Jorge Pablo Castello

Perspectivas para o desenvolvimento dos cultivos de camarões marinhos no estuário da Lagoa dos Patos, RS

Shrimp production in Brazil has presented a significant increase in the last few years, especially in the northeastern region. Although climatic conditions in southern Brazil do not allow year-round production, considerable investments have been made in the region. In the estuarine area of Patos Lagoon, the culture of the native Farfantepenaeus paulensis in cages and pen enclosures, and of Litopenaeus vannamei in earthen ponds are being developed as new activities that will certainly produce social and economical development to the region. Nevertheless, the implantation of shrimp farming without proper ordination and control may generate serious environmental problems. The present paper presents an overview of the environmental characteristics of the area and describes the farming systems currently adopted. Furthermore, the main challenges faced by this new activity, such as the discussion of a legislation adapted to local conditions, and the definition of areas appropriate for farming are presented. Finally, the sustainable development of shrimp farming is discussed under social, economical and environmental perspectives.

Dealing with temporal variation and different life stages of whitemouth croaker Micropogonias furnieri (Actinopterygii, Sciaenidae) in species distribution modeling to improve essential estuarine fish habitat identification

Understanding the habitat usage of a species is essential to assessing the impacts of human activities, conservation efforts, and management issues on that species. Whitemouth croaker, an important species in the artisanal fishery market, inhabits different habitats of the Patos Lagoon estuary year-round based on the stage of its life cycle. Our aim was to test the hypothesis that habitat preferences and changes in abundance during the life cycle influence the model outcomes in the study of species distribution. Additionally, we evaluated whether incorporating additional life stages within the model affected the outcome of what comprised the essential fish habitat. Our results showed that the model’s outcome was affected when temporal variability and additional life stages were considered. We suggest that variability in abundance and habitat preferences at different developmental stages must be considered when identifying essential fish habitat of species with complex life cycles, such as whitemouth croaker. Understanding these changes could improve conservation and management outcomes.

The Challenge of Sustainable Aquaculture: Effects on the Environment of the Patos Lagoon Estuary

Abstract Over the last ten years, catches of the pink shrimp Farfantepenaeus paulensis by artisanal fishermen in the Patos Lagoon Estuary (southern Brazil) have been decreasing. This has created economic and social problems for approximately 3500 families, who rely on this activity as their main source of income. In an attempt to solve these problems, the Mariculture Laboratory of the University of Rio Grande (FURG) has developed a technological package for the pen culture of this species in the estuarine area. This culture system requires low investment, is easy to manage and allows fishermen to continue their normal activities. This study evaluates the influences that this culture may have on the macrobenthic communities surrounding the enclosures. The experiment was carried out around a 0.3 ha pen placed in the estuarine area adjacent to Marinheiros Island (Rio Grande county). This area has a central channel over 5 meters deep and shallow areas less than 1.5 meters deep near the shore, where the pen was installed. Two linear transects were carried out in opposite directions parallel to the shoreline, starting from the edge of the pen. Monthly water and sediment samples were collected 5, 15, 30 and 100 m from the pen to evaluate oxygen consumption, chlorophyll-a, total phosphorus and total nitrogen concentrations. Characterization of the macrobenthic community revealed the presence of Laeonereis acuta, Nephtys fluviatilis, Neanthes sp., Kalliapseudes schubartii, Callinectes sapidus, Erodona mactroides, Heleobia australis, Heteromastus similis and isopods. Significant differences in the diversity and abundance of the species were detected between the samples, especially at the closest point to the pen, where more H. similis specimens were found. No significant differences in oxygen consumption, total nitrogen or total phosphorus concentrations were found between the sampled points. These results demonstrate that this kind of culture system does not influence water quality in the surrounding area. The higher abundance of H. similis near the pen (1 m) demonstrated a very limited impact on the macrobenthic community. Organic matter accumulation zones created by the presence of the pen might favor the presence of H. similis, which is a deposit feeder. This result could become more significant if the culture conditions are intensified or more pens are installed.

Use of a mathematical model to estimate the impact of shrimp pen culture at Patos Lagoon estuary, Brazil

Ecological modeling has been used as a tool to estimate potential impacts caused by aquaculture to the surrounding environment. In this work, a mathematical model was applied to estimate the maximum amount of pink shrimp (Farfantepenaeus paulensis) culture units (3,100m2 pen enclosures) that could be installed at two shallow estuarine bays of Patos Lagoon (known as Coreia and Porto do Rei) with no significant effects on either water quality or viability of the culture system. To calibrate the model, information about the culture of Litopenaeus vannamei and F. paulensis as well as field data (influence of netting material, water current speed and nitrogen concentrations) were used. Under a bad scenario (water current velocity of 0.01m s-1 and a mesh clogging effect of 40%), it would be possible to install up to 29 pens at the Coreia bay, and 39 pens at the Porto do Rei bay. Results indicate that the model was useful in determining the maximum number of culture units that could be installed at these bays, and thus have the potential to become an important tool in the definition of environmental management strategies in relation to aquaculture development.