EFFECTS OF OIL ON MANGROVE SEEDLINGS GROWN UNDER DIFFERENT ENVIRONMENTAL-CONDITIONS

The effects of oil treatments (one-time addition of 120 ml per plant a nd weekly addition of 15 ml per plant) and environmental conditions at time of oiling (air conditioned laboratory/diffuse light vs hot, dire ct sunlight) on the survival and growth of Rhizophora mangle and Avice nnia germinans seedlings were examined. No oiled A. germinans survived longer than a few weeks. Both one-time and weekly oiling depressed su rvival, stem growth, leaf production and maximum leaf size in R. mangl e. Significant interaction terms between oil treatment and environment al conditions occurred later (50 and 59 weeks) for R. mangle stem grow th and earlier (21 and 23 weeks) for leaf production. Relative to othe r treatment combinations, R. mangle mortality was greatest and growth lowest in the combination of onetime oiling under hot, bright outdoor conditions. Results indicate that synergistic interactions between oil effects and environmental conditions may contribute to the wide range of effects reported in the literature in studies of oil contamination of mangroves.