2.3 Species trait measure
Choosing the appropriate functional traits could provide valuable
insights into the relationships between environmental changes, fish
functional diversity, and ecosystem (Villéger et al., 2017; Troia &
McManamay, 2020). As habitat alteration and fragmentation associated
with low-head dams can potentially affect the habitat guilds and trophic
structure of fish assemblages in headwater streams (Helms et al., 2011;
Fencl et al., 2017; Smith et al., 2017), we estimated the functional
diversity of each community by measuring the most commonly available
traits of fish species related to feeding, locomotion, and habitat
preferences (Albouy et al., 2011). We measured a series of traits of
fish in the laboratory and used them to calculate seven morphological
ratio traits: (1) eye size; (2) oral gape position; (3) oral gape shape;
(4) gut length; (5) caudal peduncle throttling; (6) body transversal
shape; and (7) body depth (Appendix S1). At least 20 adult specimens of
each species were used to measure the traits, and all adult specimens
were measured when the species contained < 20 adult
individuals.