Species diversity and abundance of shipworms (Mollusca: Bivalvia: Teredinidae) in woody marine debris generated by the Great East Japan Earthquake and Tsunami of 2011

Abstract

The Tohoku tsunami of March 2011 ejected a vast amount of debris into the Pacific Ocean. Wood boring shipworms (Bivalvia: Teredinidae) were either already present in, or settled on, the wooden fraction of this debris, offering a unique opportunity to study shipworm diversity in rafted wood of a known origin and time of ocean entry. Lumber and other wood began appearing on Central Pacific (Hawaiian Islands) and Eastern Pacific beaches in 2013. Eighty pieces of wood Japanese Tsunami Marine Debris (JTMD) consisting of construction beams, trees, milled logs, and wood from vessels or maritime structures were analyzed. Six shipworm species resident in the coastal waters of Japan were found: Bankia bipennata (Turton, 1819), Bankia carinata (Gray, 1827), Teredothyra smithi (Bartsch, 1927), Psiloteredo sp., Lyrodus takanoshimensis (Roch, 1929), and Teredo navalis Linnaeus, 1758. Two pelagic species, Teredora princesae (Sivickis, 1928) and Uperotus clava (Gmelin, 1791), were acquired by JTMD wood in the transoceanic voyage. Several of these wood items were discovered soon after stranding and contained live shipworms. Up to five shipworm species were found in any one wooden object. The present work represents the first study of the diversity and abundance of shipworms transported across an ocean basin in a large woody debris field.