Multiple-stressors effects on Iberian freshwaters: A review of current knowledge and future research priorities


  • Cayetano Gutiérrez-Cánovas Departmento de Ecología Integrativa, Estación Biológica de Doñana (EBD – CSIC). Av. Américo Vespucio, 26. Isla de la Cartuja. 41092 Seville, Spain.
  • Rebeca Arias-Real Department de Biologia Evolutiva, Ecologia i Ciències Ambientals, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal, 643 08028 Barcelona, Spain
  • Daniel Bruno Departamento de Conservación de la Biodiversidad y Restauración de Ecosistemas, Instituto Pirenaico de Ecología (IPE-CSIC), Avda. Montañana, 1005, 50059 Zaragoza, Spain.
  • Marco J. Cabrerizo Departamento de Ecología y Biología Animal, Facultad de Ciencias del Mar, Universidad de Vigo, Campus Lagoas Marcosende, s/n, 36310 Vigo, Spain.
  • Juan Manuel González-Olalla Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071 Granada, Spain.
  • Félix Picazo Departamento de Conservación de la Biodiversidad y Restauración de Ecosistemas, Instituto Pirenaico de Ecología (IPE-CSIC), Avda. Montañana, 1005, 50059 Zaragoza, Spain.
  • Ferran Romero Plant-Soil interactions, Agroscope, 8046 Zurich, Switzerland
  • David Sánchez-Fernández Departamento de Ecología e Hidrología, Universidad de Murcia, 30100 Murcia, Spain.
  • Susana Pallarés Departamento de Biogeografía y Cambio Global, Museo Nacional de Ciencias Naturales, CSIC, Calle de José Gutiérrez Abascal, 2, 28006, Madrid, Spain.


Freshwater ecosystems are exposed to an increasing number of stressors, challenging their biomonitoring and management. Despite recent advances in multiple-stressor research, regional-scale assessments in areas with high freshwater biodiversity and increasing anthropogenic pressure are urgently needed. We reviewed 61 studies focused on freshwater individuals, populations and communities from the Iberian Peninsula to (i) quantify the frequency of experimental approaches used (manipulative, observational), aquatic systems, biological organization levels, and types of organisms and modelled responses, (ii) identify key individual stressors and the frequency of significant positive (increase in response magnitude) and negative (decrease) effects and (iii) determine types of interacting stressors and the frequency of their combined effects. Our dataset comprised 409 unique responses to 13 types of individual stressors, 34 stressor pairs and 12 high-order interactions (3- and 4-way). We found a higher prevalence of manipulative (85 %) respect to observational studies, and a greater focus on lotic systems (59 %) and heterotrophic organisms (58 %). The most studied stressors were nutrient (Nutr), thermal (Therm), hydrologic (Hydr), ultraviolet radiation (UVR), toxic (Toxic) and salinity (Sal) stress and land-use pressure. Individual stressors showed a higher proportion of negative (34 %) than positive effects (26 %). Nutr × UVR, Toxic × Toxic, Therm × Toxic, Hydr × Toxic, Sal × Therm, and Nutr × Therm were the most studied stressor pairs. Non-interactive (50 %) and interactive responses (50 %) were balanced. Antagonistic effects (18 %) were slightly more common than synergisms (15 %), reversal or opposing (13 %) and high-order interactions (4 %). Such proportions varied within experimental approaches, biological organization levels and organism types. Our findings are helpful to manage certain stressor combinations in Iberian freshwaters. Further efforts in Iberian multiple-stressor research should be directed to (i) intensify the study of lentic systems, (ii) explore more observational data, (iii) autotrophic organisms and (vi) biodiversity-ecosystem functioning responses, and (v) cover a wider range of stressors and (vi) more complex interacting stressor scenarios.