Wood taphonomy in a tropical marine carbonate environment: Experimental results from Lee Stocking Island, Bahamas

Abstract

Both teredinid bivales and limnorid isopods attacked wood that was deployed experimentally for two years in a carbonate environment. On average, wood samples collected after one year on the sea floor lost 17% of their original surface area to Limnoria and 50% of their original volume to teredinids. After two years on the sea floor, wood samples lost an average of 39% of their original surface and 74% of their original volume. All samples of kiln-dried lumber ( Pinus, Sequoia, Araucaria, Magnolia, and Quercus) experienced significantly more attack by teredinids and Limnoria than samples of Quercus stellata (post oak) branch wood that experienced terrestrial decomposition in a warm-temperate environment for five years before deployment on the sea floor. Taphonomic loss rates for wood in marine environments based on kiln-dried lumber may overestimate loss rates for natural wood entering marine environments after initial decomposition in terrestrial environments. Burial appears to play an important role in wood taphonomy. Burial to a depth of > 3 cm inhibited destruction by Limnoria, but not teredinids, possibly due to the greater tolerance of molluscs for low O 2 levels and the ability of teredinids to raise their siphons above the wood surface. Both limnorids and teredinids may contribute to the formation of Teredolites (disaggregated, sediment-filled teredinid borings). Limnorid isopods remove the surface of wood exposing the calcite-lined borings of teredinids. Once their calcite-lined borings are exposed, teredinid are susceptible to predation, and in the aftermath of predation, teredinid borings may become sediment filled. Exposure also causes the calcite-lined borings to break and disaggregate, leading to the formation of Teredolites. The fossil record of teredinids reaches back to the Jurassic. Limnoria traces in the surface of wood are distinctive and diagnostic at the species level; however Limnoria have a sparse fossil record.