Uso de sedimentos de áreas úmidas naturais na emergência de invertebrados aquáticos em arrozais do sul do Brasil

Abstract

Increased awareness of wetlands services and the extent of the loss and degradation of these habitats have resulted in greater efforts to protect and restore them. The ability to return to original states after disturbances makes the zooplankton community a useful tool for assessing restoration of degraded wetlands. The main objective of this study was to evaluate rice paddy recovery patterns by reestablishing the zooplankton community using natural wetland sediments in laboratory trials. Our hypotheses of study were: (1) the richness and abundance of invertebrates is lower in the rice fields than in the natural wetland; (2) the richness of invertebrates is greater as we increase natural wetland supplements; (3) the composition of invertebrates varies between different sediment supplements. To do this, the sediment sampling was carried out in eight wetlands in the Coastal Plain of southern Brazil. The experiment was divided into four treatments: rice paddy sediment, sediment from natural wetlands, 95% rice sediment and 5% sediment from natural areas and 70% rice sediment and 30% sediment from natural areas, corresponding percentages the weighing of dry sediment. A total of 4,493 individuals belonging to 24 taxa were found throughout the experiment. The hypotheses that the richness and abundance of invertebrates is lower in the rice paddies than in the natural wetlands and lower in sediments with fewer natural lagoon sediment supplements were rejected in our study, where treatments did not influence this variation. The hypothesis that the composition of invertebrates varies between different sediment supplements of natural wetlands in rice paddy sediments was corroborated in our study, since the composition differed mainly between rice paddy sediments and natural wetlands, and between sediments with more natural wetlands sediment in rice paddy sediment. These results indicate that natural wetland sediment supplements may be an important recovery strategy for man-abandoned crops. The results found in this study showed that there is recovery of species from the zooplankton community of dormant propagules when inserting sediments of natural moist areas in rice fields.