Figure legends
Figure 1. Conceptual diagram of the river trophic network
model. The red dashed arrows represent flux leaving the system (i.e.,
fish respiration), and the black arrows represent flux transferring from
one trophic compartment to another through the food web. Plants,
invertebrates, algae, and detritus were considered basal resources for
the fish community, so they have no input flux and respiration being
represented here. Trophic interaction through the food web was defined
by the use of gut contents. Illustration credit: Margenny Barrios
(Departamento de Ecología y Gestión Ambiental CURE, Universidad de la
República, Uruguay).
Figure 2.Long-term
trends in diversity and energy flux of fish trophic guilds. The mean (±
s.e., n = 179) of rarefied species richness (a) , abundance(b) , and energy flux (c) of whole-community (black
points) and individual trophic guilds (colored lines) along 17 years.(d) mean of changes in the energy flux of each single trophic
guild from year 1 to 17 year. Error bars show 95% confidence intervals.(e) relative contributions of fish trophic guilds to the whole
food web energy flux (n = 179).
Figure 3. Response of energy flux (whole-community and
individual trophic guilds) to changes in species richness (n = 179).Relationship between species richness and community energy fluxes.
Linear mixed effects models for (a) whole-communities, (b)
top-carnivores, (c) mesocarnivore, (d) omnivore, and (e) detritivore.
Black dashed lines denote overall model fits and coloured lines indicate
different river sites (Nuevo Berbín, Fray Bentos, and Las cañas).
Figure 5. Direct and indirect effects of HFP, climate and water
properties on the diversity and energy flux of fish trophic guilds.Direct and indirect pathways by which HFP, climate and water properties
affect diversity and energy flux of fish trophic guilds. Specifically,
the structural equation modelling was used to disentangle the direct and
indirect diversity-mediated effects of HFP, climate, and water
properties on energy flux of four fish trophic guilds, including (a-c)
top-carnivores, (d-f) mesocarnivores, (g-i) omnivores, and (j-l)
detritivores. Solid blue and red arrows represent significant positive
and negative pathways, respectively (P ≤ 0.05), while solid grey
arrows non-significant pathways (P ≥ 0.05). The thickness of the
significant pathways (arrows) represents the magnitude of the
standardized regression coefficient. Bar graphs illustrates the
standardized effect size from SEMs (a, d, g, j) for both species’
richness and energy flux of (b-c) top-carnivores, (e-f) mesocarnivores,
(h-i) omnivores, and (k-l) detritivores. Asterisk adjacent to bar
represents the significance of the effects: *P < 0.05,
**P < 0.01, ***P < 0.001. HFP = human
footprint, MMP = mean monthly precipitation and WD = water discharge.
Indirect effects of drivers on energy flux are calculated by multiplying
the path coefficient for the effect of drivers on species richness with
the path coefficient for the effect of species richness on energy flux
(see Table S5).