Responses of meiofauna and nematode communities to crude oil contamination in a laboratory microcosm experiment

Abstract

This objective was accomplished by examining changes in the structure of meiofaunal and nematode assemblages after exposure to different concentrations (0.5%, 1%, 2%, 4%, 8%, 15%, and 20%) of total petroleum hydrocarbons (TPH) in microcosms. The concentrations of TPH in the experimental microcosms did not significantly differ from those in the control microcosms after 60 days. The average density of total meiofauna in the 0.5%, 1%, 2% and 4% experimental microcosms was 157.9 individuals, which was higher than the density in the control microcosm. The average density of total meiofauna in the 8%, 15%, and 20% microcosms was 90.7 individuals, which was lower than the density in the control microcosm. The density of nematodes was similar to that of the total meiofauna. Cluster analysis divided the microcosms into two groups: group 1: control, 0.5%, 1%, 2%, and 4% microcosms and group 2: 8%, 15%, and 20% microcosms. However, SIMPROF analysis showed no significant difference between the two groups (p > 0.05). Cluster analysis results for nematode communities were similar to those for the meiofaunal communities. The total meiofaunal density, nematode density, and number of Bolbolaimus spp. individuals were significantly negatively associated with TPH concentration (Spearman correlation coefficients, p < 0.05).. The concentrations of TPH in the experimental microcosms did not significantly differ from those in the control microcosms after 60 days. The average density of total meiofauna in the 0.5%, 1%, 2% and 4% experimental microcosms was 157.9 individuals, which was higher than the density in the control microcosm. The average density of total meiofauna in the 8%, 15%, and 20% microcosms was 90.7 individuals, which was lower than the density in the control microcosm. The density of nematodes was similar to that of the total meiofauna. Cluster analysis divided the microcosms into two groups: group 1: control, 0.5%, 1%, 2%, and 4% microcosms and group 2: 8%, 15%, and 20% microcosms. However, SIMPROF analysis showed no significant difference between the two groups (p > 0.05). Cluster analysis results for nematode communities were similar to those for the meiofaunal communities. The total meiofaunal density, nematode density, and number of Bolbolaimus spp. individuals were significantly negatively associated with TPH concentration (Spearman correlation coefficients, p < 0.05).