For the 16-strong team of scientists, cameraman, team doctor, pet shop retailers, pet shop sales staff and aquarium-keepers the expedition started in Manaus, at the confluence of the Rio Negro and the Solimões, which is called the Amazon from then on. From Manaus the journey continued by light aircraft 600km up river to Barcelos, the centre for catching ornamental fish in the Rio Negro. The team then boarded the ALYSON, a typical Amazon boat skippered by John Chalmers from England, and soon after arriving they reached the first interim holding station for ornamental fish on the Rio Negro. Although the experienced pet shop retailers had seen millions of red neon in the past, the sight of the newly caught fish in net containers was something special. To be precise, the containers were eight meters up in the trees because the river had had extremely high water at the end of April and the entire area was between six and eight meters under water!
The water values of the black water were immediately measured and analysed on the spot: a low pH level of 4.5 coupled with no measurable hardness and a total salinity of 16 µS/cm confirm the details given in literature on the regions of origin of red neon and many discus. After this first stop the Alyson travelled up the Rio Negro towards Manaus until late in the afternoon. The objective was to examine some tributaries, test the different types of water and study the varied fauna and flora.
The next day the Rio Branco, a typical white water river, was reached. Although the pH level of 6.5 was 100 times less acidic than the Rio Negro, the conductivity only increased to 19 µS/cm. Underwater observations were almost impossible as, although white water looks lighter than black water, it is cloudier and visibility is shorter. Some Indios reported a lake further inland, just a few minutes on foot from the shore of the Rio Branco, so the team set off on foot to find this water. The lake turned out to be a flooded area, but offered interesting fauna, both above and under the water. From large plecos (Hypostomus) to lizards (skinks), everything could be found there. Unfortunately there were also a lot of mosquitoes, which the team on the Rio Negro were spared. The mosquito-hostile black water keeps the mosquito population very low and contains practically no plankton (microscope studies).
On the third day of the expedition, the Alyson left the Rio Negro and the team investigated the flooded rainforest at the beginning of the Rio Jauaperi, the first clear water river on the programme. In small boats the team sailed up the Rio Jauaperi between the crowns of the trees, which gave an indication of the course of the river. After travelling for half an hour the water suddenly changed and the first clear water was found. The terrarium specialists in the team hunted for firm ground so that they could also study biotopes, but there was no riverbank to be found far and wide. It was a further 30 minutes and some heavy rain showers before firm land was discovered. Some of the team concentrated on the water, observing dwarf cichlid, tetra, plecos and demon eartheaters, whilst Markus Witt, Florestan Argoud, Franz Schierer and Gernot v. Kochansky looked for terrarium animals. From this day onwards two large tarantulas and a whole host of other creepy crawlies inhabited the boat. Half of them escaped over the course of the expedition and were spotted from time to time in various cabins.
In the clear waters of the Rio Jauaperi we were finally able to carry out our first underwater lux measurements. The watertight sensor on the instrument (WinLab Luxmeter: www.windaus.de) has a 5 m long, watertight cable marked off in 1 m sections. Despite the “clear water”, of the 30,000 lux measured directly at the surface, only 12,000 lux remained at a depth of in 50 cm. A good 24 Watt T5 aquarium tube without a reflector produces just 1400 lux at a distance of 50 cm – measured without water, and unfortunately a T8 tube only delivers half this amount! Interestingly the clearwater river presented the most extreme water levels, with a pH of 4.5 and a conductivity of only 5 µS.
Back on the Rio Negro everyone was curious to see whether the river showed different water values as the depth increased. So the Alyson anchored at the edge of the river and three volunteers put their faith in the shipâ€™s own â€œhookah systemâ€ of air supply. This consisted of a long hose with a regulator attached directly to a small compressor (Baumarkt brand â€“ only partially rusted). Diving instructor Falk Lehmann was the first to test the system and reported that, at a depth of only 5 m, more water than air was breathed in. The really strong water current added to the difficulties, so that the diver had to hook into the anchor chain with the crook of an elbow, shine an underwater torch onto the depth meter with the other hand and then fill various plastic bags with water at different depths.
It was an event which none of the three divers will ever forget: at a depth of only three metres the pain in the arm holding on to the chain was extreme, the body hung horizontally in the water with the force of the current, the surface had not been seen since a depth of two metres. The water was black and you could only see your own wrist with the depth metre in the torchlight if you held it immediately in front of your face. There is better visibility in any toilet water! At a depth of five metres the regulator increasingly replaced the breathing air with water. With a bit of practise you could separate the water from the air in your mouth and make your way hand over hand down the line. At seven to eight metres only traces of air could be detected in your mouth. Thatâ€™s where the most artistic sampling movements were performed. The worst thing was the sobering result: all the levels remained constant, only the oxygen content dropped by 2 %. Okay â€“ sometimes experiments go off like damp squibs, too.
The famous Amazon dolphins could be seen from the deck every day and everyone was keen to be able to see these animals underwater too. In Novo Airão, just one day away from Manaus, there is a spot where dolphins are lured by food and therefore tolerate the company of swimmers and divers. And indeed, free-swimming dolphins, (of which there are two kinds), came to eat the food in the form of fish from the hands of the team members. It was an indescribable experience, diving and snorkelling with these grey-pink, half-blind toothed whales, up to three meters long, at such close quarters. In our heads we added up the retail price of the fish consumed: Leporinus species, Cichla occelaris, Pacus. Astounding what variety and amount a dolphin eats!
The last part of the first section of the trip took the Alyson to a short-cut between the Rio Negro and Solimões, where at last we saw the typical large floating leaves of the Victoria regia, named in 1837 in honour of the British queen. The prickly undersides of the floating leaves, which can support up to 60 kg in weight, protect the plant from herbivores.
In the nutrient-poor waters of the Rio Negro there are practically no underwater plants. Not until the linking canal, into which water was forced from the Solimões, was there any improvement in the nutrient content and the number of species of aquatic plants increased significantly.
Finally the last water analyses in Solimões/Amazon were carried out before the Alyson sailed on to the confluence of the two rivers. The water of the Amazon clearly differed optically from the Rio Negro. It was just one degree colder (the sun warms up dark water much more than light water), the pH level was significantly higher at 6.5 and the conductivity of 83 µS/cm was a clear indication of the higher nutrient-mineral content (dissolved rocks/sediment from the Andes) in comparison to the Rio Negro (dissolved humic substances from flooded regions). For the first time a carbonate hardness of 2° GCH could be measured. After the measurements had been taken, everyone assembled on deck to see the world-famous “Meeting of the two waters”. The much darker waters of the Rio Negro meet the lighter waters of the Solimões 10 km east of Manaus, joining to form the Amazon, the river with the largest volume of water on earth (but a little shorter than the Nile). The differing water values and the (mere) 1° difference in temperature prevent the two river waters mixing immediately, flowing along side by side in the Amazon for several more kilometres with a clearly visible separating line.
(obtained using JBL Water tests and WTW laboratory instruments)
(0121831 southern latitude / 6159159 western latitude)
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(0122528 southern latitude / 6151502 western latitude)
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(0122089 southern latitude/ 6131339 western latitude)
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