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Highlights Control lettuce showed higher levels of proline than lettuce from other treatments. Well water lettuce exhibited higher levels of phenols than that from other treatments. Lettuce with low-salinity shrimp effluent exhibit a quality comparable to the control.

An experiment was developed to simulate inland shrimp farming using diluted seawater (1.9 g L) containing 75 shrimps (Litopenaeus vannamei) per square meter during a growth cycle of 120 days. In this study, the environmental loads of copper and zinc were estimated and compared to anthropogenic sources and shrimp aquacultures in other locations. Both metals resulted primarily from feeding, which accounted for 91.8% of Cu and 97.0% of Zn. Concentrations of Cu (110.8 ± 11.8 μg g) and Zn (69.0 ± 0.7 μg g) measured in the harvested shrimp had higher Cu and lower Zn concentrations compared to those reported for farmed shrimp from Brazil and Mexico. Clearly, organic sludge was the main route of removal for both metals (Cu 46.2%; Zn 92.6%). The annual environmental loads estimated for inland shrimp aquaculture were 598 ± 74 g Cu ha and 5080 ± 328 g Zn ha.

The nitrite toxicity was estimated in juveniles of L. vannamei. The 24, 48, 72 and 96 h LC50 of nitrite‐N on juveniles were 8.1, 7.9, 6.8 and 5.7 mg L−1 at 0.6 g L−1; 14.4, 9.6 8.3 and 7.0 mg L−1 at 1.0 g L−1; 19.4, 15.4, 13.4 and 12.4 mg L−1 at 2.0 g L−1 of salinity respectively. The tolerance of juveniles to nitrite decreased at 96 h of exposure by 18.6% and 54.0%, when salinity declined from 1.0 to 0.6 g L−1 and from 2.0 to 0.6 g L−1 respectively. The safe concentrations at salinities of 0.6, 1.0 and 2.0 g L−1 were 0.28, 0.35 and 0.62 mg L−1 nitrite‐N respectively. The relationship between LC50 (mg L−1), salinity (S) (g L−1) and exposure time (T) (h) was LC50 = 8.4688 + 5.6764S – 0.0762T for salinities from 0.6 to 2.0 g L−1 and for exposure times from 24 to 96 h; the relationship between survival (%) and nitrite‐N concentration (C) for salinity of 0.6–2.0 g L−1, nitrite‐N concentrations of 0–40 mg L−1 and exposure times from 0 to 96 h was as follows: survival (%) = 0.8442 + 0.1909S – 0.0038T – 0.0277C + 0.0008ST + 0.0001CT–0.0029SC, and the tentative equation for predicting the 96‐h LC50 to salinities from 0.6 to 35 g L−1 in L. vannamei juveniles (3.9–4.4 g) was 96‐h LC50 = 0.2127 S2 + 1.558S + 5.9868. For nitrite toxicity, it is shown that a small change in salinity of waters from 2.0 to 0.6 g L−1 is more critical for L. vannamei than when wider differences in salinity occur in brackish and marine waters (15–35 g L−1).

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