Due to the rising demand for food, increasing intensive livestock production contributes significantly to the anthropogenic loading of the biosphere. Poultry and fish from intensive operations are a primary source for global human food consumption, and the contribution to air and water emissions. The environment can act as a sink of emissions by using it the capacity for diluting pollutants. In this way, the "support area" derived from the renewable resources supplied by region was quantified for both enterprises regarding emergy. Results suggest that poultry production seems to be a thousand times more "eco-efficient" than aquaculture as well as presenting a lower support area. Accounting for the environmental services required to dilute emissions is shown to be a necessary procedure towards the proper evaluation of long-term sustainability and quantification of externalities.