Biodiversity and distribution patterns of freshwater invertebrates in farm ponds of a south-western French agricultural landscape
- 924 Downloads
We assessed the importance for biodiversity of man-made farm ponds in an agricultural landscape in SW France lacking natural wetlands. The ponds were originally created to provide a variety of societal services (irrigation, visual amenity, water for cattle, etc.). We also assessed the environmental factors influencing invertebrate assemblages in these ponds. Only 18 invertebrate taxa out of 114 taxa occurring in the study area were common to ponds and rivers indicating that the contribution of farm ponds to freshwater biodiversity was potentially high. A Self-Organizing Map (SOM, neural network) was used to classify 36 farm ponds in terms of the 52 invertebrate families and genera they supported, and to specify the influence of environmental variables related to land-use and to pond characteristics on the assemblage patterns. The SOM trained with taxa occurrences showed five clusters of ponds, most taxa occurring only in 1–2 clusters of ponds. Abandoned ponds tended to support higher numbers of taxa, probably because they were allowed to undergo a natural succession. Nevertheless, abandoned ponds were also amongst the largest, so that it remained difficult to separate the effects of pond size and abandonment, although both factors were likely to interact to favour higher taxon richness. The invertebrate communities in the ponds appeared to be influenced mainly by widely acting environmental factors (e.g. area, regionalization of assemblages) with little evidence that pond use (e.g. cattle watering, amenity) generally influenced assemblage composition. Our results support the idea that agricultural landscapes containing man-made ponds make a significant contribution to freshwater biodiversity indicating that protection of farm ponds from threats such as in-filling and pollution can make a positive contribution to the maintenance of aquatic biodiversity. This added value for biodiversity should be considered when calculating the economic costs and benefits of constructing water bodies for human activities.
KeywordsAgriculture Artificial ponds Wetlands Macroinvertebrates Land-use Self-organizing maps
M. Dessaivre and D. Hanquet (Nature Midi-Pyrénées) contributed to the study design, field work and invertebrate sorting. This study was funded by the French Water Agency (Agence de l’Eau Adour-Garonne), DIREN, Région Midi-Pyrénées, and by Nature Midi-Pyrénées. We wish to thank J. Biggs and two anonymous referees for their constructive comments on an earlier version of this article.
- Biggs, J., A. Corfield, D. Walker, M. Whitfield & P. Williams, 1994. New approaches to the management of ponds. British Wildlife 5: 273–287.Google Scholar
- Chapman, L. J., J. Balirwa, F. W. B. Bugenyi, C. Chapman & T. L. Crisman, 2001. Wetlands of East-Africa : biodiversity, exploitation and policy perspectives. In Gopal, B., W. J. Junk & J. A. Davis (eds), Biodiversity in Wetlands: Assessment Function and Conservation, Vol. 2. Backhuys Publishers, Leiden, The Netherlands, 101–131.Google Scholar
- Kiviluoto, K., 1996. Topology preservation in self-organizing maps. In IEEE Service Center (ed.), Proceedings of ICNN’96, IEEE International Conference On Neural Networks, Piscataway, 294–299.Google Scholar
- Kohonen, T., 1995. Self-Organizing Maps, volume 30 of Springer Series in Information Sciences. Springer, Berlin, Heidelberg.Google Scholar
- Meffe, G. K. & C. R. Carroll, 1997. Principles of Conservation Biology, 2nd edn. Sinauer Associates, Inc., Sunderland, MA.Google Scholar
- Nature Midi-Pyrénées, 2005. Inventaire et préservation du patrimoine des mares de l’Astarac. 114 pp. Download at http://www.premiumwanadoo.com/naturemp/.
- Rosenberg, D. M. & V. H. Resh, 1993. Freshwater Biomonitoring and Benthic Macroinvertebrates. Chapman and Hall, London, UK.Google Scholar
- Scheffer, M., G. J. van Geest, K. Zimmer, E. Jeppesen, M. Sondergaard, M. G. Butler, M. A. Hanson, S. Declerck & L. De Meester, 2006. Small habitat size and isolation can promote species richness: second-order effects on biodiversity in shallow lakes and ponds. Oikos 112: 227–231.CrossRefGoogle Scholar
- Ultsch, A., 1993. Self-organizing neural networks for visualization and classification. In Opitz, O., B. Lausen & R. Klar (eds), Information and Classification. Springer-Verlag, Berlin, 307–313.Google Scholar
- Vesanto, J., J. Himberg, E. Alhoniemi & J. Parhankangas, 1999. Self-organizing map in matlab: the som toolbox. In Proceedings of the Matlab DSP Conference 1999, Comsol Oy, Espoo, Finland, 35–40.Google Scholar