The potential of fish families as surrogates for species and functional diversity in biomonitoring impacted Amazonian streams

Compared to the accelerated progress of environmental degradation in Amazonian ecosystems, the development of studies to support conservation efforts is slow, because it demands substantial financial and logistical investment. Intending to contribute to stream monitoring with rapid analyses, this study aimed to test the feasibility of using species composition for taxonomic families as biological surrogates of species and functional diversity in stream fish assemblages in an impacted region of the Brazilian Amazon during two seasonal periods. Sampling was conducted in 18 streams in northern Brazil, in a region heavily impacted by industrial activities and urbanization. We observed a high potential for using families Acestrorhamphidae and Cichlidae as biological surrogates. Overall, the family Cichlidae showed potential in representing species composition and functional structure in stream fish across seasonal variation. The congruence between Acestrorhamphidae, Cichlidae, and the fish assemblages was particularly high during the rainy season, in both taxonomic and functional dimensions. During the dry season, Acestrorhamphidae showed high congruence only with species abundance. These findings contribute to monitoring strategies for impacted streams in a scenario of limited financial resources and expert availability.