Enfield

Mission 3

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Location: Enfield Prospect
Position: North-West coast offshore Australia
ENC03
Depth: 400m - 550m
Water Temperature: No data
Dates: 12 - 23 December 2005
Industry Partners  
Gas & Oil Company Woodside Energy
ROV Operator: Subsea7
Rig operator: Transocean
SERPENT Representatives:

Ms Katie Robertson, University of Sydney

   

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Mission Plan

The science goals for this project are to expand on baseline environmental surveys carried out in the area on behalf of Woodside. We will conduct detailed ROV megafaunal video surveys to provide quantitative data on megafaunal ecology; particularly abundance, diversity and distribution in this area. In addition we will conduct a series of experiments to quantify the expression of heat shock proteins on deep sea organisms from within and outside of drill spoil. One set of experiments will be an in situ deployment and another set will be completed at the surface to determine the effects of drilling mud on heat shock protein expression.

Mission Outcomes

A highly successful mission resulted after 7 days of ROV operations. Eight 100m video transects were completed, for megafaunal abundance, diversity and distribution in the area. Transects were conducted every 45 degrees and extend to 100m from the drill site. Videos will be analysed for megafaunal diversity and habitat mapping during 2006.

There is only one habitat type at ENC03, soft bottom. There is no evidence of any rock formations or hard bottom of any type. ENC02 was approximately 30m away from ENC03 so there was some overlap in drill spoil. This will be accounted for when analysing video transects. Preliminary analysis indicates a high density and diversity of megafauna. The main component of the megafaunal community is consistent with soft bottom communities and includes echinoderms (asteroids, echinoids) a host of crustaceans (prawns and large isopods), eels that live in the sediment and some bottom dwelling fish. At approximately 85m along each transect, sponge beds were evident. Further investigation on subsequent missions will identify the extent of these beds.

Baited traps were deployed both within and outside of the drill spoil to attract mobile megafauna. Traps were examined every 24 hrs and video taped for 5 minutes. Isopods and amphipods from within the spoil (10m from BOP) and outside of the spoil (100 m from BOP) were collected for heat shock protein analysis. In a second experiment, isopods outside of the spoil (100m from BOP) were collected and exposed to drill mud (n=4), copper sulfate (a known inducer of heat shock proteins n=4), and sea water as a control (n=4) once brought to the surface. Traps were re-deployed every 24 hrs and collection repeated.

A variety of prawns, crabs, eels, amphipods, isopods and fish were attracted to the bait traps. Initial examination of the data suggests that there is a difference in the diversity of organisms that visit the traps (inside vs outside the drill spoil). Isopods, shrimp and eels only appeared to visit traps outside of the drill spoil. Further analysis will validate any trends in the data. Species collected for determining the level of heat shock protein expression:

Deliverables

We will conduct the same habitat mapping and bait trap experiments at other drill sites. This will allow us to compare biodiversity and processes between the locations. We will prepare a report for Woodside after analysis of all the data. This research will contribute to the honours thesis of Katie Robertson at the University of Sydney. We expect to publish these results in leading peer reviewed journals such as Marine Ecology Progress Series or Deep Sea Research in the near future.


For further information please contact:
Dr Adele Pile, University of Sydney, Australia.

Or

Cara Price, Enfield Development Environmental Advisor, Woodside Energy Ltd.


Thanks as always to our valued project partners

Australia Enfield location map Dr Ian Hudson

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E: ihudson@mail.deepwater.com