Restoration of the Das Velhas River Basin, Brazil: Challenges and Potential

Restoration of the das Velhas River Basin, Brazil: challenges and potential.

P.S. Pompeu & C.B.M. Alves Manuelzão project / Federal University of Minas Gerais, Belo Horizonte, Minas Gerais State, Brazil R. Hughes Dynamac/Corvallis, Oregon, USA

ABSTRACT: The das Velhas River is the most important and the most polluted tributary of the São Fran- cisco, one of the largest Brazilian rivers. Its possibile restoration was evaluated from historical and recent fish collections in the main river and tributaries, the current uses of this river basin, and their impacts on river hydraulics and water quality. Three main factors increase the probability of successful restoration of the das Velhas River basin: (1) new sewage treatment facilities are being implemented in Belo Horizonte and other cities, (2) the Velhas has no dams between it and the São Francisco River, and therefore no migration barriers or hydrological changes caused by dams, and (3) approximately 75% of all species identified in the basin occur in environmentally healthy tributaries. Continued mining in the headwaters, the rising number of alien species, and contamination by agricultural pesticides remain important challenges.

1 INTRODUCTION rently, the main channel is highly disturbed and fish kills are common. In Brazil most urban sewage is dumped without The possibile restoration of the das Velhas River treatment into rivers. Besides, in the large cities, was evaluated from historical and recent fish collec- river and stream channelization are common ways to tions in the main river and tributaries, the current deal with water pollution. Together with hydroelec- uses of this river basin, and their impacts on river tric dams and mining these are the most important hydraulics and water quality. threats to the Brazilian aquatic fauna. The das Velhas River is the most important tributary of the São Francisco, one of the largest Brazil- 2 METHODOLOGY ian river basins. The 2,900 km long São Francisco River crosses five Brazilian states, and is the 31o Recent fish sampling stations include five tributaries longest river in the world (Welcomme 1985). Its wa- (Cipó, Bicudo, Curimataí, Pardo Grande and da ter is used for electricity generation, irrigation, cit- Onça Rivers) and six sites along the das Velhas main ies, industries, navigation and fisheries. (Diegues stem, comprising two stations upstream and four 1994). downstream of the MRBH discharge (Fig. 1). The das Velhas River Basin has been studied Except for Rio Cipó, which was sampled five since the 1850´s, when many Danish naturalists times, every sampling station was visited two or traveled to the region (Alves & Pompeu 2001). Be- three times since 1999, representing the dry and wet tween 1850 and 1856, Johannes T. Reinhardt col- seasons. Fish were caught with gillnets, seines, cast lected fish in the basin, including the main channel nets and kick nets. Twenty meters long gillnets, with and some tributaries. Reinhardt assigned Christian F. 3 to 16 cm mesh (stretch measure), remained in the Lütken the rights to publish a monograph describing water column overnight. Seines were used in shal- his collections (Lütken 1875), that is the only his- low areas or littoral zones, kick nets were employed torical document regarding the das Velhas River fish in near-shore aquatic macrophytes and in riffles, and fauna. cast nets were used in habitats too deep to wade. The human population of the das Velhas River Gillnets were used to permit quantitative analysis basin grew rapidly after 1897, following establish- and the latter three fishing gears were employed as ment of Belo Horizonte, the capital of Minas Gerais qualitative sampling techniques, in order to provide state. The Metropolitan Region of Belo Horizonte the most complete fish species list. (MRBH), with a population of 4.5 million, is located in the upper course of the das Velhas River. Cur- Table 1. Fish richness and distance from MRBH of the das Velhas River main stem sampling points. Points Fish richness River Kilometers Native Allien RV-01 8 1 20 RV-02 18 2 114 RV-03 7 2 204 RV-04 24 3 299 RV-05 33 3 400 RV-06 40 1 493 Total 87 6

Table 2. Fish richness and drainage area in the sampled tributaries. Tributary Symbol Fish richness Drainage area Native Allien (km2)

Bicudo BI-01 42 1 2.210 Cipó CP 63 1 2.189 Curimataí CU-01 39 0 2.057 Onça ON-01 29 1 549 P. Grande PG-01 39 1 2.042 Total 78 3

The most significant disturbance of the main river is untreated sewage from MRBH. Downstream from this region, there is a distinct loss of aquatic habitat complexity and water quality, with significant effects on the richness and diversity of fish species (Fig. 2). Between sample stations RV-02 and RV- 03, the das Velhas River receives the sewage of Figure 1. das Velhas River basin, present sampling sta- MRBH. tions and relative position in Minas Gerais state and Bra- zil. 45

40 We compared current and Lütken’s historical 35 data, and fish distributions were correlated with the human alterations in the watershed. 30

25 3 RESULTS 20

15 One hundred and seven fish species were recorded Species richness from 1998 to 2002. Of these, 93 were identified in 10 the main stem (Table 1) and 81 in six tributaries 5 (Table 2). The richness in all sampled tributaries was RV-01 RV-03 RV-05 RV-02 RV-04 RV-06 higher than any point in the das Velhas River main Sampling stations stem. These tributaries also had fewer alien species. In the upper course of the das Velhas River, the Figure 2. Fish richness along das Velhas River main most important disturbance is iron mining. In this channel. area, a large portion of the river bed is covered by fine sediments, decreasing the diversity of available substrate for colonization. Three levels of comparisons with historical data were performed: (1) all data together, (2) only the das Velhas River main stem, and (3) only the Cipó River (Fig. 3). A higher relative number of species were locally extinct in the das Velhas main stem, than the Cipó River. On the other hand, a larger number of species registered for the first time oc- tributaries, including Cipó, indicate that the tributar- curred in Cipó. However, considering the entire ba- ies generally are still well-preserved. They maintain sin and its sampled tributaries, fewer than 8% of fish most of the fish diversity and can be considered fu- species seem to be locally extinct, taking into ac- ture sources for main stem recolonization. count the available historical data. Fragmentation and habitat simplification are broadly described as the major threats to biodiversity conservation, once they directly interfere with rates of colonization and extinction (Kareiva et al. 1995), and are the main cause of fish species extinction in North America (Miller et al. 1990). There are no dams in the das Velhas River main course with any observed effect on its fluvial regime. This feature, associated with the great connectivity with the São Francisco River system can be considered highly positive features for rehabilitating the das Velhas River basin. The lower das Velhas River, as well as other larger São Francisco tributaries, are considered of extreme biological importance among Minas Gerais conservation’s priority areas (Costa et al. 1998). The MRBH is clearly the main source of degrada- Figure 3. Comparisons between historical and current tion in the basin, with distinct effects on fish rich- fish richness in the das Velhas Basin. ness and distribution, caused mainly by its domestic and industrial sewage dumping. However the influ- ence of Belo Horizonte’s discharge gradually de- 4 DISCUSSION creases, with little effect 200 km downstream. In the other portions of the basin, the major disturbances Settlement of the das Velhas River basin began with are removal of riparian vegetation, water diversions, the first explorers in search of gold and gems. The and alien species introductions. discovery of precious minerals supported the first Although the highly disturbed area near MRBH urban agglomerations, such as the towns of Sabará represents a great challenge, the concentration of the and Ouro Preto, and degradation began in the eight- main impact sources in a small area increases the po- eenth century. The changes caused by mining were tential for success of the das Velhas River restora- more intense in the gravel plains and on the rivers´ tion. At the present time, the sewage of 3.2 million beds (Dean 1996). After the new capital was built, people in the Metropolitan Region is collected, but an industrial and urban center emerged that initiated only 27.5% of it receives primary treatment. How- a new cycle of mining, mainly characterized by iron ever, other treatment stations and water ways for mines and iron industries along the das Velhas River carrying the sewage to the treatment plants are being (Fundo-Fundep 2000). built, and by 2006, more than 80 % of the sewage Long-term persistence of aquatic biological di- must be treated. Presently the DRENURBS Project versity and sustainable and productive fisheries de- [Environmental Rehabilitation and Sanitation of pend on more than the current distribution of pro- Valleys and Natural Riverbeds of Belo Horizonte] is ductive habitats. They also depend on restoring being implemented. Its main goals are: water course watershed processes that create and maintain habi- cleaning; erosion control; institutional reinforcement tats across broad stream networks. At the same time of Belo Horizonte City Hall and integration of water that an attempt is made to conserve the condition of resources to the urban scenery. some healthy sub-watersheds, there must be an ac- The Manuelzao Project began an environmental tive effort to manage other watercourses with the in- monitoring program. Water physical and chemical tent of restoring more complete and functional sys- parameters, aquatic biodiversity and water quality tems (Rieman et al. 2000). bio-indicators are being used to: (1) determine the Despite the long human occupation of the das contribution of the das Velhas River to the quality Velhas basin, some near pristine sub-watersheds still and degradation of the São Francisco River; (2) can be found. The Cipó River basin is considered a identify pollution sources in the basin and locate reference basin, based on Hughes’ (1995) basic point and diffuse contributions; (3) evaluate water characteristics of a reference site. It has a low human ecosystems health and environmental quality; and population density; its headwaters drain a National (4) detect and monitor the possibility of changes in Park, and it supports a high diversity of fish and water quality due to sanitation interventions and other aquatic groups (Callisto et al. 2002). Compari- sewage treatment by counties in the basin. All these sons between the das Velhas River main stem and its interventions are being established in order to de- velop an Index of Biotic Integrity (IBI) and practical um atlas para sua conservação. Belo Horizonte, environmental quality monitoring protocols for the Fundação Biodiversitas. Dean, W. 1996. A ferro e fogo. A história da devastação das Velhas River Basin. da mata atlântica brasileira. São Paulo: Companhia The Manuelzão Project has the goal of bringing das Letras. back the fishes of the das Velhas River by 2010, and Diegues, A.C. 1994. An inventory of Brazilian wetlands. adopts the hydrographic watershed as a research, Glang, IUCN. planning and social mobilization unit. The basin FUNDO-FUNDEP. 2000. Integração homem natureza e view aids the integration of nature, history, envi- seus efeitos na saúde: uma intervenção interdisciplinar na bacia do rio das Velhas. Belo ronment and social relationships, delimiting an area Horizonte, Universidade Federal de Minas and permitting the integration of a complex social Gerais/Projeto Manuelzão. system to the watercourse’s biodiversity. This con- Hughes, R.M. 1995. Defining accetable biological status ceptualization allows the integration of social prac- by comparing with reference conditions. In W.S. tices, natural history, social history, human health Davis, & T.P. Simon (eds). Biological assessment and criteria: tools for water resource planning and deci- and biological monitoring with the basin’s waters as sion making: 31-47. Boca Raton, Lewis Publish- the focus. ers/CRC. Kareiva, P., Skelly, D. & Ruckelshaus, M. 1995. Re- evaluating the use of model to predict the conseguen- 5 CONCLUSION ses of habitat loss and fragmentation. In T.A. Pickett, R.S. Ostfeld, M. Shachak & G.E. Likens. The eco- logical basis of conservation: heterogeneity, ecosys- Three main factors improve the probability of the tems, and biodiversity: 156-166. New York: Chapman das Velhas River basin restoration: (1) new sewage & Hall. treatment facilities are being implemented in Belo Lütken, C.F. 1875. Velhas-Flodens fiske. Et bidrag til Horizonte and other cities, (2) the das Velhas has no Brasiliens ichthyologi. Elfter Professor J. Reinhardt dams between it and the São Francisco River, and indsamlinger og optegnelser. Kon Dank Vidensk Selsk Skrift (Kjoebenhavn) 12: 122-252. therefore no migration barriers or hydrological Miller, R.R., Williams, J.D. & Williams, J.E. 1990. Ex- changes caused by dams, and (3) approximately tinctions of North American fishes during the past 75% of all species identified in the basin occur in century. Fisheries, 14(6):22-30. environmentally healthy tributaries. Continued min- Rieman, B.E., Lee, D.C., Thurow, R.F., Hessburg, P.F. & ing in the headwaters, the rising number of alien Sedell, J.R. 2000. Toward an integrated classification species, and contamination by agricultural pesticides of ecosystems: defining opportunities for managing fish and forest health. Environmental management 25 remain important challenges. (4): 425-444. Welcomme, R.L. 1985. River Fisheries. FAO Fish. Tech Pap., 262: 1-330. 6 ACKNOWLEDGMENTS

We are grateful to Sílvia Magalhães for her help on the map and for geographical information about the basin, and Projeto Manuelzão para Revitalização da Bacia do Rio das Velhas (UFMG), Fundo-Fundep de apoio acadêmico 1999, CNPq, FAPEMIG, CAPES, US Fish & Wildlife Service, FAPEMIG, Pad Award, Padi Foundation, and to Fundação O Boticário de Proteção à Natureza (grant No. 0472002) for the lo- gistics and financial support.

7 REFERENCES

Alves, C.B.M. & Pompeu, P.S. 2001. A fauna de peixes da bacia do Rio das Velhas no final do século XX. In C.B.M. Alves & P.S. Pompeu (eds). Peixes do Rio das Velhas: passado e presente: 165-187. Belo Horizonte: CEGRAC. Callisto, M., Ferreira, W., Moreno, P., Goulart, M. D. C. & Petrucio, M. 2002, Aplicação de um protocolo de avaliação rápida da diversidade de habitats em atividades de ensino e pesquisa (MG-RJ). Acta Limnologica Brasiliensia. v.13: 91-98. Costa, C.M.R., G. Herrmann, C.S. Martins, L.V. Lins, & Lamas, I.R. 1998. Biodiversidade em Minas Gerais: