Three field studies were conducted to assess the impact of oil industry activities on subtidal meiobenthos. Meiobenthos samples taken during a routine survey of a North Sea drilling platform were used to investigate the impact of drilling activities on the harpacticoid copepods. An in situ experiment was designed, which aimed to investigate the recolonisation of harpacticoid copepods into azoic sediment that was oiled with a North Sea crude. Finally, an in situ experiment was designed to assess the short-term and long-term responses of nematodes and copepods to a synthetic based drilling oil.

The discharged of drill cuttings, contaminated with oil-based muds from the North Cormorant platform caused highly elevated heavy metal and hydrocarbon contamination within 500 metres of the platform. Copepod species richness and community composition were appreciably perturbed within 500 metres around the drilling platform. Members of the copepod families, Ectinosomatidae and Tisbidae, were absent within 500 metres of the drilling platform. In comparison, diosaccids dominated within 300 metres of the platform, with the almost exclusive occurrence of copepod species, Paramphiascopsis longirostris, Bulbamphiascus imus and Paramphiascella hyperborea.

Addition of low, medium and high (50, 500 and 5000 mg/kg respectively) of Total Alwyn oil (a North Sea crude) had no significant influence on the copepod abundance, copepod species diversity, evenness and richness 26 and 52 days after deployment. No significant perturbation of the copepod family Ectinosomatidae was detected, however a single ectinosomatid species Halectinosoma cooperatum, was significantly reduced in the high treatment after 52 days. One-way ANOSIM revealed that after 26 days the copepod species composition was not significantly different in any azoic treatment. In comparison, all azoic treatments except the control and medium were significantly different after 52 days. It was concluded that many of the copepod parameters measured were not sensitive to the levels of North Sea crude oil used, or copepods were able to find refuge from the oil in the top few millimetres of surface sediment.

Addition of low and high concentrations (1000 and 10000 mg/kg respectively) of Petrofree (a synthetic based drilling oil) caused significant reductions in the redox potential of the sediment after 58 days. After 58 days many copepod parameters were significantly reduced in the low and high oil treatments. Nematode parameters were only significantly perturbed in the high treatment after 58 days. The 266 days post-deployment samples revealed significant increases in many copepod parameters in the low oil treatment, in contrast to the significant reductions recorded in the high treatment. From the parameters analysed, it appeared that nematodes exhibited greater short-term tolerance than copepods to low concentrations of Petrofree oil.