Establishing limits to aquaculture in a protected coastal lagoon: Impact of Farfantepenaeus paulensis pens on water quality, sediment and benthic biota Lorena Rodríguez-Gallego a, ⁎ , Erika Meerhoff a , Luis Poersch c , Luis Aubriot a , Carlos Fagetti b , Javier Vitancurt b , Daniel Conde a a Sección Limnología, Facultad de Ciencias, Universidad de la República, Uruguay (UdelaR), Iguá 4225, Montevideo, Uruguay CP 11400 b PROBIDES, Ruta 9 km 209, Rocha, Uruguay c Luis Poersch — Fundação Universidade Federal do Rio Grande\ (FURG), Estação Marinha de Aquacultura. CP 474, Rio Grande, RS, Brazil Received 24 January 2007; received in revised form 5 December 2007; accepted 6 December 2007 Abstract Aquaculture is perceived by governments and international agencies as an economic alternative for poor communities in developing countries. Nevertheless, aquaculture must address environmental issues as well as economic and social aspects to achieve a sustainable development. Aquaculture with native species under semi-intensive conditions is a sustainable production alternative that minimizes the impact on aquatic ecosystems. An aquaculture pilot project with pink shrimp (Farfantepenaeus paulensis) was tested in a protected lagoon in Uruguay (Laguna de Rocha). Shrimp were reared in pen enclosures within their native habitat, where natural currents drive water renewal, and the natural food supply was supplemented with commercial food. The aim of this study was to evaluate the impact of F. paulensis aquaculture on the water and sediment quality and the benthic community, and to estimate the maximum number of pen enclosures that Laguna de Rocha can sustain while maintaining the minimal environmental impact. A Before, After, Control Impact (BACI) sampling design was followed and the results of abiotic and biological variables were compared between treatment site (control, pens, and two areas at 15 and 50 m from the pens) and timing (before shrimp addition, during culture and after harvest), through ANOVA. The most significant impact was found inside the pens, where ammonium levels increased and benthos species richness and abundance decreased. A nitrogen-based-model was used to estimate the maximum number of pens in relation to the minimal impact on the ecosystem. Simulation indicated that up to 13 pens could be installed in the southern area of Laguna de Rocha without increasing the usual concentration of total nitrogen in other areas of the lagoon. The BACI design, the statistical analysis and the modeling tools proved to be effective, simple and low cost instruments to assess the environmental impact in a protected area. © 2008 Elsevier B.V. All rights reserved. Keywords: Environmental impact assessment; Pink shrimp; Sustainable aquaculture 1. Introduction Presently, management efforts in protected areas admit the feasible coexistence of economic activities and the conservation of biodiversity (Brockington et al., 2006; Wilkie et al., 2006). Native shrimp aquaculture under semi-intensive conditions (i.e. pen enclosures or culture pens) could represent a sustainable production alternative that improves the welfare of human communities in conservation areas, minimizing the environ- mental impact of more intensive systems and avoiding the introduction of potentially invasive species. In pen enclosures, shrimp are reared in their indigenous habitat, shallow estuaries or brackish lagoons, where natural currents drive water renewal. The natural food supply, e.g. fisheries leftovers and benthic organisms naturally occurring inside the enclosures, is balanced with commercial food, particularly during early stages of development (Soares et al., 2004, Wasielesky et al., 2004). Available online at www.sciencedirect.com Aquaculture 277 (2008) 30 – 38 www.elsevier.com/locate/aqua-online ⁎ Corresponding author. Tel.: +598 2 5258618int7148. E-mail address: dunachirca@gmail.com (L. Rodríguez-Gallego). 0044-8486/$ - see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2007.12.003