The performance of ecological cage aquaculture of pejerrey Odontesthes bonariensis in Pampean lakes under two different hydrological scenarios

Abstract

Ecological aquaculture promotes the development of sustainable farming systems, focusing on a wide range of ecosystem elements. The ecological aquaculture of the zooplanktivorous pejerrey (Odontesthes bonariensis) in floating cages in Pampean shallow lakes (Argentina) needs to be carried out considering the hydrological and chemical variations as modulators of plankton community and consequently of the pejerrey yield. To assess its performance in lakes with contrasting hydrological regimes, an experiment was carried out in two water bodies: La Salada de Monasterio Lake (Mon), an endorheic environment, and San Lorenzo Lake (Lor), connected to several lakes and the Salado River. During the experiment, regional rainfall generated high hydrological variability in Lor Lake changing its status of unconnected lake to a run-of-the-river lake. High standard deviation in Chlorophyll-a values in Lor indicated the significant effects of hydrological instability on the plankton community. Microcrustaceans abundance and biomass were higher in Mon, and almost disappeared in Lor when it turns into run-of-the-river. The final fish growth and survival were significantly higher in Mon, endorsing the importance of zooplankton of high nutritional quality and hydrological, physical–chemical and biological stability. The results indicate that productive and stable environments with a sustained offer of natural food are better for the zooplanktivorous fish production. Connectivity with other water bodies and hydrological dependence on rainfall regimes have defining effects on phytoplankton, zooplankton and fish production, thus emerging as key factors to be considered for achieving better results in the ecological aquaculture implementation.