Least Disturbed Condition for European Mediterranean rivers.

The present report describes a three-step approach that was used to characterize and define thresholds for the Least Disturbed Condition in Mediterranean streams of four different types, regarding organic pollution and nutrients, hydrological and morphological alterations, and land use. For this purpose, a common database composed of national reference sites (929 records) from seven countries, sampled for invertebrates, diatoms and macrophytes was used. The analyses of reference sites showed that small (catchment <100 km(2)) siliceous and non-siliceous streams were mainly affected by channelization, bank alteration and hydropeaking. Medium-sized siliceous rivers were the most affected by stressors: 25-43% of the samples showed at least slight alterations regarding channelization, connectivity, upstream dam influence, hydropeaking and degradation of riparian vegetation. Temporary streams were the least affected by hydromorphological changes, but they were nevertheless affected by alterations in riparian vegetation. There were no major differences between all permanent stream types regarding water quality, but temporary streams showed lower values for oxygenation (DO) and wider ranges for other variables, such as nitrates. A lower threshold value for DO (60%) was determined for this stream type and can be attributed to the streams' natural characteristics. For all other river types, common limits were found for the remaining variables (ammonium, nitrate, phosphate, total P, % of artificial areas, % of intensive and extensive agriculture, % of semi-natural areas in the catchment). These values were then used to select the list of reference sites. The biological communities were characterized, revealing the existence of nine groups of Mediterranean invertebrate communities, six for diatoms and five for macrophytes: each group was characterized by specific indicator taxa that highlighted the differences between groups.

[1]  D. Lytle,et al.  Adaptation to natural flow regimes. , 2004, Trends in ecology & evolution.

[2]  Frederick J. Swanson,et al.  OVERVIEW OF THE USE OF NATURAL VARIABILITY CONCEPTS IN MANAGING ECOLOGICAL SYSTEMS , 1999 .

[3]  M. T. Ferreira,et al.  Assessing reference sites and ecological quality of river plant assemblages from an Iberian basin using a multivariate approach , 2002 .

[4]  M. T. Ferreira,et al.  AQUAFLORA: A predictive model based on diatoms and macrophytes for streams water quality assessment , 2012 .

[5]  P. Verdonschot,et al.  Establishing reference conditions for European streams , 2004, Hydrobiologia.

[6]  N. P. Fornells,et al.  25-years of biomonitoring in two mediterranean streams (Llobregat and Besòs basins, NE Spain) , 2006 .

[7]  John L Stoddard,et al.  Setting expectations for the ecological condition of streams: the concept of reference condition. , 2005, Ecological applications : a publication of the Ecological Society of America.

[8]  N. Willby,et al.  Harmonising the bioassessment of large rivers in the absence of near‐natural reference conditions – a case study of the Danube River , 2012 .

[9]  Alexander J. Smith,et al.  A weight-of-evidence approach to define nutrient criteria protective of aquatic life in large rivers , 2010, Journal of the North American Benthological Society.

[10]  C. Zamora‐Muñoz,et al.  Defining criteria to select reference sites in Mediterranean streams , 2009, Hydrobiologia.

[11]  T. Reynoldson,et al.  The Reference Condition: A Comparison of Multimetric and Multivariate Approaches to Assess Water-Quality Impairment Using Benthic Macroinvertebrates , 1997, Journal of the North American Benthological Society.

[12]  R. Petersen,et al.  Short term retention properties of channelized and natural streams , 1991 .

[13]  N. Skoulikidis,et al.  Analysis of factors driving stream water composition and synthesis of management tools--a case study on small/medium Greek catchments. , 2006, The Science of the total environment.

[14]  M. Graça,et al.  II. Leaf Litter Processing and Invertebrates The Role of Invertebrates on Leaf Litter Decomposition in Streams - a Review , 2001 .

[15]  C. Neal,et al.  Spring and surface water quality of the Cyprus ophiolites , 2002 .

[16]  P. Moyle,et al.  BIOLOGICAL INVASIONS OF FRESH WATER: EMPIRICAL RULES AND ASSEMBLY THEORY , 1996 .

[17]  M. Graça,et al.  Leaf-litter breakdown in 3 streams in temperate, Mediterranean, and tropical Cerrado climates , 2006, Journal of the North American Benthological Society.

[18]  J. Stromberg,et al.  Differences in seed mass between hydric and xeric plants influence seed bank dynamics in a dryland riparian ecosystem , 2008 .

[19]  B. Statzner,et al.  Taxonomic and biological trait differences of stream macroinvertebrate communities between mediterranean and temperate regions: implications for future climatic scenarios , 2007 .

[20]  M. Feio,et al.  Diatoms and macroinvertebrates provide consistent and complementary information on environmental quality , 2007 .

[21]  B. Moss,et al.  The Water Framework Directive: total environment or political compromise? , 2008, The Science of the total environment.

[22]  M. T. Ferreira,et al.  Human-disturbed landscapes: effects on composition and integrity of riparian woody vegetation in the Tagus River basin, Portugal , 2005, Environmental Conservation.

[23]  A. Haapala,et al.  Long-term recovery of stream habitat structure and benthic invertebrate communities from in-stream restoration , 2002 .

[24]  M. Zeder,et al.  Domestication and early agriculture in the Mediterranean Basin: Origins, diffusion, and impact , 2008, Proceedings of the National Academy of Sciences.

[25]  T. Isenhart,et al.  Stream bank erosion adjacent to riparian forest buffers, row-crop fields, and continuously-grazed pastures along Bear Creek in central Iowa. , 2004 .

[26]  P. M. Gale,et al.  Phosphorus Retention in Streams and Wetlands: A Review , 1999 .

[27]  S. Puijalon,et al.  Response of aquatic plants to abiotic factors: a review , 2011, Aquatic Sciences.

[28]  Arturo Elosegi,et al.  Effects of hydromorphological integrity on biodiversity and functioning of river ecosystems , 2010, Hydrobiologia.

[29]  V. Resh,et al.  Streams in Mediterranean Climate Regions: Abiotic Influences and Biotic Responses to Predictable Seasonal Events , 1999 .

[30]  V. Acuña,et al.  Effect of climate on the trophic structure of temperate forested streams. a comparison of Mediterranean and Atlantic streams. , 2008, The Science of the total environment.

[31]  J. Heino,et al.  Are biological classifications of headwater streams concordant across multiple taxonomic groups , 2003 .

[32]  N. Prat,et al.  A simple field method for assessing the ecological quality of riparian habitat in rivers and streams: QBR index , 2003 .

[33]  Andrea Buffagni,et al.  The Development of a System to Assess the Ecological Quality of Streams Based on Macroinvertebrates – Design of the Sampling Programme within the AQEM Project , 2003 .

[34]  Thierry Otto,et al.  Holocene circum-Mediterranean vegetation changes: Climate forcing and human impact , 2009 .

[35]  J. Soininen.  Assessing the current related heterogeneity and diversity patterns of benthic diatom communities in a turbid and a clear water river , 2005, Aquatic Ecology.

[36]  S. Passy,et al.  Comparative Environmental Assessment in the Studies of Benthic Diatom, Macroinvertebrate, and Fish Communities , 2004 .

[37]  Seasonal and yearly variations of macrophytes in a southern Iberian river , 2001 .

[38]  Paul Whitehead,et al.  Flow controls on lowland river macrophytes: a review. , 2008, The Science of the total environment.

[39]  R. W. Bode,et al.  A nutrient biotic index (NBI) for use with benthic macroinvertebrate communities , 2007 .

[40]  Andrea Buffagni,et al.  The European reference condition concept: A scientific and technical approach to identify minimally-impacted river ecosystems. , 2012, The Science of the total environment.

[41]  K. R. Clarke,et al.  Change in marine communities : an approach to statistical analysis and interpretation , 2001 .

[42]  Maria J. Santos.  Encroachment of upland Mediterranean plant species in riparian ecosystems of southern Portugal , 2010, Biodiversity and Conservation.

[43]  C. Zamora‐Muñoz,et al.  Concordance between ecotypes and macroinvertebrate assemblages in Mediterranean streams , 2007 .

[44]  Alexander S. Flecker,et al.  Biodiversity conservation in running waters , 1993 .

[45]  P. Moyle.  Conservation of native freshwater fishes in the Mediterranean-type climate of California, USA: A review , 1995 .

[46]  Janet Hooke,et al.  Human impacts on fluvial systems in the Mediterranean region (Invited paper for Binghamton Symposium , 2006 .

[47]  R. Pearson,et al.  Effect of low dissolved oxygen on survival, emergence, and drift of tropical stream macroinvertebrates , 2004, Journal of the North American Benthological Society.

[48]  M. Kelly,et al.  Recommendations for the routine sampling of diatoms for water quality assessments in Europe , 1998, Journal of Applied Phycology.

[49]  J. A. Camargo,et al.  Nitrate toxicity to aquatic animals: a review with new data for freshwater invertebrates. , 2005, Chemosphere.

[50]  P. Legendre,et al.  SPECIES ASSEMBLAGES AND INDICATOR SPECIES:THE NEED FOR A FLEXIBLE ASYMMETRICAL APPROACH , 1997 .

[51]  M. Bowes,et al.  How green is my river? A new paradigm of eutrophication in rivers. , 2006, The Science of the total environment.

[52]  N. Prat,et al.  Establishing physico-chemical reference conditions in Mediterranean streams according to the European Water Framework Directive. , 2012, Water research.

[53]  Charles P. Hawkins,et al.  Weak correspondence between landscape classifications and stream invertebrate assemblages: implications for bioassessment , 2000, Journal of the North American Benthological Society.

[54]  A. Buffagni,et al.  The lentic–lotic character of Mediterranean rivers and its importance to aquatic invertebrate communities , 2009, Aquatic Sciences.

[55]  John R. Olson,et al.  The reference condition: predicting benchmarks for ecological and water-quality assessments , 2010, Journal of the North American Benthological Society.

[56]  Laura A. Hyatt,et al.  INVASIVE SPECIES ACCELERATE DECOMPOSITION AND LITTER NITROGEN LOSS IN A MIXED DECIDUOUS FOREST , 2005 .

[57]  R. Norris,et al.  The influence of extreme climatic events and human disturbance on macroinvertebrate community patterns of a Mediterranean stream over 15 y , 2010, Journal of the North American Benthological Society.