@article{fdi:010057119,
  title = {{E}ffects of natural hydrological variability on fish assemblages in small {M}editerranean streams : implications for ecological assessment},
  author = {{M}atono, {P}. and {B}ernardo, {J}. {M}. and {O}berdorff, {T}hierry and {I}lheu, {M}.},
  editor = {},
  language = {{ENG}},
  abstract = {{S}mall {M}editerranean streams are shaped by predictable seasonal events of flooding and drying over an annual cycle, and present a strong inter and intra-annual variation in flow regime. {N}ative fish assemblages in these streams are adapted to this natural environmental variability. {T}he distinction of human-induced disturbances from the natural ones is thus a crucial step before assessing the ecological status of these streams. {I}n this aim, the present study evaluates the effects of natural hydrological variability on fish assemblages from disturbed and least disturbed sites in small intermittent streams of south {P}ortugal. {D}ata were collected over the last two decades (1996-2011) in 14 sites located in the {G}uadiana and {S}ado river basins. {H}igh variability of fish assemblages was strongly dependent on human-induced disturbances, particularly nutrient/organic load and sediment load, and on natural hydrological variability. {N}atural hydrological variability can act jointly with anthropogenic disturbances, producing changes on fish assemblages structure of small intermittent streams. {I}n least disturbed sites, despite the natural disturbances caused by inter-annual rainfall variations (including drought and flood events), fish assemblages maintained a long-term stability and revealed a high resilience. {O}n the contrary, disturbed sites presented significantly higher variability on fish assemblages and a short and long-term instability, reflecting a decrease on the resistance and resilience of fish assemblages. {U}nder these conditions, fish fauna integrity is particularly vulnerable and the ecological assessment may be influenced by natural hydrological variations. {H}igh hydrological variability (especially if it entails high frequency of dryer years and meaningful cumulative water deficit) may affect the impact of the human pressures with significant and consistent consequences on fish assemblage composition and integrity. {I}n this study, fish metrics that maximize the detection of human degradation and minimize the response to natural variability were based on the relative abundance of native species (insectivorous species, eurytopic species, water column species, native lithophilic species), relative abundance of species with intermediate tolerance and relative number of exotic species. {R}esults highlight the importance of assessing temporal variability on stream biomonitoring programs and emphasize the need to improve the assessment tools, accounting for long-term changes in fish assemblages, namely by selecting the most appropriate fish metrics that respond to anthropogenic disturbances but exhibit low natural temporal variability, essential both in the characterization of the biological reference conditions and in the development of fish indexes in intermittent streams.},
  keywords = {{I}ntermittent streams ; {N}atural disturbance ; {H}uman-induced degradation ; {F}ish assemblages ; {E}cological assessment ; {P}ortugal},
  booktitle = {},
  journal = {{E}cological {I}ndicators},
  volume = {23},
  numero = {},
  pages = {467--481},
  ISSN = {1470-160{X}},
  year = {2012},
  DOI = {10.1016/j.ecolind.2012.04.024},
  URL = {https://www.documentation.ird.fr/hor/fdi:010057119},
}