Abstract:
Aquatic plants in agricultural landscapes play a vital role in maintaining the ecological integrity within the aquatic systems while
facing an array of disturbances. Among them, information on herbicide exposure on non-target aquatic plants is scarce. The
present study was designed to fill this information gap by detecting the impacts of 2-methyl-4-chlorophenoxyacetic acid (MCPA)
on Hydrilla verticillata using morpho-anatomical and physiological biomarkers and assessing the environmental risk of MCPA
to the non-target environment. H. verticillata was exposed to different MCPA concentrations (10, 100, 500, 1000 μg/L) and
control (0 μg/L) for 7 days. At the end of the experiment, plant growth, pigments, H2O2 content, peroxidase activity (POD) and
plant anatomy were compared. The environmental risk was assessed using predicted environmental concentration/predicted no
effect concentration (PEC:PNEC) ratio, hazard quotient (HQ) and hazard index (HI). Control plants exhibited the highest growth,
and a growth decline was noted in parallel to MCPA exposure, where a similar trend was detected for the plant pigment contents.
MCPA induced chlorosis and oxidative stress in H. verticillata. Risk analysis detected high values for PEC:PNEC ratios (3–9),
HQ (1.92–5.79) and HI (28.15). MCPA-exposed H. verticillata could recover once those plants received natural conditions.
Overall, present findings showed the negative impacts of MCPA on non-target aquatic plant H. verticillata. These findings will be
useful to clarify the interaction between agrochemicals and non-target aquatic plants. Such information would benefit to decide
the criteria in aquatic ecosystem management.