Impacts of mineral oil and synthetic lubricant on the trophic diversity of marine nematode community: Results from Microcosm Experiments

The effects of two lubricating oils on the trophic diversity of a nematode community of a Tunisian lagoon were investigated in a microcosm experiment. Sediment from a pristine site in Ghar El Melh lagoon (Western Mediterranean) was treated with mineral oil (Mobil 20 W-50), a synthetic lubricant (Mobil 0 W-40), the same two lubricants after use in a vehicle. Univariate analysis showed significant differences between univariate indices for trophic structure of nematode assemblages from undisturbed control and those from lubricant treatments. Trophic index (2) and the 1B/2A ratio decreased in all microcosms treated with mineral oil or synthetic lubricant. Results from multivariate analyses of the trophic group abundance data demonstrated that the responses of nematode were dependent on the type of lubricant (mineral or synthetic, "clean" or "used") used for the sediment contamination. Non-selective deposit feeders (1B), most abundant in control microcosm, were very much affected and their abundance decreased significantly in response to oil contamination. Selective deposit feeders (1A) increased in response to the two types of lubricants and seemed more resistant to lubricant contamination.