The River Mersey passes through industrialised and urban areas, before discharging into Liverpool Bay, and therefore may be a source of a range of different Contaminants of Emerging Concern (CECs) to the local marine environment.

A survey was carried out by Cefas to collect flounder from four stations in a transect along the Mersey estuary and into Liverpool Bay, from 30th September to 3rd of October 2025, onboard the research vessel Mersey Guardian. Samples were collected for a range of biological endpoints, as well as for chemical analysis of priority CECs, and will be analysed under the CONTRAST project by Cefas and CONTRAST partners.

Sediments along the same transect will be collected on a later survey in December 2025 for CECs analysis.