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#10332 Igarapé de Jamaraquá, Belterra, Rio Tapajós tributary, Brazil

Brazil, Pará, Belterra, Santarém

The Igarapé de Jamaraquá is one of the hidden gems of the Tapajós National Forest (FLONA), renowned for its crystal-clear waters. Snorkelling enthusiasts are drawn to its exceptional visibility, which reveals the streambed, underwater structure, and fascinating plays of light. Surrounded by fish and aquatic plants, the creek offers the experience of swimming through a vast natural aquarium.

Submitted by: Pawel Lukasz Kocik

GPS: -2.8153059, -54.9228058

Geographical region: South America
Drainage Basin: Rio Amazonas
River catchment: Rio Tapajós
Water body type: Igarapè
Water body name: Igarapé
Water body part
Water body course: Source
Water body: tributary of: Rio
Tributary name: Tapajós

Videos above and below water

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Water Chemistry

Water information

Water type: Freshwater
Water color: Clear water
Water transparency: High
Concentration of sediments: No
Water temperature: 25°C °C
Water flow/curent: Strong

Chemical parameters

pH
Conductivity
GH: 1 mg/l
dGH
KH: 1 mg/l
dKH
Dissolved Oxygen: 6 %

Substrate in nature

Sand: Beige
Pebble/Gravel: Reddish
Stone: None
Stone form
Silt/Mud: None
Leaves: Few
Driftwood: Few
Submerged terrestrial vegetation: Yes

Aquatic Biotope

Date of collecting
Collecting area: Edge of reservoir
Water depth: 0,2m
Air temperature: 32 °C
Sunlight: Partial shade

Environment

Environment

Affected by human activity

Affected by human activity

Agriculture

Agriculture

Advanced

Deforestation

Pollution

Human settlements

Surrounding area

The Igarapé Jamaraquá is an ecosystem of extraordinary beauty, where the Amazon rainforest meets the clear waters of the Tapajós River. Located within the Tapajós National Forest (FLONA), this protected landscape preserves its wild, pristine character.

Terrestrial vegetation:

Ceiba pentandra (Malvaceae)

Underwater landscape

Igarapé Jamaraquá is what aquarium enthusiasts define as the “perfect biotope.” Unlike many Amazonian rivers with turbid waters, the visibility here is astonishing, allowing visitors to observe a submerged garden teeming with life. Sunlight filters through the dense forest canopy above, creating the so-called “God rays” (the Tyndall effect) that pierce the crystal-clear water.

The bottom, composed of fine, light-coloured sand, reflects the light, illuminating the tree roots from below. In shaded areas, the water takes on an emerald-green hue. Enormous fallen branches and samaúma roots intertwine across the bottom, creating natural labyrinths. These are often covered by a thin layer of biofilm and short algae, which the fish feed upon.

Fish

Hemigrammus stictus (Characidae)
Hemigrammus hyanuary (Characidae)
Heterocharax virgulatus (Characidae)
Nannostomus unifasciatus (Lebiasinidae)
Holopristis ocellifer (Characidae)
Iguanodectes variatus (Iguanodectidae)

Aquatic plants

Cyperus helferi (Cyperaceae)
Eleocharis fluctuans (Cyperaceae)
Cabomba aquatica (Cabombaceae)
Nymphaea amazonum (Nymphaeaceae)

Threats to ecology

Despite the pristine beauty of Igarapé Jamaraquá and the Tapajós National Forest (FLONA), this region faces significant ecological challenges. The delicate balance between crystal-clear waters, giants such as the samaúma, and small characids is extremely fragile.

Igarapé Jamaraquá is not just a “beautiful place,” but a living genetic reservoir. Many of the species listed here are fundamental to understanding the evolution of life in the Tapajós Basin. Protecting this biotope will help ensure that future generations can continue to witness those “God rays” piercing the crystal-clear waters.