Acclimation of Rhizophora mangle to petroleum: Morphological responses and implications for phytoremediation in...

Despite the recognized potential of mangrove species for phytoremediation, there remains a limited understanding of the morphological responses of mangrove seedlings to petroleum exposure. This study investigated the acclimation of Rhizophora mangle propagules to different petroleum concentrations (v/w): 0 %, 0.5 %, 1.0 %, 2.0 %, using crude oil from Campos Basin, Brazil. Seedlings were cultivated under controlled laboratory conditions for 180 days to assess changes in morphology, nutrient dynamics, and petroleum hydrocarbons in mangrove sediments. Sediment and plant samples were evaluated at 0 and 180 days. Seedlings exposed to 1.0 % crude oil exhibited the highest total biomass production (12.39 ± 0.06 g), significantly higher than the control with 0 % (8.61 ± 0.61 g, p < 0.05). The 0.5 % (11.13 ± 0.35 g) and 2.0 % (10.62 ± 0.09 g) treatments also had significantly greater biomass than the control, but did not differ from each other (p > 0.05). Total petroleum hydrocarbons decreased significantly after 180 days, with maximum reductions of 2685 mg kg^-1 in the 2.0 % treatment, 1843 mg kg^-1 in the 1.0 % treatment and 1017 mg kg^-1 in the 0.5 % treatment. Higher initial petroleum concentrations were positively correlated (ρ ≥ 0.6) with total dry mass production, root dry mass, and Dickson Quality Index. The acclimation experiment demonstrated R. mangle's resilience and capacity to survive and grow at higher petroleum concentrations (1 % and 2 %), effectively removing petroleum hydrocarbons during acclimation. Therefore, acclimation is recommended as a crucial preparatory step before field transplantation, enhancing both plant robustness and potential phytoremediation effectiveness in contaminated mangrove sediments.