DEEP-OCEAN DEEP-OCEAN BIODETERIORATION OF MATERIALS-PART IV. One Year at 6,800 Feet,
 Technical Report R456, Naval Civil Engineering laboratory, Port Hueneme, Ca, by James S. Muraoka, June 1966, 45 pages.

As Part IV of a series of reports on the biological deterioration of materials in the deep ocean, this report covers the data obtained after exposing metallic and nonmetallic specimens for 13 months on the floor of the Pacific Ocean at a depth of 6,800 feet (Test Site 1). The specimens were attached to a Submersible Test Unit that was retrieved in February 1965. Preliminary examination of the specimens was made aboard ship, and the final examination, tests, and analyses were performed at the Naval Civil Engineering Laboratory.

On recovery, most of the plastic materials and all of the rope specimens were covered with bacterial slime. Cotton and manila rope specimens were severely deteriorated by marine microorganisms. Wooden test panels, plastics, and Manila ropes were attacked by molluscan borers. Glass, metals, natural and 6utyl rubber, and certain plastic materials were not adversely affected.

The results of breaking-strength tests on ropes, weight loss measurements of wood panels, moisture absorption tests on plastics, and insulation resistance and voltage breakdown tests on electrical insulating materials are presented.