FIELD AND LABORATORY STUDIES ON THE TOXICITIES OF OILS TO MANGROVES

Abstract

ABSTRACT Field and laboratory studies on the toxicities to mangroves and associated biota of undispersed and chemically dispersed oils are being conducted in Malaysia. Results to date show the following: Most of the oils, both undispersed and dispersed, affect mainly the young Avicennia with heights less than 180 cm in the field. Toxicity to older saplings is less acute. There appear to be few differences in the impact of oils on Avicennia saplings due to tide. When the toxicities of dispersed and undispersed Arab light crude were compared, the following observations were made: most tests show either no significant differences between undispersed and dispersed oils or that undispersed crude is more toxic than dispersed crude, while a small percent show that dispersed crude is more toxic than undispersed crude. When the toxicities of oil types, namely bunker C, Malaysian crude, and Arab light crude, to the saplings were compared, it was found that bunker C was the least toxic, followed first by the Arab light and then the Malaysian crudes. Growth of the commercially important tiger prawn introduced into a flowthrough system four months after an oil spill appeared normal. These animals compared well with those reared in oil-free tanks and those cultured in situ in ponds. Most of the mortality of saplings was probably due to passive surface deposition as well as active uptake. The main accumulation site was leaf tissue as evidenced by GC analysis.