Effects of an experimental oil spill (bunker) on seedling survival and growth rate of Laguncularia racemosa (Combretaceae)

The effects of bunker oil on survival and growth rate of Laguncularia racemosa were tested using 60 seedlings planted in small plastic bags (experimental unit). One of the six treatments was randomly assigned to each bag: 0 mL (control), 10 mL, 20 mL, 30 mL, 40 mL e 50 mL of bunker oil spilled in each bag. The experiment was monitored weekly for 20 weeks. The results were analyzed by repeated measure ANOVA and linear regression. In the first seven weeks, we observed chlorosis, loss of leafs and death rate significantly superior to plants of all treatments compared to the control group. Persistent effects like reduction of stem growth and leaf production was proportional to the initial oil concentration. The plants from control and 10 mL treatments were significantly superior to all remaining treatments in height, leaf number and healthy level. Results indicated that L. racemosa seedlings suffer both lethal and sublethal effects from exposition to bunker oil exposure.