Data from: Variations of trophic structure and niche space in fish community along a highly regulated subtropical large river

The trophic interactions between consumers and resources play a vital role
in the stability of communities. In river systems, fragmentation of
natural habitats and environmental changes alters the energy basis and
community composition, consequently leading to variations in the
community's trophic structure and niche space. However, our
understanding of how the trophic structure responds to environmental
changes is still very limited. Here, based on stable isotope data, we
explored and compared trophic positions (TPs), community-wide trophic
metrics, and isotope niche space of fish communities in three reaches with
different hydrogeomorphic conditions along a highly regulated subtropical
river over three seasons. The community trophic structure and niche space
showed notable spatiotemporal variations. Overall, the downstream reach
had lower TPs and trophic diversity but higher trophic redundancy. The
middle reach occupied a wider isotope niche space than other reaches, with
the largest niche size during autumn. Furthermore, the niche overlap was
relatively high in winter between reaches and in the downstream between
seasons. The results implied a homogenization of feeding functional groups
and energy flow pathways of species in the downstream community associated
with the change of energy source and stability of hydrological conditions.
The relationship between trophic structure and environmental factors
suggested that the dam-induced alteration in hydrological-related aspects
may drive the changes in the functional group composition, together with
changes in energy basis, resulting in differences in the trophic structure
of the community. The results of the present study deepen our
understanding of how ecosystem functions respond to disturbance, thus
contributing to an improved ability to conserve river ecosystems.