Effects of nitrate concentration within legal limits on natural assemblages of plankton communities
Del Arco, Ana I.; Guerrero, Francisco; Jiménez-Gómez, Francisco; Parra, Gema
published: Sep 1, 2015
ArtNo. ESP141018701003, Price: 29.00 €
Intensive agriculture is the leading perturbation on freshwater ecosystems due to the agrochemical inputs that compromise biodiversity and ecosystem services. The importance of agriculture cannot be neglected nor the fact that freshwater biodiversity is being depleted worldwide owing to anthropogenic pressures. Therefore, a balance between economic and environmental values must be achieved. The present experiment explores the EEC legal limits on the concentration of agrochemicals (nitrate used as fertilizer) and investigates if even when assuming safe limits there are impacts in freshwater ecosystems. The objective is to assess direct and indirect effects of legal toxicant concentrations on the ecological integrity of plankton communities. This information seeks to assist policy makers with more ecological relevant results to establish legal thresholds that neither overestimates nor underestimates environmental risks. Microcosm experiments were set up outdoors with local assemblages of plankton for 8 weeks. Two nitrate treatments were established: (1) a low treatment (L) of 25 mg l–1 of nitrate, and (2) a high treatment (H) of 50 mg l–1 of nitrate. In conclusion, firstly, we detected that zooplankton taxa shifted from a cladocera-dominated to a copepod-dominated community as an indirect response to phytoplankton decrease. Secondly, both L and H treatments had a negative effect on the plankton community in spite of being within assumed safe legal limits.