The Analysis on Nanhai No. 1 Shipwreck Site Based on the Mollusca Debris Data

The Nanhai No. 1 Shipwreck is a wooden ship sunk 800 years ago during the Southern Song Dynasty of China. The zoobenthic shellfish communities in the sediments covering the wreck came from 296 species from 5 phylums, of which 290 were molluscs. These molluscs were mainly composed of local marine fauna based on the literature. By comparing the structural parameters of the zoobenthic debris communities and their changes among the different sediment layers, it is notable that the seabed environment was influenced by the wreck within a short period of time, and corroded metal objects from the ship could impact the mollusc communities. Because of the relatively continuous and stable particle deposition in the sea, the wreck was quickly covered in sediment. During this deposition process, the seabed level of the shipwreck site gradually returned to similar conditions prevalent in the surrounding area. Sedimentation sealed the wooden objects of the hull from the sea water and relatively anaerobic conditions between the sediment and the wood structures were formed. This anaerobic environment inhibited the eroding effect of aerobic bacteria and wood boring animals, thereby preserving the shipwrecked hull.