Dragging the chain: anchor scour impacts from high-tonnage commercial vessels on a soft bottom macrobenthic assemblage

• DOI: 10.3389/fcosc.2025.1487428
• Publication Date: 2025-03-26T10:15:19Z
• Authors: Andrew R. Davis; Allison Broad; Chantel Steele; Caitlin Woods; Rachel Przeslawki; W. A. (Tony) Nich...; William Maher; Frank Krikowa; Bradley Morris; Timothy C. Ingleton; Sarah O’Hea Miller; Matthew J. Rees
• Keywords: Tonnage; Assemblage (archaeology)

International shipping is the backbone of global economy with ~80% world’s trade (by volume) transported by ship. The potential environmental impacts this multi-billion-dollar industry have received considerable attention, particularly emissions into air and sea. Many these large commercial vessels lay at anchor for extended periods while awaiting their turn to enter port, yet associated anchoring remain virtually unexamined. Anchors can exceed 20 tonnes, chains up hundreds metres in length individual links weighing 200kg; there significant effects on seafloor biota where concentrated. Filling knowledge gaps deep-water wave-exposed environments logistically challenging expensive. To do so we used sediment grabs collected offshore from Port Newcastle (SE Australia) – largest coal export terminal sample infaunal assemblages anchor-affected locations relative reference (30 55m water depth). Polychaetes crustaceans were most abundant samples (~85%), whereas molluscs very low abundance (<3%), despite being well represented terms diversity (11 families bivalves 9 gastropods). Invertebrate almost doubled areas exposed compared areas. In contrast, invertebrate declined increasing activity, however relationship was weak. Importantly, observed major shifts overall assemblage anchored-affected reductions suspension feeders mirrored increases scavengers predators. We assert that negatively impacted mobilisation or direct physical damage chains, opportunistic mobile predators benefitted disturbance. contend disturbance a issue given burgeoning marine trade. Data are urgently required better inform management regularly as anchorages.