Planthouse experiments to determine the effects of oil and dispersed oil treatments on mangrove seedlings

In early 1996, experimental tidal tank systems were set up in the planthouse at the Australian Institute of Marine Science (AIMS) near Townsville, Queensland, to investigate the effects of a range of oils and dispersants on mangrove seedlings. Four species groupings of mangroves were used: Aegiceras corniculatum; Avicennia marina var. eucalyptifolia; mixed Ceriops species (Ceriops australis, Ceriops decandra and Ceriops tagal); and Rhizophora stylosa. Seedlings in two distinct age classes were used (approximately 18 months old and greater than 24 months old) and were planted in either sand or fine mud sediments. In May-June 1997, seedlings were treated with various combinations of preweathered oil and dispersant. The oils used were Bunker C fuel, Arabian Light crude, Gippsland Light crude, Thevenard crude, and Woodside condensate. The dispersants used were, Corexit 9527, Corexit 9580, BP-AB and Shell VDC. Combinations of these oils and dispersants were selected in consultation with project advisors in the APPEA Research Working Group.Seedling condition and growth were monitored until November 1997. Growth measurements included stem height, stem diameter and leaf production rate. Effects were measured by percent mortality of the seedlings. Leaves were collected from the seedlings and analysed to identify any notable changes in the amounts of key elements such as sodium, potassium or calcium.
This research was a component of the project "Fate and effects of oil and dispersed oil on mangrove ecosystems in Australia" and was undertaken to provide an assessment of immediate and short term impacts of oil spills, and to rank toxic effects.The objectives of this experiment were:1. to assess the effects on common Australian mangrove species of a range of oils and dispersed oils most likely to be released in Australian waters. 2. to better understand what caused plants to die from oiling.