Da Nhong Stream, Phuoc Binh National Park, Vietnam

Environment

Environment

Affected by human activity

Affected by human activity

Deforestation

Deforestation

Initial

Surrounding area

The Da Nhong headwater stream is located within the strictly protected core zone of Phước Bình National Park. This steep, rocky ravine habitat is surrounded by pristine tropical moist evergreen forest.

The surrounding landscape is dominated by large, mature canopy trees, particularly Dipterocarpus alatus. Their extensive root systems penetrate the underlying granite and ancient acidic igneous bedrock, helping to stabilise the steep banks against erosion during seasonal floods.

Along the riparian corridor, Ficus hispida forms part of the shaded vegetation cover. A few hundred metres downstream lies the park’s buffer zone, where ecotourism activities, small trekking campsites, and fruit orchards cultivated by the indigenous Raglai community create a limited, localised human influence on the surrounding ecosystem.

Underwater landscape

The underwater habitat represents a high-gradient torrent flowing over a hydrodynamically sorted substrate within the Cai Phan Rang River drainage basin. The strong current generated by the waterfall continually removes decaying organic matter, leaving a rugged streambed composed of weathered, rusty orange-brown igneous pebbles and gravel interspersed with dark grey granite boulders.

Fine, light yellowish-grey quartz sand accumulates only within flow-sheltered rock crevices and deep fissures beneath the vertical cliff face, forming localised mixed-substrate patches. The clear, low-TDS, highly oxygenated water creates distinct ecological zones: a fast-flowing channel where schools of Rasbora daniconius and Rasbora paviana continuously swim against the current, and calmer, shaded rock cavities where Puntius brevis finds refuge and grazes on microalgae away from the main torrent.

Fishes:

• Rasbora daniconius (Cyprinidae) – Slender Rasbora – 4
• Rasbora paviana (Cyprinidae) – Pavie’s Rasbora – 2
• Puntius brevis (Cyprinidae) – Brevis Barb – 3

Aquatic vegetation

• Limonia acidissima (Rutaceae) – Wood Apple
• Cyclosorus parasiticus (Thelypteridaceae) – Parasitic Marsh Fern
• Ficus pumila (Moraceae) – Creeping Fig
• Vesicularia ferriei (Hypnaceae) – Weeping Moss
• Microsorum pteropus (Polypodiaceae) – Java Fern

Threats to ecology

The primary ecological threat to this microhabitat stems from increasing pressure associated with unregulated ecotourism, trekking, and overnight camping along the riparian corridor of the Da Nhong Stream. During periods of high visitor activity, human presence and noise may disrupt the natural behaviour of native fauna, causing shy, cave-dwelling species such as Puntius brevis to remain hidden and reducing their natural foraging activity.

Recreational wading and foot traffic can also damage delicate epiphytic communities, including Fissidens moss, wild ferns, and Weeping Moss (Vesicularia ferriei), growing on weathered granite surfaces. Although the area currently experiences relatively low human impact, the gradual accumulation of microplastics and chemical residues from sunscreens and camping products represents a potential long-term threat to the pristine, low-TDS water chemistry of this headwater stream.

Riparian zone

Trees near the aquatic habitat

Few -

Bibliography

• → Zootaxa, Magnolia Press, Volume 5550, Issue 1, pp. 35-50 - A new freshwater goby of Rhinogobius Gill, 1859 (Teleostei, Gobiidae) from South Central Vietnam by Chen, I-S., Nguyen, A. T., & Huynh, T. Q.
  
• → Nhà xuất bản Khoa học tự nhiên và Công nghệ - Sách Đỏ Việt Nam - Phần II: Thực Vật và Động Vật Đặc Hữu Hệ Sinh Thái Vườn Quốc Gia Phước Bình (Vietnam Red Data Book - Part II) by Viện Sinh học Nhiệt đới (ITB) & Ban quản lý Vườn quốc gia Phước Bình
  
• → Species Summary and Ecological Distribution of Rasbora daniconius in South East Asia Inland Waters by Froese, R. and D. Pauly (Editors)
  

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