Biotopes of Brunei | Biodiversity of the Telamba River

On the early morning of 15^th September of 2017, our group finally resembled to embark on another trip to explore the jungles of Brunei. This time we headed to our 1^st lowland river trip where we would be investigating the lower Telamba River; this was also to our first exploration trip within Tutong district of Brunei. The Telamba river is a stream for most of its course and is approximately 5.5km long (possibly longer) and is a tributary of the Danau River.

For this trip we started off from Seria Town, we departed at 8am and drove to our destination located at where we would park beside the road, located somewhere along the controversial Telisai – Lumut Highway ( an 18.6 kilometres long highway, which officially opened in June 2016) , it took about 25 minutes drive. From our parking spot we walked for only around 200 – 250 metres in. It seems like we were the 1^st few people that went into this part of the jungle to follow the stream as there was no trail which we could walk on, thus we had to make our own, which was tiring as the jungle was dense and humid. Because of this, we only went in about 100+ metres into the jungle, but there was a lot of life around us.

Since the recent highway construction, the lower Telamba River is now sandwiched between a developed coastline, a road and a landfill site; thankfully the road does allow the river to pass below.

The construction of the highway has luckily not interfered with the river directly, but who knows what impacts will come with new access to these previously untouched areas

Although we were probably the 1^st few people to go to this part of the jungle, but as it is located near only 1 year old highway, there could be seen some remains of human trash from the construction, for example:

• The standard 200-litre (55 US or 44 imp gal) drum.
• Tangled plastic ropes.
• Empty water bottles
• Some reinforcing steel as we got nearer to the bridge of the highway. 
  

  One of the sadder and more compelling sights was this steel drum typically used to transport oil or petroleum fuels which had been dumped directly into the river; will the new access to this previously untouched area mean we will see much more of this dumping in the future?

At the place we decided to stop for the day, we placed our bags on the ground, look for potential fish habitat & finally set up some minnow traps.  The water was crystal clear, so it was easier to look for fishes from above the water. At first we set up traps in open areas of the river and waited for about 30 minutes to allow any fishes to go in but unfortunately, due to the fast flowing current, no fishes were found inside. For our second attempt, we decided to place the traps in more shallow areas, and especially next to fallen tree trunks where the flow is slower in comparison. using this technique we were then able to catch two species.

The biotope of the congeneric species Rasbora cephalotaenia and Rasbora einthovenii from Telamba River in Tutong District

The fishes caught were:

• Rasbora cephalotaenia (Specimens caught were all adults, with an average size of 7cm)
• Rasbora einthovenii (specimens caught were all adult, with an average size of 3cm)
  

  Mature individuals of Rasbora cf. cephalotaenia from the lower stretches of the Sungai Telamba

  

  Mature Rasbora einthovenii which are a slightly smaller Rasbora which live alongside R. cephalotaenia in the Telamba

At the same time, other species of aquatic fauna which could be seen from above were:

• Macrobrachium sp.
• Juvenile Hemiramphodon

The population for these 2 species was not as much as the 2 Rasbora species caught, as it was quite uncommon to see these 2 species in the area.

While we waited for the traps to be lifted up, we decided to snorkel, look for some macrophytes & find some inspiration.

We noted that:

• The width of the steam was around 5 – 6 metres wide
• The water depth was a few – 30cm on the banks of the stream, & can reach to about 1.4 – 1.5 metre depth at the centre.
• The pH Level was below 6
• The water temperature was around 25 – 26°C
• The water was crystal clear & little to no signs of tannin
• The current was fast flowing, can reach up to approximately 30cm/second.
• The substrate was mainly made up of yellow/brown sand, with mixtures of silts & debris.
• There was a lot of driftwoods, branches & tree trunks(which allows the current to flow faster at certain areas, especially deep areas)
• Not alot of fishes are found at the centre of the stream where the current is strong, most are found & caught nearer to the bank of the stream.

We would be interested to know the identity of this Cryptocoryne species from Telamba

At certain parts of the bank, we discovered a Cryptocoryne sp.  growing under a shaded area, where the current was not as fast flowing. Although the leaf had a similar shape to the Cryptocoryne longicauda we found in Belulok, Labi, but the stem length & the leaf size of the largest specimen we found were different.

This beautiful small Cryptocoryne species has a rich red underside to its leaves

  We noted that, the largest Cryptocoryne sp we were able to obtain yesterday had an average:

• Stem length of about 5 – 6cm long.
• Leaf size of about 5 – 6cm long.

Whereas the Cryptocoryne longicauda from Belulok, Labi had an average:

• Stem length of 14cm long.
• Leaf size of about 7 – 8cm long.
  

  Left: Cryptocoryne longicauda from the Belulok River in Labi. Right: Cryptocoryne sp. from Telamba River In Tutong district.

  As this was our 1^st trip to this area, we’re hoping to come here again & venture even deeper to discover more hidden treasures of the aquatic world in Tutong and the whole of Brunei.