#11549 Bensbach Creek, Western Province, Papua New Guinea

Environment

Environment

Untouched

Surrounding area

The Upper Fly-Bensbach region of Western Province, Papua New Guinea, is characterised by extensive lowland tropical rainforest, seasonally flooded forests, and freshwater swamp ecosystems. Small blackwater creeks meander through dense vegetation, where towering rainforest trees, pandanus, sago palms, and riparian shrubs form a closed canopy that shades the water throughout the day.

The region experiences a humid equatorial climate, with annual rainfall exceeding 2.500mm and relatively stable temperatures ranging from 24-30°C. Organic matter from the surrounding vegetation continuously enters these creeks, creating tannin-rich blackwater habitats that support a remarkable diversity of freshwater fishes, crustaceans, aquatic insects, amphibians, and birds.

Underwater landscape

The habitat consists of slow-flowing, tea-coloured blackwater streams with high water clarity despite their dark appearance. The substrate is primarily composed of fine sand covered with leaf litter, decomposing branches, submerged roots, and occasional fallen logs.

Dense riparian vegetation provides shelter and limits light penetration, while marginal aquatic plants occur in more open sections of the creek. Pseudomugil paskai inhabits these quiet waters together with other native fishes, gudgeons, freshwater shrimp, and aquatic invertebrates, using submerged roots and woody debris for shelter, feeding, and spawning.

Aquatic inhabitants

• Pseudomugil paskai (Pseudomugilidae) – Paska’s Blue-eye – Common
• Mogurnda sp. (Eleotridae) – Sleeper Goby – Occasional
• Giuris margaritacea (Eleotridae) – Snakehead Gudgeon – Occasional
• Caridina sp. (Atyidae) – Freshwater Shrimp – Common

Aquatic vegetation

• Cryptocoryne sp. (Araceae) – Crypt – Rare
• Cyperus sp. (Cyperaceae) – Sedge – Common

Threats to ecology

Although much of the region remains relatively undisturbed, increasing pressures from logging, agricultural expansion, mining activities, road construction, and wetland drainage threaten the integrity of these blackwater ecosystems. Sedimentation, habitat fragmentation, and declining water quality may alter the delicate environmental conditions required by native freshwater species.

Conserving intact rainforest catchments and maintaining natural hydrological processes are essential for protecting the unique biodiversity of the Upper Fly-Bensbach freshwater ecosystems and the specialised species they support.

Riparian zone

Trees near the aquatic habitat

Many - Pandanus julianettii (Pandanaceae) – Karuka Nut Palm

Trees near the aquatic habitat

Many - Melaleuca cajuputi (Myrtaceae) – Cajuput Tree

Trees near the aquatic habitat

Many - Metroxylon sagu (Arecaceae) – Sago Palm

Trees near the aquatic habitat

Many - Nauclea orientalis (Rubiaceae) – Leichhardt Tree / Yellow Cheesewood

Bibliography

• T.F.H. Publications - Rainbowfishes of Australia and Papua New Guinea by Allen, G.R. & Cross, N.J.
  ISBN 978-0866228788
  
• Christensen Research Institute - Field Guide to the Freshwater Fishes of New Guinea by Allen, G.R.
  ISBN 978-0958125506
  
• Aquatic Photographics - Rainbowfishes: Their Identification, Care & Breeding by Allen, G.R., Unmack, P.J. & Hadiaty, R.K.
  ISBN 978-0975150222
  
• T.F.H. Publications - Freshwater Fishes of Australia by Allen, G.R.
  ISBN 978-0866229426
  
• Christensen Research Institute - The Freshwater Fishes of Papua New Guinea by Allen, G.R.
  ISBN 978-0958125520
  

Sitography