Potential impacts of climate change on flow regime and fish habitat in mountain rivers of the south-western Balkans

Abstract

The climate change in the Mediterranean area is expected to have significant impacts on the aquatic ecosystems and particular in the mountain rivers and streams that often host important species such as the Salmo farioides, Karaman 1938. These impacts will most possibly affect the habitat availability for various aquatic species resulting to an essential alteration of the water requirements, either for dams or other water abstractions, in order to maintain the essential levels of ecological flow for the rivers. The main scope of this study was to assess potential climate change impacts on the hydrological patterns and typical biota for a south-western Balkan mountain river, the Acheloos. The altered flow regimes under different emission scenarios of the Intergovernmental Panel on Climate Change (IPCC) were estimated using a hydrological model and based on regional climate simulations over the study area. The Indicators of Hydrologic Alteration (IHA) methodology was then used to assess the potential streamflow alterations in the studied river due to predicted climate change conditions. A fish habitat simulation method integrating univariate habitat suitability curves and hydraulic modeling techniques were used to assess the impacts on the relationships between the aquatic biota and hydrological status utilizing a sentinel species, the West Balkan trout. The most prominent effects of the climate change scenarios depict severe flow reductions that are likely to occur especially during the summer flows, changing the duration and depressing the magnitude of the natural low flow conditions. Weighted Usable Area-flow curves indicated the limitation of suitable habitat for the native trout. Finally, this preliminary application highlighted the potential of science-based hydrological and habitat simulation approaches that are relevant to both biological quality elements (fish) and current EU Water policy to serve as efficient tools for the estimation of possible climate change impacts on the south-western Balkan river ecosystems.

Index‐based analysis of climate change impact on streamflow conditions important for Northern Pike, Chub and Atlantic salmon

“…Other studies have carried out descriptive examinations of change in IHA parameters by climate change and their implications on aquatic organisms (Gibson et al., ). The majority of studies projected an increase in frequency and magnitude of the low flow events or drought (Guse et al., ; Papadaki et al., ; Paparrizos & Matzarakis, ), but this study found a contrary situation. This is not surprising as climate projections and their impacts are region‐specific and each generation of climate models or emission scenarios can potentially suggest a different future.…”

“…The SWAT model has been used in combination with the Indicators of Hydrologic Alteration (IHA) methodology (Richter, Baumgartner, Braun & Powell, ; Richter, Baumgartner, Powell & Braun, ) to assess climate change impact on a single fish species habitat suitability by Morid, Delavar, Eagderi and Kumar () and Papadaki et al. (). The IHA consists of 33 parameters that describe the hydrological regime as: magnitude, timing, frequency, duration and rate of change (The Nature Conservancy ).…”

Climate change and water‐related ecosystem services: impacts of drought in california, usa

“…In mountain rivers of the southwestern Balkans in Europe, due to decreases in summer precipitation and increases in air temperature, minimum flows are projected to decline in the mid‐ and late‐21st century, particularly under the high emission scenario, increasing the risk of droughts (Papadaki et al. ). In a study of the influence of drought on national forests and grasslands across the United States, Sun et al.…”

“…In southwestern Balkan mountain rivers in southern Europe, with declines in summer flow and rising stream temperatures, the western Balkan trout population and other biota are projected to decline substantially in the latter half of the 21st century (Papadaki et al. ). Similarly, as a result of decreased flow (20%–29%) and increased water temperature (4–4.2°C), habitat suitability for large brown trout is also projected to decline in the near future (2011–2040) in the Cabriel river in Iberian Peninsula (Muñoz‐Mas et al.…”

The role of floods and droughts on riverine ecosystems under a changing climate

“…Still higher levels of complexity can be achieved by including a hydraulic model in the modelling chain, but such approaches are typically applied only at small catchment scales (Guse et al, ; Papadaki et al, ). Guse et al () reported variable changes in habitat suitability for fishes in a small stream in northern Germany in response to increased occurrence of seasonal habitat deficits.…”