Emission and absorption of greenhouse gases generated from marine shrimp production (Litopeneaus vannamei) in high salinity

摘要

This study aimed at identifying and quantifying greenhouse gas fluxes (CH4, CO2, and N2O) in Litopenaeus vannamei shrimp nurseries submitted to different culturing conditions. The experiment was carried out with a completely randomized design, with two treatments and four simultaneous replicates, totaling eight experimental units. Two management systems were tested. The first one (M1) used a stocking density of 92 shrimp/m(2) and fertilizer maintenance through the application of calcium nitrate and molasses. The second one (M2) used a stocking density of 14 shrimp/m(2) without fertilizer maintenance. Feeding in both treatments consisted in supplying ration through the volley method. The results showed that there were variations in the pattern of gas emission in both treatments and in the concentrations of the evaluated gases. The recorded mean values of total gas flux were -314.87 mg/m(2)/day of CH4, -3773.51 mg/m(2)/day of CO2, and 2.47 mg/m(2)/day of N2O in M1; and 653.89 mg/m(2)/day of CH4, 497.52 mg/m(2)/day of CO2, and 25.59 mg/m(2)/day of N2O in M2. The results obtained in this study suggest that environmental and management conditions interfere with the cultivation system, which acts as either a source or drainage of gases. These emissions from shrimp farming are potentially critical, mainly due to (NO)-O-2 emissions, when compared to emissions from other production systems. Conversely, the cultivation of L. vannamei, particularly when carried out with the use of organic fertilizers such as molasses, presented a potential absorption of gases such as CH4 and CO2. The greatest fluxes of gases occurred at the beginning of the cultivation due to the initial fertilization. In addition, the contribution of molasses probably favored denitrification and increased natural productivity, which may have contributed to a lower emission of these gases compared to emissions of other systems where molasses was not used. (C) 2019 Elsevier Ltd. All rights reserved.