SALINITY IMPACT ON GROWTH PARAMETERS OF EICHHORNIA CRASSIPES

Urban growth necessitates innovative strategies to integrate infrastructure development with the preservation of aquatic ecosystems, particularly in sensitive wetlands, aligning with Sustainable Development Goals (SDG) 6 (Clean Water and Sanitation) and 14 (Life Below Water) by promoting sustainable water management and marine ecosystem protection. Phytoremediation, a nature-based solution employing plants such as Eichhornia crassipes (water hyacinth), may offers a promising approach by combining pollutant removal with ecosystem regeneration. However, in some situations, its effectiveness in phytoremediation may be affected, depending on the pollutant and the environmental conditions for phytoremediation, as being an aquatic plant, it may not withstand more saline environments. As a result, in this study, the acclimatization and growth performance of Eichhornia crassipes were evaluated under progressively increasing salinity conditions to assess its potential for use in constructed wetland systems proposed for Guanabara Bay in Rio de Janeiro. Ten specimens were exposed to two conditions: Control (T1), with water from the supply system, and Brackish Water (T2), with gradual addition of sodium chloride. Salinity was increased every 14 days, from 0.2 g/L, 1.1 g/L, 2.3 g/L, until reaching the concentration of 23 g/L or until the plants died. Growth parameters were monitored. At 14 days, the results suggested that the initial exposure to low salt concentrations exerted a negative effect on aerenchyma diameter, indicating that the first contact with salinity adversely affected this tissue. By 28 days, the species appeared to acclimate to the initial salt exposure, exhibiting growth compatible with the imposed conditions for that parameter. However, a significant 38.4% reduction in leaf number was observed between the control treatment and the 1.1 g/L NaCl treatment. Progressive salt accumulation culminated in total mortality by day 42, with Eichhornia crassipes unable to tolerate concentrations exceeding 10% of the target (2.3 g/L). These results demonstrate the species’ capacity for short-term acclimatization to low salinity (≤1% NaCl), sustaining growth for 28 days, but highlight its sensitivity to moderate salinity (>1.1 g/L), which limits applicability in saline environments. The findings contribute to research on developing salt-tolerant species and improving coastal wetland restoration, supporting the 2030 Agenda’s goals for water management and ecosystem conservation.