Despite previous wood preservation efforts, USS Cairo was found to have advanced decay

University of Minnesota researchers studied the microbial degradation of the USS Cairo, one of the first ironclad and steam-powered gunboats used in the United States’ Civil War. Studying the microbial degradation of historic forests is essential to help protect and conserve important cultural artifacts.

Built in 1861, the ship was hit by a torpedo and sank in December 1862 and was recovered from the Yezu River nearly 100 years later. It remains on display at Vicksburg National Military Park in Mississippi. Although the plane has a canopy cover, it is exposed to the elements.

“The continued degradation of this historic Civil War ship poses serious concerns for its long-term preservation. To determine appropriate conservation efforts, it is important to understand the current state of the wood and the microorganisms that cause it to degrade.”

Collaborated with conservationists Claudia Camillo and Paul Murdekian from Terra Mare Conservation, the researchers assessed the types of decay, revealed the underlying chemistry of the forest and identified a large diverse population of fungi that were isolated from the ship’s timbers. Their findings were recently published in Journal of Fungi.

They found:

• Advanced stages of decay were found in many areas of the ship.
• Although some past wood preservation treatments were applied to the wood, over time the fungi have become tolerant of these preservation treatments.
• A diverse group of soft-rot and white-rot fungi was identified throughout the ship’s wood-based isolations. Many fungi found have been shown to be tolerant to compounds used to treat wood.

“Wood placed in the environment is subject to microbial degradation. Historic buildings and ships exposed to environmental conditions for long periods of time are particularly affected. This study shows that although wood preservation treatments were applied to the historic ship, these various compounds withstanding find their way into the wood over time, causing decay.”

Researchers suggest that to control these hardy fungi, it is important to control the environment by reducing humidity and exposure to the elements. A new enclosed structure for the environmentally controlled ship is recommended to prevent deterioration due to fungus that destroys the salvaged tolerant woods and external exposure of the ship.

In addition, more information is needed on the biology and ecology of these fungi. The research team hopes to study these organisms further to better understand their interactions with the wood and ways to control them.