, Volume 154, Issue 4, pp 795–807

Low oxygen pressure as a driving factor for the altitudinal decline in taxon richness of stream macroinvertebrates

Community Ecology - Original Paper

DOI: 10.1007/s00442-007-0877-x

Cite this article as:
Jacobsen, D. Oecologia (2008) 154: 795. doi:10.1007/s00442-007-0877-x


The objective of this study was to explore the altitudinal decrease in local richness of stream macroinvertebrates. I compared the explicatory power of a mid-domain effect (MDE) null model and a number of selected contemporary ecological variables, with a special emphasis on the altitude-mediated decrease in temperature and oxygen availability as possible driving factors for the observed pattern. Benthic macroinvertebrates were sampled at 30 stream sites between 2,600 and 4,000 m a.s.l. in northern Ecuador. All four measures of local richness (total number of taxa, taxa in Surber samples, Fisher’s α index and rarefied richness) decreased with increasing altitude. The MDE null model, water temperature and dissolved oxygen also decreased with altitude, while other measured variables were uncorrelated with altitude. Minimum oxygen saturation had the highest explanatory power of the density-corrected Fisher’s α and rarefied richness (R = 0.48 and 0.52, respectively), but also minimum temperature (R = 0.48 and 0.41) and the MDE null model (R = 0.48 and 0.46) correlated significantly. Multiple regression analyses using several predictive variables showed that oxygen saturation had the greatest and only significant effect on density-corrected richness. The relationship between richness and oxygen corrected for the effect of altitude (using analyses of double residuals) was significant, whereas that of richness versus temperature was not. The results indicate that the decrease in richness with increasing altitude is mainly caused by a decrease in oxygen saturation rather than by a decrease in temperature. Levels of oxygen saturation such as those found at high altitudes do not appear to be lethal to any species, but could affect macroinvertebrates through long-term, sub-lethal effects. I suggest that low oxygen availability may limit biodiversity at high altitudes not only in the aquatic, but also in the terrestrial environment.


Aquatic faunaDiversity patternsFreshwaterElevationOxygen availability

Supplementary material

442_2007_877_MOESM1_ESM.xls (33 kb)
Appendix 1. Environmental characteristics of 30 stream sites in the Ecuadorian Andes. Values of width, depth, current, Froude number, specific discharge, pH and conductivity represent near base-flow conditions. (XLS 33 kb)
442_2007_877_MOESM2_ESM.xls (22 kb)
Appendix 2. Fauna parameters for the 30 stream sites sampled in the Ecuadorian Andes. (XLS 22 kb)

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  1. 1.Freshwater Biological Laboratory, Institute of BiologyUniversity of CopenhagenHillerødDenmark
  2. 2.Escuela de Ciencias BiológicasUniversidad Católica del EcuadorQuitoEcuador