Comparison of different spatial fish communities
Noticeable differences were observed in the fish species composition
between the upper and lower reaches of the Chishui River Basin, as shown
in Figure 2(b). However, no significant differences were observed
between upstream and downstream reach. Nonetheless, there were
significant differences between the upstream and downstream tributaries,
indicating that disparities between the upstream and downstream
tributaries could be attributed to the fish communities in the
tributaries. Studies have revealed that fish diversity is associated
with river area (Oberdorff et al., 2019) and habitat heterogeneity
(Hugueny et al., 2010). Therefore, habitat heterogeneity may be a more
influential factor for community differences. Furthermore, in the
comparison of transverse gradients, it was discovered that the DaTong
River exhibited the highest level of α diversity among all tributaries.
This finding differs from the results of traditional survey studies
conducted at the same position on the Xishui River (Liu et al. 2020). We
believe that the topography and hydrological conditions of the DaTong
River tend to impede traditional surveys, leading to an underestimation
of tributary diversity. Conversely, the gentle flow speed and easy
accessibility of the Xishui River facilitated a tributary survey which
was more comprehensive. Therefore, the status of the DaTong River should
be elevated to the same level as that of the Xishui River.