Aplicação da modelagem como ferramenta de estudo para determinação do número de cercados de cultivo do camarão Farfantepenaeus paulensis em baías rasas no estuário da Lagoa dos Patos, RS.

by Milach, Ângela Machado

Abstract (Summary)
In aquaculture, nitrogen fluxes may be an important indicator of interaction between the cultures system and the aquatic ecosystem. The understanding of these interactions comprehends the knowledge of the ecological processes and the managing strategies of the culture. Modeling is used in this work as a tool to indicate possible effects of this activity.When applied to aquaculture this tool may help improving the understanding of the processes involved in the activity. Moreover, it may also allow to momentarily stratifying the causal relationships between the variables, coming into existence as an artificial world and thus reflecting the vision of the real world. A mathematical model was built to createscenarios to the culture of pink shrimp Farfantepenaeus paulensis in water column nitrogen flux based pens. This model was used to estimate the release of nitrogen by the pens and the maximum number of these production units that the bays Corea and Porto do Rei on the estuary of the Lagoa dos Patos, RS, could hold without compromising the water quality and the system sustainability. For the construction of the numeric model, the software STELLATM v.9.01 was used and the model was run at the time step 1 (DT). For thecalibration of the model, we used literature data from the shrimps Litopenaeus vanammei and F. paulensis. Furthermore field data were collected such as temperature, salinity, waterflow dynamics and the nitrogen concentrations come from historical data. The model was validated through monitoring the shrimp cultures in pens in Ilha dos Marinheiros, Rio Grande, RS. The values of the environmental variables were found to be suitable for the successful completion of the production cycle. Through the simulations, the modelpredictions were compared to the culture data. The correlation value between the predicted and observed data was found to be 0.99. Many scenarios were then built to supply the number of pens to the bays according to the different situations presented. Simulations carried out by the model indicated that it is possible to insert up to 509 pens in the Corea bay and 683 in Porto do Rei according to the chosen values. However, the pens should be settled in the aquatic environment based on a more conservative scenario taking into account the precaution principle. This way, the best suggestion would be putting the pens in a 0,01 m/s water flow dynamics and 40% of the net influence and its excess fouling to enable the collocation of 29 pens in Corea an 39 in Porto do Rei. The results of the model indicate based on its simulations that the pen shrimp culture would not be a problem to the protected bays, provided that the number of units do not out number the capacity of assimilation of the environment in what refers to the nitrogen liberation in the water column. The model and their simulations were valuable and promising tools to predict analysis based on the nitrogen. This approach may enlarge our comprehension about thebehavior and the interactions of the culture of F. paulensis and the aquatic environment. In this way, the present work may be a basis to future studies which aim at estimating thesupporting capacity of the water bodies in which the aquaculture is practiced.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Luis Henrique da Silva Poersch; Milton Lafourcade Asmus; Ronaldo Olivera Cavalli; Wilson Francisco Britto Wasielesky Junior

School:Fundação Universidade Federal do Rio Grande

School Location:Brazil

Source Type:Master's Thesis

Keywords:modeling nitrogen shrimp culture coastal management


Date of Publication:04/23/2007

© 2009 All Rights Reserved.