The Rio Atabapo during floods
The border river to Venezuela was greatly altered: In February there had been endless sandbanks, but now the coffee-brown blackwater of the river, where dolphins are often sighted, was flowing.
Once again, the confluence of the cloudy water of the Rio Inirida with the clear black water of the Rio Atabapo was impressive. The different water temperatures and compositions of the water prevent the two types of water from immediately mixing. This phenomenon is best known near Manaus, where the blackwater of the Rio Negro and the whitewater of the Solimoes flow side by side for about 15 km in the same river bed before they mix into the Amazon.
The February expedition camp was metres under water, so we continued to an indigenous tribe that had a hut with overnight accommodation ready for our teams.
The new camp had the advantage of being more integrated into the lives of the indigenous people. They showed us their finished crafts (mini-souvenir shop) and we could observe how they spend their time. Particularly impressive was their evening get-together when the electricity generator was turned on around 6pm. Then they gathered in the "cinema" and sat next to each other on the benches in order of size like organ pipes to watch TV. Since they didn't understand the language, the TV was muted and loud music accompanied the A-Team on TV. For us it was a bit bizarre.
An exciting technical project in the indigenous village was a water tower that was originally supposed to supply all the huts with running water. However, the pipeline ended right at the bottom of the tower. Not all government plans work out!
Only a short walk from the village was a river that contained very clear water with only a small amount of blackwater. The river had become just a little larger due to the high water level and so there were lots of fish visible. Because of its proximity to the camp, we visited it frequently and spotted lots of fish species.
Another advantage of the river was that it had different sections, which due to their diversity, were also home to different fish. The closer one came to the main river Rio Atabapo, the more blackwater dwellers were to be seen.
The further upstream you swam, and this was many hundreds of metres, the stronger the current became, and with it the fish fauna changed. Fish species that prefer to avoid currents were still there, but always in calmer pockets of the river.
A rock barrier in the upper reaches formed a hurdle for many fish species. Only characins, some cichlids and, of course, sucking catfish were able to overcome it and were also found above the rock barrier.
It was interesting that the water values did NOT change in the river area where we were travelling. Only the water temperature increased by about one degree downstream towards Atabapo. Slow-flowing rivers simply give the water a little more time to warm up than fast-flowing waters.
| Expedition |
JBL Colombia 2 |
JBL Colombia 2 |
| Country |
Colombia |
Colombia |
| Location |
Near the camp at the Atabapo |
Near the camp at the Atabapo |
| GPS northern latitude |
3.907149 N |
3.910415 N |
| GPS western latitude |
67.706394 W |
67.701869 W |
| Date |
Nov 22, 2022 |
Nov 28, 2022 |
| Time |
10:08 |
9:15 |
| Degree of cloudiness |
50% |
80% |
| Lux above water surface |
52,130 |
25,340 |
| PAR value |
|
|
| Air temperature in °C |
33.5 |
29.9 |
| Relative humidity in % |
61 |
|
| Water temperature surface in °C |
26.7 |
27.5 |
| Water temperature depth X in °C |
30 cm, 26.7 |
30 cm, 27.1 |
| Water temperature depth X in °C |
|
|
| Conductivity in µS/cm |
10 |
10 |
| General hardness in °dGH |
|
|
| Carbonate hardness in °dKH |
2 |
2 |
| pH value |
6.2 |
6.3 |
| Oxygen content in mg/l |
9 |
9 |
| Iron content (Fe) in mg/l |
0.02 |
|
| Magnesium (Mg) in mg/l |
|
|
| Potassium (K) in mg/l |
|
|
Reintroduction of altum angelfish
The villagers realised from our expedition T-shirts, which showed an altum angelfish, how important this fish was to us. They used to see altums in the caño behind the village, but the altums had been gone there for some time. The village elder instructed one of our guides to buy altums from the fish exporter and was keen to reintroduce them into the caño together with us. The altums cost the equivalent of about 60 cents per animal. Together we went to the caño and released the animals into the river. Under water, it was exciting to see how they swam in formation, out of the bag immediately to the deeper parts of the river and so fast that we could not follow them. We searched, but saw nothing more of them!
At last, real aquatic plants!
Strange as it may sound, there are no real underwater plants in most tropical waters! Most of the greenery found underwater comes from "drowned" terrestrial plants forced to temporarily lead a submerged lifestyle due to high water levels. In extreme blackwater, aquatic plants are extremely rare. As soon as there is clearwater influence, there is a chance. We found several submerged plants in one caño.
