A frontal zone at the south side of the mouth of the Outer Bay leads to high plant productivity, large populations of herbivorous and detritus-feeding animals, and eventually to concentrations of animals of higher trophic levels. The dominant intertidal alga is the rockweed Ascophyllum nodosum . Tidal mixing at the mouth of the Bay of Fundy is important in the growth, during the summer months, of the dinoflagellates that cause paralytic shellfish poisoning. Digby Neck, partially in response to the elevated productivity in the water. The area also supports strong lobster populations.
Herring spend the summer feeding in nearshore zones.
Witch Flounder are locally abundant in deeper waters at the mouth of the Bay of Fundy, and large spawning populations of Red Hake occur in Passamaquoddy Bay. Inshore concentrations of Atlantic Halibut are known around Grand Manan. Species of bottom animals are similar to those in the Atlantic Unit 911, but the area has several localized concentrations of particular species, probably related to the tidal currents and rock bottom in some places. Dense beds of the Horse Mussel occur across the Outer Bay from inside Digby Neck to inside Saint John Harbour. Horse Mussels are the most important suspension-feeding organisms in the Unit.