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Igarapé do Aturiá, Rio Negro Basin, Amazonas, Brazil
Brazil, Amazon, Santa Isabel do Rio Negro
The Aturiá Stream (Igarapé do Aturiá), in the middle Rio Negro basin, Amazonas, Brazil, is a pristine blackwater igapó (flooded forest) ecosystem. The habitat features extremely acidic, nutrient-poor waters stained tea-dark by humic acids and shaded by a dense forest canopy. Its underwater structure is defined by fine white sand, thick layers of natural leaf litter, and an intricate network of submerged tree roots. This structure provides vital refuge and foraging grounds for specialized acid-tolerant fish. The biotope is highly representative of the Rio Negro’s biodiversity, dominated by massive wild schools of Paracheirodon axelrodi (Cardinal Tetra). These fish rely entirely on the shaded root tangles and leaf litter for protection from predators, swimming among the fallen branches in their natural social behavior, perfectly adapted to this unique low-visibility environment.
- Submitted by
- Arthur Carvalho Valgueiro
- Approved by
- Roberto E. Reis, Pablo C. Lehmann & Antonio Machado-Allison
- GPS
- -2.5730000, -60.3724670
- Geographical region
- South America
- Drainage Basin
- Amazon Basin
- River catchment
- Rio Negro
- Water body type
- Igarapè
- Water body name
- Igarapé do Aturiá
- Water body part
- Channel
- Water body course
- Lower course
- Water body: tributary of
- Rio
- Tributary name
- Rio Negro
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Water Chemistry
Water information
- Water type
- Freshwater
- Water color
- Black water
- Water transparency
- Medium
- Concentration of sediments
- Low
- Water temperature
- 27 °C
- Water flow/curent
- Slow
Chemical parameters
- pH
- 5.0
- Conductivity
- 23.7
- GH
- 0
- dGH
- KH
- 0
- dKH
- Dissolved Oxygen
- 78.4 %
Substrate in nature
- Sand
- Beige
- Pebble/Gravel
- None
- Stone
- None
- Stone form
- Silt/Mud
- None
- Leaves
- Adundant
- Driftwood
- Many
- Submerged terrestrial vegetation
- Yes
Aquatic Biotope
- Date of collecting
- Collecting area
- Water depth
- Air temperature
- Sunlight
Environment
- Environment
- Untouched
- Surrounding area
The Aturiá Stream (Igarapé do Aturiá) is a small blackwater tributary located in the middle Rio Negro basin, Amazonas, Brazil. The surrounding area is characterized by dense, pristine Amazonian igapó forest (flooded forest). The riparian vegetation consists of large trees, shrubs, and terrestrial plants adapted to the seasonal flood pulse, during which water levels fluctuate significantly throughout the year, partially submerging the forest margins.
- Underwater landscape
The underwater landscape is defined by a slow-moving current and a very dark, tea-colored water column rich in dissolved tannins and highly acidic. The substrate consists predominantly of fine, light beige quartz sand, heavily covered by a thick layer of leaf litter, fallen branches, and large seed pods. There are no rocks or stones; instead, the complex structure is formed entirely by a dense network of submerged tree roots, fallen logs, and flooded terrestrial vegetation along the shallow margins.
Fish:
Paracheirodon axelrodi (Characidae)
- Threats to ecology
Although the area remains relatively remote, the main ecological threats to this biotope include climate change, which disrupts the natural flood cycle (causing extreme droughts or unseasonal floods), and localized river traffic. Additionally, potential deforestation throughout the Rio Negro basin and unregulated ornamental fish collecting or overfishing could pose risks to the delicate balance of this acidic, low-nutrient ecosystem.
Riparian zone
- Trees near the aquatic habitat
-
Many -
