading to the category Endangered (EN) for criterion C/D1.
EU
Red List Category Red List Criteria
Endangered C/D1
Europe
Red List Category Red List Criteria
Endangered C/D1

Confidence in the assessment

low
Red List of habitat categories and criteria descriptions

Pressures and threats

  • Pollution
    • Nutrient enrichment (N, P, organic matter)
    • Input of contaminants (synthetic substances, non-synthetic substances, radionuclides) - diffuse sources, point sources, acute events
  • Invasive, other problematic species and genes
    • Invasive non-native species
  • Natural System modifications
    • Canalisation & water deviation
    • Flooding modifications
    • Lack of flooding
    • Modifying structures of inland water courses
    • Small hydropower projects, weirs
    • Wave exposure changes
    • Dykes, embankments, artificial beaches, general
    • Dykes and flooding defense in inland water systems
    • Other human induced changes in hydraulic conditions

Habitat restoration potential

Natural recovery is hardly possible, although due to climatic changes and sea level rise the freshwater tidal habitat might change its position along the gradient. Intervention includes allowing tidal influences in dammed sea arms and rivers and cutting off polluting discharges into the surface water.

Trends in extent

Average current trend in quantity

Decreasing Decreasing
EU28 EU28+

Trends in quality

Average current trend in quality

Decreasing Decreasing
EU28 EU28+

Conservation and management needs

The current approaches to conservation and management are:
1. Restoring and improving water quality e.g. by cutting off discharge of point sources with polluted water;
2. Restoring and improving the hydrological regime e.g. by allowing tidal influence in dammed sea arms and rivers;
3. Installing protected areas large enough to maintain hydrological and water quality conditions.

List of conservation and management needs

  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
    • Restoring/Improving the hydrological regime

Distribution

For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

EU28 Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Germany Present Unknown Decreasing Decreasing
Italy mainland Present 2 Decreasing Decreasing
Sardinia Present 2 Decreasing Decreasing
Sicily Present 2 Decreasing Decreasing
Ireland Present Unknown Unknown Stable
Denmark Present Unknown Unknown Unknown
Netherlands Present 93 Decreasing Decreasing
France mainland Present Unknown Decreasing Decreasing
Corsica Uncertain Unknown Decreasing Decreasing
United Kingdom Present Unknown Decreasing Decreasing
Northern Island Uncertain Unknown Decreasing Decreasing
Gibraltar Uncertain Unknown Decreasing Decreasing
Latvia Uncertain Unknown Unknown Unknown
Spain mainland Present Unknown Unknown Unknown
Balearic Islands Uncertain Unknown Unknown Unknown
Canary Islands Uncertain Unknown Unknown Unknown
Belgium Present Unknown Unknown Unknown
EU28 + Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Norway Mainland Present Unknown Unknown Unknown
Svalbard Uncertain Unknown Unknown Unknown
Jan Mayen Uncertain Unknown Unknown Unknown

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 1148700 189 unknown
EU28+ 189 unknown
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Fishes Alosa fallax
Flowering Plants Bolboschoenus maritimus
Flowering Plants Caltha palustris
Flowering Plants Deschampsia wibeliana
Flowering Plants Elatine hydropiper
Flowering Plants Elatine triandra
Flowering Plants Leucojum aestivum
Flowering Plants Najas marina
Flowering Plants Najas minor
Flowering Plants Nasturtium officinale
Flowering Plants Nuphar lutea
Flowering Plants Oenanthe conioides
Flowering Plants Phragmites australis
Flowering Plants Potamogeton nodosus
Flowering Plants Potamogeton pectinatus
Flowering Plants Potamogeton perfoliatus
Flowering Plants Sagittaria sagittifolia
Flowering Plants Schoenoplectus triqueter
Flowering Plants Senecio fluviatilis
Flowering Plants Senecio paludosus
Flowering Plants Sparganium emersum
Flowering Plants Vallisneria spiralis
Flowering Plants Veronica anagallis-aquatica
Flowering Plants Veronica catenata
Flowering Plants Zannichellia palustris
Species scientific name English common name Species group
Alosa fallax Shad Fishes
Bolboschoenus maritimus Flowering Plants
Caltha palustris Flowering Plants
Deschampsia wibeliana Flowering Plants
Elatine hydropiper Flowering Plants
Elatine triandra Flowering Plants
Leucojum aestivum Flowering Plants
Najas marina Flowering Plants
Najas minor Flowering Plants
Nasturtium officinale Flowering Plants
Nuphar lutea Flowering Plants
Oenanthe conioides Flowering Plants
Phragmites australis Flowering Plants
Potamogeton nodosus Flowering Plants
Potamogeton pectinatus Flowering Plants
Potamogeton perfoliatus Flowering Plants
Sagittaria sagittifolia Flowering Plants
Schoenoplectus triqueter Flowering Plants
Senecio fluviatilis Flowering Plants
Senecio paludosus Flowering Plants
Sparganium emersum Flowering Plants
Vallisneria spiralis Flowering Plants
Veronica anagallis-aquatica Flowering Plants
Veronica catenata Flowering Plants
Zannichellia palustris Flowering Plants

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

This habitat may be equivalent to, or broather than, or narrower than the habitats or ecosystems in the following typologies.
Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200711 C2.4 Tidal rivers, upstream from the estuary same
European Environment Agency (EEA)
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