Use of Mytilus edulis biosentinels to investigate spatial patterns of norovirus and faecal indicator organism contamination around coastal sewage discharges.
Bivalve shellfish have the capacity to accumulate norovirus (NoV) from waters contaminated with human sewage. Consequently, shellfish represent a major vector for NoV entry into the human food chain, leading to gastrointestinal illness. Identification of areas suitable for the safe cultivation of shellfish requires an understanding of NoV behaviour upon discharge of municipal-derived sewage into coastal waters. This study exploited the potential of edible mussels (Mytilus edulis) to accumulate NoV and employed the ISO method for quantification of NoV within mussel digestive tissues. To evaluate the spatial spread of NoV from an offshore sewage discharge pipe, mesh cages of mussels were suspended from moorings deployed in a 9 km2grid array around the outfall. Caged mussels were retrieved after 30 days and NoV (GI and GII), total coliforms and E. coli enumerated. The experimentally-derived levels of NoV GI and GII in mussels were similar with total NoV levels ranging from 7 × 101to 1.6 × 104genome copies g-1shellfish digestive gland (ΣGI + GII). NoV spread from the outfall showed a distinct plume which matched very closely to predictions from the tidally-driven effluent dispersal model MIKE21. A contrasting spatial pattern was observed for coliforms (range 1.7 × 102to 2.1 × 104CFU 100 g-1shellfish tissue) and E. coli (range 0-1.2 × 103CFU 100 g-1shellfish tissue). These data demonstrate that hydrodynamic models may help inform effective exclusion zones for bivalve harvesting, whilst coliform/E. coli concentrations do not accurately reflect viral dispersal in marine waters and contamination of shellfish by sewage-derived viral pathogens.
School of Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, LL57 2UW, UK. Electronic address: benwinterbourn@gmail.com.
James B
JB
Winterbourn
School of Ocean Sciences, Bangor University, Bangor, Gwynedd, LL59 5AB, UK.
Katie
K
Clements
CEFAS, The Nothe, Barrack Road, Weymouth, Dorset, DT4 8UB, UK.
James A
JA
Lowther
School of Ocean Sciences, Bangor University, Bangor, Gwynedd, LL59 5AB, UK.
Shelagh K
SK
Malham
School of Biological Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
James E
JE
McDonald
School of Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
Davey L
DL
Jones
D000818:Animals; D004926:Escherichia coli; D005506:Food Contamination; D006801:Humans; D049880:Mytilus edulis; D029322:Norovirus / Q000235:genetics*; D012722:Sewage; D012758:Shellfish
D012722:Sewage
Food safety; Marine pollution; Risk assessment; Viral contamination; Wastewater treatment plant