A field investigation to determine the impact of offshore drilling activities on natural larval settlement

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:242346

Barnett, A; Krause, P R ^[1]; Raimondi, P T ^[2]

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1. MEC Analytical Systems, Inc., Carlsbad, CA (United States)
2. Univ. of California, Santa Barbara, CA (United States)

The authors used a manipulative field experiment to test the effects of offshore drilling activities on the natural settlement of invertebrate larvae in the deep ocean (180 m) off southern California. This experiment was conducted in conjunction with other in situ experiments at a series of three drilling rigs and three reference sites between Pt. Arguello and Pt. Conception. At each study site the authors exposed settling plates to the natural environment on moorings at each of two depths near the sea floor. The two mooring depths were used to simulate differences in natural relief found in the study area. These plates were covered with a mesh to allow only natural bacterial ``filming`` to occur and prevent settlement of larger invertebrate larvae. After filming the plates were transplanted to all sites near the bottom such that each site had plates filmed at all other sites. Sterile plates (without filming) were also placed at each site. Plates were left uncovered for periods up to three years. Settling plates were retrieved at specific intervals over the length of the experiment. Upon retrieval some plates were photographed and returned to the bottom, others were returned to the laboratory. The results showed that the overall settlement rate was very slow with little settlement occurring in the first 6 months of exposure. Settlement was higher in periods of exposure lasting between one and two years. The authors also found significant effects on the number and type of larvae that settled on the plates with respect to the location of the plates (rig vs. reference), and the height from the bottom where they were located.

• OSTI ID: 242346
• Report Number(s): CONF-9511137--; ISBN 1-880611-03-1
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
AQUATIC ORGANISMS
BIOLOGICAL STRESS
ENVIRONMENTAL IMPACTS
INVERTEBRATES
OFFSHORE DRILLING
OIL SPILLS
POPULATION DYNAMICS
WATER POLLUTION