Anthropogenic activities decrease functional richness over time, but not other functional aspects of the fish community in a tropical bay

• Published in: Estuarine, coastal and shelf science coastal and shelf science, 2024-08, Vol.303, p.108818, Article 108818
• Main Authors: Gomes-Gonçalves, Rafaela de Sousa, Ferreira, Laryssa Cordeiro da Silva, Araújo, Francisco Gerson
• Format: Article
• Language: English
• Subjects: estuarine fish; Functional traits; Temporal comparisons
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2024.108818

Functional diversity can be used to help understanding the processes shaping biological communities and the effects of human disturbances on the ecosystem's services. Untangling these biological processes is crucial to apply effective policies aiming the biodiversity conservation. Temporal changes (1983–1985, 1999–2001 and 2017–2019) in five functional indices (functional richness, divergence, evenness, specialization and originality) of the fish communities in two zones (inner and outer) of shallow areas in a tropical bay heavily human-impacted in recent decades were evaluated. The tested hypothesis was that functional indices decrease over time, because of the environmental degradation. A substantial decrease in species richness and abundance in the more recent periods (1999–2002 and 2017–2019) compared to 1983–1985 was observed. However, the functional structure remained relatively stable, with the exception of functional richness that showed a significant decrease over time. The apparent stability in the other functional indices may be due to the presence of dominant and functionally redundant species over time that compensates for the loss of species while maintaining similar functions. It was also discovered that decreases in fish richness in shallow bay areas result in losses in functional richness, with resident fish and benthivorous species being the most affected by environmental degradation. By employing a comprehensive approach that integrates the use of functional indices and taxonomic diversity to assess temporal changes in the fish community, it provides a broader understanding of ecological processes. Such insights could prove invaluable in guiding the implementation of conservation strategies. •Changes over three decades in fish functional indices in a tropical bay was evaluated.•A substantial temporal decrease in species richness and abundance was observed.•Functional structure remained stable, but the functional richness decreased over time.•Stability in other functional indices was due to dominant and functionally redundant species.•Redundant species compensates losses of species while maintaining similar functions.