Nature Study On Guyana

ABANDONED SUGAR CANE FIELD Anyone living along the coastal strip of Guyana will always remember the stench and abundant fish associated with abandoned sugar cane fields, but, have you ever paused to ponder why this practice is carried out. It is only in Guyana where such an event takes place after about 12 to 14 years of ratooning. I will now endeavour to explain. Abandoned sugar cane field. Rose Hall estate, Berbice, Guyana Many coastal areas of Guyana, Vietnam and parts of West Africa have acid sulphate soils, formed under marine conditions and built up by mangroves where the sulphate in the sea water is reduced to hydrogen sulphide in the anaerobic conditions of the flooded soil which is high in organic matter. The hydrogen sulphide reacts with iron compounds in the soil to form iron pyrites (FeS2). Where the swamp contains considerable amounts of iron pyrites, they become quite sterile after draining as the iron sulphide is oxidised to sulphuric acid (by the bacteria thiobacillus ferrooxidans) and iron is deposited. The process is identical to the much publicised “acid mine drainage” problem, associated with many mining regions of the world. This is evident if one looks at the seepage coming from the soil, one sees the iron rich solution turning brown by the deposition of haematite (Fe2O3) as it oxidises on contact with atmosphere. Anaerobic reactions are utilised in the heavy frontal clays in Guyana, where at the end of the cropping cycle, the structure of the soil is poor and rather difficult to irrigate efficiently. The land is taken out of cropping and flooded to a depth of 30cm for between 6 to 12 months. During this time all the trash from the last ratoon rots down and anaerobic reactions associated with iron oxides occur. A heavy growth of waste-weeds and algae builds up, ideal habitat for fish, but the normal cane field weeds are “drowned”. When the field is drained away to the saline (corrupted to silane) canal, any excess salts are removed and as the air penetrates, oxidation of iron and manganese compounds proceeds. The final result is a marked improvement in the tilth and an increase in fertility.

1

Modern sugar refinery under construction at Skeldon estate, Guyana This practice is confined to Guyana, which has its own characteristic system of irrigation and drainage canals, evolved over the centuries, by trial and error.

THE ELECTRIC EEL The electric eel (Electrophorus electricus) is one of the most extraordinary South American fresh water fish. A large electric eel five or six feet in length can produce outputs as high as 650 volts, and a three-foot eel can regularly produce 350 volts. There are no clearly documented cases of people being killed by these eels, but it is entirely possible. The South American electric eel is one of a select family of fishes which all share the interesting internal arrangement whereby an important part of the muscle tissue has been modified to produce significant amounts of electricity. All animals which have a nervous system produce a minute amount of electricity, but in the vast majority the current is extremely small and so confined entirely within the body, eg it takes an electrocardiograph to register the current produced in the human heart. What makes the electric fishes extraordinary is that they can release electricity outside their bodies, and that the amounts released are appreciable, ranging from minor tingles to paralyzing and fatal shocks. The electric is by far the most potent of these electric fishes. Four fifths of its elongated body is made up of the electricity producing tissue; all of its vital organs are crowded into the head end. 2

This makes it really a very short fish with a long tail, and the functions of its highly charged tail are to provide it with protection, food and the ability to detect objects in the muddy waters where it lives, all through electricity.

The habitat of the electric eel There are three electricityproducing organs in the tail of the electric eel, each of which seems to have a separate, though related, function. The largest of the three, the main battery, so to speak, produces the high voltage discharges. It starts at the head end of the tail and runs for about two thirds of its length, tapering at its hind end. It is a paired organ, i.e. there is one of such organ at either side of the tail. The electric cells within the organ are arranged in series, like storage batteries in the modern electric car. It is believed that these cells are muscles in which the contractile tissue has disappeared, so that all that is left is a concentration of motor end-plates, the electric producing nerve terminals which in any muscle govern muscular action. Where the large electric organ tapers towards the hind end of the tail, another, smaller paired organ begins. This one is known as the bundle of Sachs, and it releases discharges one tenth as strong as that of the large organ.

Electric eel in the Mazaruni River

But whereas the major discharges are discharged in trains of 10 or so at a time and up to 300 or 400 per second in a vigorous eel, the bundle of Sachs sends out single impulses at the rate of 20 or 30 per second. These discharges seem to function as a sort of locating device, replacing the eyes, which, as a young eel matures, becomes clouded and useless, probably as a result of being damaged by repeated electric shocks. A third organ, called the organ of hunter, lies along the base of the anal fin. Long and slender, it runs the full length of the tail. Its discharges are very feint and, though they seem to be related to the major discharges, their function as of now is unknown. 3

An oddity of the electric eel is that it breathes air, it must rise to the surface every 15 minutes or so, or it will drown. It has neither lungs nor gills, but numerous small folds in the mouth, covering the tongue and palate, that are specialized for absorbing oxygen. In the laboratory, an electric eel can be kept out of water for hours at a time; all that is necessary to keep it alive is to moisten the mouth once in a while with water. I went to Guyana on one of my photographic expeditions to document, on film, the effects of the El Niño drought of 1998, the worst in living memory when approximately one-third of Guyana’s livestock succumbed to this devastating natural phenomenon, caused by warm current oscillations in the Eastern Pacific Ocean, off the West coast of South America. Salt (NaCl) also crystallized in the coastal canals, permanently altering the fragile ecosystem.

Approximately one-third of Guyana’s livestock succumbed to the drought

4

Salt crystallizing along coastal canal, Corentyne coast While there, I met an old friend who had mining concessions in the Cuyuni and Mazaruni rivers from which he produced gold and diamond. In the late seventies, while working for the Guyana Mining Enterprise, I was his mining consultant. He volunteered to take me in to the Mazaruni to see how things had changed in 20 years I had been away from that area. I relished the idea of a free trip. He piloted his own Cessna plane and had been doing so since 1975. We flew from the Ogle airstrip. This was the first time I had flown into the interior and was able to see the ground throughout; normally the cloud cover obscures such views, thanks to El Niño. The suspension bridge at Garraway stream looked majestic in the rain forest. Omai Gold Mine stood out as the environmental disaster it is renowned to be. My friend mentioned that because of the El Niño, the electric eels were seeking out the deeper spots of the river where his men were dredging, and as a result, three of his men were killed in six months, suspected of electrocution. I was a bit skeptical. All the electrocutions were on one particular rig in the Mazaruni, he operated three rigs there. There was no electrocution in the Cuyuni, where he had four rigs! I asked him whether his men had seen the eels when they came up for air, something I learnt on the Discovery channel. Two hours later we landed on a bumpy Imbaimadai airstrip, chased by all the dogs from the village. A dugout canoe was waiting for us at the landing; we boarded it and motored up the Mazaruni River. The river was noticeably low, and rocks were seen everywhere in the river making navigation treacherous.

5

Electric eel in the Karowrieng River We hit rocks on several occasions but had enough warning to lift the outboard motor and save the propeller from being damaged. We turned into the Karowrieng, a tributary of the Mazaruni, renowned for its Maipuri fall. About a mile in we met my friend’s first dredge and tied up alongside it. The foreman of the rig was Batson, an old associate; he was overjoyed to see me and hugged me, nearly fracturing my ribs. Years of hard rum drinking and patronizing the whores who ply the mining camps had not taken their toll. His propensity for the Itinerant gold miner’s life in this part of the Amazon rain forest rejuvenated him, I thought! A mining dredge is fully self-contained for the 8 or 10 hours it is in operation. A cook is on hand, there is a mechanic to service the engine, compressor and pump. There are processing men who recover the diamond and gold. Divers work in stints of 30 minutes, their main function is to hold the hose pipe of the suction pump in the gravel bed. While he is there, he is fed air from the compressor. He is partnered by a hose/signal man who feeds him his supply airline and signals to him. Each crew has their unique signals, it is not universal. Because of the danger associated with such operation, a diver can surface in 10 seconds from the time he is signaled to. When we arrived Chico was diving and he had been under for about 20 minutes, the signal man was “Butter Boy”, renowned for his lightning fast reflexes. I asked Butter Boy, “Butter signal to Chico to surface,” Butter looked at foreman Batson for approval. Batson was a hard faced alluvial miner with 40 years’ experience, he worked every river in Guyana, and I first met him in the Potaro River in 1977, about 5 kilometres below Kaieteur Falls, when I was shooting some Kodachrome colour slides on “Itinerant Miners” for a photo essay I was preparing for a well-known UK mining magazine. Batson replied, “Do as the English Maan suggested, Seech will never make a wrong decision, I’ve been wucking wid him since 1978, caaalll the man up, QUICK!!!” Butter duly signaled but after a minute, Chico had not surfaced, so the crew thought that he found a rich gravel bed. I knew that that was abnormal, and asked them to pull him up. They pulled him up and when he was landed on the pontoon he was barely conscious. His appearance was that of asphyxiation, a symptom I had seen several times in Africa associated with cyanide poisoning. 6

On closer examination of the mechanics of the rig, I found that the air intake to the compressor was very close to the exhaust of the diesel engine. With the low river level, there was a lower head of water for the air to work against, so the divers were getting a higher dosage of carbon monoxide than when the river level was normal. I recommended that they shut down for a day and extend the exhaust pipe of the engine to above the pontoon’s roof. The average miner lives from hand to mouth with the sanguine hope that he will find that elusive gold nugget. Whatever spare money he has at the end of the week is spent on the prostitutes who come in to the area on special permits as “domestic servants” but practice their trade openly. On our way back, about 30 minutes before landing, I told my friend that the deaths he had were not from electric eels but carbon monoxide poisoning, he was visibly shaken, and although we had cleared the area renowned for its air pockets and turbulence, the ride was still rough, and the landing even rougher!!! YET AGAIN, THERE HAS BEEN NO CONCLUSIVE EVIDENCE OF ELECTROCUTION FROM ELECTRIC EELS

The gold dredge, post-modification

7

THE HOATZIN/CANJE PHEASANT (opisthocomus hoazin) The Guianas, a large area north of the Amazon watershed, is particularly well endowed with waterways, and its native name translates into “land of water”. Surprising, however, these forested rivers are not over-stocked with birds, despite the fact that tropical America houses the richest bird fauna in the world. The elusive hoatzin, graciously posing, up the Canje Creek in Berbice I have spent several days on these waterways and yet saw only an occasional heron, kingfisher or toucan. Nearer the coast the bird life is more plentiful, and in many areas there still exists colonies of the peculiar Hoatzin. Peculiar because they are probably in some ways the most primitive birds, and have a wing structure resembling that of the fossil Archaeopteryx. It is usually considered to be the “missing link” between modern day birds and their reptilian ancestors. Long claws on the bend of the wing help the young birds to clamber about in the branches around the nest, and if they fall into the water they can swim well, above and below the surface. Hoatzins are mainly crepuscular, sedentary birds, which rest among the river-bank foliage during the hot hours, and feed at night on the leaves, flowers and fruit of certain marsh plants known locally as moco moco. Not only does it eat leaves far more than any other bird, but it digests them like a cow or a sheep, grinding the leaves up in its specialized muscular crop. About 85% of the bird’s diet is made up of green leaves. It prefers young, fresh leaves which are richer in proteins and easier to digest. Since a Hoatzin, unlike a cow, has no teeth, it “chews” its leaves up by rubbing them against sandpapery ridges in its crop. It keeps food in its gut for 20 hours or more. Like a cow it practices foregut fermentation, the fatty acids that result lends the bird its characteristic smell.

8

The Hoatzin’s nests are roughly built platforms of twigs, built above water, often in mangroves. When the young first hatch they are naked and extremely active. If they dive into the water because of fright, one can be later see how they cling adhesively to twigs and clamber from one to another as they try to get back on to the nest platform. Artist representation of the Hoatzin chick clinging to a branch, note vestigial claws They have two little claws on the front edge of each wing, relics of the time when their reptilian ancestors had no wings but forelimbs with separate digits. When the Hoatzin chick grows up, they lose those vestigial claws. The adults are poor flyers, flapping heavily and laboriously along the rivers. They do not seem able to cover more than a hundred metres or so before they have to crash into the vegetation and rest. Widespread clearing of land along the coast for rice and sugar cultivation during the last half of the twentieth century destroyed the Hoatzin’s habitat and the bird became rare. The Hoatzin is the national bird of Guyana and is locally known as the Canje Pheasant, from the district in which it was most common. Despite being the national bird, it is estimated that less than 10% of the population has seen a wild bird!!

Ramoutar Seecharran (BSc (Hons), ACSM, MSc (Eng), DIC, CEng, IFPO)

9