551
particularly in the blue wavelengths. Its water
chemistry is that of dilute sea water. Certain thermal and chemical anomalies are, possibly,
explained by sub-surface infl ows of artesian
water. The plankton of Perched Lake is dominated by Chrysophytes with no well-defi ned seasonal change of biomass or species composition.
An unusual dinofl agellate with marine affi nities,
probably, Phalacroma sp., occurs in the lake.
Perched Lake lies at 17 m MSL (approx.) at a
distance of 0.8 km east of Buttor Island and
Gordon River 33.5 km from its mouth. The lake
has the following morphological and morphometric features: maximum length 378 m; maximum width 165 m; maximum depth 13 m, mean
depth 6 m; area 4 ha; volume 241,310 m
3 ; length
of shoreline 903 m; and shoreline development
1.2. Isopleths of temperature show the lake to be
of warm monomictic type, or it could be considered as ‘chemomictic’ in the sense of isothermal
during certain period of summer when a temperature difference of 4 °C is sometimes recorded.
The lake has low turbidity. The lake was revealed
to be acidic in nature with pH ranging from 4.0 to
6.6. DO concentration of >60 % may sometimes
be recorded. Thirty-two species of phytoplankton
were recorded from Perched Lake (King and
Tyler 1981 ).
25.3 Wetlands and Wetland
Conservation in New
Zealand
25.3.1 Introductory Note
The New Zealand (NZ) archipelago consists of
three main islands (North, South and Stewart
Islands) and a widely separated group of smaller
islands spanning a temperate zone from 29° to
53° south in the Southwest Pacifi c Ocean.
Wetland ecosystems are characteristic of NZ.
Wetlands occupy a small part of New Zealand,
less than 2 % of the total land area. Their presence
is associated with the fact that NZ experiences a
lot of storms, earthquakes and ice factors, which
contribute to the formation of wetlands. This
linkage of physical processes with physical
features is refl ected in the hydrological classes
typical of NZ wetlands, rivers and bogs from frequent rain; lakes from glaciation and volcanic
actions; swamps from the deposition of erosion
products by rivers and the sea; and estuaries and
lagoons from tidal fl ooding of old Pleistocene
valleys. Associated with these hydrological
classes are wetland communities which are particularly distinctive of the country, contributing
to the national landscape identity and the uniqueness of the NZ biogeographic region. They
include fl ax swamps of Phormium spp., braided
rivers which form good waterfowl habitat, high
country cushion bogs and tams, salt rush and reed
estuaries with Leptocarpus and Juncus spp. and
kahikatea ( Dacrycarpus dacrydioides ) swamp
forest. There is considerable history of modifi cation and use of wetlands by both Maori and
Europeans. The history of wetland conversion
and modifi cation often relates to expansive
phases of NZ history. It may be noted here that, in
addition, the rivers occupy c 294,600 ha and
lakes account for c 339,800 ha of surface area.
25.3.1.1 Threats to the Wetlands in NZ
Pervasive changes to wetland continue throughout the country: (a) the extension of urban settlements onto wetlands; (b) extraction of sand and
gravel and reclamation of estuaries, lagoons, lake
shores and river margins; (c) draining of on-farm
swamps; (d) encroachment by exotic weeds;
planting of spartina on coastal mudfl ats; etc.
25.3.1.2 Conservation of Wetlands
in NZ
As such, conservation of the wetlands is
essential. Hence, the greatest single need is the
(a) establishment of buffers of indigenous vegetation along rivers (from their headwaters to the
sea) and around the margins of lakes, swamps
and estuaries and (b) the protection of corridors
linking wetlands of all kinds to other terrestrial
and marine protected areas.
25.3.1.3 Goods and Services
by Wetlands in NZ
The wetlands have always had an important
role within Maori communities in an intricate,
25.3 Wetlands and Wetland Conservation in New Zealand
particularly in the blue wavelengths. Its water
chemistry is that of dilute sea water. Certain thermal and chemical anomalies are, possibly,
explained by sub-surface infl ows of artesian
water. The plankton of Perched Lake is dominated by Chrysophytes with no well-defi ned seasonal change of biomass or species composition.
An unusual dinofl agellate with marine affi nities,
probably, Phalacroma sp., occurs in the lake.
Perched Lake lies at 17 m MSL (approx.) at a
distance of 0.8 km east of Buttor Island and
Gordon River 33.5 km from its mouth. The lake
has the following morphological and morphometric features: maximum length 378 m; maximum width 165 m; maximum depth 13 m, mean
depth 6 m; area 4 ha; volume 241,310 m
3 ; length
of shoreline 903 m; and shoreline development
1.2. Isopleths of temperature show the lake to be
of warm monomictic type, or it could be considered as ‘chemomictic’ in the sense of isothermal
during certain period of summer when a temperature difference of 4 °C is sometimes recorded.
The lake has low turbidity. The lake was revealed
to be acidic in nature with pH ranging from 4.0 to
6.6. DO concentration of >60 % may sometimes
be recorded. Thirty-two species of phytoplankton
were recorded from Perched Lake (King and
Tyler 1981 ).
25.3 Wetlands and Wetland
Conservation in New
Zealand
25.3.1 Introductory Note
The New Zealand (NZ) archipelago consists of
three main islands (North, South and Stewart
Islands) and a widely separated group of smaller
islands spanning a temperate zone from 29° to
53° south in the Southwest Pacifi c Ocean.
Wetland ecosystems are characteristic of NZ.
Wetlands occupy a small part of New Zealand,
less than 2 % of the total land area. Their presence
is associated with the fact that NZ experiences a
lot of storms, earthquakes and ice factors, which
contribute to the formation of wetlands. This
linkage of physical processes with physical
features is refl ected in the hydrological classes
typical of NZ wetlands, rivers and bogs from frequent rain; lakes from glaciation and volcanic
actions; swamps from the deposition of erosion
products by rivers and the sea; and estuaries and
lagoons from tidal fl ooding of old Pleistocene
valleys. Associated with these hydrological
classes are wetland communities which are particularly distinctive of the country, contributing
to the national landscape identity and the uniqueness of the NZ biogeographic region. They
include fl ax swamps of Phormium spp., braided
rivers which form good waterfowl habitat, high
country cushion bogs and tams, salt rush and reed
estuaries with Leptocarpus and Juncus spp. and
kahikatea ( Dacrycarpus dacrydioides ) swamp
forest. There is considerable history of modifi cation and use of wetlands by both Maori and
Europeans. The history of wetland conversion
and modifi cation often relates to expansive
phases of NZ history. It may be noted here that, in
addition, the rivers occupy c 294,600 ha and
lakes account for c 339,800 ha of surface area.
25.3.1.1 Threats to the Wetlands in NZ
Pervasive changes to wetland continue throughout the country: (a) the extension of urban settlements onto wetlands; (b) extraction of sand and
gravel and reclamation of estuaries, lagoons, lake
shores and river margins; (c) draining of on-farm
swamps; (d) encroachment by exotic weeds;
planting of spartina on coastal mudfl ats; etc.
25.3.1.2 Conservation of Wetlands
in NZ
As such, conservation of the wetlands is
essential. Hence, the greatest single need is the
(a) establishment of buffers of indigenous vegetation along rivers (from their headwaters to the
sea) and around the margins of lakes, swamps
and estuaries and (b) the protection of corridors
linking wetlands of all kinds to other terrestrial
and marine protected areas.
25.3.1.3 Goods and Services
by Wetlands in NZ
The wetlands have always had an important
role within Maori communities in an intricate,
25.3 Wetlands and Wetland Conservation in New Zealand