Impacts of climate change on the distribution of riverine endemic fish species in Iran, a biodiversity hotspot region

Abstract

Iran is one of the world's fish biodiversity hotspots. Most riverine fish species in this country are currently under threat by human activities. In addition to those threats, climate change is expected to alter rainfall and temperature regimes, imposing further limitations, particularly to endemic fishes. Therefore, understanding how these species respond to climate change is an important issue in the conservation of Iranian freshwater biodiversity. This study aimed to predict the potential distribution of 16 endemic fish species under two climate change scenarios (i.e., RCP 4.5 and RCP 8.5) in river habitats of Iran in the 2050s and the 2080s. The analysis is conducted using the MaxEnt model. Seven environmental variables were used for modelling: maximum width, elevation, river slope, the basins occupied by the target species, average annual precipitation, annual mean temperature, and the temperature difference between the coldest and hottest months of the year . The validation of the model for each species showed that AUC (area under the ROC curve) scores range from 0.87 to 0.99. Under optimistic (RCP 4.5) and pessimistic (RCP 8.5) scenarios in the 2050s and the 2080s, species will face four different outcomes to their habitat range: reduction (three species), expansion (five species), reduction and expansion (seven species) and no change (one species). It is concluded that most species that are unique in their geographical area will face serious challenges from climate change. Delineating species range changes under climate change scenarios can help prioritise conservation measures for these valuable species. Considering our results, the translocation of species to new locations also should be investigated.

Predicting climate change impacts on the distribution of endemic fish Cyprinion muscatense in the Arabian Peninsula

“…This species is expected to be strongly affected by climate change due to its restricted distribution in mountainous areas surrounded by lowlands and sea. Our finding on loss of climatically suitable habitat align with the previous studies accessing the potential effects of climate change on freshwater ichthyofauna using SDM in some other parts of the world (e.g., Frederico et al., 2021 ; Makki et al., 2023 ; Yılmaz et al., 2021 ;Yousefi, Jouladeh‐Roudbar, & Kafash, 2020 ; Stewart et al., 2022 ), revealing that predicting the response of endemic elements to climate change is essential, especially for freshwater fish species that are restricted to a small geographic area and especially in areas with arid conditions.…”

“…Different taxonomic groups may respond to long‐term climate change through range shifts (Yousefi et al., 2017 ), reductions (Esmaeili et al., 2018 ; Makki et al., 2023 ; McMahan et al., 2020 ; Soliman et al., 2023 ), and expansions (Kafash et al., 2018 ; Makki et al., 2023 ), or by persisting in their current range (Makki et al., 2023 ). Shabani et al.…”

Habitat potential modelling and the effect of climate change on the current and future distribution of three Thymus species in Iran using MaxEnt

“…Climate change is one of the most important natural factors affecting biodiversity, agricultural production, and food security on a global scale 1 – 4 . Climate change is accepted by most scientists as a reality, with impacts to plant and animal species forecasted to be complex and dramatic 5 – 7 . Over the course of a few decades, climate change has rapidly altered the habitats of various species, leading to mass extinction, particularly among sensitive species.…”

Future climate impacts on biodiversity trends in major global rivers

“…For example, Shannon index (SI) based on eco-hydrological parameters has been suggested as a proxy for assessing biodiversity trends in river ecosystems 10,11,12 . Such an approach also represents a promising tool to assess the effects of climate change-induced ow alteration on river biodiversity, which has received increasing attention from scholars worldwide 2,13,14 . Future trends will have multifaceted and uncertain effects on riverine ecosystems as the complexity and uncertainty of climatic conditions increase, particularly due to the variability among climatic models under various scenarios of emission and across simulations by hydrological models 15,16 .…”