Recolonisation of mine tailing by meiofauna in mesocosm and microcosm experiments

The Batu Hijau copper/gold mine in Sumbawa, Indonesia processes ore at approximately 130,000 tpd and discharges tailing via a submarine pipeline to depths below 3000 m at the base of a submarine canyon. The study investigated recolonisation of tailing by meiofauna and its dependence on subsequent accumulation of natural sediment. Microcosm and mesocosm scale experiments were carried out using two tailing and two control samples, the latter comprising defaunated and unaffected natural sediment. All test materials were similar in physical and chemical respects, except for the higher copper concentration in the tailing. The abundances of meiofauna colonising defaunated controls and both tailing samples increased from zero to levels statistically indistinguishable from natural unaffected controls after 97 and 203 days. Colonisation was well established in tailing from freshly mined ore after 40 days, and in oxidized tailing from stockpiled ore after 65 days, and was not dependent on settled natural material.