1. Potamopyrgus antipodarum pool fed by drain at top of salting, Dee Estuary, Cheshire. Salinity 0 p.p.t. Filamentous algae over bare sand, black and anaerobic below surface. Near high water mark; Scirpus maritimus beyond log in image.
2. Potamopyrgus antipodarum pool fed by drain at top of salting, Dee Estuary, Cheshire. Salinity 0 p.p.t. Filamentous algae over bare sand, black and anaerobic below surface. Near high water mark; Scirpus maritimus beyond log in image.

Potamopyrgus antipodarum pool fed by drain at top of salting, Dee Estuary, Cheshire. Salinity 0 p.p.t. Filamentous algae over bare sand, black and anaerobic below surface. Near high water mark; Scirpus maritimus beyond log in image.