Molecular characterization of juvenile fish from the Amazon estuary using DNA barcoding approach.

The efficiency of the DNA barcoding relies on sequencing fragment of the Cytochrome C Subunit I (COI) gene, which has been claimed as a tool to biodiversity identification from distinct groups. Accordingly, the goal of this study was to identify juvenile fish species along an estuary of Caeté River in the Brazilian Blue Amazon based on. For this purpose, we applied the DNA barcoding and discuss this approach as a tool for discrimination of species in early ontogenetic stages. A 500-bp fragment was obtained from 74 individuals, belonging to 23 species, 20 genera, 13 families and seven orders. About 70% of the 46 haplotypes revealed congruence between morphological and molecular species identification, while 8% of them failed in identification of taxa and 22% demonstrated morphological misidentification. These results proved that COI fragments were effective to diagnose fish species at early life stages, allowing identifying all samples to a species-specific status, except for some taxa whose COI sequences remain unavailable in public databases. Therefore, we recommend the incorporation of DNA barcoding to provide additional support to traditional identification, especially in morphologically controversial groups. In addition, periodic updates and comparative analyses in public COI datasets are encouraged.

First record of rainbow shrimp, exotic species Mierspenaeopsis sculptilis (Heller, 1862), in the Brazilian coastal amazon, validated by DNA barcode.

BACKGROUND: This is the first record of the alien shrimp Mierspenaeopsis sculptilis in Brazil. The invasion was detected within Marine Extractive Reserves based on eight specimens accidentally caught by local fishermen using trawlnets focused on fisheries of native species. These specimens were transported to the Laboratory of Applied Genetics and morphologically identified as Mierspenaeopsis sculptilis (rainbow shrimp). The taxonomic status of analyzed samples was confirmed by DNA barcoding using a 627-bp fragment of the Cytochrome C Oxidase Subunit I (COI) gene. RESULTS: A single haplotype was recovered from the eight specimens, being identical to a haplotype reported in India, where this species naturally occurs, and in Mozambique, where the rainbow shrimp is considered an invasive species. The present analyses indicated a putative invasive route (i.e., India-Mozambique-Brazil) mediated by shipping trade. CONCLUSIONS: This study presents the first record of Mierspenaeopsis sculptilis in Brazil, in areas of extractive reserves on the Amazon coast. Notably exotic species can cause imbalance in the ecosystem, harming native species. In view of this, the registration of new invasions is essential as they contribute to the implementation of control plans.