Evaluation of respiration rates and mechanical aeration requirements in semi-intensive shrimp Litopenaeus vannamei culture ponds.

摘要

To increase the efficiency of dissolved oxygen management in semi-intensive shrimp Litopenaeus vannamei culture in Santa Catarina, Southern Brazil, the present study aimed at characterizing the respiration rates in three ponds (1.2 ha) and estimating the approximate calculation of the actual aeration requirements (HP ha-1) during 9 weeks of a production cycle (February-April, 2003). The sediment respiration rate (SR) and the water column respiration rate (WR) were characterized using the column method, by which ponds initial and final dissolved oxygen concentrations (surface and bottom) were determined, then incubated for 24 h in PVC tubes fixed in the experimental units. SR was significantly higher than WR, except for the third week of culture. SR showed a wide variation (0.07-0.16 g m-2 h-1) during the experiment and the highest respiration rate occurred in the last week of culture. Sediment analyses were done in the beginning and in the end of the experiment, and they also showed differences in the concentration of organic matter (3.4 and 6.3%). On the other hand, WR varied little (0.04-0.07 g m-2 h-1) and presented a pattern similar to photosynthesis, determined by the dark and clear bottles method. Temporal aeration requirements were characterized from SR and WR data, and also from the shrimp mean respiration rate described in the literature. More aeration was required in the last week of culture (2.62+or-0.06 HP ha-1). However, only the aeration calculated for the first week was close to that used in the Yakult Experiment Farm (UFSC), where the study was carried out (1.08 and 1.70 HP ha-1, respectively). All aeration estimates from this study were below those used in cultures at UFSC, especially after the third week of experiment..