The rapid growth of aquaculture has been accompanied by increased environmental impacts. This development must take place in a sustainable manner, with rational use of resources and low release of pollutants. Demonstration of greenhouse gas emissions in aquaculture systems can contribute to this process. The objective of this work was to measure the greenhouse gas exchange in different production systems of yellow tail lambari (Astyanax lacustris) and assess if the insertion of species with complementary ecological niches alters the gas exchange with the external environment.
An experiment was developed at UNESP - Aquaculture Center, in Jaboticabal - SP, Brazil (21º15'22''S e 48º18'48''O). Twelve natural bottom ponds with area of ~0.015 ha and depth of 1 m were used. The experimental design was completely randomized, consisting of three treatments and four replications: monoculture of yellow tail lambari (M-L), integrated cultivation of yellow tail lambari and Amazon shrimp (Macrobrachium amazonicum) (I-LS) and integrated cultivation of yellow tail lambari, Amazon shrimp and curimbata (Prochilodus lineatus) (I-LSC). Lambaris were fed with commercial diet with 32 % of crude protein and granules of 2.5 mm twice daily. The shrimp and curimbata were not fed and benefited from the waste produced in the system. The experiment ended 60th day. This was the time required for lambari and shrimp to reach the size of 7 and 6 cm respectively for marketing as live bait. Curimbata was marketed as juvenile. Gaseous samples were collected from the ponds and then analyzed by chromatography (GC2014 - Shimadzu). The greenhouse gas burden was determined by the sum of released (+) and absorbed (-) CO2 equivalents (kg/ha CO2eq).
The mean ± standard deviation data obtained for gas movement between treatments and atmosphere were: M-L = -2,216 ± 28,223, I-LS = 24,947 ± 78,565 and I-LSC = 81,360 ± 72,018. No statistical differences, and large variations between replicates of the same treatment were observed. These results indicate that other factors besides the combination of the cultivated species are acting in the formation of these gases and their exchange with the atmosphere. These processes may be driven by the action of the microorganisms enrolled with decomposition, nitrification, and denitrification
Current data indicate that the monoculture and the integrated cultures performed in this work do not alter the greenhouse gases exchange with atmosphere.