A blue mussel may not be the first thing that springs to mind when it comes to Northern Ireland’s water quality heroes.

But for scientist Matt Service at the Agri-Food and Biosciences Institute (AFBI), they are “little ecosystem water treatment plants on their own”.

In Belfast Lough where the mussels are cultivated, regular sewage spills are threatening the environment, the economy and public health, according to a report by NI Water.

Officials say the lough is facing a crisis if investment in sewage infrastructure is not increased.