Ecological assessment of a renaturalised pond in the quarries of Alpedrete (Spain).

Invertebrates have recently been recognised under a global decline, a situation that seems to be accentuated in continental waterbodies. In the EUROPONDS project we deepened in the contribution of aquatic invertebrates to terrestrial ecosystems, representing countries all over Europe. Our study was encompassed in a restored quarry in Alpedrete, Madrid, Spain, a landscape destined for livestock activities. We evaluated the invertebrate assemblages of a small permanent pond after restoration (physicochemical variables, macroinvertebrates assemblages and macrophytes species) and its contribution to the landscape by the emerging insects. To do that, we have carried out seasonal samplings starting in autumn 2020 and finishing by summer 2021. We detected a highly aquatic biodiversity in our study pond, showing oversaturation of dissolved oxygen concentration and a rich and dense cover of macrophytes. A diverse assemblage of aquatic macroinvertebrates included odonates, heteropterans, coleopterans, culicids, chironomids and ephemeropterans. We located two traps for emergent insects during one week each season, and we captured flying and adult individuals of some of these macroinvertebrates (even 60 chironomids in winter), revealing the importance of this pond for the adjacent landscape. We concluded that our shallow permanent pond shows a high degree of naturalisation due to the huge diversity of fauna and flora recorded. We consider of concern that the cattle’s faeces in the surroundings of the pond could reduce the water quality as detected an increase in nitrate concentration (0,16 mg/L in winter). Therefore, we encourage regional authorities to include this pond in the regional program for wetland conservation.