Species Identification and Attack Patterns Analysis of Marine Borers in Shipwreck Members and Driftwood from the Korean Coast

Abstract

In this study, we aimed to identify the patterns of perforation damage on shipwreck members excavated from the Korean coast and to estimate the organisms responsible. Two types of marine borers were collected from driftwood collected from Chupo Beach, Shinchang-ri Beach, and Biin Beach, and test piles installed at Shinjindo Beach, and species identification was conducted through visual observation and DNA analysis. The damage patterns of marine borers on the driftwood and test piles were identified and compared with the damage patterns of the shipwreck members. The marine borers found in the driftwood and test piles were identified as <i>Teredo navalis</i> and <i>Limnoria lignorum</i> through DNA analysis and visual observation. <i>T. navalis</i> bored 3-5 mm diameter tunnels in the cross-section of the wood towards the fiber direction, and the damage was severe enough to completely penetrate a 7 cm long piece of wood. The tunnels were lined with calcareous material extruded by <i>T. navalis</i>. In some driftwood, fiber-oriented as well as random-directional tunnels were observed in <i>T. navalis</i> damage scars. In shipwreck members, <i>T. navalis</i> damage was primarily seen in the upper members, which were exposed to seawater and not buried in mud on the shore at the time of excavation, where <i>L. lignorum</i> drilled and gnawed small holes of less than 1 mm diameter in the surface of the wood. Very little evidence of damage by <i>L. lignorum</i> was rarely observed on the topsides of shipwrecks or on the surfaces of members, presumably because the fragile damage was worn away by the movement of currents at sea.