Using the Ensemble Model of Climate Change to Predict and How to Sustainability the Luciobarbus barbulus in the Ecosystems Under its Distribution

Climate change, widely acknowledged as one of the most pressing global threats in recent decades, has significantly impacted biodiversity and natural ecosystems across the planet. The use of appropriate predictive tools can greatly aid conservation managers in their efforts to protect and preserve biodiversity. In this study, we investigated the effects of climate change on the spread and distribution of Luciobarbus barbulus (Heckel, 1847), a freshwater fish species, by employing an ensemble modeling approach using the Biomod2 package. We utilized six distinct algorithms to analyze current conditions and two future scenarios for the years 2070 and 2090, specifically focusing on the Shared Socioeconomic Pathways (SSP) includes SSP1-2.6 and SSP5-8.5 scenarios. To build our predictive model, we incorporated a comprehensive dataset comprising eight variables, including climatic, topographic, and anthropogenic factors. The results indicated that the model's predictive performance was robust, with evaluation metrics—specifically the Area Under the Curve (AUC) and True Skill Statistic (TSS)—showing values ranging from very good to excellent (AUC ≥ 0.87). Our analysis revealed that the most significant factors influencing the distribution of Luciobarbus barbulus were Annual Mean Temperature (Bio 1), Annual Precipitation (Bio 12), and Mean Temperature of the Warmest Quarter (Bio 10). Alarmingly, the model forecasts a decrease in the species distribution range under both optimistic and pessimistic scenarios for the years 2070 and 2090. In conclusion, it is imperative for managers and decision-makers in the field of biodiversity conservation to recognize and address the impacts of climate change. Identifying and implementing effective measures to protect this valuable species will be essential for ensuring its survival in a rapidly changing environment.
 
Extended Abstract
1-Introduction
Global warming, predominantly driven by human activities such as fossil fuel combustion, deforestation, and industrial processes, is inducing a complex web of environmental changes that extend far beyond mere temperature increases. These changes manifest as altered climate patterns, including more intense and unpredictable rainfall, prolonged droughts, and shifts in seasonal cycles. Such variability disrupts ecosystems, leading to cascading effects on biodiversity. For instance, rising sea levels threaten coastal habitats, while the increased frequency and severity of natural disasters—such as hurricanes, floods, and wildfires—further exacerbate the vulnerability of both terrestrial and aquatic ecosystems. Freshwater ecosystems are particularly sensitive to these shifts. Fish species, including Luciobarbus barbulus, face multiple challenges: habitat loss due to altered flow regimes and increased water temperatures, shifting migration patterns as they seek suitable spawning grounds, and heightened susceptibility to diseases and parasites that thrive in warmer waters. The intricate relationships within these ecosystems mean that changes affecting one species can have ripple effects throughout the food web. To effectively address the impacts of climate change on these delicate aquatic environments, species distribution modeling (SDM) has emerged as a vital tool for conservationists and researchers. SDM allows for the assessment of species vulnerability by predicting how climate variables influence their distribution. By analyzing historical data alongside current environmental conditions, SDM helps to identify distribution limits and potential shifts in habitats due to climate change. This predictive capability is crucial for developing targeted conservation strategies aimed at mitigating the adverse effects of climate change. This study serves as a prime example of the application of SDM in understanding the ecological dynamics of Luciobarbus barbulus within Iran's river systems. By integrating various environmental variables—such as temperature, precipitation, and anthropogenic influences—this research not only sheds light on the current distribution of this fish species but also forecasts its potential future habitats under different climate scenarios. Ultimately, findings from such studies can inform conservation efforts, helping to prioritize areas for protection and management to ensure the survival of vulnerable species in an era of rapid environmental change.
 
2-Materials and Methods
This research focuses on studying the distribution of Luciobarbus barbulus species in Iran, which has a diverse biogeography and unique fauna and flora due to its location at the intersection of three distinct bioregions. The study collected 187 presence points for L. barbulus through various methods and used 144 occurrence points for modeling. Environmental variables such as climate, topography, and human impact were considered, with seven key variables used in the habitat modeling process. Future climate predictions for 2070 and 2090 were also incorporated into the analysis. The study utilized Biomod2 software with various algorithms to predict current and future optimal habitats for the species, evaluating model accuracy through measures like AUC and TSS statistics.
 
3- Results and Discussion
The location of the Iranian plateau in arid and semi-arid regions, coupled with predicted increases in temperature and decreases in precipitation, indicates that Iran will be significantly impacted by climate change in the future. This will likely have profound effects on the country's ecosystems, particularly freshwater ecosystems and their biodiversity, including fish species such as L. barbulus. Species may react to climate change through strategies such as adaptation, migration to more suitable environments or extinction. Factors influencing migration include genetic adaptability, dispersal abilities, physiological conditions, and the presence of physical barriers. Human activities like land use changes, pollution, and habitat destruction can hinder species' migration efforts. The study on L. barbulus indicates that its optimal habitat in Iran is primarily located in the western, southwestern, and southern regions. Climate change projections for 2070 and 2090 suggest a significant decrease in suitable habitats for this species. It is observed to fall under the "increase and decrease distribution scenario, with a notable decline in suitable habitats by 2070. Different fish species may exhibit varying responses to climate change, as demonstrated by other recent studies. Management strategies tailored to each species' specific needs will be crucial in mitigating the impacts of climate change on fish populations.
 
4- Conclusion
The L. barbulus, an important species found in the western, southwestern, and southern regions of Iran, faces threats from both climate change impacts and excessive fishing due to its high edible value. These factors combined may lead to a significant decline in the population size of this species in the coming decades. To address these challenges, it is recommended to validate climate models with more data and variables to reduce uncertainties. The reduction in the species' distribution range highlights the need for conservation measures and habitat protection. The findings of this research can guide management strategies to identify key habitats, implement necessary conservation actions, and support the species' adaptation to climate change. This information is valuable for managers in developing effective protection strategies for the species and its habitat