RESUMEN
The age and daily growth of fish are registered through the deposition of increments in their otoliths, which are concretions formed by the precipitation of substances present in the endolymphatic fluid, mainly calcium carbonate (CaCO3). Faced with the need to fill some of the gaps in the knowledge on the occurrence and duration of the initial stages of snapper species' life cycles in the Abrolhos Bank, this study aimed to describe the growth rates, age, and period of pelagic larval duration (PLD) of three snapper species during the larval pre-settlement phase, in the Abrolhos Bank region. The post-larvae were captured using light traps. Otoliths were removed from 117 samples of snapper species; however, only 69 were viable for age estimation, of which 15 were Lutjanus analis, 25 were Lutjanus jocu, and 29 were Lutjanus synagris. Together, the samples presented individuals with total lengths ranging from 16.14 to 24.76 mm and ages from 21 to 39 days. Settlement marks were found for all three species, and the average PLD was ~25 days. The somatic growth of the snapper species was positively correlated with otolith growth. L. jocu presented the greatest daily growth compared to the other species. The three species use the Abrolhos Bank as a larval settlement site, demonstrating plasticity by using different habitats throughout their lives.
Asunto(s)
Larva , Membrana Otolítica , Animales , Larva/crecimiento & desarrollo , Membrana Otolítica/crecimiento & desarrollo , Membrana Otolítica/química , Perciformes/crecimiento & desarrollo , Parques Recreativos , Percas/crecimiento & desarrollo , Percas/fisiologíaRESUMEN
When the Fundão dam collapsed in Brazil, 50 million m3 of iron ore tailings were released into the Doce river, resulting in the world's largest mining disaster. The contaminated mud was transported 668 km downstream of the Doce river and reached the Atlantic Ocean 17 days after the collapse. Seven months later, there was evidence that the tailings had reached the largest and richest coral reef formation in the South Atlantic Ocean. This study provides the first description of species composition, abundance, and diversity patterns of fish assemblages in estuaries, coastal areas, and coral reefs affected by the rupture of the mining dam in the Doce river. A linear mixed model (GLMM) was used to evaluate the influence of salinity on fish abundance across estuarine and coastal ecosystems. In addition, based on functional traits related to habitat use and feeding habits, this study identified fish species suitable as bioindicators of the long-lasting effects of this major mining disaster. Bottom trawls were used to sample five estuaries and their respective coastal areas, and a visual census was employed to sample five reef areas, representing an impact gradient. A total of 269 species were recorded in all three habitats, but only seven were shared among them. The results showed lower similarity in assemblages among estuarine areas compared to the coastal and reef areas. Species composition among estuaries and reef ecosystems was more heterogeneous. In contrast, coastal habitats exhibited high homogeneity. Salinity had no statistically significant effect on fish abundance either in estuaries (p = 0.22) and along the coast (p = 0.14). Twelve fish species were identified as suitable bioindicators for evaluating the long-lasting effects of resuspension of contaminated sediments. These species are commonly found in the ecosystems under the influence of the disaster inhabiting potentially contaminated substrates and substrate-associated benthic preys.
Asunto(s)
Desastres , Ecosistema , Peces/clasificación , Minería , Contaminación del Agua , Animales , Monitoreo Biológico , Brasil , RíosRESUMEN
Sandstone reefs may be considered a unique geomorphologic feature within the subtropical Southwestern Atlantic Ocean region; however, biodiversity on these reefs has received little to no attention. Herein, we recorded the fish assemblage and benthic cover of sandstone reefs between 23 and 29â¯m depth in Southern Brazil and evidenced potential threats to habitat health. Video analysis and underwater censuses recorded 30 fish species. The unexpected high biomass of Epinephelus marginatus indicated that sandstone reefs may contain suitable habitats for the recovery of this endangered species. A rich benthic coverage including bryozoans, algae, hydrozoans, sponges, and octocorals increased local habitat structural complexity. However, a wide diversity of tangled fishing gear and broken sandstone slabs suggested that a valuable feature from Southern Brazil seascape is being lost by cumulative fishing impacts. An extensive mapping of sandstone reefs is urgently needed for better delineation of marine protected areas network in Southeast and Southern Brazil.
Asunto(s)
Biodiversidad , Arrecifes de Coral , Animales , Océano Atlántico , Brasil , Ecosistema , PecesRESUMEN
A single Pomacanthus maculosus was filmed during a scuba diving survey on a rocky reef from southern Brazil. The body shape and coloration pattern confirmed the species identification. The biological and ecological characteristics of P. maculosus and the long distance of Brazil from its original distribution strongly suggest of an anthropogenic pathway of dispersion.