ORCA - A comparative analysis of organic and conventional agriculture's impact on aquatic biodiversity

There is an ongoing debate on the choice of agricultural practices in terms of their impact on food security, ecosystem functioning and biodiversity. The impact of organic farming is expected to differ from that of conventional farming and is promoted under the current EU Common Agricultural Policy. To date, most comparative studies of organic and conventional agriculture focus on the agricultural land itself, on terrestrial ecosystems, or on rivers, while the numerous small ponds and shallow lakes in agricultural settings are largely ignored. Yet, they harbor the majority of regional biodiversity and are a key provider of ecosystem services.We will combine multiple existing databases with newly collected data to investigate the combined effects of agriculture type (organic versus conventional) and land use intensity (extensive versus intensive) on aquatic biodiversity in ponds and shallow lakes. More specifically, we will assess the effects of different types of agriculture practices on taxonomic, functional and intraspecific genetic diversity of multiple aquatic organism groups (macrophytes, zooplankton, macro-invertebrates, amphibians and fish) at local and regional spatial scales. Through access to extensive databases of existing data, ORCA will also be able to quantify the impact of buffer zones around the ponds on biodiversity and relate their effect to agricultural intensity and agricultural practices in the surroundings of the ponds. Using a stratified sampling design integrated in a context of the vast information offered by existing datasets, ORCA will evaluate potential effects of different scenarios of increasing organic agriculture on biodiversity at landscape scale. Based on our research findings, ORCA will develop a map of priority areas where a change in agriculture practice and land use intensity can have the largest impact on biodiversity and ecosystem services.ORCA will yield scientific insights on the importance of agricultural practice and intensity on pond water quality, biodiversity and functioning. Testing for a differential genetic impact of organic versus conventional farming practices can represent a breakthrough in the assessment of the impact of agricultural production methods on different levels of biological organisation. ORCA will also provide data and insights that are of direct relevance to policy makers and that can easily be translated into management and intervention plans. By providing solid scientific data on the environmental impact of organic versusconventional farming on pond ecosystems, ORCA will be of very direct relevance in developing overarching policy views on sustainable agriculture.

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