Composição química de otólitos de tucunaré-açu (cichla temensis humbolt, 1821) e seu potencial como marcador ambiental em populações de lagos de várzea e igapó na Amazônia-brasileira

Abstract

This study examined the application of otolith geochemistry as a natural marker of natal origins in peacock bass Cichla temensis (Humboldt, 1833) young-of-the-year (YOY) and adults in the Negro River basin. Initially were assessed variations in strontium isotopes and trace elements in otoliths of young individuals from different sampling locations comparing the results with local geology. The results suggests that patterns in otolith microchemistry of YOY, particularly 87 Sr/ 86 Sr isotopes, correspond to patterns in origin bedrock geology. This approach allowed us to correctly classify 99% of juvenile fish to their natal streams using a cross-validation table from the linear discriminant function analysis (LDFA). The results also indicates that is possible to use inferences from geologic maps to track movements of adults fish between Negro River and its tributaries. The LDFA analyses shows that the microchemistry from the central part of the adults peacock bass otolith, classified correctly each individual for its birth location with 41.9% of accuracy. Also, variation in 87 Sr/ 86 Sr isotopic rate from the transect line (from the core to the border) on the otolith surface of adults peacock bass, indicated the existence of isolated and mixed populations in the study area. The results also suggests that adult peacock bass ensure dispersal movements between studied tributaries showing a metapopulational and philopatric pattern, noticed through the individuals returned to their birth locations, and by the permanence of some individuals in those locations, showing loyalty to their origin place. Therefore, the present report offers new information about spatial distribution of C. temensis in their natural environment, which could support effective strategies of fishery management, and provides the basic information for future work to investigate the early life history and spatial ecology of fresh water fish in the Amazon basin.