Illustrating a new global-scale approach to estimating potential reduction in fish species richness due to flow alteration

Changes in river discharge due to human activities and climate change would affect the sustainability of freshwater ecosystems. To globally assess how changes in river discharge will affect the future status of freshwater ecosystems, global-scale hydrological simulations need to be connected with a model to estimate the durability of freshwater ecosystems. However, the development of this specific modelling combination for the global scale is still in its infancy. In this study, two statistical methods are introduced to link flow regimes to fish species richness (FSR): one is based on a linear relationship between FSR and mean river discharge (hereafter, FSR-MAD method), and the other is based on a multi-linear relationship between FSR and ecologically relevant flow indices involving several other flow characteristics and mean river discharge (FSR-FLVAR method). The FSR-MAD method has been used previously in global simulation studies. The FSR-FLVAR method is newly introduced here. These statistical methods for estimating FSR were combined with a set of global river discharge simulations to evaluate the potential impact of climate-change-induced flow alterations on FSR changes. Generally, future reductions in FSR with the FSR-FLVAR method are greater and much more scattered than with the FSR-MAD method. In arid regions, both methods indicate reductions in FSR because mean discharge is projected to decrease from past to future, although the magnitude of reductions in FSR is different between the two methods. In contrast, in heavy-snow regions a large reduction in FSR is shown by the FSR-FLVAR method due to increases in the frequency of low and high flows. Although further research is clearly needed to conclude which method is more appropriate, this study demonstrates that the FSR-FLVAR method could produce considerably different results when assessing the global role of flow alterations in changing freshwater ecosystems.

[1]  S. Kanae,et al.  Global flood risk under climate change , 2013 .

[2]  Petra Döll,et al.  Impact of climate change on freshwater ecosystems: a global-scale analysis of ecologically relevant river flow alterations. , 2010 .

[3]  J. Olden,et al.  Redundancy and the choice of hydrologic indices for characterizing streamflow regimes , 2003 .

[4]  S. Kanae,et al.  An integrated model for the assessment of global water resources – Part 2: Applications and assessments , 2008 .

[5]  C. Vörösmarty,et al.  Reconstructing 20 th century global hydrography : a contribution to the Global Terrestrial Network-Hydrology ( GTN-H ) , 2010 .

[6]  G. Russell,et al.  Continental-Scale River Flow in Climate Models , 1994 .

[7]  S. Kanae,et al.  A global water scarcity assessment under Shared Socio-economic Pathways – Part 2: Water availability and scarcity , 2012 .

[8]  Julian D. Olden,et al.  Quantifying uncertainty in estimation of hydrologic metrics for ecohydrological studies , 2009 .

[9]  Jean-François Guégan,et al.  Global scale patterns of fish species richness in rivers , 1995 .

[10]  S. Kanae,et al.  An integrated model for the assessment of global water resources – Part 1: Model description and input meteorological forcing , 2008 .

[11]  Mike Acreman,et al.  Defining environmental river flow requirements ? a review , 2004 .

[12]  Changsheng Li,et al.  Bi-criteria evaluation of the MIKE SHE model for a forested watershed on the South Carolina coastal plain , 2010 .

[13]  Donald A. Jackson,et al.  Community ecology of stream fishes : concepts, approaches, and techniques , 2010 .

[14]  U. Uehlinger,et al.  Rivers of Europe , 2009 .

[15]  M. Rowland,et al.  On the Size of African Riverine Fish Faunas , 1982 .

[16]  R. Palmer,et al.  Projected impacts of climate change on salmon habitat restoration , 2007, Proceedings of the National Academy of Sciences.

[17]  P. McIntyre,et al.  Global threats to human water security and river biodiversity , 2010, Nature.

[18]  David P. Braun,et al.  A Method for Assessing Hydrologic Alteration within Ecosystems , 1996 .

[19]  Taikan Oki,et al.  Assessment of Annual Runoff from Land Surface Models Using Total Runoff Integrating Pathways (TRIP) , 1999 .

[20]  Petra Döll,et al.  Global-scale analysis of river flow alterations due to water withdrawals and reservoirs , 2009 .

[21]  Peggy A. Johnson,et al.  Stream hydrological and ecological responses to climate change assessed with an artificial neural network , 1996 .

[22]  D. Lodge,et al.  Going with the flow: using species-discharge relationships to forecast losses in fish biodiversity. , 2006, Ecology.

[23]  Petra Döll,et al.  A Pilot Global Assessment of Environmental Water Requirements and Scarcity , 2004 .

[24]  Hannah G. Yamada,et al.  An assessment of global net irrigation water requirements from various water supply sources to sustain irrigation: rivers and reservoirs (1960–2050) , 2013 .

[25]  F. Ludwig,et al.  Impact of reservoirs on river discharge and irrigation water supply during the 20th century , 2011 .

[26]  Vladimir U. Smakhtin,et al.  Basin Closure and Environmental Flow Requirements , 2008 .

[27]  Thierry Oberdorff,et al.  Global and Regional Patterns in Riverine Fish Species Richness: A Review , 2011 .

[28]  B. Hugueny.  West African rivers as biogeographic islands: species richness of fish communities , 1989, Oecologia.

[29]  M. Jenkins.  Prospects for Biodiversity , 2003, Science.

[30]  H. Dürr,et al.  A scenario for impacts of water availability loss due to climate change on riverine fish extinction rates , 2013 .

[31]  Edella Schlager.  Rivers for Life: Managing water for people and nature , 2001 .

[32]  F. Chapin,et al.  A safe operating space for humanity , 2009, Nature.

[33]  J. Lamarque,et al.  Global Biodiversity: Indicators of Recent Declines , 2010, Science.

[34]  S. Kanae,et al.  A physically based description of floodplain inundation dynamics in a global river routing model , 2011 .

[35]  Rolf Weingartner,et al.  Global monthly water stress: 2. Water demand and severity of water stress , 2011 .

[36]  R. Sparks,et al.  THE NATURAL FLOW REGIME. A PARADIGM FOR RIVER CONSERVATION AND RESTORATION , 1997 .

[37]  Santiago Beguería,et al.  Hydrological response to climate variability at different time scales: A study in the Ebro basin , 2013 .

[38]  Y. Iwasaki,et al.  Evaluating the relationship between basin‐scale fish species richness and ecologically relevant flow characteristics in rivers worldwide , 2012 .

[39]  D. Lodge,et al.  Scenarios of freshwater fish extinctions from climate change and water withdrawal , 2005 .