Using a trait‐based approach to measure the impact of dam closure in fish communities of a Neotropical River

Abstract

Damming is one of the main causes of the global decline in freshwater biodiversity.Yet, many hydroelectric dams are being built (or planned) in the Neotropics, where the high species diversity and lack of basic ecological knowledge provide a major obstacle to understanding the effects of this environmental change, which has been mostly described from the perspective of taxonomic change. However, this approach does not account for biological function. Trait-based analysis provides an alternative approach to bioassessment. We assessed the impact of dam closure on the functional structure of fish communities of a Neotropical river by applying trait-based analyses to the response of individual traits aggregated at the assemblage level. Fish data were collected during three distinct time periods (1 year before, 1 year after and 5 years after dam closure), at eight sites located downstream of the dam, in the reservoir, transition zone and upstream. The results indicated that reproduction strategies (migration and parental care) and diet (detritivores) were the trait categories mostly affected by the dam, with the response of downstream assemblages differing from upstream of the dam. A trait-based analysis to the impact of damming on fish communities appears to be a promising approach using an initial descriptive analysis of individual traits and regression models of multiple traits that reflect species' adaptation to the new environment. This study provides both an alternative and complementary approach to taxonomic assessment of impacts from damming, contributing towards a more robust evaluation of the response of fish communities to dams. K E Y W O R D Sbiomonitoring, damming, fishes, functional diversity, traits, tropical river

Dams have varying impacts on fish communities across latitudes: a quantitative synthesis

“…) because they are in a perturbed state after impoundment compared to natural lakes (Thornton et al ; Pringle et al ; Davis ; Didham et al ). Several studies have found an increase in non‐native species after impoundment, and often these taxa are piscivorous species that become quite abundant post‐impoundment (Martinez et al ; Quist et al ; Guenther & Spacie ; Johnson et al ; Gido et al ; Clavero & Hermoso ; Franssen & Tobler ; Lima et al ). When introduced, they compete with, and can prey upon native species (Li et al , Minckley et al ).…”

“…Trophic level position – We extracted the mean trophic level position for each species from FishBase (Froese & Pauly ), and we calculated a mean trophic level position metric using: , where p i is the proportion of individuals belonging to the i th species and TP i is the average reported trophic level position for species i . Macrohabitat flow guild – We first categorised fish species based on their macrohabitat flow guild (generalist, fluvial facultative or fluvial specialist) by using FishBase (Froese & Pauly ) and other articles and books (Scott & Crossman ; Travnichek & Maceina ; Quinn & Kwak ; Guenther & Spacie ; Baumgartner et al ; Buckmeier et al ; Lima et al ). Generalists species were coded 1, whereas fluvial facultative taxa were coded 0.5 and fluvial specialists coded 0.…”

“…Earlier works have provided valuable information regarding the effects of dams on fish communities, but the divergences observed regarding fish responses to impoundment call for a global assessment that goes beyond taxonomic indices to include fish assemblage metrics and functional indices (Mérona & Vigouroux ; Mims & Olden ; Lima et al , ; Sagouis et al ; Santos et al ). Moreover, the effects brought about by dams and newly created reservoirs might also vary across latitudes according to the inherent adaptability of fish communities to respond to the physico‐chemical and biological changes (Rosenberg et al ; Gomes & Miranda ; Vörösmarty et al ).…”

Hydrological influences on aquatic communities at the mesohabitat scale in high Andean streams of southern Ecuador

“…However, in the tropical zones, most of the studies concentrate on the temporal variability of the aquatic communities as a function of the season in the year (Jacobsen & Encalada, ; Mesa, ; Ríos‐Touma et al, ) without considering flood and drought discharge (i.e., hydrological) thresholds and their impact on aquatic communities. Exceptions hereon are the studies in altered rivers of Castro, Hughes, and Callisto (), Miserendino (), and Herrera and Burneo () that examined the response of macroinvertebrates and Lima et al () and García, Jorde, Habit, Caamaño, and Parra () of fish.…”

Mosaic environments shape the distribution of Neotropical freshwater ichthyoplankton

“…Watersheds worldwide exhibit an association between dam presence and variation in ichthyofaunal population structure (Agostinho, Pelicice, & Gomes, ; Angulo‐Valencia, Agostinho, Suzuki, Luz‐Agostinho, & Agostinho, ; Lima et al, ; Schork & Zaniboni‐Filho, ; Winemiller et al, ). Dam construction in response to increasing electricity demands has large‐scale impact on river systems (Suzuki, Dunham, Silva, Alves, & Pompeu, ), modifying water flow and existing environments (Agostinho, Gomes, Santos, Ortega, & Pelicice, ; Pelicice, Pompeu, & Agostinho, ; Reynalte‐Tataje, Nakatani, Fernandes, Agostinho, & Bialetzki, ).…”