Modeling the Impacts of Climate Change on the Distribution of the Song Fish Luciobarbus esocinus Heckel, 1843 Under Various Climate Scenarios

Iran stands out as one of the world's biodiversity hotspots. Simultaneously, river fish species within the country face imminent threats from various human activities. Climate change, among other challenges, poses a significant risk to the biodiversity of Iran. Consequently, there is a critical need to anticipate potential habitat changes for freshwater fish species in response to climate change. This study focuses on evaluating the impact of climate change on the habitats of the Song fish, a species with economic value and conservation significance. The Song fish is currently classified as Vulnerable (VU) by the International Union for Conservation of Nature (IUCN), making the examination of climate change effects crucial for the future population of this species.

This study employs the MaxEnt model to predict the spatial distribution of the Song fish at two different time scales (2050 and 2080 AD) under both optimistic (RCP2.6) and pessimistic (RCP8.5) climate scenarios. The R software environment was used for the analysis. Environmental variables, including slope, annual temperature range, flow accumulation, annual precipitation, annual mean temperature, and upstream drainage area, were considered. The data related to the observations of this species have been collected from sampling and various library sources. Modeling performance in predicting species distribution has also been evaluated by the AUC (Area Under the Curve) criterion.

The model demonstrated excellent performance in predicting species distribution, as indicated by the high AUC (Area Under the Curve) criterion value of 0.989. Among the environmental variables, annual average temperature and slope emerge were the most influential factors in determining the distribution of the Song fish. Furthermore, the study revealed a projected decrease in the distribution range of this species under both optimistic and pessimistic scenarios for 2050 and 2080.

To safeguard the Song fish, it is imperative for managers to identify and implement appropriate measures. These measures should aim to mitigate the effects of climate change and alleviate threats associated with these changes.