Reproductive Functionality of Fish in Hypersaline Lagoons: Araruama Lagoon, Brazil

Araruama Lagoon is one of the world’s largest permanent hypersaline lagoons, and knowledge about the reproduction of fish assemblages is very scarce. This study aimed to evaluate the reproductive functionality of fishes of the Araruama Lagoon in the seasons of 2011, using functional diversity metrics. We also assessed the influence of abiotic factors (salinity, temperature, dissolved oxygen, and pH) on the distribution of sexes and reproductive stages of fish assemblages. Gonads were analyzed in 709 fish across 18 species, mainly females and juveniles. In winter, when there was a lower abundance of species, the highest reproductive incidence (gonadal development/maturation) and high salinity occurred. Summer and spring corresponded with the highest percentage of juveniles. Salinity was the abiotic factor behind the structuring of the community, while the temperature set off the start of the reproductive cycle in autumn. Thus, Araruama Lagoon played a crucial role as a nursery and reproductive area for the fish assemblage. Graphical Abstract Reproduction in Araruama Lagoon (2011). The vertical arrows indicate the main abiotic variables: temperature and salinity, which structure the fish community. Colors indicate larger (darker) and smaller (lighter) numerical values. The graphs show the percentage of juveniles, males and females, in the seasons corresponding to each season: spring (green), summer (yellow), autumn (orange), and winter (gray). The number of fish next to each graph indicates fish abundance in season, and fish colors indicate diversity.