The effects of Produced Formation Water (PFW) on coral and isolated symbiotic dinoflagellates of coral

Abstract

There is concern of the effects of Produced Formation Water (PFW, an effluent of the offshore oil and gas industry) on temperate/tropical marine organisms of the North West Shelf (NWS) of Australia. Little is known of the effects of PFW on tropical marine organisms, especially keystone species. Exposing the coral Plesiastrea versipora to a range (3–50% v/v) of PFW from Harriet A oil platform resulted in a reduction in photochemical efficiency of the symbiotic dinoflagellate algae in hospite (in the coral tissues), assessed as a decrease in the ratio of variable fluorescence (F_v) to maximal fluorescence (F_m) measured using chlorophyll fluorescence techniques. Significant differences were noted at PFW concentrations >12.5% (v/v). In corals where F_v/F_m was significantly lowered by PFW exposure, significant discolouration of the tissues occurred in a subsequent 4-day observation period. The discolouration (coral bleaching) was caused by a loss of the symbiotic dinoflagellates from the tissues, a known sublethal stress response of corals. PFW caused a significant decrease in F_v/F_m in symbiotic dinoflagellates freshly isolated from the coral Heliofungia actiniformis at 6.25% PFW, slightly lower than the studies in hospite. Corals exposed to lower PFW concentrations (range 0.1%–10% PFW v/v) for longer periods (8 days) showed no decrease in F_v/F_m, discolouration, loss of symbiotic dinoflagellates or changes in gross photosynthesis or respiration (measured using O₂ exchange techniques). The study demonstrates minor toxicity of PFW from Harriet A oil platform to corals and their symbiotic algae.