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#5204 Forest duct of Nun River basin, Bayelsa State, Nigeria

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Nigeria, Bayelsa, Odi

Nun River is the longest (160km) continuation of the Niger River. The Nun River begins near the village of Aboh, where the Niger River splits in two, forming Nun and Forcados, flows through the rain forests, swamps and mangroves, and empties into the Gulf of Guinea. Flooding from monsoon rains lasts from June to September, then the water level drops, and in February, with the arrival of the flood waters from the Niger River, rises again.

Forest rivers and streams of the Nun River basin are home to many species of fish and other aquatic organisms. Although oil production causes serious damage to the local nature, yet in clean rivers significant biodiversity can be found. Mainly semi-aquatic plants grow in places where sun can reach the earth surface through the trees.

Submitted by
Biswarup Goon
GPS
5.1833329, 6.3166671
Geographical region
Western Africa
Drainage Basin
Nun river basin
River catchment
Niger river
Water body type
Stream
Water body name
Nameless
Water body part
Water body course
Upper course
Water body: tributary of
River
Tributary name
Nun

Videos above and below water

Water Chemistry

Water information

Water type
Fresh water
Water color
Black water
Water transparency
Medium
Concentration of sediments
Medium
Water temperature
24 °C
Water flow/curent
Slow

Chemical parameters

pH
6.5
Conductivity
6.5
GH
22 mg/l
KH
20 mg/l
Dissolved Oxygen
110 %

Substrate in nature

Sand
Orange
Pebble/Gravel
Beige
Stone
Reddish
Stone form
Irregular
Silt/Mud
Brown
Leaves
Adundant
Driftwood
Many
Submerged terrestrial vegetation
Yes

Aquatic Biotope

Date of collecting
25/03/2022
Collecting area
River bank
Water depth
0,5m
Air temperature
26 °C
Sunlight
Filtered/dappled sun

Environment

Environment
Affected by human activity
Affected by human activity
Agriculture
Agriculture
Little
Surrounding area

The river bank is covered with trees and large clump of fern like Bolbitis heudelotii. The bed is filled with riversand, clay and porous stones and covered with dry leaves. Various types of worms and flies are lived in the rainforest through which the river is passing. Dry and ripe fruits, insects are the main food source of the fishes of Nun river.

Underwater landscape

Mostly there are Water lilies (Nymphaea), Crinum, Anubias on the edges of rivers but the middle parts of streams are devoid of plant growth, only with lots of rocks and dead leaves. Though there are some islands of plant growth but more made up of overhanging growth from shore based plants.

The bottom is composed of sand, gravel and sporadic larger stones . Roots of semi submerge vegetations makes hiding place for fishes and other aquatic animals. Fruits’ shells, seed pods, barks provide shelter and suitable place for egg-laying.

Fishes:

  • Pantodon buchholzi (Pantodontidae) – common
  • Pelvicachromis pulcher (Cichlidae ) – very common
  • Polypterus endlicheri (Polypteridae) – common
  • Gnathonemus petersii (Mormyridae) – rare
  • Aphyosemion bitaeniatum (Nothobranchiidae) – common

Amphibians:

  • Hymenochirus boettgeri (Pipidae) – very common

Aquatic plants:

  • Anubias barteri var. glabra Araceae) – common
  • Anubias barteri var. nana (Araceae)  – very common
  • Bolbitis heudelotii (Dryopteridaceae) – common
  • Crinum calamistratum (Amaryllidaceae) – rare
  • Ceratopteris thalictroides (Pteridaceae) – common
  • Pistia stratiotes (Araceae) – very common
Threats to ecology

Bridge construction activities within the channel of the Nun River have adverse effect on the water quality. The bridge construction activities also have the potential to cause a temporary increase in suspended sediments. Aquatic habitat will be disturbed in the vicinity of the construction area. Aquatic life uses of this portion of the Nun River will be negatively impacted. The bridge structure itself was observed during this study to cause a constant upwelling of sediments around the bridge location and is confirmed by very high turbidity values of 64NTU recorded in the area and downstream of the bridge location. The distribution of particle size fractions shows a high proportion of sand particles at the Bridge stations; indicative of higher energy environment.

Sediments in the study area were generally acidic (ranging from 4.21-5.61): acidic sediments can have an adverse effect on fisheries distribution and other benthic organisms. Available Phosphate values of 2.71-17.24mg/l and Nitrate values of 3.11-13.4mg/l recorded in this study were higher than those in other studies. Bridge construction activities within the cannel of the Nun River have adverse effect on the sediment quality.

Crude oil industry of Nigeria is another threat to Nun river’s aquatic system. Oil layer on the river water surface makes suffocating environment for fishes,crustaceans and amphibians of the river. Dissolved oxygen ratio is decreasing day by day.

Riparian zone

Trees near the aquatic habitat
Many - Bolbitis heudelotii (Dryopteridaceae)