Figure 1. Map of the Tambopata - Candamo Reserved Zone (TCRZ)

The first inventories were done at the former Tambopata Reserved Zone, at 12 50'S, 69 17'W, 290 m elevation, and covering an area of 5500 ha, situated on the confluence of the Tambopata and La Torre rivers. Other areas were sampled in the La Torre, Malinowski, Chuncho and Tdvara rivers, in the middle and upper parts of the Reserve, along the Tambopata river (Madre de Dios) and in the province of Sandia (Puno).

Geologically, this area is a lateral extension of Holocene deposits, which have been referred to the Iñapari formation, but are now termed the Madre de Dios formation (Frailey et al. 1988). Their outcrops are exposed along the rivers, with thick strata composed of alluvial deposits, supposedly originated from a catastrophic holocene flood (Campbell & Frailey 1984, Campbell & Arellano 1985).

THE RÍO TAMBOPATA (from 12 50'S, 69 18'W to 13 08'S, 69 35'W)

The Tambopata arises on the slopes of the Eastern Andes, running on Quaternary sediments, with an approximate length of 402 km, and empties into the Río Madre de Dios. Its white water, originally crystalline, transports a load of nutrients, making it a highly productive ecosystem. It becomes colored brown by sediments when the river level rises. Sand, stones and rocks are found in the bottom with outcrops of clay and fine sand exposed along its margins. The Tambopata is characterized by a varied conductivity, ranging from 45-84 µhm.cm at 29-35 C; lower values were found in ox-bow lakes: 30-32 phm.cm. pH varies from slightly acidic to neutral, 6,5-7, and dissolved O2 from 7-8 mg/l. These features do not seem to be influenced by the rainy season. Upstream, the river is characterized by trenchant morphology, while the lower part is meandering, with zonal and secondary riparian forest (Kalliola et al. 1987).

Distinctive habitats are present along the river, including pools ("resacas"), ox-bow lakes ("cochas"), streams ("quebradas") and rapids ("rápidos"). Pools are restricted to lower lying areas along the beaches and on the floodplain. They are of a temporary character as they tend to disappear in the dry season, have the same features as the adjoining river, and are tea colored by humic matter in the floodplain. An ox-bow lake is a permanent water body, formed from an old meander of the river, which has lost its connection to the river. Typically, they are in contact with the river through a narrow channel ("caño"), but evolve to exhibit a different morphology. Their black water has a successional state with trophic evolution, resulting in changes in their floral and faunal composition.

Streams are deeply influenced by the forest. Some are big creeks without closed forest, a deep, meandering channel, muddy bottom with fallen logs and organic matter, slight current and pools. Others have a narrower channel, dense closed forest, intermittent character, with black or clear water, and sand, mud or stone bottoms.

THE RÍO LA TORRE (12 53'S, 69 17'W to 12 52'S, 69 18'W)

This is a small river along the southern border of the Reserve, with black-white water, resulting from the drainage of gallery forest streams, and empties into the Rfo Tambopata. Stones and fallen logs lie over the sandy bottom, and the banks are covered by riparian forest, which are dominated by willows (Salix humboldtiana) near the mouth.

Many small streams and ox-bow lakes form its drainage system, some with clear or black water, bottom with mud, sand, stones, fallen logs, leaves and a high degree of organic' matter in them. These habitats have their origin in the primary forest.

THE RÍO MALLINOWSKI (12 36´S, 69 31'W to 12 56'S, 69 33'W)

An affluent of the left bank of the Río Tambopata, this river has its origin in the lower mountains of Tambopata. Crystalline water is present in the dry season, but mining activities along its course has produced an increase of erosion with consequent elevation of the sediment load, turning the water color red. Stones and fallen logs cover the sandy bottom; extensive beaches are observed during low water, while during high water the level rises 2-3 m and the beaches are absent.

White sand and swampy bottoms are characteristic of the streams and ox-bow lakes visited during the survey. The landscape is dominated by a swampy area, with palms, and grasses, black water being the main element influencing the enviroment. Conductivity ranges from 18?50 phm.cm at 25-30 C, pH is acid (5-6,5), and dissolved O2 varies from 2 to 5 mg/l in the "Cochas" and streams. The river has the highest conductivity, reaching 60-110 phm. cm at 27-33 C, and pH varies from 7 to 8,5.

THE RÍO CHUNCHO (13 00'S 70 50'W)

A clear water affluent on the right bank of the Río Tambopata. Sand-stony bottom was typical of the river, running through primary forest, the banks being covered by riparian veaetation. Sites sampled include the lower portion of the river and the ox-bow lake near the mouth. The conductivity in the river reaches 40-210 µhm.cm at 26-33 C. pH is neutral to alkaline, ranging from 7-8,5 and dBsolved O2 is 8 mg/l.

THE RÍO TAVARA (13 22'S, 69 37'W to 13 25'S, 69 38'W)

Connects the Huacamayo and Tambopata rivers, has meandering morphology, clear water and sand-stony bottom. Alluvial sediments and rock strata are exposed along its banks. The water flows north through a narrow channel, with moderate to turbulent current in the rapids. Both margins are covered with dense primary forest with flood areas restricted to the river edge.

The sites studied comprise different habitats within the forest, small and large streams with clear water running through lower montane forest, with mud, stone and sand bottoms. The largest stream has an open canopy, with shrubs, trees and palms near the mouth, while upstream the sedimentary rocks in the stream, and the trees along its banks are densely covered by epiphytes.

RESULTS

A total of 232 species are reported herein (Table 1). Characiforms represent 50 % of the diversity, Gymnotiforms 4.3 %, Silunforms 34.5 % and the remainder includes seven other orders.


Table 1

Species composition shows the general pattern present in other Arnazoman sites. Nevertheless, the paucity in the number and density of cichlids in Tambopata contrasts with the high dominance of this family in other areas (Ucayali or Loreto) of the Peruvian Amazon (Kullander 1986).

Characidae 'Is the most diversified family, with 90 species. Gymnotiforms were represented by II species. Among siluriforms, the p1melodids with 21 species, and loricaruds with 22 species, were the most speciose families, while doradoids are less abundant and diverse. Cichlids include only 12 species.

In general, species were distributed in the rivers and streams while some were exclusive of "cochas". Except for some species of rare or sporadic occurrence (like Gasteropelecits sternicla, Chilodus fritillits, Gvninorhamphichthys hypostomus, Ageneiosus ucayalensis, Spatuloricaria puganensis or ApionichthVs unicolor) most were present along the major portion of the basin at all times. However, several of the poorly represented species may represent collecting artifacts.

Large schools of migratory species like Brycon erithropterus, Piaractus brachyponuts (Characidae) and Prochilodits n1gricans (Prochilodontidae) were observed in the central part of the Reserve. Between September and November, schools of Prochilodus were found migrating upriver in the Tambopata, TAvara and Chuncho, while the other two species were foraging near the shore in deep pools. The curimatids were present in all places, forming dense populations. Among them, Cyphocharax spiluropsis and Steindachnerina guentheri were the commonest. Scoloplax dicra and Entontocorus benjainini, were found only in Lake Sandoval. Cichlids are abundant in streams and ox-bow lakes, appearing in the rivers only when they are rising. Aequidens tetramerus was the commonest cichlid, found in large densities in all places sampled, while Crenicara punctulatum was found only in the Río La Torre.

ACKNOWLEDGMENTS: Most of the data presented herein were obtained by the author., durino, the fisheries assessment performed as part of the project "Programa de Desarrollo Basado en la Conservación en Tambopata (PRODESCOT)" undertaken in Madre de Dios by Conservation International. First samples were taken by H. Ortega in 1982 and 1983 during a joint MUSM-USNM expedition and by the author in 1992 by an expedition sponsored by the Tambopata Reserve Society (TreeS), United Kingdom. The Consejo Nacional de Ciencia y Tecnología (CONCYTEC), Lima, provided financial assistance for the 1992 expedition. Collecting permits were issued by the Instituto Nacional de Recursos Naturales (INRENA) and the Ministerio de Pesquería, Lima. Richard Vari and Mary Hagedorn made comments on an earlier draft, and Gerardo Lamas revised the manuscript,


Ver referencias

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* Departamento de Ictiología. Museo de Historia Natural. Universidad Nacional Mayor de San Marcos. Apartado 14-0434, Lima 14, Perú