ATAS DO SIMPOSIO SÔBRE A BIOTA AMAZÔNICA VOL. 3: LIMNOLOGIA Belém, Pará, Brasil, Junho 6-11, 1966 EDITOR: HERMAN LENT Publicado pelo CONSELHO NACIONAL DE PESQUISAS RIO DE JANEIRO, GB 1967 APRESENTAÇÃO De 6 a 11 de junho de 1966, na cidade de Belém, Estado do Pará, Brasil, foi realizado o Simpósio sôbre a Biota Amazônica, organizado pela Associação de Biologia Tropical, com a colaboração do Conselho Nacional de Pesquisas do Brasil, tendo José Cândido de Melo Carvalho como Presidente Executivo. O Simpósio homenageava especialmente o Museu Paraense “Emí- lio Goeldi” que comemorava seu 100. 0 aniversário. Ao se iniciarem os trabalhos, achavam-se inscritos no Simpósio 16 países representados por 97 instituições, 256 pesquisadores irtscritos para apresentação de trabalhos que perfaziam um total de 22 confe- rências e 198 contribuições originais. Associaram-se como observadores, até êsse dia, 103 pessoas. Nos dias que se seguiram, até o encerramento, o total geral de frequência dos inscritos foi a 611 pessoas. As contribui- ções originais também aumentaram para 227. Resolvemos editar estas Atas em 7 volumes, cada qual correspon- dendo a uma das seções do Simpósito: Geociências, Antropologia, Lim- nologia, Botânica, Zoologia, Patologia e Conservação da Natureza e Recursos Naturais; serão todos publicados pelo Conselho Nacional de Pesquisas do Brasil, que assumiu a responsabilidade global da edição, da mesma forma como promoveu a realização e apoiou a execução do Simpósio. cm l SciELO 10 11 12 13 14 15 16 Em relação ao Programa do Simpósio distribuído na ocasião e, ainda, ao próprio desenrolar das reuniões de cada Seção, as Atas não incluem necessàriamente todos os trabalhos, retirados que foram al- guns por motivos vários. Êste terceiro volume corresponde à Seção III (Limnologia) que teve como coordenador Harald Sioli (Max-Planck-Gesellschaft, Plón); consta de um total de 226 páginas, 60 figuras no texto e 4 encartes, e divulga 17 trabalhos, dos quais duas conferências. O índice do volume aparece a seguir pela ordem alfabética do sobrenome dos autores, primeiro as conferências e depois as comunicações. Herman Lent Julho, 1967 cm SciELO 10 11 12 13 14 15 16 Pag. Leentvaar, P. The artificial Brokopondo Lake of the Suriname river. Its biolo- gical implications 127 Medem, Federico El género Paleosuchus en Amazônia 141 Oltman, Roy E. Reconnaissance investigations of the discharge and water quality of the Amazon 163 Paraense, W. Lobato Moluscos Planorbídeos da Amazônia 187 Sattler, Werner Primeiros resultados de pesquisas etológicas em invertebrados límnicos da Amazônia 195 Schwassmann, Horst O. Orientation of Amazonian fishes to the equatorial sun 201 Ungemach, Harald Sôbre o balanço metabólico de iônios inorgânicos da área do sis- tema do rio Negro 221 1, | SciELO Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 1-7 — 1967 HYDROBIOLOGY IN THE AMAZON REGION G. MARLIER Institut Royal des Sciences Naturelles, Brussels, Belgique The Amazon watershed is the greatest river basin of the tropical world. It has an extension of 6,5 million square kilometers (i.e. 2,5 millions square miles). Its water flow is the highest in the world and has been computed by Katzer to be near 120,000 cubic meters per second at the mouth during the dry season. A look on the hydrographical map edited by the Brazilian Insti- tute of Geography (1953) shows clearly the importance of the river network on the structure of the Amazonian region. But the best way to visualize the part played by water in the Amazonian environ- ment, is to fly by Catalina plane over the river from Belém to Ma- naus. Then the interdependence of soil and water appears without a doubt. The history of this watershed has been told many times and Pro- fessor Sioli recently gave a sum- mary of the succession of geologi- 1 — 37 121 cal events which led to the shape of the country we presently know. The actual fluvial basin is the remain of the huge freshwater lake which extended over the whole “planície” above the region of Óbi- dos, during the second half of the Tertiary and the first part of the Pleistocene. This lacustrine stage thus lasted a comparatively short time and the present river network lasted still less. The geographical conditions of the Amazon plain bring about some important consequences, from the viewpoints of Limnology and Biology. One of these is the great extension of the brackish waters in the mouth of the river itself and also on the coast of the Ocean. This has formed an almost ideal start- ing point for the invasion of the freshwaters of the region by sea animais. The most conspicuous of these are the Cetaceans. Two species of Dolphins have adapted themselves completely to freshwater condi- cm 1 SciELO 10 11 12 13 14 15 16 Atas do Simpósio sóbre a Biota Amazônica tions in the Amazon; they are the great “pink” dolphin, or Boto, Inia geoffroyensis (Blainville) and the lesser grey dolphin or Tucuxi, So- talia pallida (Gervais) . Other very typical sea animais are the shark, the saw-fish and some stingrays, of which the first two are probably marine individ- uais making migration far into the river (as far as Manaus and Iquitos) while the rays are certain- ly wholly adapted to a freshwater life. Among the bone-fishes also some marine families are now com- pletely at home in the Amazonian freshwaters such as the Needle- fishes, the Soles etc. These marine families have also representatives in some other fresh-waters, particularly in the Tropics, but we think that no- where such an array of marine ani- mais found their way in a fresh- water fauna in which a rich true freshwater fauna also exists. (We must not forget the presence of a shark in lake Nicarágua, of Dol- phins in índia and China, of sting- rays in the freshwaters of several tropical countries). Among the Invertebrates of ma- rine origin, we may mention the Nemertine Siolineus turbidus Ev. du Bois Reymond, found by Prof. Sioli in the Tapajós and which be- longs to the Order Heteronemerti- na. As the other freshwater Hete- ronemertines “Nemertes” polyho- pla and Planolineus exsul, found respectively in lake Nicarágua and in the Botanical garden of Buiten- zorg, Sliolineus shows strong ma- rine affinities and its presence in the Tapajós points to a recent evo- lution of this species from a for- merly marine environment. An- other interesting worm of recent marine origin is the Polychaete Lycastis siolii Diniz Corrêa found by the same collector in the Ta- pajós. This species must be, according to Corrêa (1948) not an old marine relict, but a “young” marine immigrant. As the knowledge of the fresh- water fauna is still in its infancy, it is likely that many more instan- ces of such marine invasions will be found in the future. Very dif- ferent conditions prevail for in- stance in África where most of the continent is high above sea levei and where marine migrants do not enter the freshwaters very far in- land. Another geographical condition of great importance and having both direct and indirect conse- quences, is the very small slope of the Amazon and its great affluents and the very flat nature of the ba- sin. The river itself has a slope of 1/100,000. But as the rainfall is very high and seasonal in the high- est reaches of the Amazon, proper and its affluents, the levei fluc- cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) tuations are very powerful (They may reach 15 meters annually in Manaus on the lower Rio Negro) . At high water time, the waters of the Amazon and of its big af- fluents flow over the banks and flood the neighbouring land, enter- ing the forests and backing up the waters of the minor affluents . These, in turn, swell and enter the surrounding country. This huge inundation area is thus accessible to the river animais which invade the formerly terrestrial environ- ments where they feed and proba- bly spawn. This explains how fish can find very favourable life con- ditions during the high water times. We know that this occurs also in several other tropical re- gions as in the African big rivers (principally the Niger and the Nile) and in the South Asian sub- continent when the Mekong shows very important levei fluctuations . But all these countries are very much more populated and deforest- ed in such a manner that fish doesn’t find as favourable feeding grounds as in the huge Amazonian forest . This third geographical feature of biological importance is the absence of old lakes in the Amazo- nian plain. All the hitherto known amazonian lakes belong to one or two types, both of which are shal- low and very young. The first type is the “varzea la- ke” which is a lake in continuous or periodical relation with the Amazon or with a white water af- fiuent and receives water from these rivers either by a permanent “furo” or by the periodical inva- sion of its effluent at high water time. The second of these types is the “terra firme” lake which flows into the Amazon by a long effluent. It may swell into a large lake when its effluent is dammed by the high waters of the Amazon but it never receives white waters from the latter. Both types of lakes are thus very dependent of the river itself and it is thus not surprising that no real lake fauna could be evolved in them, comparable with the parti- cular lake fauna of África, for in- stance. The fishes of these lakes are those of the rivers, or may be a lit- tle less numerous. But these lakes are very important spawning grounds for many of the river fish- es most of which have migratory habits. These fish migrations in the amazonian waters are well known (the piracema) and are probably obligatory for the success of repro- duction of most species (as it is for most Indian Carps in the Asian Continent). If this is confirmed, the scarcity of lake and pond spe- cies able to spawn in confined con- cm 1 SciELO 10 11 12 13 14 15 16 Atas do Simpósio sôbre a Biota Amazônica ditions may be an obstacle to the use of Amazonian fishes for fish culture. In fact one could think that af- ter the lapse of thousands of years, or after tectonic movements take place, the Amazonian region will be very rich in lakes, as so many deep drowned valleys are known to exist in this basin. We know, personally, no lake out of reach of the rise of the Amazon or its af- fluents and which could have an independent existence from that of the rivers. The orographic conditions of the basin have another result. No true lakes, with the classical characters of the deep lakes, can be found. From the theoretical considera- tions developed by Lõffler, we should expect that a deep lake in this equatorial forest of climate Af and Am would be oligomictic; it means that it would mix and cir- culate at irregular intervals, owing to the great stability due to the high water temperature. In fact most of the lakes studied by Braun and the author were of the polymictic type, being too shallow to develop a great stability. Of course this limnological condi- tion has very important conse- quences on the nature of the fauna. Apart from its freshwater fauna directly from marine origin, the Amazonian freshwaters harbour an extraordinary rich freshwater fau- na. It is yet not well known, except for some particular groups and we may suppose a great number of species remain to be found. Let us consider the class of Fishes to which many studies have been devoted. It is well known that a great part of the aquarium fishes are of south american and parti- cularly amazonian origin. More than 1500 species of fish have been described from the area, a respec- table number considering that it belongs to one watershed only. If we compare it with other fresh- waters in the Tropical regions, we see that the river Congo harbours a little more than 500 species (not included the fauna of Lake Tan- ganyika), the Ganges 300, the Nile 200 etc. South America has been isolated from North America during the greater part of the Tertiary period and was United with the latter Continent only in the Pliocene. Its freshwater fish fauna is very much endemic, owing to this long isola- tion and we find that many fish families are peculiar to South America, and have found in the huge Amazonian tertiary lake and the subsequent water network an ideal distribution area. Such are the Gymnotids, many Siluroid fa- milies and the greater part of the Characids. cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) From the point of view of the Chemical and physical conditions, the amazonian waters represent, as is well known, one of the follow- ing three types. The “white” wa- ters rivers are loaded with a rather great quantity of silt, which they collect in the Crossing of the Andes. Such are the Amazon proper, the Madeira; compared with other amazonian rivers these waters are relatively rich in salts. This assess- ment is, of course, to be taken with some caution. According to Sioli, the total hardness (expressed in German degrees) of the Amazon around Santarém, varies between 0.65 and 1.27. This compares very well with the hardness of river Congo near Stanleyville, which is around 1 . 4 but is well below that of the river Nile at Cairo, which reaches 5.0. The second type are the “clear” water rivers, coming from much older ranges which are the central brazilian plateau and the Guyana plateau. These do not give rise to great mineral transport and very scon these rivers loose their load and carry only crystal-clear waters (river Tapajós). These contain va- riable quantities of dissolved salts but generally lower quantities than the white waters (according to Sioli the Tapajós has a total hardness of 0.31 to 0.82, German degrees) . Their pH is also general- ly low when the rivers do not cross geological deposits particularly rich in calcareous salts as are the Carboniferous layers of the Middle Tapajós. As the anorganic nutrient con- tent of all waters flowing in the Tertiary layers of the Série das Barreiras is always very low and as the limestone rich layers of the Carboniferous period are of a re- duced extension we may safely as- sume that the principal source of dissolved nutrients is the Andean and Subandean region where the Amazon proper and some large white-water affluents have their headwaters. The “black “waters have a brown colour given to them by the leach- ing of the humic soils in the fo- rest swamps called Igapos. These waters are generally rather trans- parent, very poor in salt and of a very low pH (4.4 and even less) . From the biological point of view, we must point here to the influence of these Chemical pro- perties of the waters on their fau- na. As an instance we find many fish species in the black water ri- vers, even if they are less nume- rous than the white waters species. But it is generally admitted that such low pH values around 4 would preclude even the existence of fishes. Indeed it is difficult to under- stand how the hemoglobin of these cm SciELO 10 11 12 13 14 15 16 Atas do Simpósio sôbre a Biota Amazônica animais can be saturated with oxy- gen in the presence of such acidic waters and how the blood can get rid of its dissolved C0 2 . Anyway it seems, according to the expe- riences of Willmer, that the ef- fects of water acidity are less pro- nounced in warm than in cold wa- ter fishes. A last characteristic of the Ama- zon rivers is to be found in the cy- cle of production of plankton in the lakes formed on the banks on in the course of the affluents of the river. It has been found by the author that the primary productivity in the waters of the white water lakes may undergo an annual cycle according to the fluctuations of the lake levei and its relations with the Amazon. It is, of course, easy to understand knowing the relative riches of these white waters, that their invasion in the lakes may bring about a renewal of the nutrient resources of the environ- ment. This renewal is followed by an increase of the phytoplankton standing crop. We thus arrive at the conclusion that one of the most important of the factors in the amazonian en- vironment is related to fluctua- tions of the white waters and the penetration of these waters in the lakes. Knowing this, we under- stand how imperative it is for the limnologist and the fishery expert to have a good hypsometric survey of the Amazonian basin with the contour lines very close to each other. It has been said above that nu- trients brought by the waters are always rather scarce but this seems in disagreement with the great wealth of the fauna one finds in the Amazon basin. This appa- rent paradox is explained when studying the alimentary regimes of the fish of the rivers and lakes. These fishes are found to feed frequently on items which are de- rived not from the aquatic biolog- ical cycle but from the terrestrial environment of these waters, i.e. from the shore forest. Many spe- cies feed directly on leaves, seeds, fruits or on terrestrial insects or other invertebrates which take their subsistence in the riparian vegetation. It is thus the forest which maintains the fish fauna at its present high levei. AU altera- tions to this Uttoral forest could mean the disappearance of most fishes and of a valuable food re- source for the human population. This points to the necessity of respecting the littoral forest while planning development and agri- cultural schemes in Amazônia, con- sidering the Hylaea as a most valuable element even in the aqua- tic resources of the country. Any attempt to fell and burn the forest without due care to replace the cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) burned or exported nutrients would mean a loss of productivity in the waters. SELECTED BIBLIOGRAPHY Du Bois Reymond Marcus, E., 1948, Siolineus, a new Heteronemertine. Boi. Fac. Fil. Cien. Letr. Univ. S. Paulo, Zool., 13: Corrêa Diniz, D., 1948, A Polychaete from the Amazon Region. Boi. Fac. Fil. Cien. Letr. Univ. S. Paulo, Zool., 13: 245-257. Katzer, Fr., 1903, Grundzüge ãer Geo- logie des unteren Amazonas gebie- tes. Max Weg., Leipzig. Lõffler, H., 1957, Die klimatische Typen des holomiktischen Sees. Mitt. Geog. Ges. Wien, 99: 33-44. Marlier, G„ 1966, Etudes sur les lacs de rAmazonie Centrale. I. Cadernos da Amazônia 5: Myers, G. S., 1960, Notes and Com- ments on: G. Fryer’s Fish Evolu- tion in Lake Nyasa. Evolution, 14: 394-396. Sioli, H., 1964, General features of the Limnology of Amazônia. Verh. Int. Ver. Limnol., 15: 1053-1058. Sioli, H. & Klinge, H., 1962, Solos, tipos de vegetação e águas na Amazônia. Boi. Mus. Paraense Emílio Goelãi, n. s„ 1: 27-41. cm SciELO 10 11 12 13 14 15 16 Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 9-50 — 1967 STUDIES IN AMAZONIAN WATERS HARALD SIOLI Hydrobiologische Anstalt der Max-Planck-Gesellschaft, Plõn (Holstein) , Western Germany (With 10 text-figures) As no other country, no other landscape in the world, the Ama- zonian region is formed and char- acterized by its amount of waters. The Amazon is not only the might- iest river on earth, but also the fi- nal collector of the largest net- work formed by innumerable creeks, rivers and streams, which drain an area of about 7 million square kilometers situated in a very wet climate and covered by the most extensive, continuous, tropical rain-forest. Thus it is no wonder that the history of the studies of the Ama- zonian waters starts with the his- tory of the discovery and conquest of the whole country of Amazônia itself, that its very beginning coin- cides with the first expeditions of the Spanish and Portuguese dis- coverers and “conquistadores”. While Marco Polo travelled on foot or on animais back on ancient roads and paths to the fabulous Middle Kingdom, while the Boers penetrated South África, and while pioneering settlers of North America made their way to the Far West, both on their four-wheel- cars of the traditional stile of Cen- tral — and Northwestern Europe, while Sibéria was conquered by the mounted Cossack posses, while Arabs crossed Arabia, the Sahara and the Near East on camel-cara- vans, while the great discoverers of Central África made their “Sa- faris” with a more or less numerous train of barefooted negro-carriers — the Amazonian region was dis- covered, opened and conquered for Christian-European coloniza- tion and civilization, from the late Middle Ages up to recent times, by expeditions and travellers, who used the long and numerous wa- terways as the only practicable cm SciELO 10 11 12 13 14 15 16 10 Atas do Simpósio sôbre a Biota Amazônica possibility to penetrate the endless, dense jungle. By this way, the waters of Ama- zônia were the first of the factors which ccmpose the Amazonian landscape and with which the pio- neers came into contact, and the knowledge of the water-courses was a conditio-sine-qua-non for success of any colonization scheme. The history begins with the strange adventure of Don Francis- co de Orellana, who, in February 1541, started from Quito, in the high Andes, with an expedition, lead by Gonçalo Pizarro, in search of the land of “El Dorado” and of cinnamon. With 4000 Indians and 220 Spaniards they went eastward, down the mountains to the moist and warm lowlands of the un- known land. But they found neither El Dorado, the legendary gilded king in the silvery town of Manoa, nor the cinnamon-trees . Instead, the expedition ran short of food and got into extreme emer- gency. Pizarro and Orellana sepa- rated, and the latter, driven by famine, continued with his men in eastern direction in vain search for food. On the banks of the “Rio de los Omáguas”, now Rio Napo, on its confluence with the Rio Aguá- rico, he ordered to build a boat, a “bergantim”, for still exploring some stretches down the river. By the end of 1541, Capitán Francisco de Orellana embarked in it toge- ther with 55 Spanish soldiers and two fratres, one of them being Frey Gaspar de Carvajal, who became the chronicler of the voyage. They went down that river, hop- ing to come back within a few days. But also there they could not find anything to eat, and the only possibility that remained for Orel- lana and his weakened men was to continue the voyage on boax - d of that boat, down the river with the current which somewhere was to flow into the ocean. And Orellana decided to do so. So there began one of the most adventurous and remarkable voy- ages ever made by man which led to the discovery of that enormous river which at first, received the name of “Rio de Orellana”. Frey Gaspar de Carvajal wrote down what happened during the trip, but he was a typical child of his time and a representant of his profession. He reported what hap- pened on board, what the Spa- niards did and how they suffered and invoked the Holy Virgin etc., but practically nothing stands in his narrative concerning the cha- racteristics of the river or the land- scape. He always describes more and more only the hunger, the at- tacks on Indian villages which be- came less rare and finally very nu- merous as they descended the ri- ver, and where they killed the In- dians who did not achiev to flee. cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 11 and how they burnt the houses of them. Is it a wonder that the na- tives got more and more hostile, the more the discoverers came down the river? The communica- tion-system of the Indians, consist- ing of messangers and bush- drums, had the fame of robbers and killers go ahead of the des- perate Spaniards . . . Only the report on the discovery of the Rio Negro, in the eve of St. Trinity of 1542, written by Frey Gaspar de Carvajal, is worth read- ing for us. He wrote: “On the sa- me day, starting from there and continuing our voyage, we saw the mouth of another big river, on the left side, which entered that one in which we navigated, and of wa- ter as black as ink, and therefore we gave to it the name of Rio Ne- gro. It ran so much and with such ferocity that for more than 20 lé- guas (110 km) it made a strip in the other water without mixing itself with that one.” These are the laconic words by which, for the first time in history, the biggest tropical black-water-ri- ver has been made known to Eu- ropean civilization. The voyage of Orellana and his men turned more and more a flight down the river, a flight from hun- ger and the hostile Indians. Final- ly, on August 26th, 1542, the mouth of the Amazon was reached. Frey Gaspar de Carvajal writes: “We came out of the mouth of that river between two islands, separat- ed from each other by 4 léguas (22 km) of width of the river, and the whole, as we have seen above, has from one side to the other more than 50 léguas (275 km) , while the fresh water enters into the sea more than 25 léguas (137,5 km). The tides grow and fali 6 to 7 bra- ças (10 — 11 1/2 m).” The greatest river of the world was discovered — strange to see, from its headwaters at the feet of the Andes to the ocean. But almost nothing about it had been observ- ed but its colossity, its shores which were inhabited by very nume- rous “savages”, and the existence of some affluents, one of them with remarkably black water. It took some time, till the voy- age made by Francisco de Orella- na, was followed by the next ex- pedition which shall only be touched. Pedro de Orsua started from Cuzco in 1560 and descended the Rio Yutaí into the Yuruá, and from this river at 5 o S into the Amazon. But not even a report of this voyage has been left. Much later on ; Juan de Palácios came from Quito down the Rio Na- po, but he reached only the “Pro- víncia de los Encabelados” where he was killed by the natives. Only in 1636, i.e. almost 100 years after Francisco de Orellana, cm SciELO 10 11 12 13 14 15 16 12 Atas do Simpósio sôbre a Biota Amazônica there started, from Quito, two priests together with 6 soldiers on the next voyage. They succeeded in repeating the achievements of the discoverer and finally reached Grão Pará, where the Portuguese had already a fortified “praça”, which in the following time, de- veloped to what is now the city of Belém. This voyage gave rise to the fa- mous expedition of Pedro Teixeira, a Portuguese general in Grão Pará, in 1637-38, who was the first to as- cend the river from Belém to Quito and then return the same way. At that time, the lower Amazon up to the Tapajós had already been well known, not only to the Portu- guese, but also to the Dutch and the British, who had started to build fortresses and to occupy parts of the country. Pedro Teixei- ra had already fought those intru- ders and gone up the Amazon and the Tapajós for punishing the na- tives and catching slaves. By such experiences, he was well prepared for that great, new enterprise for which he took with him a total of around 2000 persons in 47 canoas “of good size”. There exist two reports on that expedition, the one by Alonso de Rojas, the other one by P. Cristo- bal de Acuna S. J., which are in part identical, in part complete each other mutually. Father Cris- tobal de Acuna had been ordered, by the Vice-Rey dei Peru to accom- pany Pedro Teixeira on his way back to Pará, while Alonso de Ro- jas seems not to have participat- ed in the expedition. The most vi- sible result for our interests — which do not coincide with the po- litical aims of that expedition — is the first map of the Amazon, idealized and, probably, designed by the pilot of Pedro Teixeira’s fleet. But not only that first map is worthy of note for us, the reports contain so many excellent observa- tions of peculiarities of our oig ri- ver and its surrounding landscape — naturally also mistakes — that for reasons, I shall explain after- wards, it seems to me worth while dedicating more time to them and to cite some parts in extenso. It is already another spirit, dif- ferent from that of Frey Gaspar de Carvajal, when Father Cristobal de Acuna writes in his preface that they arrived in Pará, on December 12th, 1639 “after having transpass- ed the mountains which feed the beginning of the great river, and having travelled on its waves till the mouth of 80 léguas (440 km) width, after having written down with special care all what is no- table, after having determined its height and annotated the names of the affluents, having verified the peoples who live on the banks, seen the fertility and admired the re- Volume 3 (Limnologia) 13 sources, having experienced the climate, come into contact with the natives and, finally, after not having neglected what all there happened and of what they had been witnesses.” We may say that, with the chro- niclers of Pedro Teixeira’s voyage, there began the exact and objecti- ve observation, the study in a mo- dem sense, of Amazónia. Cristobal de Acuna soon starts to discuss the origin of the Ama- zon: “Some people want the Ma- ranon as source with its beginning in the Cordilleras de Guanuco de los Caballeros, 70 léguas (385 km) from the “Ciudad de los reys”, with the lake Lauricocha; other ones want the sources of the Rio Macoá and with them the Caquetá as its origin.” But this is rejected by Fa- ther Acuna, and he means that in a distance of 8 léguas (44 km) from Quito, between the moun- tains Guamamá and Pulca, there are two lakes, 20’ below the equa- tor-line, from which, in direction to the south, the Amazon has its origin. According to him, the length from the spring to the mouth into the sea is 1356 léguas castelha- nas (7458 km) , “well measured”. Running in wide curves, the ampli- tude and width are very different from 1 — 2 léguas (5,5 — 11 km) and partly much more, to 80 lé- guas (440 km) in the mouth. The narrowest place has a little more than 1/4 léguas (1,4 km), at 2 2/3° S and 360 léguas (1980 km) from the “lake” (what probably must be taken for the sea). — From the mouth to the Rio Negro, in a distance of almost 600 léguas (3300 km) , the main channel is always at least 30 — 40 braças (50 — 65 m) deep; at some places one does not find any ground. Abo- ve the Rio Negro the depth varies among 20, 12, well above 8 braças (35; 20; 13 m), but it is always deep enough for boats. There are innumerous islands, commonly of 4 — 5 léguas (22 — 28 km) , other ones of 10 and 20 léguas (55 and 110 km) etc., and there are also many very small ones, which serve the natives for the plantations while on the larger ones, they have their settlings. “These small ones, sometimes also the greater islands or a great part of them are inun- dated every year by the river which fertilizes them in this way with its mud so that they can never be call- ed sterile even if there is claimed from them the same production of corn and mandioca in many sub- sequent years.” There are many fishes “which the natives catch with incredible abundance every day in the river. King of all fishes, however, and by which the whole river from the source to the mouth is inhabited, is the “Peixe boi” (“ox-fish”), 14 Atas do Simpósio sôbre a Biota Amazônica which has only the name of a fish, for there is nobody who, eating it, does not think it to be real meat. It is of the same size like a 1 1/2 years old calf and, if it had horns and ears, its head would not differ from a calf’s one. Its whole body is covered with rather short hairs like soft bristles, and it moves in the water with two short arms, which, looking like shovels, serve it for sculls. Under these “arms” the female has its teats, which it gives to the young ones, it has born. The warriors make so strong shields of the very thick leather that, if the leather is well curried, no bullet can perforate them. This fish lives only on herbs, which it grazes like a real ox, and thus its meat gets so highly nutritious and has such a good taste that a man becomes more satisfied and strong- er by a small amount of it than by double the quantity of goat- meat. It cannot stay under water for a long time, and so it lifts its snout out of the water for taking breath, wherever it is swimming. And thus this fish promotes its to- tal extermination, because it ena- bles its own enemy to find it very quickly; the Indians become aware of the animal and follow it in small canoes, waiting that it will lift its head out of the water, in order to draw a deap breath, and then they kill it with their har- poons which they make of muss- els.” This description of the manati is very exact, and till Alfred Russel Wallace, who, in 1848 — 1852 made a voyage on the Amazon and the Rio Negro, there was nobody to excel it. The number of water-turtles must have been enormous at that time: “They (the Indians) catch these turtles in such a quantity that there is not even one of those fences” (in which the Indians store the turtles alive) “which would not contain turtles in a number from 100 upward”. Acuna describes also Indian fish- ing methods, as fishing with tim- bó, or harpooning with arrows, equipped with a swimmer, which they throw with their hands. In- teresting is his description of the electric eel: “Many fishes have spe- cial pecularities, e, g. one, the In- dians call Peraque, has the shape of an enormous eel or better of a small Conger. And the one who touches this fish, begins to tremble all over like attacked by shivers of Malaria, and it lasts as long as there is a contact between the fish and this person, stopping immedia- tely when loosing the fish.” Naturally, since it was one of the main interests of his time, Acuna speaks of enormous riches in gold, “for all rivers and springs etc., which run from the Andes to Volume 3 (Limnologia) 15 the Amazon at a stretch of 600 lé- guas (3300 km), come from areas which are the richest in silver and gold on earth.” After him, the climate is “tem- perate”, and the winter is not caus- ed by changes in the position of the planets and the sun, which ri- ses and sets always at the same hour, but by floods which impede agriculture and the harvesting of fruits of the earth for some months. There are no “rotten airs”, and “if there were no plagues of mosquitos which in many zones are so innumerous, one could call the river at the top of one’s voice an enlarged paradise.” In his narrative he gives a cir- cumference of 4000 léguas (22000 km) to the whole Amazon Region, and his report contains many details about the affluents of the Amazon, and the Rio Negro called his great interest. At the mouth it is 1 1/2 léguas wide (8,25 km) . Its black water fills half the width of the bed of the Ama- zon and accompanies it for more than 12 léguas (66 km) where one can clearly distinguish between the water of the Amazon and the one of the Rio Negro, till it is mixed up into the turbid water of the Amazon. Here we also find the first mention of the connexion with the Orinoco, the famous anastomose through the Cassiquiare: “One arm which that river” (the Rio Ne- gro) “sends out through which, after informations, one comes out in the Rio Grande in the mouth of which, in the northern ocean, are the Dutch . . . This Rio Grande should be the Rio Doce or more probably, the Rio Felipe, but Acuna affirms intensi- vely that it is not the Orinoco. The other chronicler of Pedro Teixei- ra^ expedition, Alonso de Rojas, however, has a different opinion, and he writes that “there are peo- ple who think this river to be the famous Orinoco.” Acuna and Rojas have been unanimous that the rivers and the whole country are very rich, that the soils are very good ones, that there are many nations of “bárba- ros”, and that all together is by far larger and richer than whole Peru. This opinion of infinite riches, has not yet died out completely, and it has only been corrected by sci- entific studies in the last few de- cades. May be that their reports contain some intentionally added political influence, because Acuna was a Spaniard and the lower Ama- zon belonged to Portugal while both nations were interested in the still unoccupied western part of Amazónia. Rojas even beats Acuna in his enthusiastic description of the splendor and the riches of the country: “The discoverers of the Amazon maintain that its campos seem to be paradises, its islands 16 Atas do Simpósio sôbre a Biota Amazônica gardens, and that, if art would sup- port the fertility of the soil, these parts would be well treated paradi- ses and gardens. . “The river is abounding in fishes, the moun- tains are extremely rich in game, the air is overabundant in birds, the trees are full of fruits, the campos give very rich crops, and the earth is full of mines.” And he tells of an enormous number of In- dians — who, later on, after the conquista, diminished very rapidly so that Antônio Vieira writes in the 17th century that, within 30 years, more than 2 millions of the Indians on the lower Amazon and on the coast till São Luís do Maranhão were killed . . . This circumstance does not be- long to our theme, but I had found it in the old reports and I did not want to withhold it from you, be- cause there may be some ecological background in the fact that in the following time during the Europe- an occupation and introduction of European methods of treatment of the land, of agriculture, of exploi- tation of the nature etc., the num- ber of the neo-Brazilian and the surviving Indian population always remained extremely low and even today it does not exceed two mil- lions in the whole States of Ama- zonas and Pará and the Territories of Roraima, Rondônia and Amapá together, i. e. in an area of more than 2 1/2 million square-kilome- ters . . . As already mentioned, all main points of posterior studies of Ama- zonian waters are already touched in the reports on Pedro Teixeira’s expedition, written by Acuna and Rojas, as e. g.: Cartography and Hydrography (map by the pilot of the fleet and descriptions of a great number of affluents); River anastcmoses (first men- tion of the connexion with the Orinoco) ; Mcrphology of the Rivers (width and depth) ; River-types (black-water of the Rio Negro) ; Rôle of the Várzea (fertility by annual flooding) ; Nutriment-household and Eco- logy of the whole Region (“ve- ry good” soils anywhere, num- ber of native population). To continue the history of stu- dies of Amazonian waters, it is now more instructive not to report simply in a chronicle sequence, but to follow up the development of each of those different topics. After the first map of the Ama- zon according to the pilot of Pe- dro Teixeira’s fleet, which contain- ed the course of the Amazon itself and the mouths of many of its tributaries, it is only natural that the most intelligent and broad- Volume 3 (Limnologia) 17 minded among the early missiona- ries and travellers tried their best to contribute to a more exact and more complete knowledge of the big river-system. One of the next original and fa- mous maps of that time, in fact the 5th map of the Amazon at all, was the one by Pater Samuel Fritz, S. J., of the year 1691. Further on, not only the mis- sions, but also the governmental authorities were more and more in- terested in better maps of our re- gion, and there appeared maps, not only from the main river with more details, but also from some affluents. When in 1743/44 Charles Maria de la Condamine, who had been sent to the equatorial region of South America for measuring the first 3 degrees of a meridian, came down the Amazon from Quito to Pará, he designed a map of the Amazon too, and so did other tra- vellers of that period. The know- ledge of the immense Amazonian river-system grew more and more, and also in Europe there were printed new maps of that region, but it shall not be said that each new map, which appeared, signi- fied a progress. So it happened that, for giving their maps a more impressive and more complete ap- pearance, the designers also mixed fantasy into the known facts which were not too numerous. Also the voyages of the first scientific explorers of Amazónia did not too much to improve the cartography of our region. The travellers described, often excell- ently, the geographical conditions the flora etc., corresponding to their special interests and know- ledges, but new measurements of the rivers were very scarce. A systematic mapping of the af- fluents of the Amazon started only in the second half of the last cen- tury, when some of the scientific travellers dedicated a good part of their time and energy during their trips to this purpose. The common method, they used, was the survey by the help of a watch and a com- pass when they travelled in boats on the rivers. I cite here only the excellent map of the Rio Xingu, made by Dr. O. Clauss on the oc- casion of the ethnological expedi- tion of Karl von den Steinen; it contains exact geographical coor- dinates for many points, indiea- tions of the width of the river, wherever possible, and even some perfiles of the river-bed. Perhaps the most important pro- gress in the knowledge of the cour- ses of a good deal of tributaries to the lower Amazon was achieved by the French explorer, Henri Anato- le Coudreau and his wife, Olga Coudreau, who, after having lived and worked in the Guianas for mo- re than 10 years, began to explore 2 — 37 121 18 Atas do Simpósio sôbre a Biota Amazônica systematically those rivers in the last decade of the 19th century. Henri Coudreau visited first the Southern affluents Tapajós, Xingu and Tocantins — Araguaya, then he turned to the northern side, to the Yamundá and the Trombetas, where he died at the end of 1899. After his death, Olga Coudreau continued the work of her hus- band, travelling to the Rio Cumi- ná, Curuá, Mapuera, Maycuru and finally to the Rio Canumã. The re- sults were always published with the corresponding maps in a series of books. Naturally, also some captains or pilots of the river-steamers, who, during the famous “golden rubber time” penetrated the Amazonian interior as far as possible, had drawn maps of their rivers: as an example I am going to show you a map of the upper Rio Juruá, designed by Comandante Hilliges from the little steamer “Marapa- tá”. One other important map, we must not forget, is the one of a cer- tain part of the lower Amazon, ma- de by Paul Le Cointe, because it did not restrict itself only to the very bed of the river but it inclu- ded the environment of that sec- tion of the Amazon, too : all the pa- ranás (side-arms) and the shore- lagoons, the Várzea-lakes, and also the edges of the terra firme to- wards the wide valley of the Ama- zon are indicated in that map. For the first time one could get now an idea of the morphology of the valley of the lower Amazon, which was formed by the activity of the river with its erosion and se- dimentation in seasonal floods and drier periods. Finally, all what was known about the topography of the river- courses and about the Hydrogra- phy of the whole Amazon system found its expression partly in out- line maps, compiled in different countries, partly in special maps of single rivers, the best of them being collected and published in a now classical book “Hydrographia do Amazonas e seus afluentes” by Augusto Octaviano Pinto in 1930. The first volume contains the most detailed descriptions of all Amazo- nian rivers, while the second vol- ume is a collection of the best ri- ver maps of those years. All these maps, made with rela- tively rough methods, were, of course, however, subject to many omissions and inaccuracies, which could not be avoided by the lack of well-determined coordinates, and because of the impossibility to establish a triangulation system over a jungle-covered flat area of some million of square kilometers. This situation changed, when, during the last war, the United States Air Force started to make the first aerial photographic map- Volume 3 (Limnologia) 19 ping of the lower Amazon and parts of the courses of some tribu- taries, an enterprise, which was la- ter on continued by Brazilian ins- titutions as the Petrobrás etc. A great part of Amazónia is now mapped in this way, and since about two decades, we have now really authentic maps with the exact courses of the rivers, of al- ways greater areas of this large country shown e. g. in the Atlas do Brasil 1:1 000 000 of the Ins- tituto Brasileiro de Geografia e Es- tatística, or also in the World Ae- ronautical Chart, also 1 : 1 000 000, edited by USAF. By the use of ae- rial photographs, the former dif- ficulties of mapping the Amazo- nian rivers were overcome, and the history of Amazonian river carto- graphy has come to an end. The substratum for the “Studies in Amazonian Waters” was known, and new problems carne into the centre of interests. Only one principal difficulty still remains, namely the presentation of the extension of the Várzea-la- kes of the Amazon, because they shrink considerably in the dry sea- son while, in the rainy season, the water of the flood of the river co- vers many times the whole valley of the lower Amazon between the two edges of the “terra firme”. And one other feature, which is highly desirable, is not yet indicat- ed in these maps, i.e. these edges themselves of the terra firme to the Várzea filled valley of the Amazon, and eventual “islands” of terra fir- me within the same among the re- cent river alluvions of the Várzea. But these details do not belong any more to a cartographic repre- sentation of strictly only the river courses, being of greatest impor- tance, however, for an understand- ing of the morphology and the development in recent-geological periods, of the valley of the Ama- zon. For those, who want to study in detail the history of Amazonian cartography a recently published descriptive catalogue “A Carto- grafia da Região Amazônica” by Isa Adonias, which lists all maps of this country, published between 1500 and 1960, is highly recom- mended. The geomorphological problems of the Amazonian rivers have been detected in their significance for an understanding of the develop- ment of the surface of Amazônia to its present structure, only in re- latively recent times. One excep- tion are the river anastomoses which exist in South America among different river-nets and which are treated first and very intensively by Alexander von Humboldt in his “Voyage aux ré- gions équinoxiales du nouveau continent”. It is a famous fact that he was the first civilized per- 20 Atas do Simpósio sôbre a Biota Amazônica son to prove such a connexion, that between the Orinoco and the Ama- zon system by the Cassiquiare, by passing it in May 1804; Humboldt, however, is not the discoverer of it: Acuha already, as we heard, had notice about it, and it also appear- ed in maps of the year of 1778. And Humboldt himself writes that the President of the Mission in San Fernando de Atabapo had given him the route, he had to follow from the Orinoco through small blackwater rivers and finally by bringing the canoe over a strip of land of only 4000 toises (7,8 km) of length to the Cano Pimichin which leads to the Rio Negro, and then back to the Orinoco through the Cassiquiare. Humboldt follow- ed this way and writes: “On the first stretch on the course from east to west, it” (the Orinoco) “forms the famous bifurcation which has been denied by the geo- graphers so many times and the position of which I was the first to be able to determine by astrono- mical observations...” Humboldt also describes two further conne- xions between these two river Sys- tems, namely one arm of the Cassi- quiare, which under the names of Itinivini and Conorichite brings “white” water of the Cassiquiare into the Rio Negro, and another one from the Rio Negro up the Ca- baburi (= Cauaburi) to the Baria and down this river into the Cassi- quiare. The geomorphological im- plications of these river-connexions were finally discussed by Gourou in 1950. In this century, Jaguaribe de Matos has occupied himself with the studies of the connexions of the Amazon system with other river systems in South America. He found that there are such anasto- moses — besides those, described by Humboldt — between the Ja- purá and the Magdalena, the Uau- pés and the Guaviare, the Gainía and the Inírida, within the net of the Rio Branco, between the Ma- puera and the Essequibo, and in the south between the Guaporé and the Paraguai, the Tapajós and the Paraguai, this last one in the centre in South America. All these anastomoses are, however, very small and shallow, except the one between the Guaporé and the Pa- raguai, which is a bit deeper in the rainy season. — But even small boats are not able to navigate on them. The connexions among different rivers show that the relief of the surface of the earth in our region must be old, that it must have been strongly levelled while no impor- tant catastrophic geological events must have happened here for a long period. All intense geological activity in South America is con- centrated on the range of the An- Volume 3 (Limnologia) 21 Fig. 1 — Aerial photograph showing the rectangular structure of the earth’ surface in Amazónia. Fig. 2 — Delta of the Rio Branco into the Rio Negro (phot. Sioli). des, which is in steady movement, while the rest of the continent re- mains relatively calm, i. e. without any volcanic activity, without any remarkable uplift or sinking of the crust of the earth; so far as we know, even no stronger earthquake was reported in all eastern parts SciELO cm 10 11 12 13 14 15 22 Atas do Simpósio sôbre a Biota Amazônica of South America during the whole period of European colonization. Besides this interest for geomor- phology, the anastomoses among so many South American river Sys- tems are of importance for zoogeo- graphical studies, because they enable also the purely aquatic fau- na to penetrate from one river-net into the other ones. An observation concerning the phenomenon of river-anastomoses, as considered in respect to the geo- morphological viewpoints and the development of the network of the river-courses, was only made by Sternberg less than two decades ago. As we said, there had not hap- pened any great or, still less, catas- trophic movements of the earth’s crust, but there were tectonic, pro- bably eustatic movements even in recent times, by which a strong fracturation was caused. This frac- turation, also proved by recent geophysical prospections, which were made by Petrobrás, broke the earth’s crust into pieces of more or less rectangular shape and gave it a structuration, which deter- mined strongly the general direc- tions of the river courses. Stern- berg reconstructed the fractures in a map by following the orientation of the main stretches of the river courses. The result, shown in Sternberg’s map, may seem a bit theoretical or even arbitrary, but I think the last doubts will disappear when regarding an aerial photo- graph, made somewhere in the vi- cinity of Manaus, which can be bought as a postcard in Manaus (Fig 1). In this picture one can clearly distinguish that this struc- turation consists of a system of li- nes, Crossing each other rectangu- larly. Another phenomenon of Amazo- nian river morphology, linked with geomorphological peculiarities of our region and with hydrological features of Amazonian rivers, e.g. currents and sediment load, is the formation of internai deltas, which was first discussed by Humboldt. We find such “deltas of affluents” or “deltas of confluency”, e.g. at the mouth of the Japurá into the Solimões, of the Rio Branco into the Rio Negro (Fig. 2), or at the Southern end of the Estreitos de Breves into the Rio Pará (Fig. 3). That region of the Estreitos de Breves and its current conditions were described by Hartt, 1897/98 and especially by Huber, 1903; and Tastevin reported on the delta of the Japurá in 1929. The most re- cent study on Amazonian internai deltas is the one of Gilberto Osó- rio de Andrade. These deltas occur when the affluent of so-called “white water”, has a heavy sedi- ment load, and when the collector- river cannot remove the added load, because of general or local current conditions, so that this Volume 3 ( Limnologia) 23 Fig. 3 — Internai delta of the “Estreitos de Breves” into the Rio Pará (From: Preliminary Map, Amazon Delta, 1 : 500 000, 1943). load is accumulated near the mouth of the affluent, dividing it into many arms and having it grown, so that the affluent reaches out into the bed of the collector- river. The most striking feature of many Amazonian clear-and black- water rivers, however, is the shape of their lower courses, their “mou- th-bays”. The river water covers there enormous areas, the width of which is, at all, in no proportion to the sizes and the discharge of the upper courses. The shores ge- nerally consist of pure white sand- beaches behind of which rises the terra firme, often in form of cliffs of different heights. The shore-li- ne is neither more or less streight, nor consisting of alternating stret- ches of erosion and sedimentation banks, but it is jagged and, seen from above (Fig. 4) the whole ri- ver section looks like an artificial reservoir. Even where such a river 24 Atas do Simpósio sôbre a Biota Amazônica Fig. 4 — Rio Arapiuns, lower course with the shape of an artificial reservoir (phot. Sioli). is meandering, as in Fig. 5, the meanders are those of a valley, not of a river-bed. Such a morphology of lower courses cannot have been elaborat- ed by the respective rivers under their actual conditions, with their practically stagnant water in the mouthbays; they can only be un- derstood as “drowned valleys” what was pointed out first by De- nis, 1927, interpreted them as true freshwater rias. The cause of this drowning of Amazonian river val- leys, which is observed up to the affluents of the middle Solimões, where we still find large mouth- “lakes” as that of Coari, Tefé etc., can easily be deduced from the known rising of the ocean levei af- ter the glacial period. If, besides that fact, a regional sinking of the continent crust must be taken into consideration, is not easy to pro- ve. That there must have happened some up- and/or downward move- ments of the earth’s surface can be seen from the fact, that in the region between the lower Tapajós and the lower Xingu the affluents of the Amazon have no mouthbays, while east and west of that zone we find those typical drowned val- leys. cm l SciELO Volume 3 (Limnologia) 25 All these affluents with such mouthbays obey in their courses one typical scheme (Fig. 6) . After a “normal” upper course, commonly in the arquean comple- xes of granites and gneisses of Cen- tral Brazil or of the Guianas, and after passing the strips of paleo- zoic marine sediments and of dia- base eruptions, the rivers reach the Amazonian depression, filled with the relatively soft sediments of the terciary freshwater inland lake, the so-called “series of the barreiras”. Here the river valleys suddenly widen, but their first sec- tion is filled with many, generally elongated, islands, built up by re- cent river alluvions. Only after pas- sing that “sedimentation zone” in which by the slowing down of the current in the widened bed, they deposit their sediment load, the ri- vers reach the open mouthbays. The water is now decanted, very transparent, and, stretching out over an enormous perfile of the ri- ver bed, it looses its current almost completely. Side erosion is caused only by the activity of the waves, which attack the cliff of terra fir- me during the highwater season, thus enlarging the river bed still more. But there is no depth eró- sion, on the contrary, bottom-sam- ples and eco-soundings in the lo- wer course of the Rio Arapiuns, e. g. revealed a layer of very soft, Fig. 5 — Rio Arapiuns, meanders of the drowned valley (phot. Sioli) . SciELO cm _0 11 12 13 14 15 16 26 Atas do Simpósio sôbre a Biota Amazônica — UPPER COURSE -- 1 | LOWER COURSE Sedimentation-zone with Formation of Mouth-bay with open Water Fig. 6 — Scheme of the Imoer courses of Amazonian affluents. muddy and fine sediments, 3 — 4 m thick (Fig. 7) typical for laises, and which cannat be ac- cumulated under the flowing wa- ter of rivers. Also phytoplankton develops in the open water of mouthbays, even in such quantities as to form waterbloom. So, the lower sections of these Amazonian tributaries, their “mouthbays”, must limnologically be considered more as lakes than as rivers. The best term will certainly be that of “Amazonian river-lakes”. In the literature (Le Cointe, 1954, de O. Andrade, 1958, de C. Soares, 1959) these mouthbays, the sec- tions of drowned valleys of Ama- zonian affluents, are also called “lagos de terra firme”, “terra fir- me-lakes” (contrary to the “lagos de Várzea”, “Várzea-lakes”) , name- ly because of their opening into a white-water river, where the sedi- ments of that turbid, suspension- rich water have blocked by deposi- tion of fresh alluvial lands the ori- ginally widely opened funnel- cm i SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 27 -i..— - .... .. — ■ — I ' .Ml M I . - 33 - - 20 - a ~ — S 69 b -eo- - 120 - b - 45 - 70 -Í0- - 75 - .t50~— — — - 75 * Fig. 7 — Echograms of the lower Rio Arapiuns, showing the layers of soft “lake” - sediments. mouths, letting only a narrow channel as an outlet for water of the tributaiy. Also the valley of the Amazon itself, where does not be such a great, open and more or less stag- nant water area as in the descri- bed affluents, must be understood as an originally “drowned valley”. The clear- and black-water rivers brought so little amounts of sus- pended particles with their water that they built up with these par- ticles in the lower courses, after the drowning of them, only a more or less restricted sedimentation zone which is still growing, by conti- nuing sedimentation, in direction to the river mouth but which has not yet reached it. The Amazon, however, is a turbid “white water” river, i. e. its water contains a grea- ter quantity of suspensoids (50 — 150 mg/l), and by deposition of this material it has completed, sin- ce a long time, the filling of its wide drowned valley with its own recent alluvions, which now form the “Várzea”, the floodlands of that river. And not enough that the whole drowned valley has been occupied by the “sedimentation zone”, not letting any space for wide and open mouthbays as in the case of clear- and black-water ri- vers, the river alluvions of the Amazon have been accumulated even outside its mouth into the ocean, along the Guiana coast, where the Amazon water is con- ducted along the continent shore by the Brazil-Current of the Atlan- tic Ocean. There they are extended in front of the terra firme as a strip of swampy, floodable land, a con- tinuation of the lower Amazonian Várzea, in a width of up to more or less 80 km and reaching to French Guiana. cm l SciELO _0 11 12 13 14 15 16 28 Atas do Simpósio sobre a Biota Amazônica Related to the phenomenon of the drowned valleys is the great depth, found in some places in the bed of the lower Amazon. Spix & Martius were the first to measure the depth in the gorge of this ri- ver at Óbidos, where they found 83 m. The recent eco-soundings of the American group (U. S. Depart- ment of the Interior Geological Survey Information Office, 1964) in the lower Amazon found several, at least 10 places with a depth of 90 and more meters. But if the “mouthbays” of affluents are in- deed drowned valleys, it may be possible that there also persist great depths and that the original bottom of the riverbed may be ma- intained, if no products of side-ero- sion or deposition of “lake-sedi- ments” filled it up in the meanti- me. Really, a sounding, made by hand with a line in the Rio Negro below Manaus, south of the island Marapatá, where the river is so wide that there was no notable current, indicated a depth of . . . . 102 m. And later eco-soundings re- vealed the perfile of the ancient river on that place as a deep, al- most canon-like valley, as shown in Fig. 8 (Sioli, unpublished) . The morphological peculiarities of Amazonian rivers which we de- scribed and interpreted — except that of the river courses along frac- ture lines — are consequences of Ri A/ * Sv CAREIRO Fig. 8 — Echograms of the Rio Negro, indicating a greatest depth of around 100 m. cm l SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) the flatness of the country, the very small gradient of the rivers in it (the Amazon having only *« 1 cm/l km between the mouth of the Rio Negro and the ocean) and the very ancient and “old” i. e. levelled relief of the country, even in many headwater regions. In spite of that small gradient, the current speed of the Amazon is really high, varying in the lower Amazon in an average of 1 to 2 mi- les per hour ( J / 2 — 1 m/sec.) in the dry season, and 2 to 4 miles per hour (1 — 2 m/sec.) in the flood season. This high current speed at a given gradient naturally depends on the relation: water quantity/ friction on the surface of the river- bed, or: perfile through the river- bed/contact-line of the water with the bedground. The greater the water .quantity, flowing down the river, the smaller is, relatively, the friction-zone between the running water and the surface of the ri- verbed. How much water, now, is flowing down the Amazon? The discharge of the Amazon was, till very recent years, only es- timated but not exactly deter- mined. The first estimate, however, made by Katzer (1897), which un- fortunately, has almost been for- gotten and is not mentioned in mo- dem literature treating especially this question, has been astonish- ingly precise. Katzer found that the discharge of the Amazon into the ocean is around 120 000 m 3 /sec. in the dry season, an amount which might be multi- plied in the highwater season. Par- dé (1936), basing on calculations about rainfalls, evaporation etc. carne to much smaller amounts, namely only 90 000 — 110 000 m 3 / sec. as annual average. But final- ly, the recent determinations with most exact methods, made by that American group (U. S. Department of the Interior Geological Survey, 1964; Oltman, 0’R. Sternberg, Ames & Davis, 1964; Sternberg & Pardé, 1965) gave as result an ave- rage of 218 000 m 3 /sec. all over the year, a figure, which could not bet- ter confirm the indication of Kat- zer/ This means that the Amazon is by far the mightiest river of the world, having 5 times the water of the Congo and 12 times of the Mis- sissippi, and carrying 15 to 20% of the water which all rivers of the world together conduct into the oceans. Corresponding to that mass of water is the extension of the estuary of the Amazon, where Orellana and his chronicler Car- vajal aldready admired the width of the mouthfunnel. Special studies about currents in and displacement of the mixing zone of fresh and sea-water and of other limnolo- gical conditions in the estuarine section of the Amazon were made by Egler & Schwassmann (1962, 1964). cm l SciELO _0 11 12 13 14 15 16 30 Atas do Simpósio sôbre a Biota Amazônica The enormous mass of water of the Amazon, running down the wide and deep riverbed with strong current, does not carry in its tur- bid “white” water only a certain amount of suspended particles, but it also moves the bed load on its bottom, the quantity of which can- not yet be determined. It appears in sandbanks, which change their height and position by the shifting of the movable material. Where it wanders, however, on the bottom of the riverbed, it forms gigantic “ripplemarks”, true sanddunes of up to 190 m length and 8 m height Fig. 9 — Giant “ripplemarks” (sand dunes) on the bottom of the Amazon heleno the confluence zoith the Rio Negro. Echogram of a longitudinal section of the riverbed. Volume 3 (Limnologia) 31 as to be seen in Fig. 9 which shows a longitudinal perfile, taken by eco-sounding of the Amazon below the mouth of the Rio Negro (Sioli, 1965). We spoke already of turbid “whi- te” water, of clear water and of black water rivers, and with these expressions we mentioned the clas- sical river types of Amazônia. We also heard above what Carvajal had written about the black water of the Rio Negro, when Orellana and his men had seen it first, and how Acuna and Rojas had describ- ed that strange water, too. The first scientist to discuss the pheno- menon of blackwater rivers was, however, Alexander von Hum- boldt, who did not only describe the appearance of such rivers, to- gether with some biological pe- culiarities of them as e. g. lack in crocodiles ( Caiman spp.) and in black-flies (Simulidae) , and who cited the opinion of the people that these black waters do not turn the stones brown and that white rivers have black, black rivers have white shores, but who asked alrea- dy for the origin and the reasons for that black water! He writes (Humboldt, 1. c., vol. 3, pp 264-266) : “In the widely extense river-system that we travelled — and this circumstance seems to me very striking — the black waters occur preferably only in the stretch near the equator . . . ; but in that whole area, white and black wa- ters occur in the forests and on the savannahs simultaneously one near the other, in a form that one does not know to what cir- cumstance one shall contribute the coloration of the water . . . If one asks the Indians about the reasons for this strange coloration, their answer is, . . . : they repeat the fact in other words. If one address- es oneself to the missionaries, they speak as if they had the severest proofs for their conjecture, “the water colours when it runs over the roots of Sarsaparille”. The Smi- laceae are, indeed, very common ut the Rio Negro, Pacimony and Ca- babury, and their roots give, soak- ed in water, a brown, bitter, sli- my extractable mater; but how many Smilax - bushes have we seen at places, where the waters are completely white! How is it possi- ble that in the swampy forest through which we had to carry our pirogue from the Rio Tuamini to the Cano Pimichin and to the Rio Negro, we waded through the same stretch of land, now through creeks with white, now through other ones with black water? . . . Very near the equator, indeed, the vegetation is, because of the quan- tity of rains, stronger than 8 — 10 degrees to the north and to the south; but in no way it can be maintained that the rivers with black water have their origin pre- cm l SciELO _0 11 12 13 14 15 16 32 Atas do Simpósio sobre a Biota Amazônica ferably in the most dense and sha- dowy forest. On the contrary, very many “águas negras” come from the open grasslands which extend from the Meta on the other side of the Guaviare to the Caquetá. . . . The colour derives, without any doubt, from coaled hydrogen. One can observe a corresponding ap- pearance on the manure-water which our gardeners prepare, and on the water which flows out of peat-pits. Cannot, after this, be as- sumed, that also the black ri- vers . . . are coloured by a com- pound of carbon and hydrogen, by a plant-extract-matter? . . . The co- louring matter seems to be in very small amounts in the water; for, boiling water from the Guinia or the Rio Negro, I di not see that it turned brown like other liquids which contain much hydrocar- bon”. At the times of Humboldt and later on, one distinguished only two types of Amazonian rivers: white and black ones. But we have in fact three different types (Sio- Li, 1951, 1964), namely Rivers with turbid yellowish, so-called “white” water, with a transparency between 10 and 60 cm, as the Amazon, Rio Madeira, Rio Branco; rivers with more transparent water of yellowish to green and olive-green colour and a transparency between 60 cm and 4 m, to be called “clear” water rivers, as the Tapajós, the Xingu and the majority of small creeks in the terra fir- me high forest; rivers with transparent but olive-brown to darker even reddish-brown water, looking like black coffee in the river bed, in a glass like weak tea, with a transparency of 1 — 2m, so-called black-water ri- vers (as described above), as the Rio Negro (the “classic” black water river) , Rio Cururu, and certain creeks coming from areas with a special ve- getation which grows on a certain soil type . These three types of running waters in Amazônia result from characteristic landscapes, i. e. from the geomorphological and/or mi- neralogical-pedological conditions in the headwater areas. White waters are bound to more or less mountainous terrain in the region of their origin, with an ir- regular relief, where erosion fur- nishes the sediment load of the wa- ter (mainly the Andes or their foot-hills, or also the Parima-sys- tem on the Venezuelan border) . Clear water rivers have their catchment areas in the less rugged, really strongly flat reliefs of the old massives of Central Brazil and cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 33 the Guianas, or in the terciary se- diments of the Amazonian terra firme plains, with their characte- ristic brown loam soils. The black water rivers come equally from very flat regions; the Rio Negro, for example, rises on a very old peneplain. That is the rea- son for the little contents of sus- pended matter, but not for the brown colour of those waters. As shown above, Humboldt already discussed the origin of that brown colour. One thought also that the colour had its origin in the decay- ing organic matter of the flooded jungle, of the so-called igapó-fo- rests. This possibility has not been refuted nor proved — , but it could be shown (Sioli, 1954a, 1955b) that the black water is coloured by dissolved or colloidal humus sub- stances which are linked with a special soil type, namely, bleached white sands, covered by a special vegetation, the caatinga-forest of the upper Rio Negro, the “campi- nas” near Manaus and certain “campos” as e. g. around the Rio Cururu. These bleached sands re- vealed themselves as tropical low- land podsols, first indicated by Chemical analyses of the black waters, later proved by pedological investigations (Sioli & Klinge 1961, Klinge 1965). As we see, there are physical fac- tors (relief) as well as Chemical ones (soils) in the headwater re- gions which create the types of running waters in Amazónia. And we can make even a scheme of the combinations of the physical and Chemical factors which are neces- sary for the formation of the river types: TABLE 1 Factors of the headwater zones which determine the types of Amazonian rivers Mountain-slopes (as primary supplier of the suspended matter) + Even relief of the earth’s surface Podzol soils (as supplier of the eolouring humus substances) Other soils White waters + — — + Clear waters + — + Black waters + + Such a connexion respectively exclusion also clarifies the pheno- hienon that black waters are very uniform in regard to their chem- isms, that also white waters do not Show too great divergences, at 37 121 cm l SciELO 10 11 12 13 14 15 16 34 Atas do Simpósio sôbre a Biota Amazônica least in the pH values, but that clear waters present the very great- est differences in pH and in the crntents of inorganic ions: black waters: pH 3.8 — 4.9 white waters: pH 6.2 — 7.2 clear waters: pH 4.5 — 7.8 The lower pH-values (around 4.5) of the clear waters occur in creeks in the region of the “Série das barreiras”, a bit higher ones (around 5) in creeks of the ar- quean granite-zones of the upper Rio Negro, while the great clear water rivers have pH 6 to 6.7. The highest pH-values are found in the strips of carboniferous origin north and south of the lower Amazon, with occurrences of limestone and gypsite-deposits. Already this spread of the pH-values and the distribution of the clear waters over the most different geological zones of Amazônia show that the clear waters are only a collective name of chemically (and biologi- cally) very heterogenous waters and that they possess only the scarcity of suspended matter as coramon characteristic. The described river types are not always clearly distinct from each other. In nature we find transi- tions of all degrees between white waters and clear waters, and bet- ween clear waters and black wa- ters. Also one and the same ri- ver sometimes can change its “type” periodically or occasionally with the seasons or even with ev- ery single rainfall. Much less than a lake, a river is determined in its characteristics by its own, internai laws, being only a product of its surrounding landscape, mainly in the headwater zone, its water is chemically spoken the “urine of the landscape”. Thus, we now see that the river types are not abs- tractions, “ideas” of rivers, but more or less rough descriptions of sections of the framework of causes and effects of the eco-system, which constitutes a landscape (Sioli, 1965d). Rivers, however, do not receive only their qualities from the sur- rounding landscape, they are also able to build around them their ty- pical landscape. We saw already the scheme of the course of the clear water rivers, with the “nor- mal” upper course, the sedimenta- tion zone and the mouthbays with the sandbeaches. Also the Amazon, as greatest white water river, has built its ri- ver landscape, a schematic cross section of which we see in Fig. 10 (Sioli, 1964b). The wide valley of the river bet- ween the terra firme slopes, carv- ed out probably during the gla- cial period and then drowned, was filled in the meantime with recent river alluvions which form the cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 35 Valley of the Amazon £ : Fluvial island O w (à Tarclary aedimenta of "Serie* of the Barreira*'* Terrain* of recent alluvions -Maximum highwater-level * Mlnlmum lowwater-level Terciary sediments of "Series of the Barreiras" Fig. 10 — Schematic cross-section through the Lower Amazon valley; height exaggerated (From: Sioli, 1964 b). flocdlands of the so-called “Vár- zea”. The Várzea is covered with a special vegetation type, different from the high forest of the shores of clear and black waters. This may be taken as an indication that the Várzea-forest is growing on soil with (Chemical or other) qualities different from the behind terra firme soils. Our schematic cross section is derived from the conditions at the lower Amazon. But the more we go up the Ama- zon, the Solimões, the more we approach the foreland of the An- des, the more vanishes the diffe- rence between Várzea and terra firme, the more the vegetations become equal . Acuna already cha- racterized the Várzea of the lower Amazon as a very fertile land, of which the Indians profit with their plantations and which is fertilize: annually by the flood of the Ama- zon which every time lets behind a new layer of fresh sediments. After Fittkau (unpublished) , the Várzea must now be understood as an extraneous element in the lower Amazonian landscape, as an appendix-like prolongation of the pre-andean strip of material which originated from the fresh, and relatively nutrient-rich pro- ducts of the weathering crust of the mountains and has been wash- ed down, by the waters, from the slopes of the Andes and deposited first near their feet, in their fore- land. From there, these “fertile” sediments had been transported down the white water rivers where they were deposited and eroded on the way probably several times be- fore they built the Várzea of the cm l SciELO 10 11 12 13 14 15 16 36 Atas do Simpósio sôbre a Biota Amazônica lower Amazon, from where they will finally be taken to the ocean. Perhaps the most important chapter of the studies in Amazo- nian waters is that of the chemis- try of rivers and, still more, of creeks, because it did not only reveal some peculiarities of the waters themselves — important as they are for an understanding of their biology, inclusive their rôle for the distribution and expansion of certain human diseases — but it showed relations between water chemistry and geology/mineralogy as well as pedology of the head- water areas, and finally it led to first insights into the nutrient- household of whole Amazonian landscapes, to the ecology of the rain-forest . The first Chemical analyses ever made of Amazonian waters are tho- se by Katzer by the end of the last century (Katzer, 1897, 1903) : “A short time ago, one knew almost nothing about the quality of the water of the Amazon. Only by the studies of the last time, there has been proved that the water of the giant river is, in Chemical aspect, of extraordinary purity. The same is true, partly in still higher de- gree, for its affluents as far as they were analysed for this purpose so that, indeed, the rivers and stre- ams of lower Amazônia belong to the purest waters of the world.” And, after Katzer, the waters of many springs and the ground wa- ter in the lower Amazon region are of the same quality. During the last 20 years this statement has been confirmed by a lot of Chemical analyses of wa- ters from many parts of Brazilian Amazônia, from the Zona Bragan- tina, east of Belém, to Benjamim Constant at the Peruvian border, and from the Southern limit of the Hylaea near the upper Tapajós Ri- ver to the Campos of Rio Branco and the frontier-mountains of Ve- nezuela in the north. While the wa- ter of the main river, the Amazon itself, is already extremely poor in its ionic content, as Katzer and later determinations showed, the same condition is true in a still higher degree in most parts of Amazônia, where the natural waters may be compared best with “a little bit contaminated distilled water”. In the area of the so-called ‘‘Series of the barreiras”, i. e. of the terciary (pliocene to pleistoce- ne) deposits of the then enormous Amazonian freshwater-inlandlake, in the arquean complexes of Cen- tral Brazil and of the Guianas, with their granitic gneissic rocks, in the zone of cretaceous (?) sandstones around the Rio Cururu (near the Serra do Cachimbo) , the waters of the creeks and springs and of eventual lakes are all of that quality and of surprisingly cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 37 low pH-values. But we have also some other regions in Amazônia, where the waters are not so poor and acid, even if these zones are of relatively small extent in lower Amazônia, namely restricting themselves to the narrow strips of carboniferous marine sediments, with limestone and gypsite depos- its, north and south of the lower Amazon, to the “islands” of dia- base eruptions, and to the area of a miocene sea-transgression in the Zona Bragantina, east of Belém — Pará, the so-called Formation Pirabas. TABLE 2 Chemistry of Amazonian Waters pH 4.2 — 5.5 4.0 — 6.6 5.2 — 7.8 HCCVmval/l 0.00 — 0.04 0— 0.174 0.026— 6 311 Ca" mg/l 0 1-5 0— 18.4 2.6 —204 Mg" mg/l 0— 0.38 0— 5.6 — Na' mg/l 0.847 — 2.530 0.245— 2.060 — K' mg/l Li' mg/l Fe" + Fe"' y/l 0.534— 1.52 0.143— 1.000 — 0 — 143 0 — 0.160 0 — 250 0 — 1.200 Mn" 7-/1 0—82 0 — 212 0—160 Al"' y/l 0 — 488 0 — 314 0 Cl' mg/l 0— 3.5 0— 2.5 0— 16.5 S0 4 " mg/l 0.000— 0.480 0— 2.690 0 — 556.7 P (PO/") 7/1 0— 50.2 0 — 110 0—42 N (NO»') 7/1 0 — +200 0— +150 0— +550 N (Kjeldahl) 7/1 138 — 724 0 — 2.620 — Si diss. mg/l + 0.5 — 4.5 0.502— 6.650 1.5 — 22.4 Table 2 shows the extreme va- lues of the results of very many wa- ter analyses of the cited regions. It is obvious that the chemistry of the waters is neatly related with the geological, i. e. mineralogical underground of the region, it co- mes from. Naturally, that had to be expected, but in Amazônia tho- se relations are surprisingly evi- dent, thanks to the large-scale geo- logical structure of our region. Ba- sed on that experience, e. g. even the delimitation of the extension of the miocene marine transgres- sion of the Formation Pirabas in the Zona Bragantina once was tried, and I think, with certain success. Where there are some lakes in Amazônia — and they are practi- cally all shore-lakes of some rivers — their water is also related to the geology of the surrounding and, naturally, via the river, of the headwater zone of the same. The limnology of such lakes was first studied by Braun (1952), more re- cently by Marlier (in press a, b). cm l SciELO 10 11 12 13 14 15 16 38 Atas do Simpósio sôbre a Biota Amazônica The most interesting example for that relation between shore-la- kes and their river and the head- water region of the same, we saw already in the Amazon itself, the Várzea of which is a landscape- strange element in lower Amazô- nia. The water of the Várzea-lakes, however, is of double quality. In part, it comes from the Amazon, when the river, with the rising flood, overflows into the lagoons where it diminishes its turbidity by decantation of the suspended par- ticles, while getting more or less stagnant; from behind, from the slopes of the terra firme, however, those várzea-lakes receive very poor, clear and acid water, which often prevent the Amazon water from reaching the terra firme shore of the várzea-lakes. A consequence of the chemically richer Amazon water, which beco- mes decanted in parts of the Vár- zea-lakes, is that the waters with the greatest primary production of phytoplankton are to be found here. In the turbid “white” water rivers, light penetration is too small for allowing an autochtho- nous high primary production; in regard to the alimentation of the biota, living in them, these rivers are dependant biotopes. I. e. they depend on the introduction of or- ganic matter, of phytoplankton from the shore-lakes and from the mouthbays of clear water rivers for the beginning of the food-chain. On the other hand, we find in the várzea-lakes the upper layer some- times thick green from water- bloom, and the pH, during the clear day, risen to almost 10 by the consumption of CO- by the photosynthetic processes of that enormous mass of algae. It is no wonder that just in and around those várzea-lakes there is also the most intensive concentra- tion of higher animal life, from fishes to enormous amounts of wa- ter birds. In the white water ri- vers, as e. g. in the Amazon, as well as in the lakes and in the sedimentation zones of great clear water rivers, we have, however, another biotope of good primary productivity. These are the floating meadows of grasses etc. which de- velop in calm river stretches and inlets on the water surface, thus being independant from the turbi- dity of the water and profiting only from the inorganic nutrients in the water through the floating roots. Also the mouthbays of great clear water rivers, as the Tapajós and the Xingu, are, as I said, places of primary production of phytoplankton. Sometimes we can there observe even waterbloom, too, but never in such a quantity as in the cleared-off Amazon water of the várzea-lakes. The limiting factor must be sought in the inor- cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 39 ganic nutrient content of those great clear water rivers, which ge- nerally come from the old massives of Central Brazil and from the Guianas, and not in scarcity of light, as is the case in the white water bodies. And where we have the acid and chemically extremely poor “black” water, even in so great and lake- -like mouthbays like in the lower Rio Negro, the Chemical poorness and the dark colour of the water combine for reducing the primary production to extreme low values. Those large black water rivers have the general fame to be hunger-ri- vers, also for the human popula- tion, living on the banks, caused by the scarcity of fishes and wa- terfowl etc. Where there are igapó- forests on their banks, these, with their litter etc., must be the main source of organic matter to start the food Chain in them. General characteristics of the Chemical properties of Amazonian waters, also in relation to soil con- ditions, were examined and dis- cussed by Klinge & Ohle, 1964. The water of the Amazon itself, as well as of the Rio Negro, was also investigated especially by Ges- sner, who compared these rivers with the Orinoco. After him, the electrolytical conductivity in Ama- zonian waters is generally very low, in clear water rivers still by far lower than in the Amazon itself, but rises with the pH, when this exceeds ± 5. Below that value, the conductivity rises again with a fal- ling pH-value. The Amazon has its highest conductivity in the upper- most part of its course; downward it diminishes by “dilution” with the waters of low conductivity of the affluents. The oxygen content in the Amazon water is around 70% of saturation, having the low- est value during the high water period. For the phosphate content, the sediments of the Várzea act as a buffer system. We have now seen in which way the chemistry of the water in Ama- zônia is related to the geology-mi- neralogy of the underground of their headwater areas and, already before, how it indicates some pro- cesses which occur in the soils, e. g. podzolisation . But we must con- sider yet, what the Chemical poor- ness of the waters tells about the ecology of the landscapes from which they come. This is possible, because the landscapes with their relief, their soils and their vegeta- tion etc. are interposed in the cir- culation of the water on earth and determine the quality of the waters, which pass them . Galenus already knew about this connexion when he said: “Tales sunt aquae quales terrae quas percurrent.” The water, which appears in springs and then forms creeks and rivers, comes, in the last cm l SciELO 10 11 12 13 14 15 16 40 Atas do Simpósio sôbre a Biota Amazônica end, only from the rain, which falis on the bottom and partly flows away on the surface, partly penetrates the soil before reaching the groundwater, where it even- tually comes into contact with the subsoil and finally drains into the springs. Passing the soil and being in contact with the deeper under- ground, it enriches itself with ions, which originate there from wea- thering- and soilforming-proces- ses. When — as in the Amazonian hylaea — the earth’s surface, un- der the influence of a humid cli- mate, is covered by a climax vege- tation, the mass of which is cons- tant during long periods, none óf the ions liberated in the soil by the- se weathering etc. processes from the reserves, is additionally accu- mulated in the vegetation cover or in the upper soil layer where, with time, such an accumulation would provoke salting, but all will be washed out and appear in the springs and creeks where the ions can be analysed, qualitatively and quantitatively. And if we find so little ion content in the waters — a part of which must even still be contributed by the influx of the rains — as we do in the already mentioned zones of Amazônia, we are enforced to conclude that also the soils must be very poor in those ion reserves, among which the macro- and micro-nutrients for the plant growth are of special in- terest for the understanding of the “budget” of the high rainforest as well as for prospects of a practical utilization of those areas for even- tual future agricultural or silvicul- tural purposes. The general Chemi- cal poorness of the waters indica- tes an equally general poverty of the soils, and when we find these covered by high forest, the existan- ce of the forest is not to be explain- ed by a supposed “fertility” of the soil, but by the fact that the fo- rest lives in a short-circuited cir- culation of the mineral nutrients within the living and dying organ- ic matter, more or less isolated from the soil. The forest uses the soil more as a mechanical substra- tum for the trees than as a source of nutrients. The minerais, contained in the forest matter, have there been ac- cumulated during centuries or thousands of years. If now, the forest is cut down and burnt for giving space for a plantation, these minerais, and among them the nu- trient-salts, are liberated at once in the ashes. But already the next rains will wash the greatest parts of them away — as once was found occasionally when examining creeks in the area of the “Series of the barreiras”, in lower Amazônia — , only small amounts still remain for the crop and will be carried away with the harvest. It is a ge- neral experience that a new “roça” cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 41 in the jungle gives good harvests only during two, exceptionally three years. Then the soil is ex- hausted, the mineral reserves of the former jungle-cover have dis- appeared. The conclusions as to the “fer- tility” of the soils which have been drawn from the results of Chemi- cal analyses of waters from the greatest parts of the Amazonian region were simultaneously and la- ter on confirmed by soil-analyses and by practical experiences which all contradict the former idea of a never ending fertility of our re- gion. These findings are, however, nei- ther a reason for being shocked, nor for despair in regard to a be- neficiai contribution of Amazônia to the food-economy of the grow- ing population of Brazil. It only says that care must be taken not to waste uselessly the resources of our country and that new me- thods, which correspond with the ruling ecological conditions in Amazônia, must be applied and even still created by studies in loco instead of importing only methods and machinery and ideas from hi- ghly industrialized countries, in which these were developed, gene- rally under completely different conditions. All must be done to avoid a devastation of Amazônia which may easily happen because the ecological equilibrium is really unstable and very vulnerable in consequence of the shown lack of buffering nutrient reserves. There exist already enough examples of devastated landscapes in other tro- pical countries of South America and also of África. Investigations of the waters may also help to con- tribute some knowledge for the purpose of avoiding dissipation of singular riches and benefits con- tained in the Amazonian nature. That is also one aim when elabo- rating a budget of inorganic nu- triente for catchment areas of whole river systems, as Dr. Unge- mach is just doing, or when esta- blishing an ecological subdivision of this huge country, as is tried by Dr. Fittkau. These two scientiste are going to report on their work during this symposium. And so we learn that the studies of Amazonian waters are also linked with the observation about the supposed fertility of the Ama- zonian soil, mentioned by Acuna & Rojas. Finally, I should like to say that it was only along very general lines and under omission of many stu- dies and works that have been done, that I tried to give an idea of the points of view under which Amazonian waters were observed, described and analysed, from the very first contate of Europeans with them on the occasion of the cm l SciELO 10 11 12 13 14 15 16 42 Atas do Simpósio sôbre a Biota Amazônica discovery of the mightiest river of the world, to the concept of the waters being parts of greater sec- tions of the biosphere, what are the landscapes, and of using them, too, as indicators for other, more gen- eral ecological conditions in the nature of this big country. SUMMARY There is no other region in the world in which the water plays an equally decisive rôle, in the for- mation and in the character of the landscape, as it does in Amazônia. The wet climate created, in the enormous lowland, the greatest and vastest river-system on earth. Already the discovery, the con- quest and the colonization of our region were connected with the water-courses so that their know- ledge was, from the beginning, of vital importance for the Spaniards and Portuguese when they made themselves rulers of the new coun- try. The studies in Amazonian water started therefore with the mapping of the water-courses; the improvement of that task was con- cluded only in recent time with the elaboration of the modern maps based on aerial photographs. The chroniclers of the expedition of Pedro Teixeira in 1637/38 — the first one to ascend and to des- cend the Amazon in a planned trip from the mouth to the Andes — , Acuna & Rojas, however, were observers with such a wide look that they perceived, in principie, almost all aspects which the Ama- zonian waters later on offered to the scientific curiosity of mankind. Besides of the cartography — and of the hydrobiology which will be treated, in this symposium, in a special paper given by Marlier — those reports already touched the following complexes: Anastomoses between different river-systems (by the mention of the connexion between the Rio Negro and a river which leads to the ocean) ; Morphology of the rivers (by giving dates about widths and depths) ; River-types (by the descrip- tion of the black water of Rio Negro) ; Peculiarity of the Várzea in the complex of the Amazonian landscape (by the observation of its periodical fertilization by the annual floods) ; Nutrient-content and Ecology of the whole region (by the judgement — even being an enormous one — of the quali- ty of the soils). River-anastomoses between dif- ferent fluvial systems have been scientifically proved for the first cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 43 time by Humboldt who navigated through the Cassiquiare. Today, more connexions between the Ama- zonian and other Southamerican river-systems are known. In the Morphology and Hydrolo- gy of the Amazonian rivers the fol- lowing problems occupy the great- est interest: the perfiles of the beds of the big rivers, the lake- shaped lower courses of many affluents, and the discharge of the Amazon. The first measurements of great depths (e. g. in the “gor- ge” of Óbidos, Spix & Martius found 83 m) were proved and even surpassed by recent eco-soundings in the Rio Negro (~ 100 m) and in the lower Amazon. The bed- -ground of the lower Amazon con- sists of load-matter which is mov- ed down the river of giant “rip- plemarks”, of true dunes. The low- er courses of many affluents which are disproportionately widened and transformed even in “Terra firme — lakes”, have been recogn- nized, first by Denis, as drowned valleys; limnologically, the sections of river-courses are more alike to lakes than to rivers. The discharge of the Amazon, exactly measured only recently, is of 218 000m :i /sec in the annual average, i. e. 1/6 to 1/5 of the water-mass which all ri- vers of the earth together empty into the oceans. The following river-types were established in Amazónia: rivers of “white” (turbid) water, of clear (transparent) water, and of bla- ck” water (transparent but brown coloured). The types depend on landscape-factors in the headwa- ter-zones (relief, climate, vegeta- tion cover) , but they are not abso- lutely distinct from another and permanent, but they may be con- nected by intermediate types, or they may even periodically or occa- sionally change within the same river. The Várzea, the floodland, of the lower Amazon which is so diffe- rent from the Terra firme in the quality and fertility of the soil and in the vegetation, is explained as the product of geologically recent filling of the drowned valley of the Amazon with the river-alluvions; it is therefore, after Fittkau, a pro- longation, along the course of the white water of the Amazon, of the sediment-matter from the pre-an- dean strip of land, an appendix to the same through Lower Amazó- nia. This sediment-matter from the pre-andean strip differs, by its geo- logical-mineralogical origin and its age, in its geological qualities from the soils of the arquean and terciary Terra firme zones of the lower Amazon. The nutrient-content was con- cluded by Chemical analyses of ri- vers, creeks and ground-waters. Al- ready the first analyses made by Katzer showed a surprising pover- cm SciELO 10 11 12 13 14 15 16 44 Atas do Simpósio sôbre a Biota Amazônica ty in dissolved salts. Later analyses of waters from different geological zones confirmed that general Che- mical poverty with only few excep- tions, e. g. in the carboniferous strips. Such Chemical poorness of the running waters is an expres- sion of a corresponding poverty, of the soils of the headwater zones, in the same ions, among them also in nutrients for the vegetation. The chemistry of the water revealed itself, by the way, as an excellent indicator for getting a first idea of the Amazonian landscape-ecology, too, especially of the nutrient- household of the ecosystem of the Amazonian Terra firme with tne high rain-forest. SUMÁRIO PESQUISAS EM ÁGUAS DA AMAZÔNIA Não há nenhuma outra região no globo na qual a água faz um pa- pel igualmente decisivo, na forma- ção e no caráter da paisagem, como na Amazônia. O clima úmido fêz desenvolver-se, naquela enorme planície baixa, o maior e mais ex- tenso sistema potâmico do mundo. Já o descobrimento e a conquis- ta e a colonização da nossa região eram ligados aos corpos d’água de forma que o conhecimento dêstes foi, desde o início, de importância primordial para os espanhóis e por- tugueses quando se fizeram novos donos dèste país. As pesquisas em aguas amazônicas começaram, pois, com o mapeamento dos cursos de água cujo aperfeiçoamento con- cluiu-se somente no tempo atual com a elaboração dos mapas mo- dernos, baseados em aerofotogra- fias. Porém, já os cronistas da primei- ra expedição, da de Pedro Teixeira em 1637/38, a qual planejadamen- te subiu e desceu o Amazonas des- de a foz até os Andes, Acuna e Rojas, eram observadores de uma visão tão vasta que êles notaram, em princípio, quase todos os aspec- tos que as águas amazônicas ofe- receram, nos tempos posteriores, à curiosidade científica dos homens. Além da cartografia — e da hidro- biologia que se tratará, neste sim- pósio, numa conferência especial — aqueles relatórios já tocaram nos seguintes complexos: Anastomoses entre diferentes siste- mas fluviais (pela menção do conexo entre o Rio Negro e um rio que desemboca no oceano) ; Morfologia dos rios (pelas indica- ções sôbre larguras e profun- didades) ; Tipos de rios (pela descrição da água preta do Rio Negro); Peculiaridade da Várzea no conjun- to da paisagem amazônica (pe- la observação da fertilização periódica pelas inundações anuais) ; cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 45 Conteúdo em nutrimentos e Ecolo- gia da região inteira (pelo jul- gamento — aliás errôneo — da qualidade dos solos) . Anastomoses entre rios de siste- mas potâmicos diferentes foram provados cientificamente pela pri- meira vez por Humboldt quando navegou pelo Cassiquiare. Hoje co- nhecem-se mais ligações entre o sistema amazônico e outros siste- mas fluviais sul-americanos. Na Morfologia dos rios amazôni- cos, dois problemas destacam-se no interêsse dos geógrafos e limnólo- gos: os perfis dos leitos dos gran- des rios, e os cursos inferiores, la- goiformes, de muitos afluentes. As primeiras determinações de pro- fundidades grandes (na “gargan- ta” de Óbidos, Spix & Martius en- contraram 83 m) foram provadas e até superadas por recentes sonda- gens de éco, no rio Negro (~ 100m) e no Baixo Amazonas; o fundo do leito do Baixo Amazonas revelou-se como consistindo de material que se desloca em forma de “ripple- marks” gigantescos, de verdadei- ras dunas. Os cursos inferiores de muitos afluentes, alargados despro- porcionalmente e transformados até em “lagos de terra firme*”, re- conheceram-se, primeiramente por Denis, como sendo “vales afoga- dos”; limnològicamente, estas se- ções de cursos de rios assemelham- -se mais a lagos do que a rios . Como tipos de rios amazônicos estabeleceram-se os de rios de água “branca” (barrenta), de água cla- ra (transparente) e de água preta. Os tipos dependem de fatores de paisagem nas regiões das cabecei- ras (relêvo, clima, cobertura vege- tal), porém não são absolutamen- te distintos um do outro e perma- nentes mas podem ser ligados por tipos intermediários, ou até podem variar periodicamente ou casual- mente para o mesmo rio. A Várzea do Baixo Amazonas, tão diferente, na qualidade e fertilida- de do solo e na vegetação, da ter- ra firme, explica-se como produto de colmatagem geologicamente re- cente do vale afogado do Amazo- nas, sendo desta forma, segundo Fittkau, uma prolongação, ao lon- go do curso da água branca do Amazonas, do material sedimentar da faixa pré-andina, um apêndice à mesma através da Baixa Amazô- nia. Êste material sedimentar da faixa pré-andina difere, pela ori- gem geológica e pela idade, nas suas qualidades pedológicas, dos so- los das camadas do arqueano e do terciário da terra firme do Baixo Amazonas. O conteúdo em nutrimentos con- cluiu-se de análises químicas de águas de rios e igarapés e de água freática. Já as primeiras análises feitas por Katzer revelaram uma surpreendente pobreza em sais dis- solvidos. Análises posteriores de cm SciELO 10 11 12 13 14 15 16 46 Atas do Simpósio sôbre a Biota Amazônica águas de diferentes zonas geológi- cas provaram esta pureza química geral, havendo somente poucas ex- ceções, p. e. nas faixas do carbo- nífero. Tal pobreza das águas cor- rentes é uma expressão de pobre- za correspondente, dos solos nas cabeceiras, nos mesmos iônios, en- tre êles também em nutrimentos para a vegetação. O quimismo das águas, pois, mostrou-se como exce- lente indicador para ganhar uma primeira idéia também da Ecologia da paisagem amazônica, especial- mente do metabolismo de nutri- mentos do ecossistema da terra fir- me amazônica com a floresta alta pluvial. REFERENCES Acuna, C., 1941, Descobrimento do rio das Amazonas. Trad. e anot. por C. de Melo Leitão. 294 pp., S. Paulo, Cia. Ed. Nacional. (Biblioteca Pe- dagógica Brasileira. Sér. 5.: Brasi- liana, v. 203.) Andrade, G. O. O., 1958, Furos, paranás e igarapés; análise genética de al- guns elementos do sistema pota- mográfico amazônico. Rev. Geogr. Inst. Pan Amer. Geogr. Hist., Rio de Janeiro, 22 (48) : 3-36. Boi. Ca- rioca Geogr., Rio de Janeiro, 9 (3/4): 15-50. Braun, R., 1952, Limnologische Unter- suchungen an einigen Seen im Amazonasgebiet. Schw. Zeits. Hy- drol., Basel, 14 (1) : 1-128. Carvajal, G„ 1941, Descobrimentos do rio das Amazonas. Trad. e anot. por C. de Melo Leitão. 294 pp , S. Paulo, Cia. Ed. Nacional. (Biblio- teca Pedagógica Brasileira, Sér. 5.: Brasiliana, v. 203.) Clauss, O., 1866, Bericht über die Schingu-Expedition im Jahre 1884. Petermann’s Mitt. Justus Perthes’s Geogr aphischer Anstalt, Gotha, 32: 129-134. Coudreau, H. A., 1897, Voyage au Ta- pajós, 28 juillet 1895 — 7 janvier 1896. 215 pp., Paris, A. Lahure. Coudreau, H. A., 18S7, Voyage ao Xingú, 30 mai 1896 — 26 octobre 1896. 230 pp., Paris, A. Lahure. Coudreau, H. A., 1897, Voyage au To- cantins — Araguaya, 31 décembre 1896 — 23 mai 1897. 330 pp., Paris, A. Lahure. Coudreau, H. A., 1899, Voyage au Ya- mundá, 21 janvier 1899 — 27 juin 1899. 163 pp., Paris, A. Lahure. Coudreau, H. A., 1900, Voyage au Trom- betas, 7 aoüt 1899 — 25 novembre 1899. 141 pp., Paris, A. Lahure. Coudreau, O., 1901, Voyage au Cuminá, 20 avrll 1900 — septembre 1900. 190 pp., Paris, A. Lahure. Coudreau, O., 1903, Voyage au Rio Curuá, 20 novembre 1900 — 7 mars 1901. 114 pp„ Paris, A. Lahure. Coudreau, O., 1903, Voyage à la Ma- puéra, 21 avril 1901 — 24 décembre 1901. 166 pp., Paris, A. Lahure. Coudreau, O., 1903, Voyage au Maycurú, 5 juin 1902 — 12 janvier 1903. 151 pp., Paris, A. Lahure. Coudreau, O., 1906, Voyage au Canumã, 21 aoüt 1905 — 16 février 1906. 216 pp., Paris, A. Lahure. Denis, P., 1927, UAmérique du Sud. Le Brésil, chap. VII, L’Amazonie. Col. Géogr. Univers., XV, 2ème partie. Paris. cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 47 EGLER, w. A. & SCHWASSMANN, H. O., 1962, Limnological studies in the Amazon Estuary. Boi. Mus. Para- ense Emílio Goeldi, n. s.. Avulsa 1: 2-25. EGLER, W. A. & SCHWASSMANN, H. O-, 1964, Limnological studies in the Amazon Estuary. Verh. Internat. Verein. Limnol., 15: 1059-1066. Fittkau, E. J., 1964, Remarks on Limno- logy of Central-Amazon rain-fo- rest streams. Verh. Internat. Verein. Limnol., 15: 1092-1096. Gessner, F„ 1957, Die Beziehung zwis- chen pH und elektrolytischem Leit- vermõgen in den Gewâssern der Rio Negro-Gebietes. Naturwissen- schaften, 44 (8): 258-259. Gessner, F., 1960, Untersuchungen über den Phosphathaushalt des Amazonas. Internat. Rev. ges. Hy- drobiol., 45 (3) : 339-345. Gessner, f., 1960, Ensayo de una com- paracion quimica entre el Rio Amazonas, el Rio Negro y el Ori- noco. Acta Cient. Venezolana, 11 (2): 3-4. Gessner, f., 1960, Limnologische Unter- suchungen am Zusammenflufi des Rio Negro und des Amazonas (So- limoes). Internat. Rev. ges. Hydro - biol, 45 (1) : 55-79. Gessner, f., 1961, Der Sauerstoffhaush- halt des Amazonas. Internat. Rev. ges. Hydrobiol, 46 (4) : 542-561. Gessner, f„ 1962, Der Elektrolytgehalt des Amazonas. Arch. Hydrobiol., 58 (4) : 490-499. Gessner, p., 1964, The limnology of tropical rivers. Verh. Internat. Verein. Limnol., 15: 1090-1091. Gourou, P., 1949, Observações geográ- ficas na Amazônia. I. pt. Rev. Bras. Geogr., 11 (3) : 356-408. Hartt, C. F., 1897/1898, A região de Breves (Trabalhos restantes iné- ditos da Commissão Geológica do Brasil relativos à Geologia e Geo- grafia physica do Baixo Amazonas, 2). Boi. Mus. Paraense Hist. Natur. Ethnogr., Belém, 2: 173-181. Huber, J., 1903, Contribuição à geogra- phia physica dos furos de Breves e da parte Occidental de Marajó. Boi. Mus. Paraense (Museu Goeldi; , Belém, 3 (1900-1902) : 447-498. Humboldt, A., 1859, Reise in die Aequi- noctial—Gegenden des neuen Con- tinents. In deutscher Bearbeitung von Hermann Hauff. Stuttgart, J. G. Cotta’scher Verlag. Katzer, F„ 1897, Das Wasser des un- teren Amazonas. Sitz. bõhm. Ges. Wiss. Math.-naturw. cl., 17: 1-38. Katzer, F., 1903, Grundzüge der Geolo- gie des unteren Amazonasgebietes (des Staates Pará in Brasilien). 298 pp., Leipzig, Max Weg. Klinge, H., 1965, Podzol Soils in the Amazon Basin. J. Soil Sei., 16: 95- -193. Klinge, H. & Ohle, W., 1964, Chemical properties of rivers in the Ama- zonian area in relation to soil con- ditions. Verh. Internat. Ver. Lim- nol., 15: 1067-1076. La Condamine, c. M., 1775, Relation abrégée d’un voyage jait dans 1’interieur de VAmérique Méridio- nale, depuis la côte de le Mer du Sud, jusqu’aux côtes du Brésil & de la Guiane, en descendant la rivière des Amazones... par M. de cm SciELO 10 11 12 13 14 15 16 48 Atas do Simpósio sôbre a Biota Amazônica la Condamine . . . Avec une carte du Maragnon, ou de la rivière des Amazones, levés par le même. 216 pp., Paris, Pissot. Le Cointe, P., 1911, Carte du Bas Ama- zone de Santarém à Parintins, 1; 250 000 . Paris, Librairie Armand Colin. Le Cointe, P., 1945, O Estado do Pará. A terra, a água e o ar. X -f 305 pp., São Paulo, Companhia Editora Na- cional. Marlier, G., in press, Étude sur les iaes de l’Amazonie Centrale. Cadernos da Amazônia, Manaus, 5 Marlier, G., in press, Ecological studies on some lakes of the Amazon valley. Amazoniana. Matos, F.J.G., 1937, Les idées sur la physiographie sud-américainè. Communication présentée au III" Congrès International d’Histoire des Sciences — Lisbonne, 1934 (Ex- trait du livre des “Actes, Confé- rences et Communications du Congrès”, publié à Lisbonne l’an 1936), Lisboa: 391-440. Oltman, R E , Sternberg, H. O. R., Ames, F. C. & Davis, Jr., L. C., 1964, Amazon River Investigations — Re- connaissance Measurements of July 1963. Washington, Geological Sur- vey Circular 486, III: 1-15. Pardé, M., 1936, Les variations saison- nières de 1’Amazone. Ann. Géogr., Paris, 45 (257) : 502-511. Pardé, M., 1964, Fleuves e Rivièics. 224 pp., Paris, Librairie Armand Colin Pinto, A. O., 1930, Hydrographia do Amazonas e seus affluentes. 2 vol., XII -f 438 pp., 25 maps., Rio de Janeiro, Imprensa Nacional. Rojas, A., 1941, Descobrimentos do rio das Amazonas. Trad. e anot. por C. de Meio-Leitão. 294 pp., (Biblio- teca Pedagógica Brasileira. Sér. 5: Brasiliana, v. 203.) Sioli, H„ 1949, O Rio Cuparl. I. Topo- grafia e Hidrografia. Boi. Técn. Inst. Agr. Norte, Belém-Pará, 17: 1-50. Sioli, H., 1950, Das Wasser im Amazo- nasgebiet. Forsch. Fortschr., 26, 21/22: 274-280. Sioli, H., 1951a, Sôbre a sedimentação na Várzea do Baixo Amazonas. Boi. Técn. Inst. Agr. Norte, Belém-Pará, 24: 45-65. Sioli, H., 1951b, Zum Alterungsprozef) von Flüssen, und Flufitypen im Amazonasgebiet, Arch. Hydrobiol., 45: 267-283. Sioli, H„ 1954a, Beitrâge zur regionalen Limnologie des Amazonasgebietes. II. Der Rio Arapiuns, ein Gewásser des Tertiàr gebietes (Pliozân) , Serie der “Barreiras”, Unter-Amazo- niens. Arch. Hydrobiol., 49 (4) : 448-518. Sioli, H., 1954b, Gewàsserchemie und Vorgànge in den Bõden im Amazo- nasgebiet. Naturwissenschaften, 41 (19): 456-457. Sioli, h., 1955, Beitrâge zur regionalen Limnologie des Amazonasgebietes. III über einige Gewásser des oberen Rio Negro-Gebietes. Arch. Hydrobiol., 50 (1) : 1-32. Sioli, H., 1956a, über Natur und Mensch im brasilianischen Amazonasgebiet. Erdkunde, 10 (2) : 89-109. Sioli, H., 1956b, O Rio Arapiuns. Estu- do de um corpo d’água da região cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 49 do terciário, série das barreiras, do Baixo Amazonas. Boi. Técn. Insz. Agr. Norte, Belém-Pará, 32: 1-115. Sioli, H., 1956c, As águas da região do Alto Rio Negro. Boi. Técn. lnst. Agr. Norte, Belém-Pará, 32: 117- -155. Sioli, H., 1957a, Beitràge zur regionalen Limnologie des Amazonasgebietes. IV. Limnologische Untersuchungen in der Region der Eisenbahnlinie Belém — Bragança (“Zona Bragan- tina”) im Staate Pará, Brasnien Arch. Hydrobiol, 53 (2) : 161 - 222 . Sioli, h., 1957b, Valores de pH de águas amazônicas. Boi. Mus. Paraense Emílio Goeldi, Geologia, 1: 1-37. Sioli, h., 1957c, Sedimentation im Ama- zonasgebiet. Geol. Rundschau, 45 (3) : 608-633. Sioli, h., 1957d, Die “Fruchtbarkeit” der Urwaldbõden des brasilianis- chen Amazonasgebietes und ihre Bedeutung für eine zukunftige Nutzung. Staden-Jahrbuch, S. Pau- lo, 5: 23-36. Sioli, h., 1960, Pesquisas Limnológicas na Região da Estrada de Ferro de Bragança, Estado do Pará, Brasil. Boi. Técn. Inst. Agr. Norte, Belém' Pará, 37: 1-91. Sioli, 1961, Landschaftsõkologischer Beitrag aus Amazonien. Natur u. Landschaft, 36 (5) : 73-77. Sioli, h„ 1963, Beitràge zur regionalen Limnologie des brasilianischen Amazonasgebietes. V. Die Gewàssei der Karbonstreifen UnteramazO' niens (sowie einige Angaben übei Gewásser der anschlies senden De' vonstreifen) . Arch. Hydrobiol., 59 (3): 311-350. Sioli, H., 1964a, Die natürlichen Ge- wàsser der unteramazonischen Karbonstreifen ais Indikatoren füi Untergrund- und Bodenverhált' nisse im Hinblick auf zukünftige landwirtschaftliche Nutzung. C. R. XVIIIe Congrès International de Géographie, Rio de Janeiro, 1956, II: 390-398. Sioli, H„ 1964b, General features of the Limnology of Amazônia. Verh. Internat. Verein. Limnol., 15: 1053- -1058. Sioli, H„ 1965a, Zur Morphologie des Flufibettes des Unteren Amazonas. Naturwissenschaften, 52 (5) : 104. Sioli, h., 1965b, Bemerkungen zu den Fundorten. In: Scott, Arthur M. +. Rolf Grõnblad + and Hannah Croasdale: Desmids from the Ama- zon Basin, Brazil, collected by Dr. H. Sioli. Acta Bot. Fenn. 69: 5-18. Sioli, H., 1965c, A Limnologia e a sua importância em pesquisas da Ama- zônia. Amazoniana, 1 (1) : 11-35. Sioli, H., 1965d, Bemerkungen zur Ty- pologie amazonischer Flüsse. Ama- zoniana, 1 (1): 74-83. Sioli, H„ 1966, General features of the Delta of the Amazon. — Humid Tropics Research — Scientific Pro- blems of the Humid Tropical Zone Deltas and their Implications . Proceedings of the Dacca Sympo- sium. UNESCO: 381-390. Sioli, H. & Klinge, H., 1961, Übei Gewásser und Bõden des brasilia- nischen Amazonasgebietes. Die Erde, 92 (3) : 205-219. 1 — 37 121 cm l SciELO 10 11 12 13 14 15 16 50 Atas do Simpósio sôbre a Biota Amazônica Sioli, H. & Klinge, H., 1962, Solos, tipos de vegetação e águas na Amazônia Brasileira. Boi. Mus. Pa- raense Emílio Goelãi, Avulsa, 1: 27-41. Soares, L. C., 1959, Hidrografia. In: Geografia do Brasil, I, Grande Re- gião Norte, Rio de Janeiro, IBGE, Conselho Nacional de Geografia: 128-194. Spix, J. B. & Martius, K. F. P., 1823- 1831, Reise in Brasilien auf Be- fehl Sr. Majestát Maximilian Jo- seph I., Kõnigs von Bayern, in den Jahren 1817 bis 1820 gemacht und beschrieben von dr. Joh. Bapt. von Spix . . . und dr. Cari Friedr. Phil. von Martius. München, Gedruckt bei M. Lindauer. Sternberg, H. 0’R., 1950, Vales tectô- nicos na planície amazônica? Rev. Br as. Geogr., Rio de Janeiro, 12 (4): 511-534. Sternberg, H. 0’R., & Pardé, M., 1965, Information d’origine récente sur les débits monstrueux de 1’Amazo- ne. Actes du 89' Congrès National des Sociétés Savantes, Lyon 1964: 189-195. Tastevin, C., 1929, Le delta du Japurá et le Piuriny. Géographie, Paris, 51: 280-298. U.S. Department of the Interior Geo- LOGICAL SURVEY INFORMATION OFFICE, 1964: Amazon River Investigation 1963, Measuring a Mighty River- Hydrologists tackle the Amazon. Washington, Geological Survey, Forrester 343-4646: 9 pp. cm SciELO 10 11 12 13 14 15 16 Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 51-62 — 1967 COMPARATIVE LIMNOLOGY OF THE STREAMS OF FLORIDA AND THE UPPER AMAZON BASIN WILLIAM M. BECK, JR. Florida State Board of Health, Jacksonville, U.S.A. (With 7 text-figures) The long history of lake limno- logy has made possible compara- tive regional studies based on a period of many years. A typical example of this is the expedition made by Brundin (1956) to the high mountain lakes of the south ern Andes for the purpose of comparing these lakes with the equivalent lakes of Northern Eu- rope. As was pointed out by Beck (1956), limnology has been taught in North America largely in schools located in lake regions with a consequent lack of emphasis or even minor efforts with regard to streams. Most studies of streams in North America have been made by federal or state agencies for the purpose of determining water qua- üty in connection with pollution abatement, fisheries resources, the effects of impoundments, etc. Most of this work either ends up in the files of the aforementioned govern- mental agencies or is occasionally distributed in the form of mimeo- graphed reports. These reports are frequently an accumulation of re- sults gathered individually by en- gineers, chemists, bacteriologists, and biologists with the result that most lack the integrated ap- proach of a true limnological sur- vey, geology being the one factor most frequently neglected. The following quotation from Hutchinson (1963: 689) reflects to a large degree what has been stat- ed above: “The whole subject of rivers, now ordinarily though not philologically subsumed in limno- logy, appears to him [the author] as a marvelous foreign territory ex- plored by workers whose audacity is admirable in view of the diffi- culty of getting a theoretical grasp of the subject.” The many excellent publications of Sioli, Fittkau, and Klinge & Ohle give a rather thorough understanding of the limnology, in cm SciELO 10 11 12 13 14 15 16 52 Atas do Simpósio sôbre a Biota Amazônica its total aspect, of the streams of Amazônia. My own work with the streams of Florida has extended over a period of 25 years and is sufficient, I believe, for a compari- son of the streams of the two areas in question. I wish to express my sincere gra- titude to the Association for Tropi- cal Biology and the National Academy of Sciences for making possible my participation in this Symposium. FLORIDA AND ITS STREAMS The geology of the State is of primary importance in Florida lim- nology. Florida is underlain enti- rely by limestones, marls and sands of tertiary and quarternary origin which is very similar to the geo- logical background of certain areas of Amazônia. One striking diffe- rence is the presence of considera- ble quantities of dissolved phospha- Fig. 1 — Florida (1 — Perdido River; 2 — Chipola River; 3 St Marks River- 4 — Aucilla River; 5 — Santa Fe River). cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 53 Fig. 2 — Alapaha River, during normal or low flow. tes in most of the waters of Flo- rida. With the exception of the ex- treme western panhandle, Florida is an area of Karst topography ty- pified by innumerable sink-holes, lakes of solution origin, disappear- ing rivers (Figs. 1-3), numerous springs, and areas with no streams at all. According to the geologists, Pleistocene deposits due to chan- ges in sea levei have concealed a Karst topography even more striking than that of the classical region. It is in the area of topography that another striking regional dif- ference occurs. Florida has a ma- ximum elevation of about 400 feet with stream gradients in some areas sufficient for the formation of rapids but no surface water- falls over four feet in height. According to Cooke (1963), Flo- rida is divided distinctly into five topographic regions (Fig. 4). An additional topographic area was delineated by Beck & Beck (1959) and designated as the Re- lict Area. This area is one of spe- cial interest to the biologist as it consists of cool, shaded ravines in which are found many species of plants and animais representing either species confined to that area or relict populations of species not found elsewhere south of the Pied- mont of northern Geórgia. The highest elevations in Florida occur in the Central Highlands and cm l SciELO 54 Atas do Simpósio sôbre a Biota Amazônica the Western Highlands while the Coastal Lowlands occupy a major portion of the State of Florida and extend entirely around the coast, ranging in width from a very nar- row strip in the extreme western panhandle to their greatest width in the Southern portion of the Sta- te where the Southern third of the peninsula is entirely lowland. The Tallahassee Hills is an area of rol- ling hills of high pineland and hardwod forests. The term “Ma- rianna Lowlands” is a misnomer since the area is only slightly low- er in general elevation than the two adjacent areas. It is, however, one of the most interesting areas with some of the most striking Karst topography in the State and has the only caverns developed for public use. The climate of Florida ranges from south temperate in the north- western panhandle to tropical in the Keys. According to Provost (undated manuscript), no part of the mainland of Florida is truly tropical despite the presence of many tropical plants and animais (Fig. 5). Fig. 5 shows several items of spe- cial interest with regard to the cli- mate of Florida. Foremost is the in- fluence of the proximity of the Gulf Stream to the east coast, ex- tending the subtropical and Flori- dian regions much farther up the east coast than they extend up TPi ift- Fig. 3 — Alapaha River, in flood. the west coast. The subtropical re- gion delineates the range of the large bromeliad, Tillandsia utri- culata, and the West Indian land crab, Cardisoma guanhumi. The 58.° January isotherm repre- sents roughly a zone of intergrada- tion between southeastern and Flo- ridian, subspecies in the field of herpetology. Thus in the Floridian region are found most of the spe- cies and subspecies of endemic rep- tiles and amphibians. The 64.° iso- therm crosses another area of in- tergradation between Floridian and South Floridian subspecies of reptiles (Carr, 1940). Figure 6 is a climatograph based on mean monthly temperatures and rainfall for the Miami (sub- cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 55 tropical) area. It will be noted that the climatograph is an almost ty- pical example of a tropical annual cycle involving a hot, rainy season and a cool, dry season. Bates (1864: 31) makes the following statement with regard to the cli- mate of Belém: “A little differen- ce exists between the dry and wet seasons; but generally, the dry sea- son, which lasts from July to De- cember, is varied with showers, and the wet, from January to June, with sunny days.” COMPARATIVE LIMNOLOGY Sioli (1964, 1965) presents ex- cellent summaries of the limnolo- gical features of Amazónia in which he divides the streams of the area into three basic types. Beck (1965) lists five different types of streams found in Florida. These classifications are listed and com- pared in Table 1. The “white” water stream of Sioli (1964: 1054) is quite similar to the larger rivers of Beck. Ran- Mfj $1 Q Coastal Lowlands © Central Highlands © Tallahassee Hills O Marianna Lowlands © Western Highlands A Relict Areas Fig. 4 — Topographic regions o] Cooke. 2 3 cm SciELO 10 11 12 13 14 15 16 56 Atas do Simpósio sôbre a Biota Amazônica TABLE 1 Stream Classification Sioli pH Beck pH 1. “Wliite” water.. 6.5 — 6.9 6 5_6 9 2. “Clear” water 6.4 — 6.65 Calcareous streams 7.0 — 8.2 3 . “Black” water 3.8 — 4.9 Sand-bottomed streams 5.7— 7.4 4. “Black” water 5. Swamp-&-bog streams Canais of southeastern Florida 3.8 — 6.5 ges of pH are identical, probably by coincidence since the figures gi- ven for the larger rivers of Florida represent only one stream. With the exception of the St. Johns Ri- ver which is unique (Numeral 6, Fig. 7), these larger rivers are quite similar chemically and phy- sically. The values selected for comparative purposes in Table 1 are for the Apalachicola River (Nu- meral 3, Fig. 7) which has been studied more thoroughly than the others. Larger rivers, such as the Escambia, Choctawhatchee, Apa- lachicola and Ochlocknee, are all interstate streams rising in the hills of Alabama and Geórgia, and all are consistently turbid due to a suspension of Montmorillonite clay giving these waters a whitish or slightly yellowish appearance and reducing light penetration to a major degree. The second category of Sioli, the “clear” water stream, is some- what comparable to the calcareous stream of Beck although uniformly lower in pH. The calcareous stream originates entirely, or to a major degree, from springs although ge- nerally there are lateral contribu- tions of colored swamp or lake drainage. Consequently, though the water is very transparent, it often has a yellowish color. The “black” water stream of Sioli is apparently quite similar to both the sand-bottom and the swamp-and-bog streams in Flori- da (Table 1). Although I consider these two types of Florida streams distinctive, the only real differen- ce is found in the extremely low velocity of the swamp-and-bog stream and in Chemical differences associated with this lowered velo- city (extremely low pH, alkalinity, hardness; extremely high color due to “humic acids”) . Despite the higher pH limits of the sand-bot- tom stream in Florida, it is still comparable to the “black” water stream of Sioli due to its high color . The canais of southeastern Flo- rida are listed in the publication of Beck (1965) as a stream type al- though they are not streams in any true sense of the word. At most ti- mes these canais have a distinct cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 57 Fig. 5 — Climatic regions of Provost. seaward flow although at other ti- mes there may be no movement of the water at all. They are listed as a stream type simply because they are all that remain of the former streams along some 140 miles of the coast of southeastern Florida. It would thus appear that both Amazónia and Florida possess three basic, comparable types of streams with a certain amount of intergradation among the dif- ferent types. Fittkau (1964) discusses limno- logical features of the rain-forest streams of the upper Rio Negro ba- sin. The most unusual feature of these streams is their remarkably low concentration of dissolved elec- trolytes. The stream forming the western boundary of Florida, the Perdido River (Numeral 1, Fig. 1), is quite similar chemically to the rain-forest streams. Table 2 compa- res certain factors in these streams. It will be noted that these streams cm l SciELO Louisianian Floridian 58 Atas do Simpósio sôbre a Biota Amazônica are distinctly acid, may have very high free carbon dioxide content and are very low in hardness, al- kalinity, and chlorides. Fittkau attributes the paucity of life in the rain-forest streams to the extreme poverty of electrolytes and the lack of light due to the dense rain-fo- rest canopy. While the Perdido Ri- ver is neither as densely shaded nor quite as low in dissolved eleetroly- tes, it is not a particularly produc- tive stream. In areas where vege- tation occurs, growths of aquatic plants, which may support quite a rich and varied invertebrate fauna, are generally confined to small areas. Most of the stream bottom consists of coarse, shifting sand and is inhabited only by the larger species of burrowing dragonflies and mayflies. At this time no attempt will be made to compare the biology of the streams of Amazônia and Flo- rida due to the fact that relatively little has been published thus far concerning the biology of the Mean Monthly Temperature °F Fig. 6 — Climatograph : Miami area. Volume 3 (Limnologia) 59 Fig. 7 — Florida, larger rivers: (1 — Escarniria River; 2 — Choctawhatchee River; 3 — Apalachicola River ; 4 Ochlocknee River; 5 — Suwannee River; 6 — St. Johns River). streams of Amazónia despite ex- tensive study of the area performed especially by biologists from Hy- drobiologische Anstalt der Max- Planck-Gesellschaft, and also be- cause the biota of the streams of Florida has not been thoroughly studied. In December, 1965, following se- veral months spent in Amazónia, Dr. Fittkau was our guest in north- ern Florida for a brief period. During this time we spent one day examining streams in our area, mainly sampling for invertebrates. We were truly astonished at the number of different genera in di- verse groups of invertebrates that Dr. Fittkau could identify imme- diately. Many of these, including the Odonata, Trichoptera, Coleop- tera, Plecoptera, Ephemeroptera, 60 Atas do Simpósio sôbre a Biota Amazônica mollusks and other smaller groups, possessed genera which I did not realize existed in Amazônia. Al- though Dr. Fittkau has studied the chironomid fauna of Amazônia for some years, and my wife and I have conducted similar studies in Flori- da, too little has been published to support any significant compari- sons at present. CONCLUSIONS Both Florida and Amazônia have three similar, basic types of streams. Although significant dif- ferences exist among the three stream types of the two areas in question, there are enough Chemi- cal and physical similarities to sug- gest that the approach of compa- rative limnology is worthwhile. In both areas, intergradation exists among all stream types. The most interesting features of the streams of both areas are the factors in which they differ. Fore- most among these differences is the high dissolved nutrient concen- trations normally found in the wa- ters of Florida in contrast with the extremely low concentrations in the streams of Amazônia. Second is the significantly higher velocity of the upper Amazon streams, sup- porting groups of invertebrates that have not been found thus far in Florida. One type of stream not found in Florida is the rain-forest stream described by Fittkau. These streams are so covered by a canopy of trees that only 0.5 to 1 percent of the total solar radiation at noon reaches them. The Perdido River, compared with the rain-fo- rest streams in Table 2, is quite similar in some respects to those streams. It is my belief that principies exist in stream limnology just as they do in the limnology of lakes. Unfortunately, it requires more ef- fort to discover them. Ever since the origin of the concept of a lake as a microcosm, the possibilities inherent in the study of a more or less closed system have appealed to a great many students. On the other hand, streams apparently have had less appeal, perhaps due to the extensive variation of limno- logic factors in regard to both time and space. This lack of apprecia- tion for or interest in streams is reflected in the recent enactement of the Wild Rivers legislation by the United States government making rivers the last natural re- sources to be recognized and pre- served in their natural state for the benefit of future generations. Already we have developed a specialized terminology with re- gard to flowing waters including such terms as rheophile, rheobiont, Spritzwasserarten, etc. in addition to many generic names of aquatic organisms beginning with Rheo. or Potamo. Many special items of Volume 3 (Limnologia) 61 TABLE 2 Comparison of Low Electrolyte Waters Upper Rio Negro Factors Perdido River 4.1 —5.2 pH 5.3 — 5.5 4.4 — 91.5 free C0 2 mg/L 60 — 150 0 — 0.65° DGH hardness 5 — 8 mg/L 0 — 3 chlorides mg/L 4 — 8 0 — 0.5 NO 3 -X 0.1 nh 3 -n 0 — 7 bicarbonates mg/L 10 — 15 equipment have been developed specifically for work in streams: the fresh water current meter, the electronic oxygen probe (especial- ly the type which measures oxygen only in waters with a minimum ve- locity of 1 foot per second), the Brundin net, the Catherwood dia- tometer, the Hestler-Dendy plate sampler and the Tebo sampler . Both the specialized terminology and specialized equipment reflect distinctive aspects of a specialized field and suggest rather precisely where to look for possible univer- sal principies of stream behavior. The following items are offerred as being basic to the formation of any principies of stream limnology: 1 . 2 . A stream is a body of water of geographical significance typi- fied by unidirectional flow. A stream is highly variable in its physical, Chemical and bio- logical characteristics with res- pect to both time and space. 3. These variations are cyclic in nature, the variations depend- ing on both geographic loca- tions and climatic differences. 4 . A stream is a function of its en- tire drainage basin. 5. Water is the most extraordina- ry of all compounds known to Science. Whether in lakes or in streams or indeed in the oceans themselves, water reacts every- where to the same laws of phy- sics and chemistry regardless of the Container in which it is found. SUMMARY Streams of the areas in question have many features in common. The basic classification of stream typology as presented by Sioli (1964, 1965) does not differ great- ly from the classification of Flo- rida streams as proposed by Beck (1965). Although there are some strik- ing similarities in the streams of cm SciELO 10 11 12 13 14 15 16 62 Atas do Simpósio sôbre a Biota Amazônica the two areas in question, it is in the differences — Chemical, physi- cal, biological, and geological — that we find the most striking and informative features. A compa- rison of both the common and the distinctive features may contribu- te significantly to a better under- standing of comparative regional limnology and further development of that branch of limnology devot- ed to the study of flowing waters. Probably more has been publish- ed on the limnology of the Upper Amazon than on all the streams of Florida combined. This literatu- re makes possible comparisons bet- ween streams of an area in which I have worked for many years and streams of an area which I have never seen. The writings of Sioli, Ohle, Klinge, and Fittkau, in addition to correspondence and personal contact with these wor- kers, have further contributed to an understanding of mutual and unique problems. Dr. Fittkau spent several days with us in December, 1965, and we were astonished at his familiarity with our local stream faunas. He recognized many genera of aquatic inverte- brates that we did not realize exist- ed in South America. REFERENCES Bates, H. W., 1864, The naturalist on the River Amazon. 407 pp., J. M. Dent and Sons, Ltd., London. Beck, E. & Beck, Jr., W. M„ 1959, A checklist of the Chironomidae (In- secta) of Florida (Diptera: Chiro- nomidae) . Buli. Fia. State Mus., 4 (3) : 85-96. Beck, W. M., JR-, 1965, The streams of Florida. Buli. Fia. State Mus., 10 (3): 91-126. Brundin, L., 1956, Die bodenfaunistis - chen Seetypen und ihre Anwenã- barkeit auf die Suãhalbkugel. Ins- titute of Freshwater Research, Drottningholm. Rep. N.° 37: 186- 235. Carr, A. F., JR., 1940, A contribution to the herpetology of Florida. XJniv. Fia. Publ., Biol. Sei. Ser., 3(1): 1- 118. Cooke, C. W„ 1939, Scenery of Florida interpreted by a geologist. Fia. State Dept. Conserv., Geol. Buli., 17: 1-118. Fittkau, E„ J., 1964, Remarks on lim- nology of central-Amazon rain- -forest streams. Verh. Internatl Verein. Limnol., 15: 1092-1096. Hutchinson, G. E., 1963, The prospect bejore us; in Limnology in North America, ed. David G. Frey. Univ. Wisconsin Press: 683-690. Klinge, H. & Ohle, W., 1964, Chemical properties of rivers in the Ama- zonian area in relation to soil con- ditions. Verh. Internatl. Verein. Limnol., 15: 1067-1076. Provost, M. W., Mosquitoes and climate in Florida, unpublished manus- cript: 1-15. Sioli, H., 1964, General features of the limnology of Amazônia. Verh. In- ternatl. Verein. Limnol., 15: 1053- -1058. Sioli, H., 1965, Bemerkung zur Typo- logie amazonischer Flusse. Amazo- niana, 1: 74-83. Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 63-82 — 1967 LA SUPERFAMILIA UNIONACEA EN LA CUENCA AMAZÔNICA ARGENTINO A. BONETTO Instituto Nacional de Limnologia, Santo Tomé (Santa Fe), Argentina (Con 10 figuras en ei texto) El conocimiento sistemático de las Nayades de la cuenca dei Ama- zonas resulta bastante pobre aun si lo comparamos con el que se po- see respecto al resto de América neotrópica. Tal situación no depen- de tanto de la falta de trabajos dei tipo corriente sino, por el contra- rio, de la existência de una gran cantidad de tipos descriptos sobre la base de unos pocos ejemplares, muchas veces de pobre conserva- ción, con referencias geográficas imprecisas cuando no con desco- nocimiento total de su procedência. A esto debe sumarse la falta de co- lecciones básicas, los problemas que plantea la gran extensión de la cuenca y, sobre todo, la carência de trabajos orgânicos y de cierta con- tinuidad, respaldados en métodos adecuados de investigación. Resulta un hecho bien conocido aunque muchas veces olvidado en los trabajos sistemáticos, que las Nayades experimentan notables variaciones bajo la acción modifi- cadora dei biotopo en que se desar- rollan, dando así lugar a formas de reacción sumamente diversas, de modo que no es de extranarse que los distintos autores, ante ejempla- res aislados de tales variaciones, hayan podido distinguir otros tan- tos tipos diferentes describiéndolos como tales. Tal situación, que es de validez general, ya fue senalada en nuestro caso por Haas en varias oportunidades y en especial en su trabajo de 1930/31 (19). Reciente- mente se ha dado a conocer un in- teresante ensayo estadístico por parte de Zilch (53) , respecto a las especies paleárticas, donde se se- hala que de 1309 especies descrip- tas sólo resultan válidas 19 de ellas y 58 subespecies. Esto revela in- cuestionablemente la necesidad de efectuar estúdios revisivos en pro- fundidad, tendiendo a la reducción cm SciELO 10 11 12 13 14 15 16 64 Atas do Simpósio sobre a Biota Amazônica de la frondosidad sistemática re- sultante de una modalidad de tra- bajo puramente descriptiva y de es- caso fundamento científico. A tal efecto venimos ensayando desde un tiempo considerable la aplicación de los caracteres deter- minativos preconizados por Haas, fundado en el estúdio de la escul- tura umbonal y dei análisis de la forma de la concha joven, combi- nándolos con los propuestos por Ortmann, basados en el estúdio dei “glochidium”, la posición de la marsupia en la branquía interna y la forma y estructura de las bran- quías. A todo ello debe sumarse, lo- gicamente, el análisis conchológico de amplias colecciones correspon- dientes a una serie de localidades representativas dentro de los gran- des sistemas hidrográficos dei con- tinente, tratando de correlacionar tales variaciones con los caracteres dei biotopo en que se desarrollan. Debemos confesar que tal méto- do sólo ha podido ser ensayado par- cialmente en el caso de los Uniona- cea dei Amazonas, ya que no he- mos podido contar con la cantidad de material suficiente, sobre todo con las partes blandas conservadas, ni con mayores informaciones acer- ca de los caracteres de las aguas en que fueron obtenidas, lo que ha venido a limitar considerablemente los alcances dei trabajo propuesto. Pese a lo expuesto, se considera de interés dar a conocer el presen- te ensayo en la convicción de que el mismo ha de ser de utilidad para esclarecer, aunque sea en parte, la complicada marana sistemática creada en torno a estos moluscos, y que es necesario proveer a una información revisiva actualizada — aun a riesgo de cometer errores — que persistir en una situación como la actual, tan confusa como esté- ril, y carente de mayor significa- ción científica. LOS UNIONACEA AMAZÔNICOS Los Unionacea de la cuenca ama- zônica están compreendidos en la familia Hyriidae, que contienen a todos los representantes de Austra- lasia y América neotrópica. Los úl- timos integran la subfamilia Hyri- inae, agrupándose en tres tribus: Prisodontini, Castaliini y Diplodon- tini (44). Las dos últimas son co- munes a todas las grandes cuencas dei continente sudamericano, en tanto que la primera sólo se da en el Amazonas y en algunas cuencas más septentrionales, faltando com- pletamente en los rios integrantes dei sistema dei Plata. La tribu Diplodontini comprende sólo el género Diplodon Spix, cuyos dos subgéneros Diplodon ss y Rhi- pidodonta Mõrch, poseen especies en la Amazônia. Castaliini posee dos géneros: Castalia Lamarck y Callonaia Simpson (10) , ambos con representantes amazônicos, siendo el último exclusivo de esta cuenca. Volume 3 (Limnologia) 65 La tribu Prisodontini es descom- puesta en los trabajos más actuali- zados (42) en dos géneros: Paxyo- don Schumacher y Prisodon Schu- macher, siendo el último descom- puesto en dos subgéneros : Prisodon ss y Triplodon Spix. En realidad, como se verá luego, se considera que tal ordenamiento requiere con- siderables ajustes y que, aun a tí- tulo provisório, los últimos pueden ser llevados a la categoria de gé- neros. El rasgo más característico de los Unionacea de la cuenca amazô- nica está dado por la presencia de un género propio de la tribu Casta- liini, el género Callonaia, y por contener a los representantes de la tribu Prisodontini, que si bien exis- ten también en los rios de las Gua- yanas, son características de este sistema, faltan por completo en las aguas de los grandes potamos que concurren al Rio de la Plata. Cabe destacar que aunque en la cuenca amazônica se dan todos los géneros que existen en la dei Pla- ta, poseyendo además algunos ex- clusivos y otros que faltan en la última, el número de las especies registradas no es mucho mayor, ya que gran parte de los últimos, por no decir su totalidad, son monotí- picos. Es decir, que el número de especies realmente válidas, en ge- neral, aparece como muy limitado contrastando tal situación con la amplitud de la extensión geográ- fica alcanzada por las mismas . La enorme extensión de la cuen- ca también se refleja en diferen- cias distribucionales que, de mo- mento, no parecen muy claras. De mucho interés resultan en tal sen- tido algunas áreas de engranaje, especialmente las que definen los afluentes que arrancan en puntos próximos a las nacientes dei rio Pa- raguay, donde parece producirse el ingreso de algunas especies propias dei sistema dei Plata, y viceversa, fenómeno este que debe ser recien- te o que no alcanzaría todavia una gran extensión sobre ambas cuen- cas. Tribu: DIPLODONTINI Género DIPLODON Spix El género Diplodon Spix es el más común y extendido entre todos los Hyriinae, presentando una eviden- te unidad de conjunto, distingui- éndose claramente de los restantes géneros de la subfamilia. La con- formación regular de la concha, la sencillez de la escultura umbonal y dei aparato articular de las val- vas, son bien característicos y no exigen mayores comentários. Den- tro de este conjunto se distinguen dos subgéneros : Diplodon ss y Rhi- pidodonta Mõrch, especialmente en base a la forma “larval”, aunque también puede sumarse a estos ciertos detalles conchológicos y anatómicos menos claros y defini- 3 — 37 121 cm SciELO 10 11 12 13 14 15 16 66 Atas do Simpósio sôbre a Biota Amazônica torios. El subgénero Diplodon ss, posee “glochidium” parásito, en tanto que Rhipidodonta se caracte- riza por que las crias se desarrol- lan directamente, completando en la marsupia la formación de la al- meja juvenil, es decir, sin requerir una etapa de vida parásita. Subgénero DIPLODON ss Diplodon (Diplodon) granosus granosus (Bruguière) Unio granosa Bruguière, 1792 Haas al ocuparse de esta especie en su importante trabajo de 1930/31 (19), distingue la existên- cia de tres subespecies, haciendo llegar a la típica desde las Guaya- nas al estado de São Paulo, en tan- to que distingue a D. granosus el- lypticus (Spix) para el rio San Francisco y los rios costeros de Bahia, y a D. granosus multistria- tus (Lea) para los rios de la pen- diente atlântica dei sur de Brasil hasta el estado de Santa Catarina y el Alto Paraná. Tales distingos no parecen muy claros ni correctos pero, de cual- quier forma, pueden ser aprovecha- dos en parte, sehalando que lo considerado como D. granosus el- lypticus corresponde parcial o to- talmente a simples formas de D. rhombeus (Wagner) y reservan- do el nombre de D. granosus mul- tistriatus para el conjunto de for- mas que se hacen presentes en los rios de la pendiente atlântica de Brasil, al sur dei rio San Francisco, y en el Alto Paraná. Cabe sehalar, además, que entre los materiales estudiados por Haas, así como por otros distintos auto- res, no parecen encontrarse ejem- plares de esta especie de procedên- cia amazônica. Por mi parte sólo posee unos pocos ejemplares, mal conservados, que quizas puedan corresponder a esta especie y cuya única referencia es la “Rio Amazo- nas”. El hecho llama poderosamen- te la atención ya que si la especie se extiende desde las Guayanas hasta Santa Catarina y el Alto Pa- raná, parecería definir un extenso hiatus correspondiente a toda la cuenca amazônica. Claro está que es posible que esta anomalia pueda atribuirse a las de- ficiências de las colecciones existen- tes, o a falta de una verdadera re- lación específica entre D. granosus, propiamente dicho, y el grupo de especies que se subordinan cor- rientemente a U. multistriatus Lea. Caso contrario debemos admitir que el Amazonas posee condiciones que resultan inadecuadas al desar- rollo de D. granosus, lo que indi- caria que se trata de una es- pecie particularmente estenotopa. El problema merece un adecuado estúdio y sólo puede ser resuelto mediante la intensificación de las investigaciones acerca de la espe- cie típica, muy poco conocida, y la Volume 3 (Limnologia) 67 realización de colecciones sistemá- ticas en la cuenca que nos ocupa. Diplodon (Diplodon) rhombeus rhombeus (Wagner) (Fig. 2) Unio rhombeus Wagner, 1827 Unio rotundus Wagner, 1827 Unio patelloides Lea, 1860 Diplodon enno Ortmann, 1921 Diplodon jacksoni Marshall, 1928 Diplodon (Diplodon) beskeanus nordestinus Haas, 1938 En diversas publicaciones ante- riores se hizo referencia al hecho de que D. rotundus Wagner y D. fontaineanus Orb., pertenecían a una misma especie, la que en su distribución probablemente alcan- zaría también al Amazonas. Reci- entes estúdios llevados a cabo en el museo de Senckenberg, Frankfurt, sobre la colección de Ihering, han venido a confirmar tal identidad y a demostrar que la especie se ex- tiende al Amazonas por el norte, llegando por el sur hasta el Alto Paraná y los rios costeros hasta el estado de Santa Catarina, experi- mentando a lo largo de tan exten- so território grandes variaciones conchológicas que dieran lugar a una considerable cantidad de tipos descriptos. En conjunto, podemos distinguir dos subespecies: Diplodon rhom- beus rhombeus (Wagner) para el Amazonas, el San Francisco y los rios de la pendiente dei Atlântico comprendidos entre ambas cuen- cas; y a D. rhombeus fontaineanus (Orb.) , que se extiende desde el rio Doce y los rios costeros hasta el estado de Santa Catarina y el Alto Paraná. La identidad de D. rhombeus con D. rotundus no deja lugar a dudas, confirmándose así lo expresado por Haas en su fundamental trabajo de 1930/31. Lo mismo cabe expresar respecto a D. patelloides (Lea). Pero, a este conjunto de formas de- cididamente redondeadas, que Haas considerara equivocadamente como propias dei subgénero Cyclomya Simpson — Rhipidodonta Mõrch, se hace necesario sumar otro, algo más bajas, aunque local y circuns- tancialmente pueden adquirir per- fil redondeado. Entre ellas se en- cuentra D. enno Ortmann, Diplo- don beskeanus nordestinus Haas y D. jacksoni Marshall. El rasgo co- mún que las vincula está dado por un conjunto de caracteres a los que nos hemos referido anteriormen- te (5) , y entre los que se destacan una escultura de variable conver- gência, a veces con varias costillas confluentes, una ligera depresión dei margen ventral por debajo de los umbones, la forma moderada- mente alargada de la concha ju- venil con tendencia posterior al crecimiento en altura, el escaso de- sarrollo dei aparato articular de la charnela, la tonalidad azulada-gri- sácea dei nácar y ei color pardo oscuro o negro mate dei periostra- co. Por otra parte, la conformación cm SciELO 10 11 12 13 14 15 16 68 Afas do Simpósio sôbre a Biota Amazônica dei “glochidium” parásito y la po- sición de la marsupia en la bran- quia interna (subcentral o ligera- mente desplazada hacia adelante) aportan otros tantos elementos diagnósticos complementarios. Cabe senalar la posibilidad de que D. ellypticus (Spix) correspon- da también a este conjunto de for- mas, cuando que en general se lo considerara vinculado a D. grano- sus. En este caso, los otros nom- bres deberían subordinársele por razones de prioridad. Diplodon (Diplodon) parodizi Bonetto Diplodon parodizi Bonetto, 1960 Unio burroughianus Lea, parcial- mente en Orbigny, 1834 Unio burroughianus Lea, en So- werby, 1886 Diplodon eharruanus (Orb.), par- cialmente en Haas, 1930 Diplodon eharruanus (Orb.), en Bo- netto, 1953 Esta especie, tan común en aguas dei Paraná medio e inferior y dei rio Paraguay, se hace presente también en los afluentes dei Ama- zonas que nacen en Bolivia, de acuerdo a lo expressado — aunque no muy claramente — por Orbig- ny (41), lo que se deduce dei ejem- plar que reproduce y comenta So- werby (49) * y a lo que hemos podido establecer a través de al- gunas muestras procedentes dei rio San Miguel, afluente dei Guaporé. En el resto de la cuenca amazô- nica parece ser desconocida, lo que * La referencia de estos autores corresponde a D. burroughianus (Lea) vendría a indicar que se trata de una especie de reciente incorpora- ción a la misma a través de las ca- beceras dei rio Paraguay. La especie es fácilmente recono- cida por su forma moderadamente alargada rematada posteriormen- te en un ângulo marcado, por el relieve de la escultura con clara convergência de las costillas cen- trales, y la posesión de un “glochi- dium” parásito. Diplodon (Diplodon) parallelopi- pedon (Lea) (Fig. 1) Unio parallelopipedon Lea, 1834 Unio acutirostris Lea, 1866 ? Diplodon trifidus (Lea) , en Ort- mann, 1921 En el ano 1921 Ortmann (43) describe, sin proporcionar figura, a lo que considera el verdadero U. trifidus Lea, expresando su con- vicción de que esta especie es ama- zônica y que la localidad origina- ria (Buenos Aires), senalada por Lea, correspondería a un error ya que, hasta entonces, no había vuel- to a ser encontrada. En el ano 1953, al ocupamos de la fauna de Nayades dei rio Para- ná (3), sehalábamos que esta es- pecie existe, aunque parece ser al- go rara, en el Paraná medio. Por otra parte, el lote origi- nal de Ortmann constituido por 6 ejemplares obtenidos por Hase- man en el rio Guaporé, cerca de Volume 3 (Limnologia) ò cal podzols are charac- terized by the tendency of one or some plant species towards domi- nance (Richards, 1945) . Bakker (without year) gives some reasons of extreme bleaching of soils, under tropical environ- mental conditions. One of them is the extreme acidity of leaf extract and litter of certain tropical plant species. DISTRIBUTION OF TROPICAL PODZOLS The distribution of lowland tro- pical podzols shows a remarka- ble geographic pattern (Klinge, 1965a). After D’Hoore (1964) they are rare in África where they occur in small patches. They have devel- oped from both Coastal sandry se- diments along the east and west coast of this continent, and from river sediments, and at few places in the Congo basin; they are also known to exist on the islands of Mafia and Madagascar. Most Afri- can blackwater rivers, however, flow from moor and swamp land. In Australasia (Dudal & Moor- mann, 1964) where lowland tropi- cal podzols are often associated with swamps and peat formation, they partially occupy extent areas. These podzols are known to occur in the Mekong basin, eastern Ma- lay Península, upon Borneo, New Guinea, and some other Indone- sian islands as well, in tropical and cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 119 subtropical Australia, and upon the North Island of New Zealand. Seepage of podzol areas is of the blackwater type (Dudal & Moor- mann, 1964; van Steenis, 1957) . Lowland tropical podzols of Ame- rica are reported from Florida and the Guianas as well where they occur in areas of relatively large extent. Podzols have been describ- ed from some of the Antilles and eastern Central America. In the Amazon basin where lowland tro- pical podzols are widespread they occupy small isolated patches. Low- land tropical podzols are always associated with blackwater rivers, but these rivers flow also from peats and swamp soils, mainly in Florida and the Guianas. Podzols of mountains within the tropical belt have been reported from all continents and are bound to acid rocks, or impeded drainage, and to cool humid climatic condi- tions as well. UNESCO, within its Humid Tro- pics Research Programme, is ac- tually preparing a symposium on tropical podzols, their vegetation, and blackwater rivers associated with these soils. PODZOLS OF TROPICAL SOUTH AMERICA In tropical South America pod- zols are known to exist in both low- lands and uplands. Podzols occur at some places of the Coastal regions of Colombia and Brazil as well. There is no literature on podzols of the Orinoco basin. Rather detail- ed informations, however, are available on lowland tropical pod- zols of the Coastal plains in Suri- name, British and French Guiana as well. There are only few informations on podzols in western Amazônia including the eastern parts of Co- lombia, Ecuador, Peru, and Boli- via. Ellenberg (1959; 1964) report- ed shortly on these soils which were observed in the surroundings of Iquitos, Peru, and Wright (1964) described a mature soil trending towards a tropical gley podzol, from eastern Bolivia. Grubb. et al. (1963) referred brief- ly to soils which show similarities with podzols of temperate regions, in Ecuadorean Amazônia. Podzols of Brazãlian Amazônia are dealt with in the subsequent chapter. Mountain podzols have been re- ported from the Andes and the Guiana Highlands as well. LOWLAND TROPICAL PODZOLS OF BRAZILIAN AMAZÔNIA The relationship between black- water rivers and podzols of Ama- zônia is not touched in the pre-war literature. But Sioli (1954; 1956), cm l SciELO LO 11 12 13 14 15 16 120 Atas do Simpósio sôbre a Biota Amazônica in papers on blackwater rivers of the Upper Rio Negro, pointed out that these rivers flow from sandy wet soils (not studied by the au- thor) covered with caatinga forest (Hueck, 1966; Rodrigues, 1961; Takeuchi, 1962). The fact that these blackwaters contained free aluminum which never before were found in any other Amazonian ri- ver water, induced the conclusion that the aluminum content of the blackwater is due to the breakdown of aluminum silicates in the sandy soils from which the blackwater flows and that podzolation is going on in these soils. The association of blackwater ri- vers and white sandy soils has been already observed by Spruce (1908) and others. The pedologist who first studied Amazonian podzols appears to be Day (1961). He described both very sandy groundwater podzols devel- oped on Quaternary sediments un- der poor to imperfect drainage con- ditions, and well drained Pará pod- zols which are more of academic interest than of any agricultural value. Some data on both types of podzols are tabulated below. TABLE 1 Groundwater podzols and Pará podzols of Amazônia (After Day, 1961) Groundwater podzols Pará podzols Relief Levei to gently sloping, low lying terraces. Fiat to gently sloping or undulat- ing. Drainage High water table. Natural drainage is poor. Run-off of surface water is slow. Excessivo. Vegetation Poor to very poor forest. Brushes and low trees. Use Essentially non agricultural soils of very low fertility. Extremely low fertility and water- holding capacity limit the agri- cultural usefulness of these soils. Distribution In small drainage-ways. Probably widespread throughout the Lower Amazon. Of very limited extent in any individual unit and total area is relatively small. Observed in two loealities in the Lower Amazon (near Belém, Pará, and north of Macapá, Territory of Amapá). In 1962, several authors have nian soils, inclutíing some podzols reported on Amazonian podzols. under caatinga and campina fo- Klinge published data on carbon rests, and wet campos as well. Sio- and nitrcgen contents of Amazo- li & Klinge discussed relations be- cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 121 tween podzols, blackwater rivers and podzols vegetation, especially of the Rio Negro. Vieira & Santos described a groundwater podzol of the surroundings of Breves, Pará, giving also some analytical data on this soil. Vieira & Filho discuss- ed results of soil investigations performed in caatingas of Uaupés, the soils being described as podzo- lic regosol, on brown soils of gra- nitic origin, and regosol, both de- veloped from sandy river sedi- ments. Falesi (1964) described podzols of the Zona Bragantina, Pará, and Klinger & Ohle (1964) reported on Chemical properties of both soils and waters, in Amazónia. Recently, Altemüller & Klinge (1964), and Klinge (1965 b) de- scribed catenary soil sequences in which giant podzols occur, from the Manaus area. The catenas were found on slopes of small valleys drained by blackwater rivers. The giant podzols occupying the lowest sites of the catenas are characte- rized by a few meters deep bleached sand layer and a remarkable thin humic cemented ortstein as well. The thin ortstein is suggested to be related to lateral percolation of rain water which carries away the organic matter migrating through the podzol profile. The mobil or- ganic matter, subsequently, passes into the creeks and so doing deter- mines the characteristics of the blackwater. Blackwater rivers have been re- lated to lateral percolation on pod- zols, in other tropical countries too (Dames, 1962; Dost, 1964). RELATIONS BETWEEN TROPICAL PODZOLS AND BLACKWATER Since von Humboldt (1860) re- ported on blackwater rivers of equatorial South America, and Muntz & Marcano (1888) dis- cussed the origin of blackwater co- lour, literature on black-water in South America has grown much, and many theories about blackwa- ter rivers and the colouring sub- stances as well have been for- warded . Koch-Grünberg (1909) reported on Indian talks in which the colour of blackwater rivers is explained by extracts of the salsaparilla plant. ( Smilax ) . After Beebe (1927) the colour is mainly caused by staines derived from the leaves of the Wallaba tree ( Eperua falcata Aubl.) The same explanation was given by Davies & Richards (1933). De Civrieux & Lichy (1950), in a brief historical summary of opi- nions about blackwater and its co- lour, referred to von Humboldt who reported on thick grass mats and roots of salsaparilla (Smilax), cm l SciELO LO 11 12 13 14 15 16 122 Atas do Simpósio sóbre a Biota Amazônica as sources of the staines; von Hum- boldt gave notice too on Upper Ori- noco Indians who believed that the staines are extracts of the moriche- to palm. De Civrieux & Lichy themselves supposed that the key to solve the problem is in the swamp forests from which black- water rivers flow. By other authors (Huber, 1906, Sioli, 1956) the opinion was ex- pressed that blackwater rivers ori- ginate in the so-called igapó fo- rests which accompany many Amazonian blackwater rivers. In tropical and non-tropical re- gions as well, blackwater rivers are known to flow from peat soils. In these cases the colour of the water is due to organic matter derived from the peat. There are, however, tropical blackwater rivers flowing from poázol soils. The following facts speak in favour of a genetic rela- tionship between both podzols and blackwater: I) Blackwater rivers may be in- timately associated with pod- zols growing specific forest ty- pes, in Amazônia and other tropical South America as well, mainly the Guianas (Bleackley & Khan, 1963), and others) . This association has been observed too by geo- graphers, botanists and limno- logists as well, in the tropical belt (cf. Proc. Unesco Sympo- sia held at Abidjan, Tjiaw and Kuching) . II) The blackwater character of groundwater in podzols soils points on a genetic relation- ship between both the soils and the water, in the tropics (van Steenis, 1935 a; 1935 b; 1957) . III) The observa tion that the co- lour of blackwater becomes more intensive when it rains after a period of droughtiness, is supposed to be related to the outflow of dark coloured groundwater which subse- quently is diluted by further rain. IV) Podzol ortsteins the thickness of which does not correspond to that of the bleached sand horizons, are found at sites where drainage is mostly la- teral, and have been described from Amazônia (Klinge, 1965 a) , and the Guianas (Bleackley & Khan, 1963; Dost, 1964) as well. This communication based more on literature studies than on field or laboratory work may be con- cluded with a reference to Richards (1957) who wrote: “Blackwater’ streams are also found flowing from Tropical moor forest (peat swamp), but where no cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 123 extensive swamps are known to exist ‘blackwater’ is a trustworthy guide to the presence of bleached sands.” As said above, these bleach- ed sands are often to be classi- fied as podzols, from the pedolo- gical point of view. SUMMARY The intention of this literature review is to point on the very strik- ing association of blackwater ri- vers and podzols under specific plant communities which is known since the first naturalists traveled through the humid tropical belt. After defining the pedological terms podzol, tropical podzol, and lowland tropical podzol as well, the distribution of lowland tropical podzols and their association with blackwater rivers in África, Ame- rica, and Australasia are regarded. Special reference is made to Amazônia and its Brazilian portion from where podzols have been re- ported in recent years. These pod- zols are found under both caatinga and campina forests, and wet cam- pos as well, and are always asso- ciated with blackwater rivers. It is well understood that black- water rivers flow from peat and swamps, in tropical and non-tropi- cal countries as well. There is no doubt, however, that blackwater rivers originate in podzol areas, in the humid tropics. Some facts which point on a genetic relation between both blackwater rivers and podzols are tabulated. REFERENCES Altemüller, H. J. & Klinge, H„ 1964, Mikromorphologische Untersuchun- gen iiber die Entwicklung von Pod- solen im Amazonas-becken. In: Soil Micromorphology (A. Jonge- rius ed.) Amsterdam, Elsevier, p. 295-305. Anon., 1960, Multilingual vocabulary of soil Science. G. V. Jacks, R. Traver- nier, D. H. Boaleh (ed.) Rome, FAO 2nd ed. 430 p. Anon., 1964, Preliminary definition, le- gend and correlation table for the soil map of the world. World Soil Resources Reports, 9: 74 p. Beebe, W., 1927, Studies on a tropical jungle. Zoologica, N. Y„ 6: 5-193. Bleackley, D. & Khan, E. J. A., 1963, Observations on the whitesand areas of the Berbice formation, British Guiana. J. Soil Sei., 14 (1) : 44-51. DE CIVRIEUX, M. & Lichy, R., 1950, Es- tado actual dei problema de las coloraciones observadas en águas ecuatoriales de Venezuela. Boi. Acad. Cien. fis., Caracas, 13 (40) : 19-36. Dames, T. W. G., 1962, Soil research in the economic development of Sarawak. FAO Rep. no. 1512. Davies, T. A. W. & Richards, P. W., 1933, The vegetation of Moraballi creek, British Guiana. J. Ecol., 21 (2): 350-384. cm l SciELO L0 11 12 13 14 15 16 124 Atas do Simpósio sôbre a Biota Amazônica Day, T. H„ 1961, Soil investigations conducted in the Lower Amazon valley. FAO Rep. no. 1395. Dost, H„ 1964, Soil conditions and soil classiíication in Surinam. Abstr. 8th Int. Congr. Soil Sei. 5: 30-33. Dudal, R. & Moormann, F. R., 1964, Major soils of Southeast Asia. J. Trop. Geogr., 18: 54-80. Ellenberg, H„ 1959, Typen tropischer Urwàlder in Peru. Schweiz. Z. Forstwes., 3: 169-187. Ellenberg, H., 1964, Stickstoff ais Stan- dortfaktor. Ber. dtsch. bot. Ges., 67 (3): 82-92. Falesi, I. C., 1964, Levantamento de re- conhecimento de talhado dos solos da Estrada de Ferro do Amapá. Boi. tec. Inst. Pesq. Exp. agropec. Norte, 45: 1-53. Grubb, P. J„ Lloyd, J. R., Pennig- ton, T. D. & Whitmore, T. C„ 1963, A comparison of montane and low- land rainforests in Ecuador. I. J. Ecol., 51: 567-601. Huber, J„ 1906, La végétation de la vallée du Rio Purus (Amazone). Buli. Herb. Boissier, 6 (4) : 249-276. Hueck, K., 1966, Die Wãlder Südame- rikas. 422 p., Stuttgart. Fischer. D’Hoore, J. L., 1964, La carte des sois d’Afrique au 1/5.000.000. Lagos. C.C.TA. Publ. no. 93. von Humboldt, a., 1860, Reise in die Aequinioctial-Gegenden des neuen Continents. Vol. 3. Stuttgart, Cotta. Klinge, H., 1962, Beitrâge zur Kenntnis tropischer Bõden. V. Z. Pfl-Ernãhr., Düng-Bodenk., 97 (2): 106-118. Klinge, H., 1965a, Report on tropical podzols. Paris, UNESCO. 139 p. (Under press.) Klinge, H., 1965b, Podzols soils in the Amazon basin. J. Soil Sei., 16 (1) : 95-103. Klinge, h. & Ohle, W., 1964, Chemical properties of rivers in the Amazo- nian area in relation to soil con- ditions. Verh. int. Verein. theor. angew. Limnol., 15 (2) : 1067-1076. Koch-Grünberg, T„ 1909, Zwei Jahre unter den Inãianern. Berlin, Vol. I. Muir, A., 1961, The podzol and podzolic soils. Adv. Agron., 13: 1-56. Muntz, A. & Marcano, V., 1888, Sur les eaux noires de régiones équatoria- les. C. R. A.cad. Sei. Paris, 107 (14) : 908-909. Richards, P. W., 1941, Lowland tropical podzols and their vegetation. Na- ture, 148 (3774): 129-131. Richards, P. W., 1945, The floristic composition of primary tropical rain forest. Biol. Rev., 20: 1-13. Richards, P. W., 1957, The tropical rain forest. Cambridge, University Press. Reprint of the 1948 ed. 450 p. Rodrigues, W. A., 1961, Aspectos fitos- sociológicos das caatingas do Rio Negro. Boi. Mus. Paraense “Emílio Goeldi”, n.s„ Bot. no. 15. Schneider, S„ 1961, Synonyma-Liste “Moor und Torf”. Torfnachrichten, 12 (7/8): 1-61. Sioli, H„ 1954, Gewásserchemie und Vorgange in den Bõden im Ama- zonasgebiet. Naturwissenschaften, 41 (19): 456-457. Sioli, H., 1956, As águas da região do Alto Rio Negro. Boi. téc. Inst. agron. N„ 32: 117-155. Sioli, H. & Klinge, H„ 1962, über Gewásser und Boden des brasilia- nischen Amazonasgebietes. Erd. Berl., 92 (3) : 205-219. cm SciELO 10 11 12 13 14 15 16 Volume 3 (Limnologia) 125 Spruce, r., 1908, Notes of a botanist on the Amazon and the Andes. Lon- don, Macmillan, 2 vols. van Steenis, C.G.G.J., 1935a, Maleische vegetatieschetsen. I. Tijdschr. K. ned. aardrijksk. Genoot, (2) 52: 25-67. van Steenis, C.G.G.J., 1935b, Maleische vegetatieschetsen. II. Tijdschr. K. ned aardrijksk. Genoot., (2) 52: 171-203. Van Steenis, C.G.G.J., 1957, Outline of vegetation types in Indonésia and some adjacent regions. Proc 8th Pacif. Sei. Congr. 1953, 4: 61-97. Takeuchi, M., 1962, The strueture of the Amazonian vegetation. IV. J. Fac. Sei. Tokyo Univ. Section 3, Bot., 8 (2): 27-35. Vieira, L. S. & Santos, W. H., 1962, Con- tribuição ao estudo dos solos de Breves. Boi. téc. Inst. agron. N., 42: 33-55. Vieira, L. S. & Filho, J.P.S.O., 1962, As caatingas do Rio Negro. Boi. tec. Inst. agron. N., 42: 7-32. Wright, A.C.S., 1964, Report on the soils of Bolivia. World Soil Resour- ces Reports, 10: 54 p. Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 127-140 — 1967 THE ARTIFICIAL BROKOPONDO LAKE OF THE SURINAME RIVER. ITS BIOLOGICAL IMPLIC ATION S P. LEENTVAAR State Institute for Nature Conservation Research (Rivon), Zeist, The Netherlands (With 6 text-figures, 1 map and 3 graphs) On February 1, 1964, the dam across the Suriname River at Afo- baka (Surinam) was closed and the artificial Brokopondo Lake be- gan to fill. The lake will ultimate- ly cover an area of 1.500 km 2 tro- pical forest and the water is being used for hydroelectric purposes. At the end of 1963 a team of four bio- logists were enabled by the Nether- lands Foundation for the Advance- ment of Research in Surinam and the Netherlands Antilles (Wosu- na) to study the alterations in plant and animal life in the lake region. The work is being carried out under the auspices of the Ne- therlands Foundation for Scienti- fic Research in Surinam and the Netherlands Antilles (“stu- diekring”) . Hydrobiological re- search was started some months before the closure of the dam by P. Leentvaar and continued at pre- sent by J. V. D. Heide. The bota- nist, Dr. J. Van Donselaar carries out botanical inventarisation. Ich- thyological inventarisation is being carried out by various investiga- tors. Few biological data were known from the river before the closure and the available time un- til the dam was closed was short; consequently our knowledge of plant and animal life before the changing of the environment is scarce. A few trips on the river and regular sampling at Pokigron in the upper course, yielded an im- pression of the undisturbed river. The description of the river is of interest for comparison with tributaries of the lower Amazon ba- sin which rise also in the Guiana highlands. The Suriname River and its tributaries Pikien Rio and Rivon communication nr 234. 128 Atas do Simpósio sobre a Biota Amazônica Gran Rio rise in the highlands of Guiana just north of the Brasilian border. The river flows northward through tropical rainforest. The ri- verbed is rocky. Trees border the river, but neither swampy vegeta- tion nor areas with stagnant wa- ter occur along the banks. The wa- ter flows swiftly where rapids and falis are present. Between these obstacles the river flows, sluggish- ly. The river carries little silt and there is practically no mud at the bottom. Sand flats are visible at dry times. The water is poor in mi- nerais, as is shown by the low elec- tric conductivity of about 20uS. The pH is about 6.5 and the wa- ter is almost saturated with oxy- gen. The temperature varies bet- ween 28 and 30°C. The transparen- cy, measured with the Secchi-disc, is about 1 . 5 meters. The colour of the water is greyish-brown; it ori- ginates from brown particles sus- pended in the water and not from dissolved humic substances. There is a high amount of silica and some iron. In small, shallow tributaries, such as the Sarakreek (map), the turbidity of the water is higher and more iron is present; the elec- tric conductivity is higher, the oxy- gen content is lower and the tem- perature is also lower due to sha- dow by trees. The colour of the wa- ter is turbid-brown. For the Ama- zon basin Sioli (1964) distin- Fig. 1 — The barrage in the Suriname River at Afobaka, with dead trees in the lake (June 1964). cm 1 SciELO 130 Atas do Simpósio sôbre a Biota Amazônica The total mass of organisms and also of plankton is low. Therefore it is surprising, that the river is comparatively rich in fish. The food Chain of the fish is not clear; probably some of the fish feed on the relatively numerous shrimps, but several species prey on other fish. River conditions vary in the dry period and the rainy period. Ac- cording to weekly observations at Pokigron in the upper course of the river, the water levei is fairly stable from December until March. In the last week of May, the main rainy season starts and the water levei rises about 2 meters for a pe- riod of two months. In the dry sea- son plankton is developing but soon after the beginning of the rains, this plankton is washed downstream. Plankton catches ire composed now of species, which occur in tributaries; when the rains last long practically no more plankton is found. Therefore, du- ring the months of July and Au- gust, pure water flows down the ri- ver. At this time the pH and elec- tric conductivity of the water are lowest. This seasonal fluctuation Fig. 3 — Growth of filamentous algae in quiet parts of the lake, between inundated trees, near the village Koffiekamp (July 1964). VO o o 2 < vo O) LU < O o o CL O 2É O 0: CD Q 2 < cc LU > 2 <1 z ü: D LO > LU _l < $ O 2 < (/> LU LO -I T3 ■ ■£ -<- -S N — s -s — s -s. — s ! -3 »- l£> ■S- — s - -s o > cm 1 SciELO 10 11 12 13 14 15 CHEMICAL ANALYSES ANO WATER LEVEL OF THE SURINAME RIVER AND THE BROKOPONDO LAKE IN 1963 AND 1964 ÍN Volume 3 (Limnologia) 131 Fig. 4 — Suriname River near the village Koffiekamp in the dry season < January 1964). in plankton and mineral content in the flowing river affected con- ditions in the expanding lake, when the water entered this lake. After the closure of the dam ob- servations were started at 2 of the future 10 sampling stations. The following data concern only these two stations, (until September 1964) located at Afobaka near the dam in the midst of the river and in the Sarakreek inside the forest. As is shown in graph 2, the wa- ter levei rose quickly. The gauges are given in NSP = New Surinam Levei. During the short rain in March and in the long rainy pe- riod following the end of May the rise in levei was accellerated. In the same graph the surface values are given of oxygen, temperature, pH, electric conductivity and transpa- rency measured with the Secchi- disc. The differences between Suri- name River and Sarakreek before the closure are easily detected in the graph. Soon after the closure the water stagnated at both sta- tions and a Sharp drop in oxygen content occurred. At Sara the exhaustion was greater as more de- caying organic matter was present and stagnation was enhanced by lack of wind between the trees. In Sara station for several weeks no oxygen was found from top to bot- 132 Atas do Simpósio sobre a Biota Amazônica tom. After 18 March 1964 the oxy- gen content increased again, but only in the upper 3 to 4 meters. Two periods of increasing oxygen content are obvious, especially in the curve of Sara . The first increase occurred during the dry time of April and May; the second during the prolonged rain period after June. In September both stations obviously became equal in oxygen content. At this time more open space appeared between the trees by the rising water levei at Sara, even more, by the total inun- dation of trees. As a consequence the improved illumination of the water surface favoured oxygen proàuction by the plankton. Also the temperature increased, but the temperature at Sara — more sha- dowy by trees — remained about two degrees lower than at Afoba- ka. Higher temperatures were found at the surface of the stag- nant water than in the flowing stretches. At Afobaka the maxi- mum temperature recorded was about 35° C. Temperature and oxygen were fluctuating strongly during the day in the stagnant water (graphs 3 and 4). The trans- parency of the water at Sara in- creased more than at Afobaka, de- Fig. õ — Grmcth of waterhyacinth in the lake (August 1964). BROKOPONDO BARRAGE LAKE NEAR AFOBAKA £ e CM CM CM Ê Ê £ Ê í ! n E £ Ê £ £ i Ê Ê tfl »R ifl (M^ SC SC -'C CTl* s: í« ac -sc -sc irN sc SC SC -sc SC sc : Sc lO lT) U"> ifl i/) cm l 10 11 12 13 14 15 16 17 SciELO 21 22 23 24 25 26 27 29 30 31 32 33 34 35 36 37 Volume 3 (Limnologia) 133 Fig. 6 — The dry riverbed below Afobaka, after the closure of the dam f February 1964). monstrating the greater stagnation in the water between the totally drowned trees. During the rain time the transparency increases and the electric conductivity de- creases by dilution . In dry times the electric conductivity increas- ed gradually. In deeper water layers an increasing amount of minerais was found, as is shown in graph 3 in which curves are plot- ted for each depth. The fluctua- tions in the deeper water are great- er. After stagnation the pH drop- ped to about 5.5 at both stations; in graph 3 it is clearly visible, that a fluctuation of short duration occurred at the beginning of each rain time, in all water layers. The lower pH found after stagnation may be caused by the larger amount of CO- derived from decay- ing material and also from dissolv- ed humic substances, which now made their appearance in the water. The colour of the water turned to light brown. Iron was precipitated and could be found suspended near the anaerobic zone at 3 or 4 meters. In the anaerobic deeper water the amount of dis- solved iron increased and the same was true with regard to phosphate. Also H-S was formed . The said physical and Chemical alterations in this aquatic environ- 134 Atas do Simpósio sôbre a Biota Amazônica ment strongly affected plant and animal life. It is hardly possible to indicate which of the factors had the strongest influence on the biocommunity. The absence of flow caused a Chain of alterations of which the change in oxygen con- tent is the most important. This is illustrated by the general obser- vation, that in the flowing river the oxygen content was higher at night than at daytime and that in the stagnant water of the lake the oxygen content at night was considerably lower than at day- time. The oxygen metabolism in the river is abiogenie. Differences in temperature rule the oxygen content in the diurnal cycle since plant and animal life is scarce in the river. Oxygen production and consumption in dark and light bottles could hardly be measured by the paucity of plankton. In the lake oxygen was found in an up- per layer where the ligth penetrat- ed; the present larger amount and other species of plankton produ- ces sufficient oxygen at daytime. At night the oxygen content drop- ped sharply by respiration activity and by the presence of large amounts of reducible substances (see graph 4). The differences in temperature in the diurnal cycle cause conver- sions in the upper layers only. The effect of insolation is restricted to the upper 2 . 5 meters of water (see further Leentvaar, 1966) . Braun (1952) found instable thermocli- nes at 2-3 meters in shallow lakes in the Amazon region. As mentioned above, the river plankton was composed mainly of diatoms and desmids. The most frequent diatom was Eunotia aste- rionelloides; other species were Mc- losira sp., Rhizosolenia spp. and Surirella spp. After closure the ri- ver plankton could not exist any longer; it became succeeded by a transitional plankton and even- tually by a more stable “lake plankton”. In the transitional pe- riod, when the oxygen decreased in all layers, the diatom Eunotia dis- appeared and also other species from the river plankton. Other ele- ments such as Eudorina elegans developed in great numbers and the water got a green colour. Thus the transitional zone (period) could be detected by its colour; as the lake area expanded southward a green “wave” of the transitional zone also moved southward . Other elements in this plankton were Cyclops, Diaphanosoma and rotifers. In special cases and tem- porarily the organisms of the tran- sitional zone also developed strong- ly in the flowing river, i.e. during disturbances, occurring at the be- ginning and at the end of a rainy period. It is an example of selfpu- BROKOPONDO BARRAGE LAKE - DAILY OBSERVATIOIMS (1964 ) Volume 3 (Limnologia) 135 rification of the river under natu- ral circumstances. The permanent disturbance caused by the dam interrupted the normal cycle and the community was succeeded by plankton, composed of many uni- cellular flagellates ( Trachelomo - nas, Strombomonas) and nume- rous crustaceans and rotifers, oc* curring only in the oxygenated 3 or 4 meters below the surface. This community was composed of many species typical of stagnant water. No detailed description is given here of the final “lake plankton”; it may be said however, that at the end of my observation period (Sep- tember 1964) large colonies of green algae, such as Dictyosphae- rium, and many crustaceans and rotifers seemed to be the more per- manent components of the plank- ton. It is interesting to note, that near the anaerobic zone of the lake numerous specimens of the ro- tifer Sinantherina spinosa appear- ed and also numerous wiftly mov- ing turbellarian worms ( Catenu ■ la lemnae). The above picture of various plankton stages is based on observations in open water. In forest areas with drowned trees, oxygen was limited to a thin top layer and, as a result, the vertical distribution of plankton was more restricted. Also other organisms typical of shallow stagnant water were found. Since the trees acted as a windscreen extensive fields of Lemnaceae developed temporarily, as well as large masses of float- ing filamentous algae ( Spirogyra , Mougeotia) . The algae produced large amounts of oxygen, often leading to supersaturation, but outside the algal mats oxygen was absent. Many organisms were found in the threads of algae, such as bottom living Cladocerans ( Eu - ryalona occidentalis, Iliccryptus, Chydorus ) and many specimens of the big Conchostracod Cyclesthe- ria hislopi. These organisms occur- red also in open water, transport- ed by wind action. Also other or- ganisms could be found in the al- gal mats, such as ephemerids, odo- nata, hemiptera, and locally the gastropods Drepanotrema anati- num, Aplexa marmorata, Gundla- chia, Taphius khünianus and Acro- loxus. They did not occur in the former flowing water and must have come from shallow, stagnant parts. The dead leaves of the drowned trees soon became covered with green masses of filamentous algae. When the water levei rose these algae died by lack of light but reappeared at a higher levei. On the dead leaves also many tu- bes could be found of oligochaetae {Der o, Aulophorus, Pristina, Aeo- Icsoma) . Most of the organisms which liv- ed on the former riverbed died on 136 Atas do Simpósio sôbre a Biota Amazônica account of lack of oxygen at the bottom. Some however were found living at floating substrate such as sponges, ephemerids and odonata. Fish only cccurred as surface dwel- lers in the oxygenated layer. The bottom dwelling fish of the former river died or escaped the anaero- bic water. At Afobaka the first dead fish were seen on 28 Februa- ry. The number of dying fish, how- ever, was only a small fraction of the former population in the nor- mal river. Most fishes probably fled upstream and for this reason, after the longer stagnation in Au- gust and September, many fish was seen in the upper courses of the Suriname River. The first fish found dead were the stingray and a Plecostomus sp. The latter lives in the turbulent water of the rapids and soon after stagnation this species could be found floating dead on the water above former rapids. The amount of fish which remained in the oxy- genated layer after stagnation was not great. Catfish ( Siluridae , Cal - lichthyidae) disappeared; species such as Leporinus, Characidae and a few Serrasalmus remained. Gym- notus sp. was found living between the roots of water-hyacinth. The records of the organisms present before and after the clo- sure are given in a table at the end of this communication. The greatest depth of the lake will be 50 meters near the dam. Large areas of the shallower parts will become swampy. Fishing with nets and navigation will be diffi- cult. The submerged trees of the forest will decay very slowly in the acid anaerobic water; it was impos- sible to clear the area of the futu- re lake before filling. The tree tops remaining above water will serve as centres of floating vegetation. The waterhyacinth ( Eichhornia crassipes) , which was scarce in the river, developed into great num- bers after stagnation because of favourable conditions: the illumi- nation of the water surface increased as the dead leaves lost their leaves and also the mineral content of the water increased. The control of this “million-dollar- weed” was started by spraying, but the result is not quite satisfactory. Perhaps it is worth to make an ex- periment of biological control by introducig manatees into the lake (Bertram, 1963) . The introduc- tion of the manatee into the lake would be, at the same time, a con- tribution to the protection of this threatened animal. Finally we would point out the possibility of explosions of mosqui- tos and malaria on account of the developing and expanding water- hyacinth, and perhaps of the waterfern Ceratopteris pterioides. Volume 3 (Limnologia) Presence of various organisms before and after the closure 1 February 1964 until September 1964 137 SURINAME RIVER Fishes: Many species and specimens Potamotrygon hystrix Siluridae, Callichthyidae Plecostomus sp. Electrophorus electricus Gymnotus sp. (in creeks) Hoplias sp. Serrasalmus sp. Characidae Belone sp. (in creeks) etc. Other organisms: Diatoms and Desmids are the most important plankters. Freshwater shrimps (Macrobrachium) and crabs ( Potamocarcinus sp) are common . Hemiptera : Gerridae, Velidae and Be- lostomidae are scarce. Ephemeroptera on bottom and in rapids. Trichoptera on rocks and in rapids. Libellulidae, many species. Megaloptera and Cataclysta lived in rapids. Simulidae and other midge larvae recorded. Sponges on rocks. Bryozoa recorded. Moliusca: Pomacea spp. and Doryssa spp. lived on rocks. Diplodon voltzi and Castaliella lived on sand. Otigochaetae: earthworm species oc- curred in the sand. p °dostemaceae in rapids. Few Eichhor- nia crassipes. Few Ceratopteris pte- riodes. Filaments of blue algae on rocks in rapids. BROKOPONDO LAKE Few species and specimens. Dead fish appeared shortly after stagnation. Most fish escaped anaerobic water. Some hide in floating water-hyacinth. Surface dwellers like Leporinus re- mained in the oxygenated layer at the surface. Other species of phytoplankton deve- loped. Cladocera, Copepods and Roti- fers appeared in great numbers, but only in the oxygenated toplayers. New elements typical of stagnant water appear: Cladocerans : Euryalona occi- dentalis, Iliocryptus; Conchostraca : Cyclesteria hislopi; Rotifers: Sinanthe- rina spp., Octotrocha, Lacinularia flos- culosa. Bottom living organisms died or appeared on floating substrate. Many Microvelia sp'. Also Belostomidae in floating material. Only Asthenopus and Callibaetes were recorded. Trichoptera disappeared. Libellulidae are still present. Both di sappeared. Larvae of Simulidae disappeared; other forms were recorded. Spcnges disap- peared except those cn floating subs- trate. Bryyozoa not recorded. All species disappeared, some were found dead. New elements typical of stagnant water are recorded: Drepanotrema anatinum, Aplexa mar- morata, Gundlachia, Acroloxus, Ta- phius. Not recorded. Many small species like Dero, Aulophorus and Pristina appear on decaying substrate. No Podostemaceae. Strong development of Eichhornia and Ceratopteris. Filaments of blue algae on roots of waterhyacinth and floating substrate. Temporary growth of filamentous green algae ( Spirogyra , Mougeotia ) floating at the surface. Growth of Lemnaceae. SciELO 10 11 12 13 14 15 cm 138 Atas do Simpósio sôbre a Biota Amazônica SUMMARY The construction of big dam across the Suriname River, which was completed at February 1, 1964, caused a radical change of the en- vironment in which so far a tropi- cal rainforest dominated .The im- pounded Suriname River soon flooded large areas of forest: the artificial lake will ultimately cover an area of about 1.500 km-. About 5.000 inhabitants of negro villages along the river were transmigrated to new settlements. Wild animais such as deer, pig, opcssum, baboon, tree porcupine, tree anteater and sloth tried to escape the rising wa- ter. Many of them were rescued by the action of the American Socie- ty for the Protection of Animais. Game hunting is forbidden for some years in the lake region. The drowned forest trees died after a few months but their stems remained below the water levei, so- me parts also above it. No attempts could be made to clear the future lake region before actual filling oc- curred. The dead trees are a nui- sance for navigation and fishing with nets. They also prevent water circulation, resulting in great stag- nation and oxygen exhaustion. Open spaces of water remain only in the former riverbed and in those of the tributaries. As the water of the lake will be used only for ge- nerating electric power little atten- tion is being paid to the said draw- backs. The waterhyacinth Eichhornia crassipes was a rare plant in the former Suriname River but deve- loped rapidly as soon as the water stagnated. Large fields of floating plants formed along the borders. Attempts were made to control it by Chemical sprays, without much result. At the midst of 1965 the plant covered an area of 18000 ha. which is about 1/8 of the total area of the lake. Also the waterfern Ce- ratopteris thalictroides spreads ra- pidly; it used to be limited to the smaller tributaries of the Surina- me River. As the lake will remain shallow for the greater part (the greatest depth does not exceed 50 meters, near the dam) , large areas will be covered by a swampy vegetation. This vegetation will cause an in- crease of the evaporation, which will be much higher than that of open water. (The rate of evapora- tion of open water in the lake has only been measured incidentally) . The lake did nct reach its final le- vei at the expected date. In fact the water levei lowered slightly when two of the turbines were started. Volume 3 (Limnologia) 139 An invertebrate fauna — for- merly scarcely noticed — develop- ped in the stagnant water among the floating vegetation of water- hyacinth. It may be that inalaria mosquitos will become numerous after prolonged impoundment. Snails, a potential vector in bilhar- zia disease, were not recorded; as a matter of fact they were absent in the Suriname River because of the acidity of the water and the absence of a suitable environment. Other species of snails occurred however . After stagnation of the water occurred, the river fish of the run- ning water disappeared. Exhaus- tion of oxygen caused some dying of fish. Oxygen started decreasing some weeks after the stagnation and then only few specimen were found at the surface. Below a depth of 2 to 3 meters no oxygen was found. H..S developed by de- caying of organic material. The plankton community of the running river was mainly compos- ed of desmids and diatoms. It soon changed and became limited to an upper layer of 2-3 meters. Cladoce- ra, Copepoda, Rotifer and unicel- lular Flagellates (Strombomonas, Trachelomonas) developed, some- times in large numbers. Bottom or- ganisms of the former riverbed died or were found living on float- ing material. Plant species belong- ing to the family of Podostema- ceae, typical of the rapids, died also. The Chemical composition of the water changed too. The water of the Suriname River was poor in minerais, slightly coloured by iron and silica and had a pH of about 6.5. It resembles the “Clear water type” as characterized by Sioli in the Amazon. The tributaries are brownish and turbid cn account of iron. The Suriname River Sys- tem originally has turbid-brown water and differs from the so- called “Brown waters”, where co- lour is due to dissolved humic sub- stances. After impoundment the water colcur changed into light brown, due to dissolved humic substances, the pH dropped to about 5.5. The mineral content increased. The amounts of mg pro liter of P0 4 NO;: and S0 4 increased already after 6 months of stagnation. Very little was known of the wa- ter, plants and animais in the Su- riname River region. Some months before the closure of the dam a team of four biologists began its investigations. The project is being financed by the Netherlands Foun- 140 Atas do Simpósio sôbre a Biota Amazônica dation for the Advancement of Tropical Research (Wotro) and the National Museum of Natural History, Leyden. REFERENCES Bertram, C., 1963, In search of Mer- maids. 183 pp„ Peter Davies, Lon- don. Braun, R., 1952, Limnologische Unter- suchungen an einigen Seen im Amazonasgebiet. Schweiz. Zeits. Hydrol., 14 (1) : Leentvaar, P., 1966, The Brokopondo Research Project, Surinam, In: Symposium on Man-Made Lakes, London. Sioli, H., 1964, General features of the limnology of Amazônia. Verh. Intern. Ver. Limnol., 15: Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 141-162 — 1967 EL GÉNERO “PALEOSUCHUS” EN AMAZÔNIA FEDERICO MEDEM Departamento de Investigaciones Ictiológicas y Faunísticas; Corporación Autónoma Regional de los Valles dei Magdalena y dei Sinú (C.V.M.) ; Cartagena (Bolívar) , Colombia (Con 1 mapa) El género Paleosuchus consiste en dos especies, P. trigonatus y P. palpebrosus. Representa indu- dablemente un grupo muy anti- guo, quizás, el más primitivo de la familia Alligatcridae y difiere de los géneros Caiman y Melanosu- chus por una serie de caracteres morfológicos externos y anatómi- cos craneales. Se desconocen toda- via datos paleontológicos exactos sobre el orígen de este género. Langston (1965: 151) anotó que “La ascendência dei caimán se ras- trea hasta el principio dei Eoceno, en cuya época el Eocaiman caver- nensis parece haber sido un ade- cuado antecesor estructural de formas semejantes al caimán, con la posible excepción dei Paleosu- chus”. El autor de la presente contribu- ción hizo observaciones y estúdios desde 1950 en las hoyas dei Ama- zonas y Orinoco, coleccionando principalmente de noche con ar- pón y desde una canoa para evi- tar la destrucción dei cráneo, si se recolectaran mediante armas de fuego. Durante estas cacerías se hi- cieron numerosas observaciones so- bre la ecologia y las costumbres en el ambiente natural de ambos Pa- leosuchus, comunmente denomina- dos como “Cachirre” y “Jacaré co- roa” por los nativos de las diferen- tes regiones. Los datos aqui presentados no pretenden ser completos; consti- tuyen más bién base para estúdios futuros más profundos. A pesar de que ambas especies se conocen desde la época de Cuvier (1807), existen solamente unos pocos datos aislados y generalizados sobre su ecologia. La nomenclatura también permaneció en estado bastante confuso debido a las numerosas al- teraciones que ha sufrido la sino- nimia. 142 Atas do Simpósio sôbre a Biota Amazônica Debido al espacio limitado, pre- sentamos únicamente la sinonimia principal, evitando así meras rei- teraciones, y nos referimos para una nomenclatura más completa a Medem (1958 a: 228-230). Igual- mente nos limitamos a presentar los datos más esenciales acerca de las características morfológicas ex- ternas y de anatomia craneal, ya que han sido descritos anterior- mente por vários autores, entre ellos Kàlin (1933), Mertens .... (1943) y Medem (1952, 1953 1958 a). En cambio, nos referimos en forma más detallada a las obser- vaciones sobre la ecologia y com- portamiento por razón de que re- presenten posiblemente informa- ciones útiles para otros profesio- nales en su trabajo en el campo. Se usan las siguientes abrevia- ciones: cnhm — Chicago Natural History Museum; mvz — Museum of Vertebrate Zoology, University of Califórnia, Berkeley; mnhnp — Museum National d’histoire Na- tural de Paris; icn — Instituto de Ciências Naturales, Universidad Nacional de Colombia, Bogotá; fm, Pp, Pt — Federico Medem, colec- ción particular, P. trigonatus y P. palpebrosus. El material está de- positado en el cnhm, mvz, icn y en la colección particular. Nomenclatura Orden Crocodylia Familia Alligatoridae Género Paleosuchus Gray, 1862, Ann. Mag. Nat. Hist., (3), 10: 330; propuesto como subgénero de Caiman. Tipo: Crocodilus tri- gonatus Schneider. Paleosuchus trigonatus (Schneider) Crocodilus trigonatus Schneider, 1801, Hist. Amph., p. 161, pis. 1-2. Tipo: actualmente perdido. Localidad típica: desconocida. Caiman trigonatus Boulenger, 1889, Ca- tai. Chelon. . . : 296. Jacaretinga trigonatus Vaillant, 1898, Nouv. Arch. Mus. Hist. Nat. Paris, (3), 10: 171 etc., fig. 1. Paleosuchus trigonatus K. P. Schmidt, 1928, Field Mus. Nat. Hist. (Zool. Ser.), 12: 209, fig. 1. Crocodilus palpebrosus, var. 2, Cuvier, 1807, Ann. Mus. Hist. Nat. Paris, 10: 38 pl. 2, fig. 1. Tipo: mnhnp No. 7.525, ejemplar de 80 cm., Gautier don. Localidade típica: Cayenne — /ide Vaillant, 1898: 174, fig. 1. Alligator palpebrosus, var. B, Dumé- ril & Bibron, 1836, Erp. Gén., 3.: 72. Tipo: mnhnp No. 7527, ejemplar de 1.17 metros, localidad desconocida fide Vaillant ( op . et loc. cif.). Jacaretinga moschifer Spix, 1825, Ani- malia nova... lacertarum, p.l Tab. I. Tipo: Originalmente en München, actualmente perdido. Localidad típica: lago en la ciudad Bahia, Brasil. Vaillant (op. cit.: 173-174, nota al pié) anotó que moschifer es una composición de ambas especies. Se- gún la descripción se trata de pal- pebrosus, mientras la ilustración Volume 3 (Limnologia) 143 muestre indubablemente un trigo- natus de tamano mediano. Seria lo más indicado, incluir a moschifer definitivamente en la sinonimia de trigonatus ya que no solamente la Tabla I de Spix comprende una ilustración en colores bien elabo- rada de trigonatus, sino también en el texto se notan algunas dis- crepâncias: mientras la descrip- ción dei color corresponde a pal- pebrosus, la de la cabeza reza “ca- put acutum” (p.l), lo que es carac- terístico de trigonatus. Paleosuchus palpebrosus (Cuvier) Crocodüus palpebrosus, var. 1, Cuvier, 1807, Ann. Mus. Hist. Nat. Paris, 10: 28; pi. 1, figs, 6, 17; pl. 2, fig. 2. Tipo: mnhnp No. 7530, ejemplar de 1.29 metros, Gautier don, Localidad tipica: Cayenne, fide Vaillant (op. et. loc. cit.) . Alligator palpebrosus, var. A. Duméril & Bibron, Erp. Gén., 3: 67. Tipo: mnhnp No. 7530, Jide Vaillant (op. et loc. cit). Caiman (Aromosuchus) palpebrosus Gray, 1862, Ann. Mag. Nat. Hist., (3) , 10: 330. Paleosuchus palpebrosus Müller, 1924, Zeitschr. Morph. Okol. Tiere, 2: 441, pl. 5, fig. 31. Champsa gibbiceps Natterer, 1841, Ann. Wien. Mus., 2: 324, pl. 28. Tipo: Ori- ginalmente en Viena, evidentemente perdido. Localidad típica: Ribeirão do Gua- curizal, um cano en las montanas al- rededor de Jacobina, 3 millas al ori- ente de Villa Maria, rio Paraguai, Mato Grosso, Brasil. Coloración — El color de los ejemplares vivos ya ha sido descrito anteriormente (Medem, 1952 1953) ; por esta razón anotamos solamente las diferencias principa- les correspondientes a los adultos y juveniles. En P. trigonatus la tabla craneal es parda oscura y una faja ancha negra se extiende desde el borde posterior de espacio interorbital ha- cia adelante a lo largo de los na- sales hasta los clientes maxilares Nos. 5-6. En cambio, en P. palpe- brosus la tabla craneal es de color rojizo de herrumbre intenso y ia cabeza carece de la faja negra. Las mandibulas presentan zonas anchas amarillas, interrumpidas por unas 5-6 fajas transversales pardas oscuras en trigonatus, mi- entras las de palpebrosus muestran un color rojizo, salpicado por unas 4-5 manchas pardas oscuras de ta- maho y configuración irregulares. La parte dorsal dei cuerpo y de la cola de trigonatus es básicamen- te parda oscura; existe, sinembar- go, el fenómeno en que virtualmen- te todos los juveniles desde unos 600 mm para arriba y los adultos tienen el lado dorsal cubierto por una densa capa de algas verdes la cual es aún más espesa en ejem- plares viejos; por esta razón un trigonatus de tamano mayor pa- rece, en realidad, verduzco mohoso. El lado dorsal de palpebrosus es más oscuro y en ejemplares viejos 144 Atas do Simpósio sôbre a Biota Amazônica negruzco. Nunca se ha observado la presencia de algas verdes en palpebrosus en su ambiente natu- ral, sino únicamente en un solo ejemplar (No. 370), que vivió dos anos en cautividad. Ventralmente el color dei tegu- mento es gris ratón con varias zo- nas más oscuras en trigonatus, mi- entras en palpebrosus es negro bri- llante con algunas zonas grises claras o de color de cuerno. Los juveniles de ambas especies tienen una coloración más clara y intensa que los adultos. Ejempla- res muy pequenos se distinguen facilmente en que la tabla craneal en los de trigonatus es carmelita clara, mientras en los palpebrosus es amarilla yema brillante. Este color cambia después de unos ocho meses; así por ejemplo, de tres ejemplares capturados en diciem- bre 1, 1950, uno (MVZ No. 2018) de ellos sobrevivió hasta septiembre 5, 1951; según Hendrickson ( in litt., octubre 11, 1951) el color perman v ció amarillo hasta julio 1951 y lue- go cambio a rojizo caoba (Medem, 1953: 417). El iris de los ojos de ambas especies es carmelito claro. Escamado — Desde la época de Cuvier (1807) se considero la cisposición de las escamas postoc- cipitales como uno de los factores diagnósticos específicos, es decir, se postulo que trigonatus invariable- mente tenía una sola hilera y, en contraste, palpebrosus dos de ellas. En realidad, 28 de los 37 ejempla- res de trigonatus estudiados en 1954, tenian las escamas postocci- pitales en dos hileras claramente discernibles, independientes de la edad y procedência; en cambio, de unos 50 palpebrosus, todos poseían dos hileras. Existen también diferencias cla- ramente discernibles entre ambas especies respecto al escamado cer- vical, dorsal, ventral y caudal (Medem, 1958 a: 236). Finalmen- te, nos referimos a las diferencias más esenciales y fácilmente discer- nibles tanto dei escamado como de la anatomia craneal de ambas es- pecies que sirven como factores diagnósticos para su clasificación. ESCAMADO Paleosuchus trigonatus 1) Escamas postoccipitales en una o dos hileras; las de la segunda siempre más pequenas. 2) Hileras pre-lumbares de 2-3-4 placas; las centrales o lisas o con cresta vestigial; existe gran variedad individual. 3) Hileras lumbares igualmente de 2-3-4 placas; las centrales o li- sas o con cresta vestigial. Paleosuchus palpebrosus 1) Escamas postoccipitales siem- pre en dos hileras; las de la se- gunda ligeramente más peque- nas; solamente en los s £ vie- jos de tamano igual. 77i° 76 1 c 75 e 74 ® 73 ° 72 * 70 o 67 1 65 < 3° 735 HAPA ÍNDICE / ~7] / / VILLAVICENCI / I* Sor Vicnt.^ \_AAÇ»h« . ^ Coguon. Anton.o-^^ Santo Ros■ bank bank Fig. 7 — Distribution of mean velocity in cross section at Óbidos. Volume 3 (Limnologia) 179 Depth, in Depth, meters in feet 40 45 50 1 - 1000 f eel - 25 f eet (305 m. - 76 m.) Fig. 8 Section of fathometer chart taken near midstream and Crossing general location of measuring section. ment, total dissolved solids, and some other information on the Chemical and physical nature of the Amazon water in the general vicinity of Óbidos. Pinto is quoted by Camargo as having computed a mean daily discharge of suspend- ed load at mouth of Amazon to be 3 million tons . Undoubtedly, the lack of means for collection of suspended sedi- ment samples from various depths at the relatively high flow veloci- ties discouraged investigators from attempting to assess the mean an- nual suspended sediment dischar- ge by Óbidos. Similar difficulties would have discouraged attempts to collect samples of the material •n place on the streambed. The joint reconnaissance ven- ture of 1963-64 was well equipped to collect water samples at any point in the measuring cross sec- tion at Óbidos. Samples of the ma- terial on the top of any part of the bed could also be taken with an oceanographic clamshell type sam- pler or standard U.S. BM-54 sam- pler. The U.S. P-61 suspended sedi- ment sampler (equipped with 3/16-inch-diameter intake nozzle), having an electrically controlled intake and closure valve, permitted water samples for analysis of sus- pended sediment to be taken at any location in the cross section of flow. Thus, the distribution of sus- pended sediment concentration from bed to surface could be deter- em 1 SciELO 10 11 12 13 14 15 180 Atas do Simpósio sobre a Biota Amazônica TABLE 3 Concentration of dissolved and suspended material (ppm) [mg/l], Amazon River at Óbidos Constituent July 16, 1963 Xovember 2°, 1963 August 9, 1964 Discharge (cms) 216,000 72,500 165,000 Sílica (SÍO 2 ) 7.0 9.0 9.0 Aluminum (Al) .07 .02 .15 Iron (Fe) .06 .06 .09 Calcium (Ca) 4.3 10 3.9 Magnesium (Mg) 1.1 .4 .6 Sodium (Na) 1.8 4.2 1.8 Potassium (K) — .4 .6 Bicarbonate (HCO 3 I 19 32 16 Sulfate (S0 4 ) 3.0 6.4 1.0 Chloride (Cl) 1.9 4.5 1.6 Fluoride (Fl) .2 0 0 Xitrate (NO 3 ) .1 0 .1 Total dissolved solids 28 51 21 Hardness as CACO 3 15 27 12 Dissolved oxvgen 5.8 5.6 5.4 Specific conductance 40 84 34 pH 6.5 7.1 6.5 Temperature (°F) 83 86 83 Suspended sediment 89 60 110 mined at any selected vertical. A bathythermograph furnished tem- perature-depth profiles at desired verticais. Chemical-quality samples were taken with an oceanographic sampler consisting of an open tube that allowed flow through of wa- ter until it was closed, as desired, by ball-type valves. The quality of water aspects of ihe investigation were conducted by Mr. F. C. Ames, Geological Sur- vey, Denver, Colorado. Mr. Ames furnished Table 3, which shows the results of the three series of sam- plings made at Óbidos. The tabu- lated suspended-sediment concen- trations are the calculated avera- ge concentration for the cross sec- tion. Suspended sediment samples were taken at many points in each vertical sampled, so that the dis- tribution of suspended material in the vertical could be charted. In a personal communication (April 1966) , Mr. Ames has furnished in- formation, as follows, on the range of suspended-sediment concentra- tions measured in the cross sec- tion: November 1963 August 1964 50 mg/l 70 mg/l 280 340 July 1963 Upper portion of verticais 60 mg/l Near the bed 300 Volume 3 (Limnologia) 181 As expected, the concentration of suspendei sediment is high in the vicinity of the bed. Ames reports (personal coramu- nication) this information on the bed material at Óbidos: “The median diameter of bed material averaged about 0 . 20 mm. The median diameters indicated by individual samples ranged from 0.15 to 0.25 mm. Only one to two percent of the bed material (by weight) was finer than 0.062 mm and only one or two percent was coarser than 0.4 mm . ” Katzer reported total dissolved solids of 56 mg/l in a sample ta- ken at Óbidos June 30, 1896. Be- cause the turbulent mixing and lack of major tributary inflow in the vicinity of Óbidos (the dischar- ge from the Rio Trombetas would have small effect) should guaran- tee uniformity of dissolved-solids concentration in a cross section of the stream, the minor differences in the four analyses can be attri- buted to seasonal variations. One would expect the total dissolved solids found by Katzer on Ju- ne 30, 1896, to be more dilute than he reported unless the flow for that season was very low. The concen- tration of dissolved solids on Au- gust 9, 1964 (discharge 165,000 cm) if there were a relatively fixed in- verse curvilinear relation bet- ween total dissolved solids and wa- ter discharge, would be expected to be slightly higher than found on July 16, 1963, (discharge 216,000cm). The contrary findings, 21mg/l and 28 mg/l t respectively, show the importance of seasonal variations in the proportions of to- tal Óbidos flow contributed by “white water” and “black water” tributaries. It is apparent that a minimum of one water sample per month collected over several years would be necessary to describe ac- curately the dissolved-solids load variation at Óbidos. The three determinations of mean concentration of suspended sediment in the Óbidos cross sec- tion also show the need for many more samples to be taken during several years before one could cal- culate a mean annual concentra- tion of suspended sediment. How- ever, on the basis of reconnaissan- ce results at Óbidos, if the mean annual concentration were assum- ed to be 100 mg/l, one would ar- rive at a calculated mean daily sus- pended load at Óbidos (using 157,000 cm) of about one-half that which Pinto computed for the mean daily load at mouth. The dissolved oxygen content is close to saturation levei at the ob- served stream temperature. Bathy- thermograph results showed no d> tectable variation of temperature in any of the verticais where obser- vations were taken from surface to bed and return. The pH was cm l SciELO 10 11 12 13 14 15 182 Atas do Simpósio sôbre a Biota Amazônica found to be as expected from the analyses reported by Sioli for the vicinity of Santarém. ESTIMATED DISCHARGE AT MOUTH The drainage area tributary to the Óbidos location is about 5,000,000 sq km (square kilome- ters) . The drainage area above the mouth is about 6,000,000 sq km, or an increase of about 20 percent over that for Óbidos. If equal con- tribution of runoff existed for the basin above mouth, the mean annual discharge at mouth would be expected to be about 190,000 cm. However, there are several data that indicate the yield per unit drainage area from the approxi- mately 1,000,000 sq km of drainage intervening between Óbidos and the mouth to be less than that occurring above Óbidos. Only two large tributaries, the Tapajós and the Xingu, enter the Amazon downstream from Óbidos. In August 1964, the gaging party measured the dry season discharge of the Tapajós at São Luís, loca- tion of the first rapids, about 300 km upstream from Santarém. The discharge was found to be 2,840 cm. A stage-discharge rela- tion for the Tapajós gage at Ford- landia was drawn on the basis of the one discharge measurement, measured geometry of the high- -flow cross section at São Luís, and a consideration of the apparent variation of water-surface slope with stage for the Tapajós location at São Luís. On the basis of avai- lable daily gage readings from the Fordlandia gage and the cons- tructed stage-discharge relation, a mean annual discharge for the Rio Tapajós has been calculated as. . . 7,100 cm. No measurement was made on the Xingu. A low-water-season measurement made by the joint survey group on the Tocantins (not considered an Amazon tributary) at Marabá in October 1963 showed the dischar- ge to be 1,500 cm. Using the cross- -sectional area at Marabá that would be occupied by bankful dis- charge and an estimated mean ve- locity at bankful stage, the writer has calculated a bankful discharge of 33,000 cm. No stage records are available at Marabá. The mean dis- charge for the Tocantins was esti- mated, on the basis of the low-wa- ter measurement and the estima- ted bankful discharge, as 11,000 cm. The Tocantins is not tributary to the Amazon (its basin has a com- mon drainage boundary with the Amazon) but its estimated mean discharge and that of the Tapa- jós permit a “bracketing” of an estimated mean annual discharge for the Xingu. The sum of mean Volume 3 (Limnologia) 183 annual diseharges for Tapajós, Xingu, and minor tributaries bet- ween Óbidos and the mouth is es- timated to be 18,000 cm. On this basis, the partly estimated avera- ge annual discharge of the Ama- zon at mouth is 175,000 cm. Estimates of the runoff from the intervening area between Óbidos and the mouth based on the Thornthwaite potential evapo- transpiration approach result in a discharge of about double that ba- sed on hydrometric data. The esti- mates based on hydrometric data are considered to be more reliable than those based on rainfall-runoff computations. The writer conclu- des that the most realiable value of average annual discharge for the Amazon at its mouth is 175,000 cm. CONCLUSIONS The results of the joint investi- gations show the previously pub- lished estimates of mean annual flow past Óbidos to be much too low. The mean discharge comput- ed on the basis of a stage-dischar- ge relation developed from three complete discharge measurements and daily stage readings for the period 1928-46 is 157,000 cm. The great flood of 1953 which probably reached a state of 7.6 meters at Óbidos is calculated to have dis- charged at 350,000 cm through the niain channel with an indetermi- nate quantity of overflow on the flood plain. The observations of dissolved- solids suspended sediment and other water-quality parameters provide much more information on these aspects for the Óbidos loca- tion than had been determined previously, but thre is insufficient information to permit an accurate assessment of either the mean an- nual suspended load or the salt load discharge. The bed material samples and fathometer charts provide much insight into the na- ture of the streambed at Óbidos. The objective of the joint inves- tigation to provide reconnaissance information on the flow and water quality of the Amazon was achiev- ed . If more refined determinations of the average annual flow and water quality characteristics are needed, it will be necessary to con- duct intensive investigations at Óbidos and elsewhere in the basin. The maintenance of a river-stage gage at Óbidos — above tidal ef- fects during all but extremely low flow — would provide valuable in- formation at small expense. SUMMARY Selected published estimates of the discharge of Amazon River in the vicinity of Óbidos and the mouth are presented to show the great variance of available infor- mation. The most reasonable esti- 184 Atas do Simpósio sôbre a Biota Amazônica mates prepared by those who mea- sured some parameters of the flow were studied by Maurice Parde, who concluded that the mean annual discharge is 90,000 to 100,000 cm (cubic meters per se- cond). A few published estimates of discharge at mouth of 110,000 cm based on rainfall-runoff rela- tionships developed for other hu- mid regions of the world are avai- lable . Three measurements of dischar- ge made at the Óbidos narrows in 1963-64 by a joint Brasil-United States expedition at high, low, and médium river stage are referred to the datum used at the Óbidos gage during the period of operation, 1928-46, and a relationship between stage and discharge prepared on the basis of the measurements and supplementary data and compu- tations. Recovery of the original Óbidos gage datum is verified by referring the 1963-64 concurrent river stages at Manaus, Óbidos, and Taperinha to gage relation curves developed for Manaus-Obidos and Obidos-Taperinha for periods of concurrent operation, 1928-46 and 1931-46, respectively. Based on the stage-discharge relation and record of river stage for the period 1928-46 an average discharge of 157,000 cm is computed for the Óbidos site. The greatest known flood at Óbi- dos, that of June 1953, is comput- ed to have been a flow of 350,000 cm at stage of 7 . 6 meters in the main channel with an inde- terminate amount of overflow which, under the best assumed overflow conditions, may have amounted to about 10 percent of the main channel flow. Overflow discharge at stage equivalent to mean annual discharge is judged of flow down the main channel . Miscellaneous data collected du- ring the flow measurements Show that the tidal effect reaches up- stream to Óbidos at extremely low flows; the distribution of velocities in stream verticais is affected by large-scale turbulence; the stan- dard procedure of basing mean ve- locity in vertical on the average of point velocities measured at 20 and 80 percent of the total depth is valid; and there is a low Manning roughness coefficient of 0.019 (English units) . Samples of suspended sediment taken with a point sampler at va- rious depths in selected verticais Show, for the Óbidos site, a varia- tion in concentration from 300 to 340 mg/l (milligram per liter) near the streambed to 50 to 70 mg/l in the upper portion of the verticais. Median diameter of bed material at Óbidos averaged about 0.20 mm in a range of 0.15 to 0 . 25 mm. Analyses of water sam- ples collected at Óbidos in July and November 1963 and August 1964 are presented. Volume 3 (Limnologia) 185 The reconnaissance measurem- ents of 1963-64 provide a well-sup- ported value of mean armual water discharge of Amazon River at Óbi- dos and the mouth. Many more measurements of flow and water- quality characteristics are needed to obtain more exact values of dis- charge, suspended sediment, and salt loads. REFERENCES Cárter, R. W. & Anderson, I. E., 1963, Accuracy of Current Meter Measu- rements. J. Hydraulics Div., ASCE., 89: No. HY4, Part 1. Carvalho, D., 1942, Rev. Bras. Geogr., 4 (2): Güppy, H. P„ 1880, The Yang-Tse, the Yellow River, and the Pei-Ho. Na- ture, 22: 488. Jarvis, C. S., 1945, River Discharge in Brazil, South America. Trans. Amer. Geo. Union, 25th Anniversary Meeting. Part IV. Katzer, f„ 1898, Die Stromenge des Amazonas bei Óbidos. Glolus, 74: 47-49. Katzer, F., 1897, Das Wasser des untu- ren Amazonas, Gesellschaft der Wissenschaften, Prague. Lallemont, R., 1860, Trip around Nor- thern Brazil. Le Conte, P„ 1922, VAmazonie Bresi- lienne. Paris. L’Vovich, M. I., 1945, Elements of the water regime of the rivers of the earth, Moscow. (Russian) . Oltman, R. E., Sternberg, H. 0’R„ Ames» F. C. & Davis, L. C., Jr., 1964, Ama- zon River Investigations, Recon- naissance Measurements of July 1963, Geological Survey Circular 486. Parde, M., 1955, Quelques aperçus re- latifs a Vhydrologie Brazilienne. La Houille Blanche, Grenoble. Pinto, A. O., 1930, Hidrografia do Ama- zonas. reclus, E., 1880, The Earth and Its Inhabitants. Vol. II. Revy, J. J„ 1874, Hydraulics of Great Rivers, E. and F. N. Spon, London. Selfridge, T. O., 1882, The Amazon River. Siemens, A., 1896, Cable Laying on the Amazon River. Nature, 54: 163. Sioli, H., 1957, Valores De pH De Aguas Amazônicas. Boi. Mus. Paraense Emílio Goeldi. Smith, H. H., 1880, Brazil, The Amazons and the Coast. London. (Sampson Low, Marston, Searle, and Riving- ton) Soares, L. C., 1956, Amazónia, Excur- sion Guidebook No. 8, I.G.U. Rio de Janeiro. Spix, J. B. & Martius, E. F., 1831 Reise in Brasilien, Munchen. (Page 1355) Wallace, A. R., 1853, Traveis on the Amazon and Rio Negro. Reeve and Co., London. Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 187-194 — 1967 MOLUSCOS PLANORBÍDEOS DA AMAZÔNIA W. LOBATO PARAENSE Instituto Nacional de Endemias Rurais, Centro Nacional de Pesquisas Malacológicas, Belo Horizonte, Brasil (Com uma figura no texto) A fauna de planorbídeos da re- gião amazônica é ainda muito mal conhecida, devido às naturais difi- culdades de trabalho nessa vasta região e também ao escasso núme- ro de investigadores interessados nesse grupo zoológico. Consideran- do-se tôda a área drenada pelo rio Amazonas e seus tributários, foram aí assinaladas até agora 11 espé- cies de planorbídeos, das quais 6 pertencem ao gênero Bicmphalaria Preston, 1910, e 5 ao gênero Drepa- notrema Fischer & Crosse, 1880. 1 . Biomphalaria straminea (Dun- ker, 1848) Esta é a espécie de Biomphala- ria que tem sido encontrada em maior número de localidades e que ocupa a maior área de distribuição aparecendo na literatura amazôni- ca sob as denominações de Tropi- corbis (Obstructio) paparyensis (Baker, 1914), Australorbis centi- metralis (Lutz, 1918) e Armigerus ( Tropicorbis ) centimetralis (Lutz, 1918). A sua sinonímia foi discuti- da per Paraense (1963). O reco- nhecimento da B. straminea na Amazônia deve-se principalmente a Sioli (1953), que a coletou nas se- guintes localidades: Estado do Amazonas: lago Calado, à margem norte do baixo Solimões, perto de Manacapuru; lagos Comprido e Matafome, no médio Madeira, per- to de Três Casas; Estado do Pará: rio Cuminá, afluente da margem esquerda do Amazonas, perto de Óbidos; lago Salgado, à margem leste do rio Cuminá, cêrca de 50 km ao norte de Oriximiná, na foz do Trombetas (fazenda Tim- bó) ; lago do Tracoá, à margem do rio Cuminá, em frente ao lago Sal- gado; lago do Tostão, à margem norte do rio Amazonas, entre Óbi- dos e Alenquer; lago Grande Ca- cheie de Pesquisas do Conselho Na- cional de Pesquisas. 188 Atas do Simpósio sôbre a Biota Amazônica ruaí, em Caraubal, entre Parintins e Santarém; Santarém; Jacaré (Retiro Daniel de Carvalho), em frente a Aveiro; Pindobal, pôrto de Belterra; Fordlândia; lago Tim- bó, perto de Curi; rio Cupari, per- to de sua foz e perto de Flechal; lagos Caxias e Curuçá, à margem direita do baixo Cupari; rio Anipe- ri, afluente da margem direita do rio São Manuel, perto de sua foz. O material acima referido foi es- tudado por Haas (1949 a, b, 1952), que o identificou ao Tropicorbis ( Obstructio ) paparyensis. No Estado do Pará a B. strami- nea foi também assinalada em Be- lém (Costa, 1952; Pinto & Des- landes, 1953). No Estado do Acre foi coletada em Cruzeiro do Sul e Rio Branco (Paraense, não publi- cado). No Estado de Goiás foi en- contrada em Arraias, à margem es- querda do rio do mesmo nome, afluente do rio da Palma que dre- na para o Tocantins através do rio Paranã (Cunha Neto, comunicação pessoal) . Na localidade de Fordlândia, à margem direita do baixo Tapajós, a B. straminea transmite a esquis- tossomose mansoni no único foco até agora conhecido dessa parasi- tose na bacia amazônica, descober- to por Machado & Martins (1951). Êstes autores examinaram 400 es- pécimes esmagados entre lâminas, com resultado negativo para Schis- tosoma. Resultados idênticos foram obtidos por Maroja e por Sioli (Maroja, 1953) e por mim, ao exa- me de 100, 900 e 5.000 espé- cimes, respectivamente. Experi- mentalmente obtive a infecção de 3 entre 28 espécimes expostos, cada um, a 10 miracídios de S. mansoni de Belo Horizonte. A B. straminea ocorre na Vene- zuela, nas três Guianas, no Para- guai, no norte da Argentina e em todos os sistemas de drenagem do território brasileiro com exceção apenas da bacia do Uruguai, do lado oriental da bacia do Paraná e da área que drena para o Atlân- tico ao sul do paralelo 21°. 2. Biomphalaria schrammi (Cros- se, 1864) Na região amazônica esta espé- cie até agora foi encontrada ape- nas em Belém por mim próprio (Paraense, Fauran & Courmes, 1964). Ela tem sido também assi- nalada nas Antilhas, na Guiana Francesa e no Brasil, onde tem o seu limite sul no Estado de São Paulo. Entre os seus sinônimos mais conhecidos contam-se Planor- bis janeirensis Clessin, 1884 e P. ni- grüabris Lutz, 1918. 3. Biomphalaria amazônica Pa- raense, 1966 Esta espécie, que descrevi recen- temente em material coletado pelo Instituto Nacional de Pesquisas da Volume 3 (Limnologia) 189 Fig. 1 — uistnouu^ao aos pianorbiaeos até agora reconhecidos na região amazônica. Amazônia, foi encontrada até ago- ra apenas em Manaus e na ilha do Careiro, situada à margem direita do rio Amazonas, em frente à de- sembocadura do rio Negro. Segu- ramente deve ocorrer em outras lo- calidades, o que será demonstrado por estudos futuros. 4. Biomphalaria lauricochae (Phi- lippi, 1869) Espécie do lago Lauricocha, nas- cente do rio Marahon, no Peru, foi descrita com base nos ca- racteres exclusivamente conquilio- lógicos. São necessários estudos anatômicos para definição de sua verdadeira identidade. Segundo Harry (1962), trata-se de provável sinônimo da Biomphalaria andeco- la (Orbigny, 1835) do lago Titi- caca. 5 . Biomphalaria raimondi lippi, 1869) (Phi- Êste planorbídeo, como o ante- rior, também não está ainda bem definido. Foi coletado “em riachos das florestas da região do Peru cha- mada Pampa dei Sacramento”, SciELO ABiomphalaria atraminea ^B. amazônica ^8. ochrauBni AB. lauricochae AB. raimondi A3. philippiana ODrepanotrema anatinum OD. lucidun CD. depre 8 sÍ 83 Íraum ©D. Icermatoides ©D. cimex cm 10 11 12 13 14 15 190 Atas do Simpósio sôibre a Biota Amazônica vasta pcrção da Amazônia perua- na que se estende entre os rios Uca- yali e Huallaga. 6 . Biomphalaria philippiana (Dunker, 1848) A descrição original desta espé- cie refere-se a material de Cocha- bamba, na Bolívia, situada nas ori- gens de tributários dos rios Beni e Mamoré. Em 1953, o Dr. Ennio Luz coletou em Morretes (Estado do Paraná) espécimes de um planor- bídeo que enviou a Lucena e que, a pedido dêste (Lucena, 1956: 92), foram determinados por Bequaert como Tropicorbis philippianus (Dunker, 1848). Mais tarde Pa- raense & Deslandes (1958 b) estu- daram exemplares pertencentes à mesma população de Morretes, tra- tando-os como philippianus por já ter sido êste nome aplicado à refe- rida população. De acordo com os dados de que disponho atualmente, êste planorbídeo distribui-se pelos Estados do Paraná, Santa Catari- na e Rio Grande do Sul, e mante- nho séria dúvida quanto a ser êle idêntico ao verdadeiro philippianus de Cochabamba. Barbosa, Barbosa & Carneiro (1958) estudaram, sob a denominação de Tropicorbis phi- lippianus, um planorbídeo de Gua- iaquil (Equador) cuja anatomia é diferente da dos espécimes do sul do Brasil e assemelha-se à da Biomphalaria peregrina (Orbigny, 1835) . Comparando conchas dos espécimes estudados por Paraen- se & Deslandes e por Barbosa, Barbosa & Carneiro com o mate- rial depositado no Museu Britâni- co, observou Hubendick (1962) que “o material tipo desta espécie no Museu Britânico é perfeitamente semelhante conquiliològicamente à concha figurada por Paraense & Deslandes, 1958, a qual, entretan- to, não é topotípica. O material de- terminado por Morrison como T. philippianus e estudado por Barbosa et dl. 1958 òbviamente não pertence à mesma espécie, mas é provàvelmente idêntico ao T. ha- vanensis.” Como se vê, a identidade da ver- dadeira Biomphalaria philippiana, a de Cochabamba, ainda precisa ser estudada pelos métodos moder- nos de investigação malacológica. Caso seja diferente da espécie do sul do Brasil, terá esta de receber outro nome. 7. Drepanotrema anatinum (Or- bigny, 1835) Foi coletado pela Expedição Stanford em um lago artificial em frente à Catedral de Belém (Baker, 1914) e aparece nas Ests. 79 (Fi- guras 16-18) e 124 (Figs. 1-3) da monografia de Baker (1945) com a indicação “Pará, Brazil”, provàvel- mente referindo-se a Belém. Em material coligido por Sioli (1953) e identificado por Haas Volume 3 (Limnologia) 191 (1949 a, b, 1950, 1952) como Gy- raulus ( Drepanotrema ) anatinus, aparece esta espécie nas seguintes localidades, quase tôdas comuns à Biomphalaria straminea : Estado do Amazonas: lago Calado, no bai- xo Solimões; lagos Comprido, Ma- tafome e Paxiúba, no médio Madei- ra; Estado de Mato Grosso; rio Ju- ruena, à margem direita; lago do Peri, no rio Juruena, perto da Bar- ra do São Manuel; Estado do Pará: rio Cuminá, perto da fazenda Tim- bó; lago Salgado; rio Branco de Óbidos, na sua desembocadura no lago Mamuru; lago Grande Curuaí, em Caraubal; Santarém; Fordlân- dia; lago Curi; rio Cupari, perto de sua foz e perto de Flechal; lagos do Caxias e Curuçá, no baixo Cupari. Entre o material enviado a êste Centro, para identificação, pelo Instituto Nacional de Pesquisas da Amazônia, tem sido reconhecido o D. anatinum em amostras de Ma- naus e da ilha do Careiro, Estado do Amazonas. A sua presença no Peru foi assinalada por Baker (1945, Est. 124, Fig. 30), que apre- senta a concha de um espécime de Yurimaguas (incorretamente gra- fada “Juminaguas”) , localidade à margem esquerda do rio Huallaga, Departamento de Loreto. O D. anatinum é encontrado, sob várias denominações, nas Antilhas, no México, na América Central e na América do Sul a leste dos An- des, chegando até a Argentina. A oeste dos Andes encontrei-o no Equador. 8. Drepanotrema lucidum (Pfeif- fer, 1839) Foi coletado por Sioli e identifi- cado por Haas (1949a, 1952), sob a denominação de Gyraulus ( Dre- panotrema ) schubarti (Haas, 1938) na Fordlândia (Pará) e no lago Matafome, médio Madeira (Ama- zonas) . Sioli (1953) encontrou-o no lago Grande Curuaí, perto de Caraubal (Pará) . Identifiquei-o em material da ilha do Careiro (Ama- zonas), de Cruzeiro do Sul e Rio Branco (Acre) e de Pôrto Velho (Rondônia) . No Peru foi assinalado por Baker (1945, Est. 124, Figs. 29, 31, 32) em Yurimaguas, juntamente com o D. anatinum. O planorbídeo de Buena Vista, Santa Cruz (Bolívia) , que aparece sob a denominação de Drepanotrema paropseides na Est. 124, Figs. 14-20, da monogra- fia de Baker (1945) , parece perten- cer realmente à espécie D. lucidum. Esta espécie corresponde ao D. melleum (Lutz, 1918). Sua distri- buição compreende a região das Antilhas e a América do Sul a les- te dos Andes. 9. Drepanotrema depressissimum (Moricand, 1839) Sob o nome de Gyraulus {Drepa- notrema) depressissimus, foi iden- 192 Atas do Simpósio sôibre a Biota Amazônica tif içado por Haas (1949 a) no rio Cupari, perto de sua foz (Estado do Pará), em material coletado por Sioli. No Estado do Amazonas tem sido encontrado na ilha do Carei- ro, perto de Manaus, em coletas do Instituto Nacional de Pesquisas da Amazônia, conforme identificação feita neste Centro. O D. depressissimum foi assina- lado até agora nas Antilhas e no Brasil, distribuindo-se neste país desde o extremo norte até o Esta- do de São Paulo. 10. Drepanotrema kermatoides (Orbigny, 1835) Sioli coletou esta espécie no igarapé do Guaranazal, pequeno afluente do rio Cupari (Pará) , que foi identificada como Gyraulus (Drepanotrema) kermatoides por Haas (1949 b). O D. kermatoides distribui-se pelo oeste do Brasil, através de Goiás e do oeste de Minas, na di- reção do Paraná, Santa Catarina e Rio Grande do Sul, estendendo-se para o Paraguai, Uruguai e Argen- tina. A oeste dos Andes ocorre no Peru e no Equador. 11. Drepanotrema cimex (Mori- cand, 1839) Coletei esta espécie em Fordlân- dia (Pará). Sua distribuição com- preende as Antilhas e, na América do Sul, comprovadamente o Brasil e o Uruguai. A identificação da maioria das espécies acima referidas poderá ser feita sem dificuldade de acordo com as descrições conquiliológicas e anatômicas constantes dos traba- lhos de Paraense & Deslandes so- bre B. straminea = centimetralis (1955), D. anatinum (1956 a), D. lucidum — melleum (1956 b), D. depressissimum (1957), D. ci- mex (1958 a), B. philippiana (1958 b), D. kermatoides (1958 c), de Paraense, Fauran & Courmes sôbre B. schrammi (1964), e de Paraense sôbre B. amazônica.... (1966). SUMÁRIO Como contribuição ao inventário da biota amazônica, um dos prin- cipais objetivos dêste Simpósio, são apresentados os dados existentes sôbre a distribuição das espécies de planorbídeos da região Amazônica. Esta região é considerada aqui no seu sentido hidrográfico mais am- plo, abrangendo tôda a área drena- da pelo rio Amazonas e seus tribu- tários, mas não inclui as áreas con- vencionalmente consideradas como extensões da Amazônia, como por exemplo a zona Bragantina do Pará e a parte vizinha do Mara- nhão, onde ocorrem planorbídeos, inclusive transmissores da esquis- tossomose mansoni. São as seguintes as espécies de planorbídeos assinaladas na Ama- zônia: Biomphalaria straminea Volume 3 (Limnologia) 193 (Dunker, 1 8 4 8), B . schrammi (Crosse, 1864) , B . amazônica Pa- raense, 1966, B. lauricochae (Phi- lippi, 1869) , B. raimondi (Philippi, 1869) , B. philippiana (Dunker, 1848) , Drepanotrema anatinurn (Orbigny, 1835) , D. lucidum (Pfeif- fer, 1839) , D. depressissimum (Mo- ricand, 1839), D. kermatoides (Or- bigny, 1835) e D. cimex (Moricand, 1839). REFERÊNCIAS Baker, f., 1914, The land and fresh- water mollusks of the Stanford Ex- pedition to Brazil. Proc. Acad. Nat Sei. Philadelphia, 65: 618-672. Baker, F. C., 1945, The molluscan fa- mily Planorbidae. xxxvi + 530 pp., Univ. Illinois Press, Urbana. Barbosa, f. S., Barbosa, I. & carneiro, E., 1958, The anatomy of Tropicor- bis philippianus (Dunker) and its relationships to the Brazilian Pla- norbidae. J. Conchyliol., 97 (4) : 180-185. Costa, O. R., 1952, Contribuição ao co- nhecimento da esquistossomose na Amazônia. Rev. Serv. Esp. Saúde Públ., 5 (2) : 401-409. Crosse, H., 1864, Description d’espèces nouvelles. J. Conchyliol., 12 (2) : 152-154. Dunker, w., 1848, Diagnoses specierum novarum generis Planorbis collec- tionis Cumingianae. Proc. Zool. Soc. London, 16: 40-43. Haas, F., 1949a, On fresh water mol- lusks from the Amazonian region. An. Inst. Biol. (México), 20 (1/2): 301-314. Haas, F., 1949b, Land- und Süsswasser- mollusken aus dem Amazonas-Ge- biete. Arch. Moll., 78 (4/6) : 149-156. Haas, F., 1950, Some land and fresh- -water mollusks from Pará State, Brazil. Nautilus, 64 (1) : 4-6. Haas, F„ 1952, South American non- -marine shells: further remarks and descriptions. Fielãiana (Zool.) , 34 (9): 107-132. Harry, H. W., 1962, A criticai catalogue of the nominal genera and species of Neotropical Planorbidae. Mala- cologia, 1 (1): 33-53. Hubendick, B„ 1962, Report on studies of museum material of Neotropical Planorbidae. 5 pp. mimeografadas, Gothenburg. Lucena, d. T„ 1956, Resenha sistemática dos planorbídeos brasileiros. 104 pp., Gráf. Edit. Recife S.A., Recife. Machado, W. G. & Martins, C., 1951, Um foco autóctone de schistosso- mose no Pará (Nota prévia) . Hos- pital, 39 (2) : 289-290. Maroja, R. C., 1953, Incidência da es- quistossomose em Fordlândia, mu- nicípio de Itaituba, Estado do Pará, Rev. Serv. Esp. Saúde Públ., 6 (1) : 211-218. Moricand, S., 1839, Premier supplément au mémoire sur les coquilles ter- restres et fluviatiles de la Province de Bahia. Mém. Soc. Phys. Hist. Nat. Genève, 8: 139-148. Orbigny, A., 1835, Synopsis terrestrium et fluviatilium molluscorum, in suo per Americam Meridionalem itinere collectorum. Mag. Zool., 5, Classe V, N. 62: 26-28. Paraense, W. L., 1963, The nomencla- ture of Brazilian planorbids. III. Australorbis stramineus (Dunker, 1848). Rev. Brasil. Biol., 23 (1) : 1-7. 13 — 37 121 194 Atas do Simpósio sôbre a Biota Amazônica Paraense, W. L., 1966, Biomphalaria amazônica and B. cousini, two new species of Neotropical planorbid molluscs. Rev. Brasil. Biol., 26 (2). Paraense, W. L. & Deslandes, N., 1955, Studies on Australorbis centime- tralis. I. Morphology, in comparison with A. glabratus. Rev. Brasil. Biol, 15 (3): 293-307. Paraense, W. L. & Deslandes, N., 1956a, The Brazilian species of Drepano- trema. I. D. anatinum (Orbigny, 1835). Rev. Brasil. Biol., 16 (4): 491-499. Paraense, W. L. & Deslandes, N., 1956b, The Brazilian species of Drepano- trema. II. D. melleum (Lutz, 1918). Rev. Brasil. Biol., 16 (4) : 527-534. Paraense, W. L. & Deslandes, N„ 1957, The Brazilian species of Drepano- trema. III. D. depressissimum (Mo- ricand, 1837) . Rev. Brasil. Biol., 17 (3): 339-344. Paraense, W. L. & Deslandes, N„ 1958a, The Brazilian species of Drepano- trema. IV. D. cimex (Moricand, 1837). Rev. Brasil. Biol., 18 (2): 187-192. Paraense, W. L. & Deslandes, N., 1958b, Another Brazilian species of Ta- phius. Rev. Brasil. Biol., 18 (2) : 209-217. Paraense, W. L. & Deslandes, N., 1958c, The Brazilian species of Drepano- trema. VI. D. kermatoides (Orbigny, 1835) . Rev. Brasil Biol., 18 (3) : 293-299. Paraense, W. L., Fauran, P. & Courmes, E., 1964, Observations sur la mor- phologie, la taxonomie, la réparti- tion géographique et les gites d’ Australorbis schrammi. Buli. Soc. Paih. Exot., 57 (6) : 1236-1254. Pfeiffer, L., 1839, Bericht über die Er- gebnisse meiner Reise nach Cuba im Winter 1838-1839. Weigmanns Arch. Naturg., 5 (1) : 346-358. Philippi, r. a., 1869, Diagnoses mollus- corum terrestrium et fluviatilium peruanorum. Malak. Blat., 16: 32- -42. Pinto, D. B. & Deslandes, N., 1953, Con- tribuição ao estudo da sistemática de planorbídeos brasileiros. Rev. Serv. Esp. Saúde Públ, 6 (1) : 135- -167. Sioli, H„ 1953, Limnologische Untersu- chungen und Betrachtungen zur erstmaligen Entdeckung endemis- cher Schistosomiasis ( Sch . man- soni) im Amazonasgebiet. Arch. Hydrobiol., 48 (1): 1-23. SciELO 10 11 12 13 14 1 Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 195-200 — 1967 PRIMEIROS RESULTADOS DE PESQUISAS ETOLÓGICAS EM INVERTEBRADOS LÍMNICOS DA AMAZÔNIA WERNER SATTLER Instituto Hidrobiológico da Sociedade Max-Planck, Estação Potamológica, Schlitz (Hessen), Alemanha (Com 4 figuras no texto) Em geral, distinguem-se vários grupos ecológicos-etológicos de lar- vas de Efemeróptercs (Needham, Traver & Hsu, 1935; Wesenberg- Lunci, 1943), dos quais as larvas escavadoras provàvelmente têm o comportamento mais diferenciado. Enquanto representantes do gru- po dos “revolvedores” (sprawlers) (p. ex Potamanthus) , que podem ser considerados como precursores das formas escavadoras, movimen- tam-se na lama fôfa em todos os sentidos sem deixar rastro nítido, as larvas escavadoras propriamen- te ditas produzem túneis irregula* res no substrato, que se podem ra- mificar e que se desfazem pouco depois de serem construídos ( Ephe - mera) (Wesenberg-Lund, 1943; Sattler, no prelo) , ou então os tú- neis não se ramificam, têm forma de U e são permanentes (Poiymi- tarcis, Tortopus) (Réaumur, .... 1734 42; Fric & Vávra, 1901) . As larvas escavadoras na litera- tura são geralmente indicadas su- màriamente ccmo devoradoras de lama e de minhocas (Despax, 1949). Isto, entretanto, não vale para a larva palaeotrópica Povilla, que mina em esponjas de água doce e em pau submerso. Ela reveste os túneis com uma secreção produzi- da pelos tubos de Malpighi e elimi- nada pelo ânus. Com movimentos respiratórios das brânquias a lar- va conduz uma corrente de água pelo túnel, da qual partículas co- mestíveis suspensas na água são filtradas. Isso acontece por meio de tufos de cerdas localizadas na ca- beça e nas patas anteriores (Har- tland-Rowe, 1953, 1958) . Pesquisas nas larvas neotropicais do gênero Asthenopus (Sattler, no prelo), mostraram que, nelas, a evolução de devorador de lama para filtrador progrediu mais ain- da. As larvas roem, com suas im- cm l SciELO 10 11 12 13 14 15 196 Atas do Simpósio sôbre a Biota Amazônica Fig. 1 — Túnel em forma de U, de Asthenopus, a parede divisória de lascas de madeira. ponentes mandíbulas, a madeira submersa na água, construindo ga- lerias cuja curva estreita em U pro- vém da acumulação, entre os dois braços do U, de lascas roídas cola- das com a secreção dos tubos de Malpighi (fig. 1). Trata-se, pois, de um verdadeiro trabalho construti- vo e não só, como de costume, de uma escavação destrutiva do subs- trato. O aparelho filtrante consis- te de longas cerdas em 8 tufos com forma de funil. Em cada lado do animal acham-se dois tufos na tí- bia, um no fêmur da pata anterior e um na base do lado exterior da mandíbula (fig. 2). Todos os funis são dirigidos para frente contra a corrente de água respiratória e pre- enchem o diâmetro do túnel. Tôdas as cerdas dos funis possuem duas filas de finos pêlos, dirigidos para um só lado. e a distância entre um e outro mede ca. 4 u. Com isso o efeito do aparelho filtrante torna- -se bastante aumentado. A secre- ção produzida pela larva, não só cola as lascas da parede divisória, Volume 3 (Limnologia) 197 mas reveste também as outras pa- redes da galeria, alisando-lhe irre- gularidades e evitando assim fen- das entre as paredes e os tufos de cerdas, que possam perturbar a fil- tração. A larva de Asthenopus pode, pois, por meio de sua atividade construtiva e com sua disposição morfológica com cerdas, ganhar minúsculas partículas comestíveis das águas geralmente cristalinas dos igarapés amazônicos, ficando ela mesma num abrigo seguro. Com os mesmos princípios, po- rém de maneira completamente di- ferente, a larva do Tricóptero Ma- cronema, que vive no mesmo bió- topo, descobriu igual fonte de ali- mento. Esta larva também faz um abrigo, pelo qual a água, doadora de alimento, flui, e ela também dis- põe de um aparelho filtrante. Cer- das especiais na cabeça e nas pa- tas anteriores servem à alimenta- ção. Gêneros parentes afastados (Holocentropus, Plectrocnemia) so- mente constróem abrigos tubifor- mes e irregulares, feitos da secre- ção filiforme das glândulas labiais e ampliados em frente em forma de um funil para captura. Gêneros parentes mais próximos de Macro- iiema (Rhyacophylax, Hydropsy- che, Diplectrona) fazem tubos de FiK. 2 — Larva de Asthenopus. vista diayonalmente de frente, mostrando o aparelho filtrante (F, T, M = tubos de cerdas, F - do fêmur. T = da tibia, M — da mandíbula). SciELO cm 10 11 12 13 14 15 198 Atas do Simpósio sôbre a Biota Amazônica Fig. 3 — Abrigo da larva de Macro- nema ( A . = chaminé de saída de água, Bb. = solo do igarapé, E. = chaminé de entrada, EW. = entrada do tubo de moradia, N. = teia, NK. = câmara para teia, R. = moldura da teia, S. — areia, T. = argila, Wa. = água, Wr. = tubo de moradia) . secreção e material heterogêneo, que têm em frente, em vez de fu- nil, uma teia plana de malhas re- tangulares (ca . 300x200 (i) muito regulares . O tubo e a teia de Macronema, entretanto, evolucionaram para uma das construções de animais mais complicadas, que conhece- mos (Sattler, 1963). Do simples tubo de Rhyacophylax etc. desen- volveu-se um sistema de quatro tu- bos (com chaminé para entrada, outro para saída da água, câma- ra para teia, tubo de moradia), cuja parte inferior está metida no solo do igarapé e que é colado com areia e secreção das glândulas sa- livares (fig. 3). As duas chaminés estão dispostas de tal maneira, que na embocadura de entrada age a pressão total P_. da água corren- te do igarapé e na embocadura de saída age somente a pressão está- tica P.. Da diferença das pressões P e — P< resulta, que pelos tubos e pela teia estendida na sua câmara constantemente flui água (Sat- tler & Kracht, 1963). A teia é construída pelo mesmo princípio dos gêneros parentes; tem também malhas retangulares de uma extre- ma regularidade, que parecem ser feitas à máquina (fig. 4). Mas são tão minúsculas, que não menos do que 630 — 4.300 delas cabem numa malha de Rhyacophylax; medem ca. 2-4 x 14-24 u. Os poros dêste aparelho filtrante têm, pois. Volume 3 (Limnologia) 199 tamanho correspondente ao da lar- va de Asthenopus. Os tufos de cer- das na cabeça e nas patas anterio- res de Macronema, que seus paren- tes não possuem, apesar de terem semelhança com as de Asthenopus, não servem à filtração mas para apanhar as partículas comestíveis da teia. Para ter uma idéia do tripton or- gânico (partículas de origem orgâ- nica transportadas pela água cor- rente) levado das águas de iga- rapés amazônicos, foram tiradas amostras de água de um lugar, onde os dois tipos de larvas vivem um ao lado do outro, e passadas por um filtro membranoso de po- ros com 0,45)1 (Sattler, 1963). Disso resultou que 1 cm :! desta água só continha 4 partículas com diâmetro maior de 100 p, 208 par- tículas entre 100 e 30 u, mas 12.925 partículas entre 30 e 3 p. Estas par- tículas da última categoria, que não obstante o número relativa- mente grande delas, não turvam a água dos igarapés amazônicos, re- presentam evidentemente a base de alimentação dos dois tipos de larvas. Agradecimentos — As pesquisas fo- ram realizadas, em parte, com auxílio do Conselho Nacional de Pesquisas, Rio de Janeiro, ao qual dirijo agradeci- mentos. RESUMO É estudado o comportamento construtivo e a alimentação de 200 Atas do Simpósio sobre a Biota Amazônica duas larvas aquáticas dc inse- tos, ( Asthenopus , Ephemeroptera, e Macronema, Trichoptera) . Os dois animais representam termos finais bastante diferenciados de duas progressões evolucionárias etológicas-morfológicas . A sua contemplação comparativa aqui efetuada tem sua justificação peia maneira, pela qual êstes animais com os mesmos princípios, mas com técnica bem diversa, acharam como fonte de alimento o “Nanno- Tripton” orgânico dos igarapés amazônicos. SUMMARY Building-behaviour and way of feeding of two aquatic insect-larvae ( Asthenopus , Ephemeroptera, an:l Macronema, Trichoptera) are dealt with. Both are the strongly modi- fied final members of two ethologi- cal-morphological lines of evolu- tion. The comparative considera- tion of them, which is performed in this paper, is justified by the fact that both have made accessi- ble the organic “nanno-tripton” of the forest-creeks in the Amazon- -region as a food-source in princi- pally equal ways but the quite dif- ferent technics. REFERÊNCIAS BIBLIOGRÁFICAS Despax, r., 1949, Ordre des Éphémérop- tères, in Grassé, Traité de Zoologie, 9: 279-309, 19 figs. Masson & Cie., Paris. Fric, A. & Vávra, V., 1901, Untersuchun- gen über die Fauna der Gewàsssr Bõhmens. V, Arch. naturw. Landes - durchf. Bõhmen, 9, 3: 1-154. Hartland-Rowe, T„ 1953, Feeding xne- chanism of an Ephemeropteran Nymph. Nature, 172 (4389) : 1109- -1110, 1 Fig. Hartland-Rowe, T., 1958, The biology of a tropical mayfly Povilla adusta Naves (Ephemeroptera Polymitar- cidae) with special reference to the lunar rhythm of emergence, Rev. Zool. Bot. Afr., 58 (3/4) : 185- -202, 4 Figs. Needham, J. G., Traver, J. R. & Hsu, Yin-Chi, 1935, The Biology of May- flies, New York. Réaumur, R„ 1734/42, Memoires pour servir à Vhistoire des Insectes. Paris. Sattler, W., 1963, über den Kõcherbau, die õkologie und Ethologie der Larve und Puppe von Macronema Pict. (Hydropsychidae) , ein ais Larve sich von “Mikro-Drift” emãhrendes Trichopter aus dem Amazonasgebiet. Arch. HydrobioL, 59 (1) : 26-60, 24 Figs. 4 Taf. Sattler, w. & Kracht, A., 1963, Drift- fang einer Trichopterenlarve unter Ausnutzung der Differenz von Gesamtdruck und statischem Druck des fliessenden Wassers. Natuncissenschaften, 50: 362, 2 Figs. Sattler, W„ über die Lebensweise, ins- besondere das Bauverhalten, neo- tropischer Eintagsfliegenlarven (Ephemeroptera, Polymitarcidae) 14 Figs. (no prelo). Wesenberg-Lund, C„ 1943, Biologie der Süssicasserinsekten, 682 pp., 501 figs., 13 Taf., Berlin. Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 201-220 — 1967 ORIENTATION OF AMAZONIAN FISHES TO THE EQUATORIAL SUN HORST O SCHWASSMANN Scripps Institution of Oceonography, La Jolla, Califórnia, U.S.A. CWith 8 text-figures) Some of the most challenging problems in modern biology are concerned with the orientation of animais in time and in space. A great deal of research of a merely descriptive nature is still needed in this field, but some experimental studies of the sensory mechanisms involved in orientation have yield- ed results as surprising as the dis- covery of time-compensated sun- -compass orientation in the honey bee (Frisch, 1950), in birds (Kra- mer, 1950), and in fish (Hasler, Horrall, Wisby & Braemer, 1958). Many fish are known to under- take long distance migrations in the ocean and some even home to particular spawning sites. Exam- ples are the many species of sal- hionids, the eel, and the tainha (Mugil brasiliensis) . While in the salmon the clfactory sense appears to play an important role in de- tecting the home stream (Wisby & Hasler, 1954) , and probably also the spawning ground, olfactory orientation can not explain ade- quately the directed movements cf fish in the ocean. Therefore, orien- tation by visual means was consi- dered to be a likely hypothesis, and has been studied in field and labo- ratory experiments since 1955 at the Laboratory of Limnology, Wis- consin, under guidance of Prof. A. D. Hasler. Field experiments showed that white bass ( Roccus chrysops Raf.) oriented towards the spawning ground significantiy better when released under sunny conditions than under a cloudy sky. In addition, it was discovered that centrarchid fish, which were trained to swim into a compass di- rection, depended on the sun in maintaining this direction throughout the day and that they could allow for the sun’s daily mo- vement (Hasler et al., 1958) . All earlier experiments about sun-orientation of vertebrate ani- cm l SciELO 10 11 12 13 14 15 202 Atas do Simpósio sôbre a Biota Amazônica mais had been made in higher northern latitudes where the sun’s apparent daily movement around the horizon (the sun’s azimuth curve) is relatively uniform and where a uniform rate of changing the angle of orientation to the sun’s azimuth (at 15 degrees per hour) would allow the animal to remain oriented into one compass direction. Moreover, in contradic- tion to an early theory about bird navigation which emphasized the importance of the sun’s changing altitude (Matthews, 1955), seve- ral experimental results seemedto disprove an effect of the sun’s height on the orientation of birds (Hoffmann, 1954; Rawson & Rawson, 1955; Kramer, 1955; Schmidt-Koenig, 1961), and it became customary to speak about “sun-azimuth-orientation” . This simplified concept of orientation to the sun’s azimuth had to be re- -examined after experiments by Braemer (1959, 1960), and after results with cichlids from the Ama- zon at the equator (Hasler & SCHWASSMANN, 1960) . To illustrate one of the major problems for sun-orientation in the tropics, Fig. 1 shows the sun’s movement from sunrise to sunset at a place in the northern hemis- phere (50°N) and at the equator when the sun’s declination is 10°S (22 March and 19 October) . The hourly intervals in the azimuth curve of the sun are rather uniform at 50° N, but they are quite diffe- rent at the equator where there is little change in the sun’s azimuth during morning and evening and a more than 100° change during the two hours around noon. If a sun- compass animal compensated for the sun’s azimuth movement at a uniform rate of approximately 15°/hour, it could not be oriented into a compass direction at the equator . In adition, the direc- tion of the sun’s azimuth move- ment reverses itself twice during the year in the tropics. Near the equator, it changes from clock- wise in late March to counter- clockwise, and becomes again clockwise in late September. Sun- compass animais which live in the tropics must be able to allow for the sun’s movement in the two different directions at different times of the year. Subsequent experiments with fish demonstrated that the sun’s altitude was of importance and that it influenced the change of the conditioned angle to the sun’s azimuth (Braemer & Schwas- SMANN, 1963; SCHWASSMANN & Hasler, 1964), confirming and ex- tending the earlier results by Bra- emer (1959). It could also be shown how the rate of change of the sun’s altitude determined the rate of change of the trained ho- rizontal orientation angle in young Volume 3 (Limnologia) 203 centrarchid fish at first exposure to the sun (Schwassmann & Has- ler, 1964). The duration of day- light which changes considerably throughout the year at higher la- titudes was found to influence the rate of change of the trained an- gle to the sun in centrarchid fish ' (Schwassmann & Braemer, 1961). This factor can be of no impor- tance near the equator because the day length here is a constant twelve hours all year. Sun-compass behavior in fish de- pends on a circadian clock mecha- nism, continuously synchronized with the natural day by sunrise and sunset which can be replaced in experiments by the onset and termination of artificial light. Shifting the “on” and “off” times in the light cycle results in a pre- dictable shift of the compass direc- tion to which the fish had been trained (Braemer, 1959) . In cons- tant artificial light, the orientation rhythm was found to continue, but the period length was now slightly different from 24 hours (Schwass- mann, 1960). The present paper describes ex- periments on sun-compass orien- tation of fish from the Amazon re- gion which illustrate and partial- ly answer some of the problems in the tropics. METHODS The apparatus for training and testing fish in a metal tank of 1.60 meter diameter with slanted walls which is filled with water and which prevents the fish inside from seeing any landmarks on the hori- Pig- 1 — Hourly positional changes of the sun at 10° S ãeclination for a latitude of 50° N in A, aiid at the equator in B. An observer, stationed in the center of the half-circles would see the zenith (center of the sky) ãirectly above and the horizon represented as the periphery. The sun moves across the sky at a constant speed of 15°/hour. At a low inclination of the sun’s arc 'A), the azimuthal po- sition of the sun changes at a fairly uniform rate. At the same time of year. the rate of change of the sun’s horizontal projectory (azimuthi is highly alinear at the equator ( Bi because of the high inclination of the sun’s arc. cm l SciELO 10 11 12 13 14 15 204 Atas do Simpósio sôbre a Biota Amazônica zon (Fig. 2). Sixteen metal boxes are arranged in a circle inside the tank, their openings pointing out- wards. They are covered by a cir- cular plate and cannot be seen by the fish upon release from the cen- ter where it is held captive in a cylinder of transparent plastic. Releasing the fish is done remotely by a lever underneath which causes the plastic center cage to recess into the well. Observation of the fish is accomplished by two observers through four concentri- cally mounted periscopes. In order to prevent orientation to marks within the tank, the latter is rotat- ed between trials. For training, only one of the sixteen boxes is open and always points into the same compass direction. Training is repeated daily at the same time fcr usually 10 to 20 minutes, un- til the fish has apparently learned, to relate the position of the one open box, in which it can hide, with the sun’s position at this time of day. During later testing all six- teen boxes are open and tests are conducted at áifferent times of the day. Every test consists of at least five trials and the observers record the exact place at which the fish swims over the margin of the co- ver plate before entering a box. Some experiments at Belém were made utilizing a large mirror to reflect the sun into the tank, whereas the real sun was blocked from the view of the fish by a large sunshade (Fig. 2) . The fish species used were the following cichlids: Cichlaurus se- verus s. Heckel, Crenicichla saxa - tilis L., Varn amphiacanthoides He- ckel, and Aequidens portalegrensis Hensel. In addition, experiments are reported with Anableps micro- lepis Mueller & Troschel, and the North American centrarchid Lepo- mis cyanellus Rafinesque. All fish were immature and between five and eight centimeters long. RESULTS 1) Orientation to the equatorial sun — Once a fish has been traim ed for a few weeks to swim at a certain angle to the sun, and al- ways during the same ten minutes every morning, it is then tested at different times of day. Two differ- ent modes in the behavior have been found. The great majority of t.ained fish will swim into the same compass direction. Because of the daily movement of the sun, these fish alter the angle of swim- ming in relation to the sun’s azi- muth position continuously. This behavior is called time-compensat- ed sun-compass orientation . Some- times a fish will swim at the same angle to the sun, to which it had been trained, also at other times of the day; it will not allow for the sun’s movement with time. Such “azimuth constancy” is rare Volume 3 (Limnologia) 205 Fig. 2 — Training and testing apparatus shown in testing condition. The fish is held captive inside the plastic cage in the center of the water-filled tank. The release mechanism (R) causes the centei cage to recede into the well, liberating the fish which can swim into any ãirection and will seek cover in one of sixteen open boxes. Two of four periscopes (Pi for observation are shown. The turn- -table icith the tank is rotated after every trial. For some expe- riments the sun iças blocked by a shade (St and reflected into the tank by a mirror (M). under the real sun, but is usually found when the real sun is replac- ed by an electric light bulb. For the first behavior, the com- monly observed sun-compass ori- entation, it remains to be shown that the fish actually utilize the position of the sun only, and that their compass constancy is not caused by some other factor un- known to us. In order tc demons^ trate if the sun was the important externai reference, a large mirror was used in 1962 at Belém. As a re- p 206 Atas do Simpósio sôbre a Biota Amazônica sult, the orientation of all the ci- chlids used in these experiments was 180° reversed (Fig. 3). The an- gle between mean direction of the scores and the real sun in A is the same as the one between mean di- rection and reflected sun in B. The mirror worked so effectively that it was employed to test the influen- ce of the sun’s altitude on the ori- entation of these fish. Changing the apparent altitude of the sun could easily be accomplished by tilting the mirror in its horizontal axis. The results have been report- ed in detail elsewhere (Braemer & SCHWASSMANN, 1963). Having established the sun’s po- sition as the effective externai re- ference in the orientation behavior of the fish, justifies recording cf individual test scores as angles to the right or left of the sun and the data can be presented in this man- ner with the sun’s position kept stationary and indicated as a strai- ght line (Figs. 4, 6, 7) . A compass direction is represented in these graphs as a curve d line which is computed from the sun’s azimuth curve during the time of the expe- riments. If a fish would swim ac- curately into this compass direc- tion, its scores should follow this latter curve. Usually, the orientation of one trained fish is not very accurate; the mean direction of a test often deviates from the compass direc- tion and the scatter around the mean is great. However, when a great number of scores from tests Fig. 3 — A mirror experiment. A: directioiial scores of five cichlids under the real sun. B: scores under the reflected sun. Immediately after the tests in A, the view of the sun was blocked by a shade (S) but the sun was re- flected by the mirror ( M ) into the tank. All fish sxoim at approximately the same angle to the mirror image of the sun in B, as they swam to the real sun in A, but reversed in compass direction by 180°. The experiment de- monstrates that the sun is the only externai reference point in the orien- tation of these fish. Data by Braemer & Schwassmann (1963) SciELO 10 11 12 13 14 15 cm Volume 3 (Limnologia) 207 LOCAL MERIDIAN TIME Fig. 4 — Sun-compass orientation of six cichlid fish at the equator during June and early July 1962. The daily pattern of angular change over the entire day to the sun’s azimuth can be seen. All scores of the six fish falling into each hourly interval were averaged, and the mean was plotted (circles), with its standard deviation ( vertical bars), as angle to the right or left of the sun’s azimuth position (straight horizontal Une). The procedure is examplified for four of the ten means (scatter diagrams showing all scores and the sun’s position at this time). The curved Une indicatéS how a compass direction changes in relation to the sun’s azimuth with time of day. If the fish allowed precisely for the sun’s azimuth movement, their recordeá means should follow this Une Data computed from 402 scores. From experiments ■ by Braemer and Schwassmann (1963). of several fish is averaged, the com- bined results show a good fit to the theoretical curve. This is shown in Fig. 4 where a total of 402 scores of six cichlid fish was used. These fish were tested throughout the day from 31.5. to 7-7-1962 at Belém. All test scores falling into each hourly interval were pooled and the common mean with its standard deviation is indicated. The rate of angular change to the sun is small during morning and evening hours but is great during the two hours around noon. Si- milar data have been presented by cm 1 SciELO 10 11 12 13 14 15 208 Atas do Simpósio sôbre a Biota Amazônica SCHWASSMANN & HASLER (1964). Very few experiments have been done at the equator during the time of the equinoxes when the sun’s noon position approaches the zenith (Hasler & Schwassmann, 1960); and it was found that the fish did not orient as well under a very high sun. 2) Innate and learned behavior in the sun-ccmpass of fish — An- other experiment in collaboration with Braemer in Wisconsin du- ring 1958 yielded results of far- reaching significane (Braemer, Braemer & Schwassmann in prep.). Green sunfish and Portcich- lids were reared from the egg in artificial light for several months until they had reached a size suita- ble for experiments on sun-orien- tation. These fish never experienc- ed any natural daylight, but their regime of artificial lighting was continually adjusted to the chang- ing times of sunrise and sunset at 43° N. During early September, the fish were trained at local noon in a darkened rcom to swim to- wards an electric light bulb, simu- lating the sun. They were tested subsequently out-of-doors under the sun in the morning and after- noon. In these tests, they compen- sated for the movement of the sun correctly according to season and latitude, although they had never seen the sun, or its apparent daily movement, previously (Fig. 5). All green sunfish swam south which corresponds to the sun’s po- sition at noon, the time of previous training towards the light (Fig. 5, A„-A-). The behavior of the equal- ly treated cichlids was different from that of the North American sunfish. At least the diagram Bi shows a bimodal distribution. A few scores point towards the sun, indicating that the fish had not changed the trained angle. A con- centration of scores in the Southern sector correspcnds to the behavior of the sunfish. In addition, many scores fali into the northern sec- tor. A bimodality seems also indi- cated in diagram B_. from the after- noon test but the two modes are not clearly separated, possibly ob- scured by some “constant-sun-an- gle” scores towards the sun. The orientation behavior of the cichlids can be analyzed in the fol- lowing way: In the northern tem- perate zone, the sun moves in a clockwise direction through the Southern part of the sky, its posi- tion at ncon is South. Sun-compass fish, like the Lepomis i compensate for this movement by changing the angle of swimming to the sun in a counter-clockwise manner. In the Southern hemisphere, the di- recticn of the sun’s movement, as well as that of the compensating angular change of compass fish to the sun, are the reverse. If the mo- vement of the sun were to be com- Volume 3 (Limnologia) 209 pensated for in the “wrong” direc- ge had the same sign, the change tion, if sun motion and the in orientation angle of the fish fish’s compensating angular chan- would be added to, instead of sub- Fig. 5 — Demonstration of the innateness of sun- compass behavior. The orientation behavior of six North- American sunfish is shown on the left (scatter diagrams A n — AJ and contrasted with the behavior of six equálly tredteã tropical cichlids on the right (B t . — B.J. A tl , B tl : scores at the training time under thè electric light; A v B 1 : orientation scores at first exposure to the sun, afternoon and morning respectively ; A„. B.,: second tests under the sun, morning and afternoon respectively. The mean directions from the control tests under the electric light are indicated as solid arrows in the four lower diagrams. In B 1 and B, the direction to be expected for a compensation of the sun’s movement in the "wrong” direction is marked by the open arrow. Data from experiments by Braemer and Schwassmann. M — 37 121 cm 1 SciELO 10 11 12 13 14 15 16 p 210 Atas do Simpósio sobre a Biota Amazônica tracted from, the amount which the sun had moved around the ho- rizon in azimuth. In this case, the compass direction which the fish indicates would be continually changing. The cichlids apparently also compensate for the movement of the sun, otherwise all scores should point towards the sun, but they change the orientation angle to the sun in both directions, clock- wise as well as counter-clockwi- se. The compass directions, are in- dicated in Bi and Bj, and the re- sults seem to conform to the hy- pothesis outlined above. The results are evidence that sun-compass orientation in fish is basically an inherited behavior pattern, requiring no learning of the sun’s movement. In addition, the apparent necessity for tropical cichlids to learn in which direction the sun is moving seems of biolo- gical significance. Later experi- ments have confirmed the innate- ness of sun-compass behavior in the green sunfish (Schwassmann & Hasler, 1964). Experiments which illustrate the “two-direction ability” of cichlids are reported in the following pages. The ability of cichlid fish from the Amazcn to learn to accomodate their orientation behavior to a re- versed sun movement was demon- strated by transporting them, after training and testing at Belém, to Madison, Wisconsin (43° N) during 1961. The orientation of two fish at Belém in late May is shown in Fig. 6 A, where the sun’s move- ment was counter-clockwise and the fish’s angular change occured in a clockwise manner. In early June the two fish were tested at 43° N (Fig. 6, B) where they con- tinued to change their angle to the sun as they did at the equator pre- viously. After five days exposure to the sun out-of-doors, and one 15 minute period cf re-training in the morning to an electric light in- doors, one of the two fish appeared to have learned and accommodat- ed for the locally correct direction of the sun’s movement (Fig. 6, C) . The other fish lost its oriented be- havior during the five days of out- door exposure and a brief re-train- ing was ineffective. Confirmation of these results was obtained by data from two more cichlids which had been brought from Belém to 43° N where they were trained to swim towards an electric light at noon. In the first tests under the real sun of 43° N they scored like the two cichlids in Fig. 6, B, but after two weeks of partial exposu- re to the local sun one had com- pletely reversed the direction whereas the other now seemed un- decided and showed scores accord- ing to the two different modes of compensating angular change, si- milar to the inexperienced cichlids in Fig. 5, B. These and further data SciELO 10 11 12 13 14 15 cm Volume 3 (Limnologia) 211 Fig. 6 — Data which demonstrate the ability of cichlids to accomodate their compass orientation to a sun movement in the reverse direction. The uiean directions with standard deviations are plotted as in Fig. 4 (filled and open circles ]or the two dif- ferent fish) and each was computed from a mi- nimum of five scores. A: pattern of angular change to the counter-clockwise movement of the sun at Belém in May 1961. B: the orientation o f the same fish after transport to 43° N in early June under a clockwise sun movement. C: the pattern of angular change to the clockwise moving sun is “locally cor- rect” in one of the two fish after five days exposure to the sun. The solid curve indicates a compass di- rection under the local sun movement, the dasheã curves in B and C indicate the pattern of angular change to the sun at Belém. were reported earlier (Schwass- ported above were made at a time mann, 1962). The experiments re- when the sun’s altitude curves 212 Atas do Simpósio sobre a Biota Amazônica were quite similar at both loca- tions; at least the noon position of the sun was of the same height. Since the day at 43° N was consi- derably longer than 12 hours, the fish were kept in an artificial light cycle with 12 hours, light, except for the day of exposure to the local sun. To test the two-direction concept in the sun-orientation of cichlids further, and to compare it with the apparently hereditarily fixed sin- gle direction of compensation in centrarchids, experiments were de- signed which enabled training of fish to a sun apparently moving in the opposite direction. The ex- periment did not require transport- ing the fish over long distances and also left the daily sun arc unaltered except for the reversal of direction. This was accomplished by mounting a tank on a turn-ta- ble which had fastened to its un- derside an excentrically mounted ring gear. This gear was driven by a constant speed motor with reduc- tion box and final pinion which, as a unit, remained stationary in azi- muth but was sliding in and out radially because of the ring-gears excentricity. The resulting rotation was in the same direction as the sun’s movement, but at exactly twice its azimuth velocity (Fig. 7, B). Sufficient reference marks in- side the turning tank, in addition to the usual single training box, were provided so that the fish in- side had opportunity to relate their successive positions with the sun. Fig. 7, A shows the orientation of two Cichlaurus severus cichlids which were brought from Belém to Madison, Wisconsin. They had been kept in natural daylight and were trained during early Septem- ber 1962 to swim towards the sun between 0700 and 0800 hours. They compensated locally correct for the sun’s movement (Fig. 7, A, 1-2). After five sunny (and more clou- dy) days inside the azimuth-rever- sal apparatus, they were tested again and had now reversed the direction in which they changed the orientation angle to the sun (Fig 7, A, 1-3). They allowed for the sun’s movement as it was at this time of year (autumnal equi- nox) at the same latitude in the Southern hemisphere. 3) Sun-compass orientation of fish in nature — Few experiments with fish have been made which investigated if sun - orientation might be involved in movements to a spawning ground, or towards “home”, after experimental displa- cement, during a certain phase of active migration. Simple displace- ment and release at a distant pla- ce might not always yield conclu- sive data, since additional factors could provide orientational cues, like odors, landmarks, etc. Better directed orientation under a sunny Volume 3 (Limnologia) 213 B LOCAL M ER1 Dl AN TIME Eig. 7 — Experimental reversal o) the direction of the sun’s movement at 43° N latitude. The principie of the azimuth-reversal apparatus is shown schematically V} At 0800 hours the open training box inside the tank (T) is in Une with the sun’s azimuth. At 1000 and at 1200 hours, since the tank has been rotated at twice the sun’s azimuth velocity, the open box has traveleã tivice as much as the azimuth of the sun, simulating a sun movement in the opposite direction. In A is shown the orientation behavior of tico cichlids from the Amazon, after training at 0800 hours (tests 1). They changed the orientation angle correctly for the clockioise sun movement (1. to 2.J. After five sunny days of treatment in the azimuth-reversal apparatus, they had reversed the direction of angular change to the sun and allowed for a movement of the sun as it tcas correct for the Southern hemisphere <1. to 3.). sky than under cloudy conditions is an indication for the sun’s im- portance in guiding the fish (Has- ler et. al., 1958; Winn, Salmon, & Roberts, 1964). If the direction °f “homing” after release is shift- e d by the amount predicted by a phase-shift of the fish’s time sense (conditioning the fish in a delayed or advanced artificial light cycle for several days), sun-orientation can be assumed to be the orienting hiechanism (Winn et. al., 1964). ff the fish are sufficiently small, they can be tested in a circular tank where possible environmental cues other than the sun seem to be eliminated. Groot (1965) used this method to investigate the orientation of sockeye smolt during their seaward migration and the data indicate that the sun plays at least a certain role in the orien- tation of these salmonids. Experiments in the field with fish, of which some natural ten- dency to swim in a certain compass direction is known, are promising. They have the great advantage that no directional training is ne- cm 1 SciELO 10 11 12 13 14 15 214 Atas do Simpósio sôbre a Biota Amazônica cessary. One experiment of this kind was done in 1964 at Salinas, Pará, with Anableps microlepis. Previous studies on a large popu- lation of these fish near Salinas had shown that they form schools, the size and compactness of which depends on the age and sex of the fish. Adult females were ob- served in lcose groups of from two to ten, the smaller males and younger females in groups of five to twenty. These schools of large and médium sized Anableps swam along the beach in open water and in bays and river out- lets. They were never found in very deep water but stayed close to shore. Most striking was their change in behavior during the later part of every rising tide, day or night, when these fish literally stranded themselves on the beach with every incoming wave, often being left on the sand by the rec- eding water . A similar behavior of moving close to shore with every rising tide was thought to be cor- related with increased feeding ac- tivity, since many shore insects are trapped by the rising water. Studies of the Salinas population demonstrated an obvious purpose of the cyclic behavior . During March of 1962, at the time of the high tides of the equinoctial syzygies, many hundreds of the fish entered in this manner through an 80 meter long channel into a large brackish water lagoon. With every rising tide, day or night, the fish concentrated in large numbers at the channel entrance. At about the time of highest water levei, the fish revers- ed this movement and had left the lagoon before the channel had be- come dry. Inside the lagoon, many large schools of often more than a hundred newly born and up to se- ven centimeter long Anableps were found. The small fish did not leave the lagoon until a considerably later date. The lagoon obviously served as breeding ground for this Anableps population. Later obser- vations were made during April 1964, when the tidal change in wa- ter levei was insufficient to flood the channel leading into the la- gocn. Now only a few Anableps, seven to ten centimeters long, were found inside, but all the larger fish outside still showed the same behavior of concentrating at the channel mouth with every rising tide. These fish seemed ideally suited for sun-orientation tests because of their strong directional tendency and also because of the known outstanding performance of their visual system, especially of the ae- rial portion of the “amphibious” eye (Schwassmann & Krugeh, 1965). The orientation tank was placed on a high sand dune near the lagoon so that the horizon was «•o Volume 3 (Limnologia) 215 occluded by the rim of the tank. Since large Anableps could not be accomodated in the apparatus, fi- ve immature fish, eight to ten cen- timeters in length, were captured out of a larger school which dis- played consistently strong swim- ming in an E-N-E direction. This was the generally observed tenden- cy of the entire population corre- sponding to the direction of chan- nel and lagoon. Time of capture was the 26-4-1964, 1730 hours, dur- ing rising tide which had begun around 1400 hours. After over- -night storage in individual cover- ed containers, the fish were tested the following morning shortly be- fore high tide levei, and again in the late afternoon during the early part of the next rising tide. Bad weather prevented further testing and there was from 50 to 70% cloudcover during the tests. In these trials all fish showed a strong preference for the E — and N-E sector (Fig. 8, A, B) . Three of these fish could be tried again after sunset and under complete cloud- cover with beginning heavy rain before it became completely dark. They now displayed random scat- tering in their orientation, al- though it was still the time of ri- sing tide (Fig. 8, C). Equally dis- oriented behavior was noted in three small Anableps from a dif- ferent population inside a nearby bay which were captured during falling tide and tested immedia- tely. The results show that Anableps can utilize the sun’s position as di- rectional reference when other means of orientation are excluded, and that they are capable of time- compensated sun-compass beha- vior. When the sun was in the East in the morning, they swam to- wards it, whereas they swam away from it in the late afternoon, thus maintaining one compass direc- tion. No orientation seemed possi- ble without the presence of the sun in the artificial environment of the testing apparatus. Fig. 8 — Sun-orientation of five Anableps at the equator. A: Scores during the B: scores in the late afternoon, both tests under 50-70% cloudcover. ■ apparent random behavior after sunset and in heavy rain. The sun’s position indicated in A and B; North is up. Each fish is indicated by a different symbol. 216 Atas do Simpósio sôbre a Biota Amazônica DISCUSSION The fish species used in the ex- perimente are mostly non-migrato- ry and usually inhabit small bo- dies of water; they were chosen be- cause of the easiness with which they could be maintained in capti- vity and trained to compass direc- tions. That all the investigated spe- cies were found to be capable of time-compensated sun-orientation, together with the evidence about the innate nature of the basic pat- tern to alter the angle of swimming to the sun with time of day, makes it appear likely that sun-orienta- tion plays an important role in the directional movements of fish in nature. Of further significance should be the considerable accura- cy of this compass orientation which is noted when many data of several fish are averaged, as com- pared to the performance of an in- dividual fish. Most species that un- dertake long distance migrations are schooling and usually migrate together in large numbers. Major difficulties were envisaged in sun-orientation for animais li- ving in the tropics, where not only the sun’s movement occurs along a very steep arc but where also the direction of movement reverses it- self twice during the year. It could be demonstrated that South Ame- rican cichlids can compensate for the sun’s movement in either di- rection, and that they are able to learn to accomodate for a sun mo- vement in the opposite direction within a few days. Sun-compass orientation in fish is the expression of an endogenous circadian rhythm. The poor accu- racy, usually apparent in the re- corded directional performance of trained fish, is certainly not a true measure of the precision of the in- volved time sense. Another species of fish from the Amazon, the gym- notid Gymnorhamphichthys hy- postomus Ellis, exhibits a high de- gree of precision of its endogenous rhythm when a different parame- ter, the daily onset of activity, is used for its measurement (Liss- MANN & SCHWASSMANN, 1965 ). It is not known how important the sun-compass might be for the orientation of fish in nature. Its usefulness seems to be limited to times of day with sunshine. Certainly, other means of orienta- tion must also be important, since many fish migrate in an apparent- ly oriented manner also at night. That the sun can become an im- portant reference for orientation when other directional cues are excluded, was shown by the expe- rimente with Anábleps. The beha- vior of Anábleps is of additional in- terest, because it not only resem- bles the peculiar spawning beha- vior of the Califórnia grunion (Leuresthes tenuis Ayres), but the Volume 3 (Limnologia) 217 urge to return to the original place of birth (at least in the observed population) is reminiscent of the homing behavior of salmon. It might well be possible that similar principies of early imprinting and orientation are involved. Acknowledgements — Most of the experiments reported here were part of the author’s thesis work on sun- orientation of fishes, conducted under the guidance of Prof. A. D. Hasler at the Laboratory of Limnology, Univer- sity of Wisconsin, and supported by the National Science Foundation (G-3339) and the Office of Naval Research (NR-301-903) . The orien- tation studies on Anableps were made while the author was a post-doctoral fellow of the Public Health Service and affiliated with the Department of Anatomy, University of Califórnia, Los Angeles. Research support was obtain- ed from the Office of Naval Research (NR-301-790) and the National Science Foundation (GB-2796) . The Museu Goeldi, Belém, provided necessary fa- cilities and Services for the experi- ments near the equator. The azimuth- -reversal apparatus was built by Mr. E. Hanson of the Department of Zoology, University of Wisconsin. The data shown in Figs. 3, 4, and 5 were obtain- ed in collaboration with the late Dr. Wolfgang Braemer. SUMMARY Fish can orient into compass di- rections by using the sun’s posi- tion as externai reference and by making allowance for its daily mo- vement. Reflecting the sun from a large mirror, it could be demons- trated that the sun was the only environmental reference point in this orientation. Under the very steep sun arc at the equator, cor- related with a greatly alinear rate of the sun’s movement around the horizon, the compass-orientation of cichlids from the Amazon is as precise as the sun-compass of fish at higher latitudes. Very little change of the orientation angle to the sun’s azimuth is observed du- ring morning and evening hours; practically all angular change oc- curs during the two hours around noon. Raising centrarchid and cichlid fish from the egg in conditions of artificial light, gave evidence that the basic feature of sun-compass behavior, the tendency to alter the angle of swimming to the sun with time of day, must be considered an innate behavior pattern. In the N or th- American centrarchids also the direction in which this angu- lar change to the sun occurs ap- pears hereditarily fixed, whereas the tropical cichlids need to learn the direction in which the sun moves around the horizon. About five days of exposure to a sun movement, in a direction opposite to that which the cichlids had learned previously, suffices to cause the fish to reverse the direction of changing its orienta- tion angle to the sun. cm 1 SciELO 10 11 12 13 14 15 218 Atas do Simpósio sobre a Biota Amazônica Anableps from a population which displayed strong directional swimming during rising tide were found to orient to the sun and to allow for its daily movement when they were deprived of other xneans of orientation. SUMÁRIO Os peixes são capazes de se ori- entarem no espaço usando como referência a posição do sol, toman- do em consideração o seu movi- mento diurno (“sun-compass ori- entation”). Com a reflexão do sol, usando um grande espelho, foi pos- sível demonstrar que o sol é o úni- co ponto de referência externa usa- do nesta orientação. Em condições equatoriais onde a inclinação do sol aproxima o ze- nite e, em conseqüência, o movi- mento solar segue uma trajetória horizontal não linear, a orientação dos ciclideos amazônicos é tão pre- cisa como a dos peixes em latitu- des maiores. Durante a manhã e a tarde, os peixes quase não mudam o ângulo de orientação ao azimu- te solar, mas durante as duas ho- ras antes e depois do meio-dia a mudança angular é considerável. Baseado no fato de que peixes (Centrarchidae e Cichlidae) t cria- dos em laboratório sob luz artifi- cial desde o ôvo, têm a capacidade de se orientarem ao sol, levando em consideração o movimento so- lar, concluímos que êste tipo de orientação é inato. Nos Centrar- chidae norte-americanos, a direção em que a mudança do ângulo ao sol se efetua, também parece ser hereditária, enquanto que nos ci- clideos tropicais os peixes precisam aprender em que direção o sol mo- ve ao redor do horizonte. Expon- do os ciclideos ao movimento so- lar oposto ao prèviamente aprendi- do por cêrca de cinco dias é sufi- ciente para que êles revertam a di- reção em que êles alteram o ângulo de compensação. Os tralhotos de uma população que demonstraram marcada ten- dência em nadar numa certa dire- ção durante a maré enchente são também capazes de se orientar ao sol levando em consideração o seu movimento, quando desprovidos de outros meios de orientação. REFERENCES Braemer, W., 1959, Versuche zu der im Richtungsgehen der Fische enthal- tenen Zeitschàtzung. Verh. Deut. Zool. Ges., 1959: 276-288. Braemer, W., 1960, A criticai review of the sun-azimuth hypothesis. Cold Spring Harbor Symp., 25: 413-427. Braemer, w. & Schwassmann, H. O., 1963, Vom Rhythmus der Sonneno- rientierung am Aquator bei Fis- chen. Ergebn. Biol., 26: 182-201. Volume 3 (Limnologia) 219 Braemer, w., Braemer, H. & Schwass- mann, H. O., Z. Tierpsychol. in prep. Frisch, K., 1950, Die Sonne ais Korapass im Leben der Bienen. Experientia, 6 : 210 - 221 . Groot, c„ 1965, On the orientation of young sockeye salmon (Oncorhyn- chus nerka) during their seaward migration out of lakes. Behaviour, Suppl. 13: 1-198. Hasler, A. D., Horrall, R. M., Wisby, W. J. & Braemer, W., 1958, Sun orientation and homing in fishes. Limnol. Oceanogr., 3: 353-361. Hasler, A. D. & Schwassmann, H. O., 1960, Sun-orientation of fish at different latitudes. Cold Spring Harbor Symp., 25: 429-441. Hoffmann, k., 1954, Versuche zu der im Richtungsfinden der Vogei enthaltenen Zeitschátzung. Z. Tier- psychol., 11: 453-475. Kramer, G., 1950, Orientierte Zugakti- vitàt gekàfigter Singvõgel, Natur- wiss., 37: 188. Kramer, G., 1955, Ein weiterer Versuch, die Orientierung von Brieftauben durch jahreszeitliche Anderung der Sonnenhõhe zu beeinflussen. Glei- chzeitig eine Kritik zur Theorie des Versuches. J. Ornithol., 96: 173-185. Lissmann, H. W. & Schwassmann, H. O., 1965, Activity rhythm of an electric fish, Gymnorhamphichthys hypostomus. Z. vergl. Physiol., 51: 153-171. Matthews, G. V. T., 1955, Bird Naviga- tion, 141 pp., Cambridge University Press, Cambridge. Rawson, K. S. & Rawson, a. M., 1955, The orientation of homing pigeons in relation to sun declination. J. Ornithol., 96: 168-172. Schmidt-Koenig, K„ 1961, Die Sonne ais Kompass im Heimorientierungs- System der Brieftauben. Z. Tier- psychol., 18: 221-244. Schwassmann, H. O., 1960, Environ- mental cues in the orientation rhythm of fish. Cold Spring Harbor Symp., 25: 443-449. Schwassmann, H. O., 1962, Experiments on sun orientation in some fresh- water fish, Thesis, Univ. Wiscon- sin, Jan. 1962: 153 pp. Schwassmann, H. O. & Braemer, W., 1961, The effect of experimentally changed photoperiod on the sun- -orientation rhythm of fish. Phy- siol. Zool. 34: 273-286. Schwassmann, H. O. & Hasler, A. D„ 1964, The role of the sun’s altitude in sun orientation of fish. Physiol. Zool, 37: 163-178. Schwassmann, H. O. & Kruger, L., 1965, Experimental analysis of the visual system of the four-eyed fish, Ana- bleps microlepis . Vision Res., 5: 269-281. Winn, H. E„ Salmon, M. & Roberts, N., 1964, Sun-compass orientation by parrot fishes. Z. Tierpsychol., 21: 798-812. Wisby, W. J. & Hasler, A. D., 1954, Effect of olfactory occlusion on migrating silver salmon (O. kisut- ch). J. Fish. Res. Bd. Canada, 11: 472-478. Atas do Simpósio sôbre a Biota Amazônica Vol. 3 (Limnologia): 221-226 — 1967 SÔBRE O BALANÇO METABÓLICO DE IÔNIOS INORGÂNICOS DA ÁREA DO SISTEMA DO RIO NEGRO HARALD UNGEMACH Hydrobiologische der Max-Planck-Gesellschaft, Plõn, Alemanha e Instituto Nacional de Pesquisas da Amazônia, Manaus, Amazonas O abastecimento de elementos nutritivos inorgânicos para os or- ganismos terrestres vem primeira- mente do solo. Além disso têm im- portância a alimentação através de precipitações. Em certas regiões te- mos o fenômeno do abastecimento com elementos nutritivos transpor- tados pelo vento. Além disso é ne- cessário a indicação do abasteci- mento particular de compostos ni- trogênicos formados pela atividade microbiológica utilizando nitrogê- nio atmosférico. O cálculo quanti- tativo dêstes abastecimentos natu- ralmente é difícil. Todavia, o ba- lanço dos elementos nutritivos é de alto interêsse. Um fator importante no balan- ço dos elementos nutritivos é a per- da dêsses elementos por lixiviação em uma dada região. Em parte ês- tes elementos alcançam camadas inferiores do solo onde formam compostos insolúveis não tomando mais parte na circulação biogêni- ca dos elementos nutritivos. Outra parte é carreada pelas águas cor- rentes superficiais, enquanto que provàvelmente a maior parte é ar- rastada, com a água de percolação, a água freática com a qual apare- ce nas fontes e é eliminada, da re- gião, com os córregos e rios. As condições para êste transporte são muito favoráveis na bacia do rio Negro em virtude das elevadas pre- cipitações (segundo o Atlas Pluvio- métrico do Brasil de 1948, alcan- çam 1.500 a 3.500 mm). Outros- sim, existem vastas regiões com so- los permeáveis; e há solos cujas características físicas e químicas apresentam pouco poder de absor- ção de elementos nutritivos. Final- mente, observando a bacia do rio Negro, vê-se que é coberta por ex- tensa rêde de afluentes, o que per- mite uma conexão efetiva entre o solo e a água. Os problemas dessa comunicação entre o solo e água foram pesquisados por Sioli e cm 1 SciELO 10 11 12 13 14 15 222 Atas do Simpósio sôbre a Biota Amazônica Klinge e são citados em diferentes publicações básicas (Sioli, 1951, 1955 a, 1955 b, 1960 e 1964; Sioli & Klinge, 1962). Nesta coerência é que estamos realizando pesquisas sôbre as quan- tidades dos elementos de importân- cia biológica que o rio Negro trans- porta para fora de sua bacia. Re- presentam êles as reservas em nu- trimentos para o crescimento da vegetação que são liberadas nos solos daquela região progressiva- mente. Êsses trabalhos estão concentra- dos na foz do rio, perto da cidade de Manaus, onde realizamos regis- tros ecográficos do perfil do rio e determinações de velocidade da correnteza. Com êsses dados foi- -nos possível calcular sua vazão, que em 13-4-66 atingiu a 27.000 m 3 /s. Para pesquisas químicas coleta- mos amostras de água pouco aci- ma da cidade a fim de evitar a po- luição. Outrossim foram realizadas em 13-4-66 pesquisas químicas, cujos resultados multiplicados pela va- zão forneceram dados sôbre as quantidades de elementos trans- portados por segundo naquele dia, como também a perda de elemen- tos nutritivos inorgânicos no mes- mo dia e por quilômetro quadrado de sua bacia. Em fevereiro, março e abril, em oito diferentes dias, realizamos as mesmas pesquisas; os dados quími- cos indicaram apenas pequenas di- ferenças das realizadas em 13-4-66, não sendo por isso seus dados aqui referidos. A amostra de 13-4 vai mais pormenorizada porque nesta data o rio apresentava uma vazão aproximadamente média; por isso mesmo os resultados terão talvez um valor mais generalizado. TABELA Concentração Transporte Transporte Transporte em /ug/1 em kg/s t/dia g/dia/km- N total 357 9,7 840 1 300 N (NH+) 15 0,40 35 54 N (NCT) 17 0,46 40 61 N Orgânico 325 8,8 765 1 180 P total 7,0 0,19 17 26 P (PO* - ) 4,9 0,13 11 18 Fe total 370 10 860 1 300 Fe diss 280 7,6 660 1 000 Fe não diss. 90 2,4 200 300 Ca++ 360 9,7 840 1 300 Mg ++ 230 6,2 540 830 Volume 3 (Limnologia) 223 Das análises químicas evidenci- ou-se inicialmente serem pequenas as concentrações de substâncias, principalmente de fósforo total e fósforo de fosfatos que se apresen- taram extremamente baixas; sen- sivelmente baixas são também as concentrações dos compostos de ni- trogênio, o cálcio e o magnésio. Digno de nota apresentou-se a quantidade de feiTO, superando por si a soma dos alcalino-terrosos, es- tando êste fenômeno em correla- ção com as características geoquí- micas e edáficas da bacia que em sua maior parte está pobre em cál- cio. Da concentração total de fer- ro somente 3 4 estão em dispersão iônica, enquanto que 1/4 distribuí- dos em forma não ionisada acham- -se em suspensão, ou seja incorpo- rados em outras substâncias. A bacia do rio Negro apresenta uma área de aproximadamente . . . 650.000 km- (determinação plani- métrica usando-se o mapa do Brasil de 1964, da escala 1: 5 000 000, edi- tado pelo IBGE, Divisão de Carto- grafia), e em 13-4-66 transportou elementos na ordem de' 840 t de nitrogênio total; 17 t de fósforo to- tal e 1.380 t de alcalino-terrosos. O fluxo dêsses elementos diàriamen- te, por quilômetro quadrado é cal- culado em : 1.300 g de nitrogênio total; 26 g de fósforo total; 1.300 g de ferro total e 2.100 g de cálcio e magnésio. Objetivamos continuar estas ob- servações por um período mais pro- longado, pelo menos um ciclo anual inteiro, intensificando o trabalho também por comparações entre ba- cias de diferentes afluentes a se- rem estudadas separadamente. Os dados que apresentamos são análises preliminares sôbre o ba- lanço dos elementos inorgânicos nutritivos da bacia do rio Negro, pois os trabalhos estão agora ini- ciados e não podemos por enquan- to positivar o porque das condições especiais dessa bacia. SUMÁRIO Pesquisas hidrográficas e quími- cas estão sendo realizadas no rio Negro, perto da cidade de Manaus, para determinação das quantida- des absolutas dos elementos da im- portância biológica que êle trans- porta. Estas pesquisas desenvol- vem-se em duas partes distintas: 1) hidrográficas, para determina- ção da velocidade da corrente e re- gistro ecográfico da profundidade. Êstes resultados permitirão cal- cular a vazão do rio; 2) Químico- analíticas, para determinação do N, P e Fe sob vários aspectos par- ticularmente Ca e Mg. Em 13-4-66, as análises químicas apresentaram os seguintes resulta- dos para os vários aspectos quími- cos do N, Fe e P e para os alcali- nos-terrosos (Ca e Mg). Devemos assinalar as diminutas concentra- cm l SciELO 10 11 12 13 14 15 224 Atas do Simpósio sôbre a Biota Amazônica ções encontradas para os mesmos: a concentração do ferro foi de 370 pg/1, é digna de atenção, su- perando pouco a dos alcalinos-ter- rosos, que se apresentaram com 360 ug/1 aproximadamente. O Fe não dissolvido constituiu % da concentração total dêsse elemento, estando o restante em dispersão iônica. A concentração do N, como amónia, foi de 15 ug/1. Como ni- tratos, 17 ug/1 e como N orgânico, 325 Hg/l. O fósforo como fosfatos, estêve presente em pequena quantidade — 4,9 ug/1 — enquanto a concen- tração total de P chegou à atingir a quantidade de 7,0 ug/1. Em 13-4-66, em uma das de- terminações feitas, a vazão do rio Negro foi determinada em 27 000 m ;i /s. O fluxo total diário dos elementos, apresentou os se- guintes valores: Nitrogênio total, 840 t (sendo 35 t como N de amó- nia e 40 t sob a forma de nitratos) ; Fósforo total, 17 t (sendo 11 t sob a forma de fosfatos) ; Ferro total (com 860 t) ; Cálcio (840 t) ; Magnésio (com 540 t), respectiva- mente. Com relação à área da bacia do rio Negro que é aproximadamente de 650 000 km-, calculamos a par- tir dos dados analíticos, referidos acima, que a vazão diária de ele- mentos químicos nesta bacia por km- é de: nitrogênio total, 1 300 g; nitrogênio orgânico, 1 . 180 g; fós- foro total, 26 g; ferro total, 1.300 g; cálcio, 1.300 g; magnésio 830 g. SUMMARY Hydrographical and Chemical observations were carried out in Rio Negi '0 near Manaus to determine the amount of elements of biologi- cal importance transported by the river. The hydrographic work in- cluded determinations of current speed and echographic depth re- cording. The data thus received permitted the calculation of the amount of water effluent out of the basin of the Rio Negro. The Che- mical determinations were extend- ed to nitrogen, phosphorus, and iron, each in different components, and to calcium and magnesium. On 13th of April 1966, for ins- tance, the following data in a wa- ter sample from Rio Negro were found: 370 ug/1 of total iron, al- most the concentration cf earth alkalines present in 360 pg/1. Only one fourth of the total iron is not dissolved, three fourths are suspend- ed. Ammonia-nitrogen was found in a concentration of 15 gg/l. The amount of nitrate-nitrogen is ... . 17 ug/1, and of organic nitrogen 325 ug/1- The sample contains phosphate-phosphorus in a concen- tration of 4,9 Hg/l, and total phos- phorus in 7,0 ug/1. The out-flow of the Rio Negro basin on 13 ,h of April 1966 was cal- culated to 27.000 m :i /s. The efflu- Volume 3 (Limnologia) 225 ence of elements per day was as follows: total nitrogen: 840 t, am- monia-nitrogen : 35 1, nitrate-nitro- gen: 40 t, total phosphorus: 17 t, phosphate-phosphorus : 11 t, total iron: 860 t, calcium: 840 t, mag- nesium: 540 t. The area of the basin of the Rio Negro is approximately 650 000 km 2 . The effluent of ele- ments per square-kilometre per day was calculated as follows: total ni- trogen: 1.300 g, organic nitrogen: 1.180 g, total phosphorus: 26 g, to- tal iron 1.300 g, calcium: 1.300 g, magnesium: 830 g. BIBLIOGRAFIA Conselho Nacional de Geografia, Divi- são de Cartografia, 1964, Mapa da República dos Estados Unidos do Brasil, 1: 5 000 000. Ministério da Agricultura, 1948, Atlas pluviométrico do Brasil (1914-1938) Sioli, H., 1951, Zum Alterungsprozess von Fluessen und Flusstypen im Amazonasgebiet. Arch. Hydrobiol. 45: 267-283. Sioli, H., 1955, Beitraege zur regionalen Limnologie des Amazonasgebietes. III. Ueber einige Gewaesser des oberen Rio-Negro-Gebietes. Arch. Hydrobiol., 50: 1-32. Sioli, H„ 1955, Die Bedeutung der Lim. nologie fuer die Erforschung wenig bekannter Grossraeume zu prak- tischen Zwecken, anhand der Er- fahrungen im Amazonasgebiet. Forsch. u. Fortschr., 29: 73-84. Sioli, H„ 1960, Estratificação radicular numa caatinga baixa do alto Rio Negro. Boi. Mus. Paraense Emílio Goeldi, n. s., Botânica, 10: 1-9. Sioli, H., 1964, General features of the limnology of Amazônia. Verh. In- ternai. Verein. Limnol., 15: 1053- -1058. Sioli, H. & Klinge, H., 1962, Solos, tipos de vegetação e águas na Amazônia. Boi. Mus. Paraense Emílio Goeldi, n. s„ Avulsa, 1: 27-41. COMPOSTO E IMPRESSO NAS DO SERVIÇO GRAFICO DO LUCAS, RIO DE JANEIRO, GB ■ OFICINAS IBGE. — - BRASIL.