RESUMEN
Coral reefs rely heavily on reef fish for their health, yet overfishing has resulted in their decline, leading to an increase in fast-growing algae and changes in reef ecosystems, a phenomenon described as the phase-shift. A clearer understanding of the intricate interplay between herbivorous, their food, and their gut microbiomes could enhance reef health. This study examines the gut microbiome and isotopic markers (δ13C and δ15N) of four key nominally herbivorous reef fish species (Acanthurus chirurgus, Kyphosus sp., Scarus trispinosus, and Sparisoma axillare) in the Southwestern Atlantic's Abrolhos Reef systems. Approximately 16.8 million 16S rRNA sequences were produced for the four fish species, with an average of 317,047 ± 57,007 per species. Bacteria such as Proteobacteria, Firmicutes, and Cyanobacteria were prevalent in their microbiomes. These fish show unique microbiomes that result from co-diversification, diet, and restricted movement. Coral-associated bacteria (Endozoicomonas, Rhizobia, and Ruegeria) were found in abundance in the gut contents of the parrotfish species Sc. trispinosus and Sp. axillare. These parrotfishes could aid coral health by disseminating such beneficial bacteria across the reef. Meanwhile, Kyphosus sp. predominantly had Pirellulaceae and Rhodobacteraceae. Four fish species had a diet composed of turf components (filamentous Cyanobacteria) and brown algae (Dictyopteris). They also had similar isotopic niches, suggesting they shared food sources. A significant difference was observed between the isotopic signature of fish muscular gut tissue and gut contents, pointing to the role that host genetics and gut microbes play in differentiating fish tissues.
Asunto(s)
Bacterias , Arrecifes de Coral , Peces , Microbioma Gastrointestinal , ARN Ribosómico 16S , Animales , ARN Ribosómico 16S/genética , Peces/microbiología , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Herbivoria , Especificidad de la Especie , Isótopos de Carbono/análisis , Isótopos de Nitrógeno/análisis , Perciformes/microbiología , Dieta/veterinariaRESUMEN
The Fundão Dam rupture released tons of iron ore tailings into the environment. This study analyzes the long-term impacts and provides a possible scenario of Doce River (DR) plume dispersion. For this, water and surface sediment were collected in November 2019 along three Brazilian states to determine metal concentrations and δ13C and δ15N compositions. The δ13Csediment values of the DR plume showed a dispersion pattern mainly to the north but also in areas closer to the south of the DR mouth. Furthermore, the most negative values of δ13C and δ15N were observed in mud, followed by suspended particulate matter, sediment and the dissolved fraction, indicating that geological matrices are involved in the transport of organic matter coupled to metals to the ocean and pointing to the DR as the main source of metals in the region. Thus, this study highlights the need for continuous studies to monitor the environmental and biological conditions in these areas.