Temporal genetic monitoring, illegal commercialization, and trophic growth of epinephelus itajara (lichtenstein, 1822) on the brazilian coast
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Data
2023-04-27
Autores
Almeida, Lorena Lopes
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Universidade Federal do Espírito Santo
Resumo
The Atlantic goliath grouper, Epinephelus itajara, is the largest grouper species in the Atlantic Ocean with high economic and ecological importance. Slow growth, late sexual maturity, habitat fidelity, and ontogenetic and reproductive migrations are characteristics that make the species vulnerable to overfishing and the degradation of marine and coastal environments. The intense fishing pressure has led the species to a great decline in its populations and although the species is protected in Brazil, illegal fishing of the Atlantic goliath grouper is still common. In this context, considering the vulnerability of the species, this thesis was divided into three chapters and aimed to evaluate the trophic enrichment and the temporal genetic diversity of juvenile Atlantic goliath grouper, as well as to identify the illegal sale of Atlantic goliath grouper along the Brazilian coast. Chapter 1 aimed to estimate the trophic enrichment of juvenile Atlantic goliath grouper during a critical phase of their life cycle. To this end, we examined how the δ 15N values of juvenile Atlantic goliath grouper varied with the total length of fish collected in the estuaries of the São Mateus and Itaúnas rivers. A total of 100 juvenile Atlantic goliath grouper were analyzed, and we observed positive relationships between δ 15N values and fish length. Trophic enrichment was slow but consistent between the two sites, possibly reflecting different isotopic baselines. In chapter 2, 126 samples of juvenile Atlantic goliath grouper collected in the estuary of the São Mateus river in 2013, 2015, 2018, and 2022 were analyzed using 18 microsatellite loci. Among the analyzed loci, 13 were polymorphic and there were no differences for He, FIS, and FST for the temporal genetic structuring test. The AMOVA results indicated that 99.64 % of the total genetic variation corresponded to differences within individuals. There was no detectable substructure for Bayesian cluster analysis, indicating that all individuals shared mixed ancestry. The bottleneck test suggested a possible bottleneck effect in the past, however, we found no evidence of temporal genetic structure for this population over the last 10 years. Finally, in Chapter 3, the DNA barcoding tool, employing the mitochondrial COI gene, was used to identify the illegal sale of Atlantic goliath grouper in fish markets in three Brazilian states. DNA barcoding allowed the identification of 24 (85.7 %) of the 28 collected fish samples. The three sampled areas had the confirmation of illegal sale of Atlantic goliath grouper and from the 22 commercialized samples, 17 (77.3 %) were confirmed as E. itajara. The results obtained in this thesis aim to provide important information for future monitoring, surveillance, and coastal management programs for the species, as well as to generate information for the assessment of the species that will take place in the year 2023 to assess the need to extend the moratorium that currently protects the species.
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Conservação , DNA barcoding , Estrutura populacional , Isótopos estáveis , Mero , Microssatélites , Nitrogênio