Potential role of meiofauna in bioremediation: results from a microcosm experiment

Meiofauna can act as remediation organisms by stimulating microphytobenthos, sequestering carbon dioxide, and degrading organic debris. Sediments from two basins in Lake Mariut, Egypt, which had undergone multiple rounds of restoration, were used in microcosm experiments to assess the role of meiofauna in organic matter degradation. Treatments included sediments with and without fauna, and four chlorophyll-a additions (0.002, 0.035, and 0.005 mg/ml, with 0.000 mg/ml as the reference). Meiofauna, chlorophyll-a, and organic matter were measured over two 8-month periods in 2014. Most treatments exhibited a rapid loss of organic matter, reducing organic content by two to eight times by study end. By the end, meiofaunal populations increased one- to 13-fold in microcosms with algae additions of 0.035 and 0.005 mg/ml chlorophyll-a in the Main and Northwest basins but had no change in those with 0.002 and zero mg/ml. Meiofauna abundance rose with rising temperature and oxygen levels, while organic matter declined. There was no correlation between chlorophyll-a levels and meiofauna abundance indicating that meiofauna likely play a role in the aerobic decomposition of organic matter at high temperatures. The meiofauna contribute to the diversity of ecosystems and have a potential role in ecosystem processes; therefore, conservation efforts should also include meiofauna.