Search

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Diet composition of Pterodoras granulosus was investigated from June 2004 to June 2005 in the Upper Paraná River floodplain, following invasion by two mollusc species Corbicula fluminea and Limnoperna fortunei. Stomach and intestinal contents analysis showed spatial differences in the diet composition. In the Baía River, P. granulosus diet consisted mainly of C. fluminea, whereas plant items dominated in the Ivinheima River, and L. fortunei was the most important food in the Paraná River. There was little selectivity in shell length consumed. In spite of C. fluminea being a larger mollusc, L. fortunei appears to be energetically more profitable because its shell is more fragile and is rapidly opened and digested. A considerable amount of closed shells of C. fluminea at the end of the digestive tract points to a possible role of P. granulosus as a mollusc disperser. [ABSTRACT FROM AUTHOR]

The literature indicates that exotic species have a greater tolerance to environmental stressors compared with native species. In recent decades, the introduction of contaminants into the environment has increased as a result of industrialization. The objective of this study was to verify the resistance of bivalve mollusks from freshwater native (Anodontites trapesialis) and exotic (Limnoperna fortunei) species to chemical contamination using an ex vivo/in vitro approach. Gill and muscle tissues were exposed to two different types of environmental stressors, copper (metal), and Roundup Transorb® (herbicide). The tissues were submitted to a cytotoxicity test in which the lysosomal integrity was assessed, from the adaptation of a method to isolated cells, and multixenobiotic resistance (MXR) test which evaluated cellular defense. In the exotic species, only copper at 9000 μg/L and Roundup Transorb® at 5000 μg/L were cytotoxic. In the native species, copper cytotoxicity at 900 and 9000 μg/L and Roundup Transorb® at 50 and 5000 μg/L were observed. Results were the same in both tissues. The MXR, responsible for the extrusion of contaminants (cell defense), was inhibited in both species when exposed to the contaminants, this cell defense system seems to be more inhibited in the native species, when exposed to both pollutants, indicating greater sensitivity. Therefore, cytotoxicity may be related to the lack of capacity of cellular defense. In relation to lysosomal integrity, the native species was more sensitive to cytotoxic pollutants, where a greater number of experimental conditions of metals and herbicide showed cytotoxicity, as well as more experimental situations inhibited its ability to defend itself.