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Danube floodplains, Galati, I.C Bratianu village, Romania

Sponsored by

Romania, Dobrogea, Tulcea

Spring time is usually when Danube floods the forests and the plains situated on it’s banks. The water level can stay high for many months and it’s not out of the ordinary for the flooding to last from March to July.

Comparing the two seasons, dry vs. wet, things look very different. The aquatic vegetation is made of 90% amphibious plants that can survive for months underwater and who also can outstand very dry and hot weather. They survive these extreme changes by adapting the leaves shapes and stem structures, so one plant can look like two different species.

These type of unique habitats are at risk because of the building of levees and because of the climate change. All the aquatic life in the Danube basin depends on the floodplains and flooded forests to reproduce.

Submitted by
Alexandru Andrei Rosu
Approved by
Francesco Denitto & Aleksey Malyshev
GPS
45.4106560, 28.0478039
Geographical region
Eastern Europe
Drainage Basin
Danube Delta and the Black Sea
River catchment
Danube
Water body type
Wetland
Water body name
Danube
Water body part
Flood plain
Water body course
Lower course
Water body: tributary of
Wetland
Tributary name
Danube

Water Chemistry

Water information

Water type
Fresh water
Water color
Mixed water
Water transparency
Medium
Concentration of sediments
Medium
Water temperature
2-30 °C
Water flow/curent
Strong

Chemical parameters

pH
7.7
Conductivity
570
GH
110 mg/l
KH
120 mg/l
Dissolved Oxygen
82 %

Substrate in nature

Sand
Grey
Pebble/Gravel
Grey
Stone
Grey
Stone form
Irregular
Silt/Mud
Brown
Leaves
Few
Driftwood
Few
Submerged terrestrial vegetation
Yes

Aquatic Biotope

Date of collecting
03/06/2023
Collecting area
Flood plain/Várzea
Water depth
Air temperature
21 °C
Sunlight
Partial shade

Environment

Environment
Affected by human activity
Affected by human activity
Pollution
Pollution
Moderate
Surrounding area

This biotope, by going with the waterflow, is present on the right side bank of Danube river, near I.C Bratianu village, in the geographical region named Dobrogea. Across the river, on the left side bank is the Galati city, part of the Moldova region, not to be confused with the Moldova country. Crossing the river is made by boat or with the local old ferry.

In this area, the river gets wider because of the Siret waters that flow into Danube’s course. This amount of water and the strong current increases the river’s depth to 30 meters or more in some places, and 1,15 km wide, making it suitable for marine ships to navigate from the Black Sea to Braila city.

This habitat was considered to be the starting point of Danube Delta, until the 60′ when the levee was built to protect the village from the spring floods and to increase the agricultural process of that time. Before the levee’s built, Danube waters combined with the Siret river waters, were flooding a very large surface of floodplains, creating a miniature Danube Delta, with multiple lakes and small islands, truly a water paradise.

The reminiscence of that power and flow of that time can still be seen from the satellite pictures provided by google maps. From above it looks like an ancient drawings left by the flowing water, undisturbed by the agricultural process. Now days, the habitat is just a fraction of what it used to be, but it can still hold great diversity and beauty.

Underwater landscape

The landscape can change dramatically. Today it can be a dried or green grass plain used by animals to feed on, and tomorow it can be transformed in a floodplain, full of aquatic plants that come out from nowhere, most likely from underground, where they stayed all the winter buried in the form of pods, bulbs, or seeds.

Many fish and amphibians come from the main river to spawn and together with the birds, they create once again a flooded paradise.

All the vegetation on the river bank is somehow amphibius, even the terrestrial grass itself can survive and grow for months underwater in shallow parts that have full sunlight. The truly amphibius plants, change their leaves and stems, from hard rigid structures to soft and light leaves that can easily flow in the water without breaking.

The water depth can vary because the floodplain has been shaped by the flowing water over the years. It can go for tens of meters with only a depth of 20 to 50cm and then can slowly sink in deep holes of 2-6m deep, across few meters then again comes out in shallow waters. This flowing process and the vegetation, including the flooded forests, polish the water with the end result of a crystal clean water that eventually find it’s way back in the main river course.

The substrate is mainly made of hard mud and clay with a lot of spots where the substrate is just a light grey and very fine river sand. Across the floodplain, underwater there is just a carpet of grass made of terrestrial types of grasses, amphibius plants like Eleocharis acicullaris, Mentha aquatica and aquatic plants. Also water brings on the floodplains pieces of driftwood and some leaves carried away from the near by flooded forests. Rocks are also present on the sides of the flooded levee.

Fishlist:

  • Syngnathus abaster (Syngnathidae)
  • Rhodeus amarus (Cyprinidae)
  • Cobitis elongatoides (Cobitidae)
  • Alburnus alburnus (Cyprinidae)
  • Pungitius platygaster (Gasterosteidae)
  • Gasterosteus aculeatus (Gasterosteidae)
  • Umbra krameri (Umbridae)
  • Proterorhinus marmoratus (Gobiidae)
  • Babka gymnotrachelus (Gobiidae)
  • Neogobius fluviatilis (Gobiidae)
  • Neogobius melanostomus (Gobiidae)
  • Ponticola kessleri (Gobiidae)
  • Misgurnus fossilis (Cyprinidae)
  • Leucaspius delineatus (Esocidae)
  • Esox lucius (Cyprinidae)
  • Rutilus rutilus (Cyprinidae)
  • Leuciscus idus (Cyprinidae)
  • Leuciscus aspius (Cyprinidae)
  • Tinca tinca (Cyprinidae)
  • Scardinius erythrophthalmus (Cyprinidae)
  • Pelecus cultratus (Cyprinidae)
  • Blicca bjoerkna (Cyprinidae)
  • Abramis brama (Cyprinidae)
  • Ballerus sapaa (Cyprinidae)
  • Ballerus ballerus (Cyprinidae)
  • Vimba vimba (Cyprinidae)
  • Barbus barbus (Cyprinidae)
  • Chondrostoma nasus (Cyprinidae)
  • Cyprinus carpio (Cyprinidae)
  • Carassius gibelio (Cyprinidae)
  • Silurus glanis (Siluridae)
  • Lota lota (Lotidae)
  • Perca fluviatilis (Percidae)
  • Gymnocephalus cernua (Percidae)
  • Gymnocephalus schraetzer (Percidae)
  • Sander lucioperca (Percidae)
  • Zingel streber (Percidae)
  • Zingel zingel (Percidae)
  • Lepomis gibbosus (Centrarchidae)
  • Perccottus glenii (Odontobutidae)
  • Pseudorasbora parva (Cyprinidae)
  • Knipowitschia caucasica (Gobiidae)

Mollusc list:

  • Theodoxus fluviatilis (Neritidae)
  • Theodoxus danubialis (Neritidae)
  • Theodoxus transversalis (Neritidae)
  • Theodoxus pallasi (Neritidae)
  • Viviparus acerosus (Viviparidae)
  • Viviparus viviparus (Viviparidae)
  • Esperiana esperi (Melanopsidae)
  • Holandriana holandrii (Amphimelaniidae)
  • Bithynia danubialis (Bithyniidae)
  • Potamopyrgus antipodarum ()
  • Belgrandiella dobrostanica ()
  • Iglica acicularis (Moitessieriidae)
  • Valvata piscinalis (Valvatidae)
  • Galba truncatula (Lymnaeidae)
  • Stagnicola corvus (Lymnaeidae)
  • Stagnicola palustris (Lymnaeidae)
  • Radix auricularia (Lymnaeidae)
  • Radix balthica (Lymnaeidae)
  • Myxas glutinosa (Lymnaeidae)
  • Lymnaea stagnalis (Lymnaeidae)
  • Physa fontinalis (Physidae)
  • Aplexa hypnorum (Physidae)
  • Planorbarius corneus (Planorbidae)
  • Planorbis planorbi (Planorbidae)
  • Anisus leucostoma (Planorbidae)
  • Bathyomphalus contortus (Planorbidae)
  • Ancylus recurvus (Planorbidae)
  • Corbicula fluminea (Cyrenoidea)
  • Anodonta cygnea (Unionidae)
  • Unio pictorum (Unionidae)

Amphibian list:

  • Pelophylax esculentus (Ranidae)
  • Bufo viridis (Bufonidae)
  • Bombina bombina (Bombinatoridae)
  • Pelobates fuscus (Pelobatidae)
  • Triturus dobrogicus (Salamandridae)
  • Lissotrion vulgaris (Salamandridae)
  • Hyla arborea (Hylidae)

Crustacean list:

  • Daphnia sp. (Daphniidae)
  • Gammarus pullex ( Gammaridae)
  • Chirocephalus diaphanus (Chirocephalidae)
  • Astacus fluviatilis (Astacidae)
  • Triops cancriformis (Triopsidae)

Aquatic vegetation list:

  • Alisma gramineum (Alismataceae)
  • Sagittaria sagittifolia (Alismataceae)
  • Alisma lanceolatum (Alismataceae)
  • Alisma plantago-aquatica (Alismataceae)
  • Myriophyllum spicatum (Haloragaceae)
  • Myriophyllum verticillatum (Haloragaceae)
  • Sparganium angustifolium (Typhaceae)
  • Sparganium erectum (Typhaceae)
  • Eleocharis acicularis (Cyperaceae)
  • Stuckenia pectinata (Potamogetonaceae)
  • Stuckenia vaginata (Potamogetonaceae)
  • Potamogeton acutifolius (Potamogetonaceae)
  • Potamogeton berchtoldii (Potamogetonaceae)
  • Potamogeton coloratus (Potamogetonaceae)
  • Potamogeton crispus (Potamogetonaceae)
  • Potamogeton friesii (Potamogetonaceae)
  • Potamogeton gramineus (Potamogetonaceae)
  • Potamogeton lucens (Potamogetonaceae)
  • Potamogeton natans (Potamogetonaceae)
  • Potamogeton perfoliatus (Potamogetonaceae)
  • Potamogeton pusillus (Potamogetonaceae)
  • Vallisneria spiralis (Hydrocharitaceae)
  • Mentha aquatica (Lamiaceae)
  • Juncus subnodulosus (Juncaceae)
  • Nymphoides peltata (Menyanthaceae)
  • Ceratophyllum demersum (Ceratophyllaceae)
  • Salvinia natans ( Salviniaceae)
  • Lemna minor (Araceae)
  • Spirodela polyrhiza (Araceae)
  • Persicaria amphibia (Polygonaceae)
  • Hydrocharis morsus-ranae (Hydrocharitaceae)
  • Elodea nuttallii (Hydrocharitaceae)
  • Iris pseudacorus (Iridaceae)
  • Najas marina (Hydrocharitaceae)
  • Najas minor (Hydrocharitaceae)
  • Butomus umbellatus (Butomaceae)
Threats to ecology

This type of habitat is almost at an extinction level caused by the climate change that makes the natural spring floods to last too shortly or to completely be non existent.

Main cause is the severe droughts that went in the past years. As an example, the last normal flood with normal spring high water levels for this habitat was in 2019. The present year, 2023 as I currently writing this, the water levels at last reached a normal level and life in the floodplain is once again flourishing.

Many aquatic species depend on the flood plain in order to spawn, others depend on the floodplain in order to exist, like the annual crustaceans Chirocephalus diaphanus – fairy shrimps, or the european triops, Triops cancriformis.

These spawn only once a year and their eggs stay beneath the ground for years waiting for perfect conditions to hatch. But if the flood season is not long enough, the entire population will hatch and none will ever reach maturity in order to reproduce, because of the water retreating too fast. The same problems occur for the fish and the amphibians, like the crested newt Triturus dobrogicus, that can’t reproduce in the main river.

Riparian zone

Trees near the aquatic habitat
Few -

Bibliography

  • FAUNA R.P.R. VOL.XIII PISCES by Petru Banarescu

Sitography

→ Wikipedia

Comment by the expert

Francesco Denitto: Exhaustive description of the natural habitat through video and photo supports. Limited biblio/sitography sources! Just a suggestion to all participants: Wikipedia is not always a reliable and complete source of the information sought.

Aleksey Malyshev: