for aquatic animals, a contiguous hydrological system with a distinct health status with respect to a specific disease or specific diseases that forms an area that is referred to in one of the following:
i gcás ainmhithe uisceacha, córas hidreolaíoch comhtheagmhálach a bhfuil stádas sláinte ar leith aige i ndáil le galar sonrach nó galair shonracha arb ionann is ceantar é dá dtagraítear i gceann acu seo a leanas: