Browsing by Autor "Alfons J. P. Smolders"

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EFECTOS DE LA CONTAMINACIÓN MINERA SOBRE LA COMPOSICIÓN DE LA MACROFAUNA BENTÓNICA EN EL RÍO PILCOMAYO
(2013) Alfons J. P. Smolders; Gijs van Hengstum; J. Loermans; A. Montes Barzón; H. Rizo del. Castillo
IMPACT OF HEAVY METAL CONTAMINATION ON THE COMMUNITY OF BENTHIC MACROINVERTEBRATES IN PILCOMAYO RIVER Los macroinvertebrados son usados como indicadores de la calidad del medio ambiente acuatico, debido a que estan presentes practicamente en todos los sitios acuaticos y por presentar diferentes sensibilidades a los contaminantes. En este trabajo se desarrollo una investigacion sobre el Rio Pilcomayo permitiendo comparar sitios con diferentes niveles de contaminacion de la cuenca alta y baja, encontrando Ephemeroptera, Trichoptera, Coleoptera, Simuliidae, Chironomidae y otras especies de Diptera. Se encontro que en la cuenca baja la contaminacion del agua y sedimentos era menor; comparada con la cuenca alta en la zona minera de Potosi, encontrandose contaminacion por metales pesados en el agua y sedimentos, donde predominaban los Chironomidae. Los Chironomidae son conocidos por su resistencia a la contaminacion con metales pesados al contrario de los Ephemeroptera, que son muy sensibles. En las zonas con menor contaminacion, los Ephemeroptera forman una parte importante de la macrofauna acuatica. Los resultados demuestran que la contaminacion minera afecta la macrofauna acuatica en la zona comprendida entre Potosi y Sucre. En la cuenca baja del Pilcomayo los efectos son menores, probablemente por causa de la autodepuracion del agua a lo largo de su cauce. Palabras clave: Macroinvertebrados, Bioindicadores, Contaminacion metales pesados, Rio Pilcomayo, Bolivia. ABSTRACT Macroinvertebrates are used as indicators of aquatic environmental quality since they are present in all aquatic environments and have variable sensitivity to contaminants. In this work a comparison is made between macrofauna in afeas with different levels of contamination in the River Pilcomayo. Ephemeroptera, Trichoptera, Coleoptera, Simuliidae, Chironomidae, and other Diptera species were found in both the higher and lower parts of the river basin.At these lower points water and sediment contamination was low. In the high part of the basin, in Potosi's mining region, contamination of water and sediment with heavy metals was high. Chironomidae species were dominant. Chironomidae are known for their resistence to heavy metals, whilst Ephemeroptera are very sensitive to contamination. In less contaminated afeas, Ephemeroptera make up an important part of the aquatic macrofaunao The results show that contamination from mines affects aquatic macrofauna in the zone between Potosi and Sucre. In the lower part of the Pilcomayo basin, the effects of contamination from mines are less evident, probably due to self-purification of the river downstream. Key words: Macroinvertebrates, Bioindicators, Heavy metal contamination, Pilcomayo River, Bolivia.
Effects of Mining Activities on Heavy Metal Concentrations in Water, Sediment, and Macroinvertebrates in Different Reaches of the Pilcomayo River, South America
(Springer Science+Business Media, 2003) Alfons J. P. Smolders; R.A.C. Lock; G. van der Velde; Richard Ivan Medina Hoyos; Maurice Hoffmann
El Niño Caused Collapse of the Sábalo Fishery ( Prochilodus lineatus , Pisces: Prochilodontidae) in a South American River
(Springer Science+Business Media, 2000) Alfons J. P. Smolders; G. van der Velde; Jan G. M. Roelofs; Marco Antonio Guerrero Hiza
Population dynamics of the migratory fish Prochilodus lineatus in a neotropical river: the relationships with river discharge, flood pulse, El Niño and fluvial megafan behaviour
(Sociedade Brasileira de Ictiologia, 2010) M Stassen; Max W. P. M. van de Ven; Tjisse van der Heide; Marco Antonio Guerrero Hiza; G. van der Velde; Alfons J. P. Smolders
The relative importance of flood pulse dynamics and megafan behaviour for the Sábalo (Prochilodus lineatus) catches in the neotropical Pilcomayo River is studied. The Sábalo catches can mainly be explained by decreased river discharges in the preceding years resulting in smaller inundated areas during rainy season floods and thereby in a decreased area of feeding grounds for the fishes. The decreased river discharges and the related decline of Sábalo catches in the 1990's can be linked to the 90-95 El Niño event. In 2007 the Sábalo catches were comparable to the catches before the "El Niño" event. The connectivity (continuity) between the main river and flood plain areas, which is influenced by sedimentation processes, is also of great importance and very probably plays a more important role since the late 1990's.
Suspended sediment causes annual acute fish mortality in the Pilcomayo River (Bolivia)
(Wiley, 2012) L. H. Swinkels; Max W. P. M. van de Ven; M Stassen; G. van der Velde; H.J.R. Lenders; Alfons J. P. Smolders
Abstract Fish mortality in the middle reaches of the Pilcomayo River (Bolivia), locally called ‘borrachera’, can be observed almost every year at the onset of the rainy season. In order to study the potential causes of the ‘borrachera’, suspended sediment (SS) and selected water quality parameters have been monitored from mid‐September until mid‐December 2010. Gill samples were taken and analysed, before and during the ‘borrachera’ event on December 7 th 2010. Data on river discharge were obtained from a database. During the sampling period, the river hydrology changed dramatically. At the day of the ‘borrachera’, heavy rains in upstream reaches of the river catchment changed the river from a quiet stream into a turbulent river with extremely high concentrations of SS (> 100 g l −1 ). This may be caused by the inundation of the entire riverbed, which causes easily erodible material, left on the riverbanks at the end of the former rainy season, to be transported by the river during the first peak discharges. As concentrations of heavy metals in filtered water samples did not show higher values during the ‘borrachera’, it is concluded that the ‘borrachera’ is unlikely to be caused by heavy metal toxicity. Results showed a strong association between the SS concentration and the ‘borrachera’. Gills of fish collected during the ‘borrachera’ were clogged with sediment to such an extent that oxygen uptake became virtually impossible. High SS concentrations are therefore considered to be the cause of this typical fish mortality phenomenon. Copyright © 2012 John Wiley & Sons, Ltd.