Rio Doce Basin Research Articles

Disponibilidade hídrica do solo e produtividade do eucalipto em três regiões da Bacia do Rio Doce

Analisou-se a produtividade de povoamentos de eucalipto, localizados nas regiões Belo Oriente, Nova Era e Guanhães, situadas na Bacia do Rio Doce, em Minas Gerais. Estudaram-se as precipitações ocorridas nas estações chuvosas e os componentes do balanço hídrico de Thornthwaite e Mather (1955), relativos ao período de janeiro de 1985 a dezembro de 1998, objetivando estudar a influência desses componentes com o ganho de volume médio anual de madeira (m³ ha-1). Para tal, utilizaram-se dados do inventário florestal da Empresa Florestal Celulose Nipo-Brasileira - CENIBRA, relativos à idade de três a sete anos. A produtividade de madeira foi influenciada pelo total precipitado na estação chuvosa (PEC). Os menores valores de incremento periódico mensal (IPM) foram observados nos anos precedidos de estação chuvosa seca (S) ou muito seca (MS), sendo que os maiores valores de IPM ocorreram nos anos precedidos de estações chuvosas, classificadas como chuvosa (C) ou muito chuvosa (MC). Considerando que tal fato foi mais pronunciado em Guanhães e Nova Era, verificou-se a correlação da PEC, finalizada em cada ano, com o IPM nos períodos de aumento (1986 a 1992) e diminuição na PEC (1992 a 1995), sendo que essas correlações atingiram um r² superior a 80%. Para um aumento de 100 mm na PEC de um ano para outro, o aumento no IPM foi, em média, de 0,445 m³ha-1mês-1, enquanto para uma redução de 100 mm a diminuição no IPM foi de 0,64 m³ha-1mês-1, para as duas regiões. Guanhães apresenta o maior índice de local médio, assim como a maior produtividade média, seguindo-se Nova Era e Belo Oriente.

Neotropical Monogenoidea. 49. Four new species of the Diplectanidae (Dactylogyrinea) from the gills of some pachyurines (Teleostei: Sciaenidae) from the Rio Tocantins and Rio Doce Basins, with the proposal of Anoplectanum n. g. and Spinomatrix n. g.

Four new species of the Diplectanidae from the gills of freshwater sciaenid species (Pachyurinae) in Brazil are described and two new genera, Anoplectanum n. g. and Spinomatrix n. g., are proposed. These are: Diplectanum copiosum n. sp. from Pachyurus junki and Petilipinnis grunniens; Anoplectanum haptorodynatum n. g., n. sp. from Pachyurus junki and Petilipinnis grunniens, and A. microsoma n. g., n. sp. from Petilipinnis grunniens, all in the Tocantins Basin; and Spinomatrix penteormos n. g., n. sp. from Pachyurus adspersus in the Rio Doce Basin. Anoplectanum is proposed to accommodate diplectanids lacking squamodiscs and having a superficial root of the ventral anchor as long or longer than the deep root. Spinomatrix is proposed for species having a haptoral and peduncular armature composed of spines, hooks, anchors, squamodiscs and armed muscular pads.

Gastrópodes e bivalves límnicos do trecho médio da bacia do Rio Doce, Minas Gerais, Brasil

A survey of the lymnic malacofauna from the mid-segment of the Rio Doce basin was carried out from 1999 to 2001. The studied region is permanently submitted to the impact of mining, reforestation, urban waste, metallurgy, and includes two areas of high priority preservation. Sixteen sampling station distributed into 6 sub-basins were investigated. Eight thousand four hundred and eleven specimens of mollusks were collected, 6.224 (74%) being gastropods and 2.187 (26%) bivalves. The presence of the following mollusks with their relative frequency, respectively, could be observed: 1) Gastropods: Ancylidae (0.1%), Planorbidae, Biomphalaria (1.4%), Hydrobiidae (2.9%), Thiaridae, Melanoides tuberculatus (59.6%), Physidae, Physa (10%) and specimens of the family Ampullariidae, Pomacea (0.1%); 2) Bivalves: Sphaeriidae (0.5%), Corbiculidae (25.3%), Mycetopodidae (0.1%). It was observed that 84.9% of the collected specimens were Melanoides tuberculatus and Corbicula, both introduced mollusks. The presence of the mollusks detected was connected to the environment of each sampling place.

Trophic state and microorganisms community of major sub-basins of the middle Rio Doce basin, southeast Brazil

Total phosphorus concentration was used to define the trophic state of the main sub-basins of the middle Rio Doce, in Minas Gerais State (southeast Brazil) and physical, chemical, and microbiological variables of water were analyzed during 2000 to 2001. The study evaluated changes in water quality caused by seasonality and human activities. Water temperature, conductivity, pH, total alkalinity, dissolved oxygen, and concentrations of NH4-N, NO2-N, NO3-N, total-N, PO4-P, total-P, DOC, and chlorophyll-a were measured in seven rivers stretches (sampling stations). Total yeasts, faecal and total coliforms, and heterotrophic bacteria were also determined. The studied areas were considered to be under oligotrophic to eutrophic conditions. The variables that presented highest positive correlation with faecal coliforms were total-P and total-N, and heterotrophic bacteria density was identified as a good parameter to differentiate the ecosystems. These results suggested the inclusion of the trophic level and the distinct activities within a watershed as important elements when proposing conservation and restoration areas.

Diel variations of phytoplankton and bacterioplankton production rates in four tropical lakes in the middle Rio Doce basin (southeastern Brazil)

Studies on phytoplankton production conducted in lakes of the middle Rio Doce basin demonstrated significant diurnal and seasonal variations with high phytoplankton production rates recorded in the morning hours during the dry periods. Bacterial production data for these lakes had not been recorded until now. The present study had as working hypothesis that bacterial production may contribute significantly to carbon fixation, particularly in lakes rich in organic matter and that this production varies diurnal and seasonally thus altering BP/PP ratios. In order to test this hypothesis the study had as objective to estimate phytoplankton and bacterioplankton production rates along with the concentrations of carbon, nitrogen, and phosphorus in two periods of the day (morning and afternoon) and in two seasons (dry and rainy), in four lakes, being two lakes within the Rio Doce State Park and two at its surroundings. Among the selected lakes, Lake Amarela showed the highest nutrient concentrations and highest bacterial production. The results allow to conclude that despite exhibiting lower values when compared with the ones recorded for phytoplankton production, bacterioplankton production is essential to the general metabolism of the lakes, particularly for those rich in organic matter and exhibiting oligo-mesotrophic conditions.

Phylogeography and RAPD-PCR variation in Hoplias malabaricus (Bloch, 1794) (Pisces, Teleostei) in southeastern Brazil

In the Rio Doce basin of southeastern Brazil, the freshwater fish Hoplias malabaricus (trahira) is a widespread predatory characin and one of the few resilient native fishes in a highly impacted lake system. In order to test for genetic differentiation in populations within this basin and for biogeographic relationships among populations of this species in other basins, a study was conducted using RAPD-PCR analysis of Rio Doce samples (N = 63) and phylogeographic analyses with mitochondrial DNA (mtDNA) haplotypes, including the Rio Grande and Macacu river basins. In the Rio Doce basin, the patterns of genetic similarity of RAPD-PCR markers (individual fingerprinting and Nei’s genetic distance) suggest the existence of two genetically different groups, one composed of the lacustrine populations Carioca and Dom Helvécio, and the other of riverine and the remaining lacustrine populations. The differences in the RAPD-PCR patterns may be explained by the existence of sub-basins within this lacustrine system. A maximum parsimony tree of cytochrome b fragment (383 base pairs) supports the view that trahiras of the Rio Doce share a complex biogeographic history with those of neighboring basins. The phylogeographic patterns may be explained by a common history of the watersheds of the Rio Doce, Paraíba do Sul, and Rio Grande basins, corroborating the hypothesis of a Plio-Pleistocene separation of these drainage systems, forming the Mantiqueira "divortium aquarium".

Biological quality of waters from an impacted tropical watershed (middle Rio Doce basin, southeast Brazil), using benthic macroinvertebrate communities as an indicator

Taking the watershed as the unit for intervention and conservation, in this study we assess water quality along a stretch of impacted watershed of considerable economic importance, the middle Rio Doce basin, using the benthic macroinvertebrate community, along with physical and chemical characteristics as parameters, for the classification of 20 sampling stations. The results showed that parameters often used in temperate regions are also useful to assess water quality in tropical ecosystems, where no specific methodology has yet been developed. In spite of a clear distinction between stations of good and bad quality, the multimetric biological analysis alone was not sensitive enough to identify intermediate conditions. Grouping similar and dissimilar stations by Cluster analysis of physical and chemical variables and biological data, however, it was possible to distinguish three categories based on the biological quality of the water: (1) stations with poor quality water; (2) stations with high quality water, and (3) stations with water of intermediate quality. Classifications of water quality of this sort will hopefully assist decision-makers in defining restoration/conservation strategies, and will provide an important tool for monitoring biodiversity and water quality in tropical watersheds.

The Avifauna of Rio Doce Valley, Southeastern Brazil, a Highly Fragmented Area1

ABSTRACTWe analyzed the avifauna from four areas of the Rio Doce basin (the municipal districts of Nova Era [NE], António Dias [AD], Caratinga [BSC], and Marliéria [RDSP]) located in eastern Minas Gerais state. Based on captures with mist nets, 75 bird species belonging to 15 families were inventoried; however, the species composition varied gready among the study areas. Fifty species and 231 of the 466 individuals recorded during this study were captured at NE. In the AD area, 33 species and 132 individuals were captured. The other two areas, BSC and RDSP, contributed only 103 captures and 22 species. By analyzing species composition as a function of altitude of the study areas, it was verified that a variation of 500 m altitude was sufficient in determining the difference in existing bird communities. Formicariidae species, such as Drymophila squamata, Thamnophilus punctatus, and Conopophaga melanops, were captured exclusively in the BSC and RDSP areas, located below the 500 m altitude limit while their congeners (D. ochropyga, T. caerulescens, and C. lineata) were found exclusively in the highest areas (NE and AD). Significant seasonal variations in die species composition were observed (Green's test: Q = 12.79 in NE, 12.84 in AD, 12.4 in BSC, and 20.68 in RDSP; P < 0.05), and we believe that such variations could be associated with seasonal movements between die highest and lowest areas of the Rio Doce basin. As such, the impacts of fragmentation to the Atlantic Forest along this stretch of the Rio Doce basin may have affected the natural dynamics of avian movements. The destruction of > 90 percent of the original Atlantic Forest vegetation cover already may have seriously compromised the population viabilities of birds endemic to this area.

The Avifauna of Rio Doce Valley, Southeastern Brazil, a Highly Fragmented Area1

We analyzed the avifauna from four areas of the Rio Doce basin (the municipal districts of Nova Era [NE], Antônio Dias [AD], Caratinga [BSC], and Marliéria [RDSP]) located in eastern Minas Gerais state. Based on captures with mist nets, 75 bird species belonging to 15 families were inventoried; however, the species composition varied greatly among the study areas. Fifty species and 231 of the 466 individuals recorded during this study were captured at NE. In the AD area, 33 species and 132 individuals were captured. The other two areas, BSC and RDSP, contributed only 103 captures and 22 species. By analyzing species composition as a function of altitude of the study areas, it was verified that a variation of 500 m altitude was sufficient in determining the difference in existing bird communities. Formicariidae species, such as Drymophila squamata, Thamnophilus punctatus, and Conopophaga melanops, were captured exclusively in the BSC and RDSP areas, located below the 500 m altitude limit while their congeners (D. ochropyga, T. caerulescens, and C. lineata) were found exclusively in the highest areas (NE and AD). Significant seasonal variations in the species composition were observed (Green's test: Q = 12.79 in NE, 12.84 in AD, 12.4 in BSC, and 20.68 in RDSP; P < 0.05), and we believe that such variations could be associated with seasonal movements between the highest and lowest areas of the Rio Doce basin. As such, the impacts of fragmentation to the Atlantic Forest along this stretch of the Rio Doce basin may have affected the natural dynamics of avian movements. The destruction of > 90 percent of the original Atlantic Forest vegetation cover already may have seriously compromised the population viabilities of birds endemic to this area.

Distribution and abundance of Chironomidae (Diptera, Insecta) in an impacted watershed in South-east Brazil

Patterns of abundance and distribution of chironomid midges (Diptera, Chironomidae) in the middle Rio Doce basin were analysed. Human activities (mining, steel processing, and Eucalyptus spp. forestry) contribute to environmental degradation and low water quality in this watershed. Physical and chemical water traits (dissolved oxygen, pH, total alkalinity, electric conductivity, phosphorus and nitrogen concentrations) of 20 sampling points were used in a Principal Component Analysis (PCA) to establish the best and worst water quality. Sampling points recorded as the most polluted showed low genus richness of Chironomidae, less than five genera from the total 23, and dominance of the genus Chironomus, a bioindicator of environmental stress. Following Chironomus, the second most frequent and abundant genus was Cricotopus, whose distribution could not be related to pollution levels. The Tanypodinae sub-family showed certain sensitivity to low dissolved oxygen concentrations and high nutrients levels, and was not found at points of high pollution levels.

Simaba docensis, a New Brazilian Species of Simaroubaceae

Simaba docensis, a new species of Simaroubaceae, is described and illustrated. Its geographical distribution seems to be restricted to semideciduous forest in the region of the Rio Doce basin, Minas Gerais, southeastern Brazil. Accordingly, it is likely to be a rare endemic and endangered species. It is very closely related to the only other Amazonian species of section Floribundae Engler, S. paraensis Ducke, from which it is basically distinguished by the number and shape of leaflets, leaf indument, and flower and fruit size. We describe here a new species of Simaba Aublet (Simaroubaceae), S. docensis. Its geographical distribution is apparently restricted to southeastern Minas Gerais, Brazil, in the semideciduous forest of the Rio Doce basin. The closest species to S. docensis is S. paraensis Ducke. The South American genus Simaba has 25 species, divided into three sections: Tenuiflorae, Floribundae, and Grandiflorae (Engler, 1874; Cronquist, 1944). They are trees or shrubs with pinnately compound leaves. The main diagnostic characters used to distinguish the three sections of Simaba are listed in Table 1. Section Tenuiflorae is an Amazonian taxon, whereas the other two sections are mostly extra-Amazonian. Simaba paraensis is noteworthy because it is the only Amazonian species of section Floribundae. Furthermore, it can have small flowers, as found in section Tenuiflorae, and it has stamen appendages as occur in section Grandiflorae. However, S. paraensis has large paniculate inflorescences and other flower characters similar to those found in Floribundae, which places it in this section. The new species resembles S. paraensis in its general appearance and because it has androecium characteristics of the section Grandiflorae. However, S. docensis fits better the characteristics of section Floribundae than S. paraensis because of its larger flowers. Couepia monteclarensis Prance, another endemic species of the Rio Doce basin, is also taxonomically very close to two Amazonian congeneric species: C. sandwithii Prance and C. bernardii Prance (Prance, 1989). Other field collectors (J. A. Lombardi & K. Yamamoto, pers. comm. 1999) have noticed the occurrence of Amazonian species affinities in the semideciduous forest of the Rio Doce basin. The conservation and detailed studies of this forest can help us to understand the evolution and history of the South American forests. Simaba docensis Franceschinelli & K. Yamamoto, sp. nov. TYPE: Brazil. Minas Gerais: Marli6ria, Parque Estadual do Rio Doce, on peninsula at Lake Helv~cio, 24 Nov. 1975 (fl), Heringer & Eiten 15182 (holotype, MO; isotype, US). Figure 1. Ad sectionem Floribundae Engler referenda, S. paraensis Ducke androecio similis, sed foliis 7-10 jugatis, foliolis subtus puberulis vel pilosis, floribus majoribus 8-10 mm longis differt. Tree 10-30 m tall. Branches glabrous with gray bark, strongly grooved and furrowed longitudinally, with prominent transversal scars due to leaf and bud abscissions. Leaves with 6-21 leaflets, usually 7-10 jugate, at apex of the branches; rachis 7.520 cm long, cylindric, puberulous. Leaflets sessile or subsessile, opposite or subopposite, interjuga 21.5 cm long. Leaflet 2.5-5 x 1.1-1.7 cm, blade oblong to obovate or elliptic, chartaceous, apex usually acute, sometimes obtuse to rounded, with gland at the tip, lateral leaflet base usually oblique and terminally cuneate, puberulent beneath with prominent central vein, glabrescent and slightly wrinkled above with prominent and puberulent central vein; lateral veins not visible. Inflorescence paniculate, 8-22 cm long, with ferrugineous tomentose axes, secondary axes 1.5-11 cm long, usually forming a right angle with the primary axis, subtended by bracts narrowly oblong to obovate with gland on the tip, 2.0-5.0 cm long, flowers at NovoN 9: 345-348. 1999. This content downloaded from 207.46.13.16 on Wed, 25 May 2016 06:45:37 UTC All use subject to http://about.jstor.org/terms

Indícios de Variações Climáticas Neo-quaternárias no Médio Vale do Rio Doce

A tentative stratigraphy for the Upper Quaternary events in the Jacare lake area, middle rio Doce basin, was obtained through the analysis of borehole samples. The deposition of a thick sequence os slope deposits was interrupted at the beginning of the Holocene (9.840 220 years B.P.) by a transgression of the lake waters. This submersion is thought to be contemporaneous to the expansion of the rainforest over the area. More recent fluctuations of the lake level seem to denounce variations in the hydrologic budget.