Oil Pollution Effects on Nematodes in Mangrove Sediment: A Microcosm Study
Abstract The effects of oil pollution on meiobenthic nematode assemblages in a mangrove sediment were investigated. Microcosms comprised 350 ml plastic jars that were filled with 200 g mangrove sediment and subjected to oiling, with or without addition of fertiliser. In the oiled treatments, 15 ml of Bunker fuel oil 180 and 5 ml/L fertiliser (N: P: K: 3: 2: 5) were added to the soil. After four weeks, nematodes were extracted and identified. In the unfertilised oiled treatment, nematode abundance and species richness were significantly reduced by 87% and 53%, respectively, compared to the control. In the fertilised oiled treatment, nematode abundance and species richness increased by 56% and 30% respectively. The eight taxa present in the control but absent in the oiled treatments (Monhystera, Prodesmodora, Plectus, Rhabditis, Koerneria, Rotylenchus, Tobrilus, and Fictor) were characterised as oil-intolerant. The seven taxa present in the oiled treatments (Monhystera, Ethmolaimus, Panagrolaimus, Camacolaimus, Hemicycliophora typica, and H. ripa and a species of the family Xyalidae) were characterised as oil-tolerant and resilient. In all treatments, the dominant species was Ethmolaimus. Taxa such as Rhabditis, Koerneria and Rotylenchus survived oiling, due to the addition of fertiliser. Fertilizer amendment favoured survival of Rhabditis, Koerneria and Rotylenchus and increased reproduction in Camacolaimus.