Biodiversity of aquatic invertebrates in urban ponds: effects of land use

Urban ponds have the potential to hold large abundance and diversity of aquatic invertebrates, which could maintain an overall high biodiversity in the urban landscape. Little is known about how aquatic systems, such as ponds, are affected by the fast rate of urbanisation caused by an increasing human population together with the expansion of cities. The aim of this study was to investigate how landscape variables affect the abundance of six invertebrate groups. Thirty ponds in Stockholm, Sweden, were studied by sampling aquatic invertebrates of the taxonomic groups: Bivalvia, Gastropoda, Odonata, Trichoptera, Coleoptera and Hemiptera. The percentage of open land, developed land, forest and other water bodies around the ponds were investigated to examine possible correlations with invertebrate abundances. In addition, the relationship between the ponds distance to the city centre and invertebrate abundances were examined. The results indicate that the surrounding landscape has an important effect on the abundance of aquatic invertebrates living in the urban ponds. Odonata abundances showed increasing abundances with percentage of forest cover and decreasing abundances with more developed land. Bivalvia and Trichoptera abundances together with Odonata were found positively correlated with distance to the city centre. No significant results were found for Coleoptera, Hemiptera and Gastropoda. Since the taxonomic groups were affected differently by the landscape variables in the urban area, further investigation on how landscape variables affect the diversity of aquatic invertebrates are needed. Such knowledge would contribute to understand how the landscape variables should be optimised to maintain a high biodiversity in urban ponds