About WLG
The Area
Status of Lake Waituna




A case study

By Brian Rance & Wynston Cooper, DOC, New Zealand

Waituna Wetlands comprise an area of approximately 3,556ha situated on the southern coast of the South Island of New Zealand. The wetlands encompass the Waituna Lagoon along with adjacent peatlands, numerous ponds/lakes and coastline forming part of a larger complex of estuaries and lagoons within the Southland area.

Conservation of flora and fauna, and protection of wildlife are the primary uses of the wetland. However, other uses include sport fishing (for Brown Trout Salmo trutta) and game bird shooting. Much of the surrounding area is used for pastoral agriculture.

View of the break out
View of the southern edge of Lake Waituna, towards the break-out.

Major Wetland Types

Within the wetland there are:

Peatlands: this vegetation is governed by the height of the water table and drainage. The most extensive vegetation type is Wire Rush Empodisma minus with Tangle Fern Gleichenia dicarpa, Manuka Leptospermum scoparium and Dracophyllum longifolium. Better drained areas are dominated by Leptospermum scoparium shrublands or Red Tussock Chionochloa rubra (local). Low lying sites are generally dominated by sedges, rush and bryophytes with ponds or pools. One of the special features is a cushion-bog community containing many species adapted to cold, peaty conditions including some species more typically found in montane or subalpine conditions rather than at sea level. The wildlife in the peatlands is not diverse but the area forms the Southland stronghold for Australasian Bittern Botaurus poiciloptilus, South Island Fernbird Megalurus punctata punctata, Spotless Crake Porzana tabuensis and Marsh Crake P. pusilla. All these species have declined elsewhere through habitat loss in Southland.

Waituna Lagoon, ponds and lakes: Due to periodic opening to the sea following the lagoon reaching high water levels, the lagoon is subject to considerable fluctuations in water level. It is a different habitat when open to the sea and thus tidal, from when it is closed and ponded. When open there are extensive tidal mudflats, which form an important summer wader habitat. A large number of wader species (including up to 18 species of trans-equatorial waders) utilize the mudflats. Other waterfowl also utilize Waituna Lagoon as well as the numerous small ponds and lakes. In particular Waituna Lagoon is the principal Black Swan Cygnus atratus site and one of the most important Grey Duck Anas superciliosa sites in Southland. There is a Black Shag Phalacrocorax carbo colony on one of the ponds. The lagoon is a trout fishery of some importance. Several types of vegetation associated with the lagoon edge are present - saltmarsh and allied communities are extremely well developed in southeastern New Zealand.

Gravel coastal beach: This contains a discontinuous vegetation of grasses, herbs and shrubs, most common being Muehlenbeckia axillaris, Gentiana saxosa, and Poa cita.

Streams and waterways: Sea-run Brown Trout are found in the Waituna Lagoon. The streams provide spawning grounds for both the introduced trout and native fish. Populations of Giant Kokopu Galaxias argenteus and Banded Kokopu Galaxias fasciatus, Inanga Galaxias maculatus, Long Finned and Short Finned Eels Anguilla dieffenbachii and A. australis as well as other estuarine and freshwater fish have been recorded.

Major Features of the Waituna Wetlands

the scrub
Looking north from the south coast at the manuka etc growing on the wetland reserve - also note the tarns...

Waituna Lagoon was designated a Ramsar site in 1976 since it met three of the four 'Ramsar General Criteria based on plants or animals' for identifying such sites: it supports an appreciable assemblage of endemic and/or threatened species and communities; it has special value for maintaining the genetic and ecological diversity of the region; and it provides a habitat for plants and animals at critical stages of their biological cycles.

Notable endemic taxa include:


Giant Kokopu Galaxias argenteus; National status: vulnerable
Banded Kokopu Galaxias fasciatus; National status: vulnerable


New Zealand Shoveler Anas rhynchotis variegata; uncommon endemic subspecies
Variable Oystercatcher Haematopus unicolor; National status: rare
South Island Pied Oystercatcher Haematopus ostralegus finschi; uncommon endemic subspecies
South Island Fernbird Megalurus punctata punctata; National status: rare
New Zealand Dotterel Charadrius obscurus obscurus; National status: endangered (less than 100 individuals remaining)
Banded Dotterel Charadrius bicinctus bicinctus; National status: vulnerable


Pingao Desmoschoenus spiralis
Tufted Hair Grass Deschampsia caespitosa var. macrantha, endemic subspecies, National status: vulnerable

Aside from these species of special significance, the area supports a large diversity of birds, native fish, invertebrates and plants. Seventy six species of birds have been recorded, including both international and internal migratory waders. A significant aspect of the migratory wader population is the number of rare species (by New Zealand standards) that have been recorded in the reserve. These include Mongolian Dotterel Charadrius mongolus, Grey Plover Pluvialis squatarola, Marsh Sandpiper Tringa stagnatilis, Sanderling Calidris alba and Asiatic Whimbrel Numenius phaeopus variegalus. The wetlands also serve as an important moulting refuge for the New Zealand Shoveler.

Native fish species include several endemic species some of which are rated as vulnerable. Many of the insects and some plants are typically subalpine species. Over 80 species of moth alone have been found in the Awarua Bay/Waituna Wetlands complex and the area is the type locality for a number of species of moth, some of which are not known to occur elsewhere. The diverse flora of the area includes the presence of the interesting cushion bog vegetation and sand ridge plant associations (Pingao, Coastal Tussock and locally uncommon species of mat-daisy).

Current Status

The wetland, which is Crown-owned and managed by the Department of Conservation, was gazetted as a Scientific Reserve in 1983. Entry to the reserve is not restricted, but the relative isolation and difficulty of access ensure minimum disturbance. Monitoring continues on lagoon levels, effects of past fires and the impact of nesting gulls on the cushion bog vegetation. There are also bi-annual wading bird counts undertaken at Waituna Lagoon.

The Wetlands of Ecological and Representative Importance database gives the wetland a ranking of international importance and the wetland was designated a Ramsar site in 1976. The Department of Conservation is investigating the expansion of this Ramsar site to include additional wetland areas.

Major Threats and Management Issues

There are three major threats to the wetland:

Fires - there have been several large fires in adjacent peatlands in recent years; in the area surrounding the wetland, an intensification of land use including draining, ploughing and sowing grass influences water quality; exotic weed species - Gorse Ulex europaeus, Broom Cytasus scoparius and Spanish Heath Erica lusitanica are found in peripheral areas and are spreading within the wetland.

When the sea outlet from the lagoon is blocked during periods of high rainfall, the water floods back into marginal vegetation. This is a desirable feature for many of the reserve's botanical features which remain because of the occasional flooding of areas and maintenance of a high water table. If this occurs during July-November it can stimulate the breeding activity of Black Swan to a marked degree.

However, it can also be detrimental for other species such as waders, as the mudflats used for feeding are not exposed, or for terns, oystercatchers and stilts when the small islands they favour as nesting sites are submerged. Blocking of the inlet also causes drainage problems on some farms close to the lagoon, so a management regime exists whereby periodically the bar is artificially opened to the sea.

... and of interest

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