Padrões de uso de habitat e conectividade populacional do dentão Lutjanus jocu em ambientes tropicais do Atlântico Sul-Ocidental e estudos ecológicos complementares
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Data
2025-05-12
Autores
Derviche, Patrick
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Universidade Federal do Espírito Santo
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Although the dog snapper (Lutjanus jocu), plays a major ecological and economic role in coastal and marine systems, the populations are currently facing overfishing in the Abrolhos Bank, SW Atlantic. Therefore, the following three specific goals were established: (i) to assess the habitat use along the ontogeny of juveniles in a tropical estuary, (ii) to assess the effects of water chemistry variability on otolith elemental signatures of juveniles within a dynamic estuarine nursery habitat, and (iii) to assess the contribution of distinct nursery habitats (NHs) to the exploited individuals found in adult grounds (AGs). Briefly, in the first chapter, stable isotope analysis of 57 juveniles revealed a major dependency on sheltered estuarine habitats (75.9 ± 5.5%), represented by mangroves. However, the contribution of marine habitats to their isotopic composition decreased considerably as TL increased (from 26.8% to 6.2%), suggesting their recent ingression into the estuarine NH. The second chapter assessed the otolith elemental signatures and water chemistry of a range of elements (Mg, Mn, Cu, Zn, Sr, and Ba) relative to calcium along a salinity gradient and monthly for a year, covering distinct seasons. Using generalized linear mixed models (GLMMs), we found that water chemistry alone does not fully explain the otolith signatures, suggesting that additional factors play a role depending on the element. The environmental signals driving otolith signatures varied by element, with Ba:Ca showing the narrowest temporal window of influence. The third chapter assessed the connectivity among juvenile (n = 98) and adult (n = 69) dog snappers across three NHs and two AGs along over 400 km of a tropical coastline. Otolith multi-elemental signatures, analyzed using a Random Forest model, revealed that 84.0% of exploited stock from southward upwelling AGs originated from estuarine environments, highlighting mangrove dependency. In contrast, stock from northward warm-waters AGs displayed a higher diversity in In contrast, stock from northward warm-waters AGs displayed a higher diversity in nursery origins, with most individuals coming from the sea environment (75.0%), consisting of biogenic coral and rocky reefs. Our findings provide new insights into the understanding of the dog snapper’s biology and ecology, which may support decision-making and conservation efforts. Besides that, I present four complementary studies related to marine ecological studies conducted during my doctorate
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Stable isotopes , Otolith chemistry , Nursery habitats , Fish movement , Commercial species , Food web , Stock delineation , Upwelling , Lutjanidae