An ecosystem model for the Buccaneer Oil Field

Abstract

From the Abstract: “A model was developed for the Buccaneer gas and oil field that integrated biological, chemical (hydrocarbon), and physical submodels. State-of-the-art flow analysis techniques were used to describe the structure and function of the system. Five compartments consisting of phytoplankton, zooplankton, plankton feeders, fouling flora, and fouling fauna were identified as being system importers. Fouling feeders, particulates, the benthos, benthic feeders, and large predators compartments are exporters from the system.

Two distinct assemblages were identified based on the origin of the material that was stored in the compartments. The major portion of the biomass stored in the zooplankton, plankton feeders, particulates, benthos, benthic feeders, and large predators originates in the phytoplankton. However, the fouling flora provides the primary source of carbon for the pathway that includes the fouling fauna and fouling feeders. Nevertheless, phytoplankton contribute a significant source of carbon to this assemblage. This may be due to the feeding behavior of the barnacles which dominate the fouling fauna. Large predators also appear to be opportunistic feeders although relying predominantly on the pelagic/benthic species. Particulate matter in the form of fecal material and dead and decaying organisms derived from the platform is not a significant source of carbon to the overall system suggesting that detrital materials from the fouling community are internally cycled.

Hydrocarbons discharged from the platform are rapidly dispersed from around the platforms. However, the hydrocarbon model suggests that the hydrocarbons can be transported long distances as only a 10% loss is estimated over a 24-hr. period. Transport of hydrocarbons into the sediments around the platforms appears to occur through incorporation of fecal material or attachment to sulfur particles.

Different routes (i.e., from the sediments versus direct uptake from the water) of contaminant uptake may exist for barnacles as opposed to other members of the fouling community. However, there are no large accumulations or evidence of biological magnification of hydrocarbons in the Buccaneer field biota. This suggests that any accumulated hydrocarbons are being rapidly and effectively depurated or metabolized.”