Pluto

Location:	Pluto Prospect - Sedco 703
Position:	North-West coast offshore Australia 19' 57 43.95 S 115' 08 18.44 E
Depth:	400m - 550m
Water Temperature:	No data
Dates:	21 March - 1 April 2005
Industry Partners
Gas & Oil Company	Woodside Energy
ROV Operator:	Sonsub
Rig operator:	Transocean
SERPENT Representatives:	Dr. Adele Pile, University of Sydney

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Mission Plan

• Expand on environmental baseline surveys
• Detailed ROV megafaunal video surveys
• Detailed and targeted approach to examine species composition
• Collection of organisms away from and in the area of physical disturbance

Mission Outcomes

1. In 5 days of ROV operations we completed 4 x 100 m video transects for megafaunal abundance, diversity and distribution in the area.
2. There is only one habitat type at Pluto 2, soft bottom. There is no evidence of any rock formations or hard bottom of any type.
3. The drill spoil extends in a west, north west direction and down slope. Preliminary analysis indicates a low density and diversity of megafauna.
4. The main component of the megafaunal community is consistent with soft bottom communities and includes a host of crustaceans (spider crabs decorated with sea anemones, prawns, snapping shrimp, and large isopods), eels that live in the sediment and various types of worms.
5. We deployed baited traps both within and outside of the drill spoil to attract mobile megafauna.
6. A variety of prawns, isopods, and fish were attracted to the bait traps. Initial examination of the data suggests that there is no difference in the diversity of organisms that visit the traps (inside vs outside the drill spoil.
7. Species collected for determining the level of heat shock protein expression:
   • 7 isopods
   • 3 prawns
   • 3 eels
   • 1 hag fish
8. Behavioural observations revealed the tracks of many of the megafauna and this will be used for the identification of lebenspurren tracks.
9. Eels that burrow into the sediment tail first were found. When eels are disturbed they then escape by contracting backwards into the sediment and burrowing away forward rather than swimming out of the sediment.

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. 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 – SEA SERPENT Project, University of Sydney, Australia

apile@bio.usyd.edu.au

Thanks to crew of the Sedco 703 and the ROV crew from Sonsub for all their help and enthusiasm offshore, and to our project partner Woodside and Transocean.