The aim of this study was to determine acute toxicity in the post larvae of the white shrimp Litopenaeus vannamei after 96 h of exposure to dissolved arsenic under three different temperatures and salinity conditions. Recent reports have shown an increase in the presence of this metalloid in coastal waters, estuaries, and lagoons along the Mexican coast. The white shrimp stands out for its adaptability to temperature and salinity changes and for being the main product for many commercial fisheries; it has the highest volume of oceanic capture and production in Mexican shrimp farms. Lethal concentrations (LC50-96 h) were obtained at nine different combinations (3 × 3 combinations in total) of temperature (20, 25, and 30 °C) and salinity (17, 25, and 33) showing mean LC50-96 h values (±standard error) of 9.13 ± 0.76, 9.17 ± 0.56, and 6.23 ± 0.57 mgAs L(-1)(at 20 °C and 17, 25, and 33 salinity); 12.29 ± 2.09, 8.70 ± 0.82, and 8.03 ± 0.59 mgAs L(-1) (at 25 °C and 17, 25, and 33 salinity); and 7.84 ± 1.30, 8.49 ± 1.40, and 7.54 ± 0.51 mgAs L(-1) (at 30 °C and 17, 25, and 33 salinity), respectively. No significant differences were observed for the optimal temperature and isosmotic point of maintenance (25 °C-S 25) for the species, with respect to the other experimental conditions tested, except for at 20 °C-S 33, which was the most toxic. Toxicity under 20 °C-S 33 conditions was also higher than 25 °C-S 17 and 20 °C (S 17 or 25). The least toxic condition was 25 °C-S 17. All this suggests that the toxic effect of arsenic is not affected by temperature changes; it depends on the osmoregulatory pattern developed by the shrimp, either hyperosmotic at low salinity or hiposmotic at high salinity, as observed at least on the extreme salinity conditions here tested (17 and 33). However, further studies testing salinities near the isosmotic point (between 20 and 30 salinities) are needed to clarify these mechanisms.

Coronaviruses are pathogens recognized for having an animal origin, commonly associated with terrestrial environments. However, in a few cases, there are reports of their presence in aquatic organisms like fish, frogs, waterfowl, and marine mammals. None of these cases has led to human health effects when contact with these infected organisms has taken place, whether they were alive or dead. Aquatic birds seem to be the main group carrying and circulating these types of viruses among healthy bird populations. Although the route of infection for COVID-19 by water or aquatic organisms has not yet been observed in the wild, the relevance of its study is highlighted because there are cases of other viral infections known to have been transferred to humans by aquatic biota. It is encouraging to know that aquatic species, such as fish, marine mammals, and amphibians, show very few coronavirus cases. Some other aquatic animals may also be a possible source of cure or treatment against, as some evidence with algae and aquatic invertebrates suggest.