There are high quality examples of several rare and threatened coastal habitats present within its area.
The biosphere reserve is significant from a conservation perspective since it supports well-developed salt marshes and dune systems displaying all stages of development from the earliest phase of colonization to stable and full maturity.
Species such as grey heron (Ardea cinerea), goldeneye (Bucephala), red-breasted merganser (Mergus serrator) and greenshank (Tringa nebularia) are regular in winter in numbers of regional or local importance.
The North Bull Island and parts of the buffer zone in north Dublin used to include populations of Irish mountain hare (Lepus timidus hibernicus), a uniquely Irish sub-species of a species of national and international importance, which came under severe pressure from recreational disturbance and illegal poaching.
Dublin Bay is the only biosphere reserve worldwide which includes within its area parts of a national capital.