The wetlands of The Phoenix Park (lakes, ponds, streams and drainage ditches) are of particular value for biodiversity as wetlands are rare in Dublin (0.63%) and they thus provide habitats for species which are rare elsewhere in the city. Dublin Zoo contains the largest areas of wetland. The lake in the African Plains section of the Zoo, which covers 2.8ha, is the largest lake in Dublin City.
Water quality in ponds and watercourses is typical of urban streams and their origin means they have limited capacity to flush out pollutants. Water quality in the lower lake of Dublin Zoo is poor due to the concentration of animals. It contains specimen size eels due to the vast amount of food available. The presence of eels proves the ability of this species to travel through culverts from the Liffey. Water quality from the lake improves as it flows through the pond in the People’s Garden. The pond in Áras an Uachtaráin has good water quality and supports stoneworts and invertebrates associated with clean water such as mayfly, three cased caddisfly, dragonfly, and damselfly. The pond in the People’s Garden is fringed by a mature reedbed.
Coarse fish such as common Rudd, Perch, Tench or Roach are found in all ponds. The small native fish three spined stickleback is also found. Ponds can also provide a home for unwanted goldfish. Another exotic species is the North American Shrimp. It was first recorded in Ireland from a pond in the Park and is now present in all ponds. The original native shrimp is present only in the Khyber stream. Emergent vegetation on the margins of wetlands is important for the resident breeding mallard, coot and moorhen. Wetlands are also used by spawning frogs. The most important spawning sites include wet ditches at the base of “ha-ha’s”. Each spring, from late January onwards, masses of frog spawn may be seen in these locations.
Within the Park, important features of wetland biodiversity include:
- The emergent wetland vegetation around Glen Lake and the Fish Pond in Dublin Zoo, which is important for birds, plants and aesthetically.
- Presence of charophytes indicating relatively good water quality.
- Presence of Rudd and Tench with potential to improve fishery interest in all ponds.