Transcript The wetland ecosystem & urban development

The wetland
ecosystem
&
urban development
producer: Tam Kit Ying 7A no.6
CONTENT
 What are wetlands?
 Importance of wetlands
 Wetlands in Mei Po
- Introduction
- Biotic and abiotic components
- Linkages of ecosystem
- Effect of urban development
- Conservation
 Conclusion
What are wetlands?
[1]
 Transitional zone between permanently wet and
generally dry environments
 Support a large variety of plant and animal
species
 Can be found on the coasts and inland
What are wetlands?
[2]
Definition in Ramsar
Convention
… areas of marsh, fen, peatland or water,
whether natural or artificial, permanent or
temporary, with water that is static or
flowing, fresh, brackish or salt including
areas of marine water, the depth of which
at low tide does not exceed 6 m…
Importance of wetlands
 As a winter
ground
 Support many
Species
 Improve water
quality
 Prevent flooding
 Economic
benefit
 As an
educational
environment
Wetland in Mei Po
Introduction
[1]
 Location
 One of the wetlands in Hong Kong
 located at Deep Bay at the mouth of
Zhujiang.
 cover an area of 380 hectares
 comprise shallow fish and shrimp
ponds, dwarf mangroves and reed
beds
Introduction
[2]
 Values
 recognized as one of the 41 SSSI in HK
 listed in the Sixth Schedule of the Wild
Animals Protection Ordinance
 access is restricted by the Agriculture,
Fisheries and Conservation Department
of the Hong Kong Government.
Introduction
[3]
 Land use
 24 Gei Wais
 Mei Po Marshes Wildlife Education
Centre and Nature Reserve
 offers a wide range of educational
opportunities for students, scientists,
bird watchers, and the general public.
Biotic components: Plant
1.Mangroves
 refer to groups of
plants belong to
several families
which share a
common habit and
habitat.
 soft depositing
shores in tropical
and subtropical
regions
 receive nutrients from both regular tidal
flushing and freshwater streams and
rivers
 four common mangroves: Kandelia,
Bruguiera, Aegiceras and Avicennia.
 To overcome
extreme conditions,
develop:
i) Droppers
ii) Prop roots
iii) Pneumatophores
iv) "Knees" of roots
v) Salt glands
2. REEDBEDS
 one of the largest remaining stands in
Guangdong Province
 rich feeding habitat for migratory birds
Biotic components: Animals
1. Shrimp




feed on the rich
mangrove litter and
accumulated detritus
protein rich food source
for predators
Economical value: sold to
market
increasing water
pollution , reducing the
productivity of the
shrimp ponds and
economic gain
2. Fishes
 enriched with
nutrients from
Shenzhen River
 About 20 species of
fishes occur in the
Gei Wais.
 fishes can grow
very rapidly and are
generally nonselective feeders
3. Mammals
 nocturnal and not easily seen during the
daytime
 include House Mouse, Brown Rat, Lesser
Ricefield Rat, Large Bandicoot Rat,
Chinese Common Otter, Civet cats
 feed on plants and animals in the
Marshes
a. Fiddler Crab
•
most distinctive species living in the mud
banks of sluice channels
•
featured with prominent different sized
chelae
one is for attack and defence, the other is
for feeding
channels provide good shelter, protection
and constant nutrient supply to the crabs
that are abundant
•
•
b. Mudskippers
 amphibious fish which has
developed means for short period
survival out of the sea
 dark grey-brown or green
coloring, several darker dots or
oblique stripe across their bodies
 feed on either insects or mud
 prized as a delicacy and are
caught and consumed locally in a
considerable quantities
c.
Reptiles and Amphibians
 marshes provide a variety of habitats ranging from
tidal mangroves to fully terrestrial areas
 Gei Wais provide rich and permanent food supply to
these animals
 earth bunds between ponds are sufficiently dry and
well vegetated to allow them shelter and breed
 animals include snakes, Water snakes, chelonians,
lizards, Gold-headed Terrapin, Reeves' terrapin,
Redeared Terrapin, Chinese Soft-shelled Turtle,
Steindachner's Turtle
d. Birds
 Wetland acts as a
refueling station and
wintering site for
thousands of migratory
birds in their migration
between the Arctic Russia
and Australia.
 More than 120,000
migratory birds stay in
this area in a year
 Some birds are globally
threatened / endangered
species, such as Blackfaced Spoonbill (黑臉琵
鷺), Saunders' Gull,
Baikal Teal etc
Black-faced Spoonbill
 one of the most
endangered species of
birds (only 700 left on
Earth)
 feeds on small fish and
shrimp in wetlands
 25% of the world's
Black-faced Spoonbills
spend winter in and
around the wetlands of
the Mei Po
Abiotic components : Gei Wai
 Covers an area of 240
ha
 Ponds are stocked by
flushing in young
shrimps from Deep
Bay in autumn, and
the shrimps feed on
naturally occurring
organic matter ,on the
bottom of the pond.
 So fishermen
protected the stands
of mangroves inside
the pond as a source
of food for the shrimps
and fish.
[1]
Abiotic components : Gei Wai
 Gei wai are completely drained in
turn for harvesting the remaining fish
inside
 Large areas of vegetation within the
gei wai, principally mangroves,
reedbeds and sedges
[2]
Abiotic components :
Freshwater ponds (fish pond)
 triangular pond at the back of the Mei
Po Education Centre
 aim to manage as a freshwater pond
using rainwater to provide the
freshwater
 Problems: leaks in the bunds of the
pond allowing brackish water in from
adjacent ponds.
 So, whole pond has had to be drained
and the leaks plugged.
Linkage between biotic and
abiotic components (Food Web)
 close inter-relationship
 Mutualism: an association in which 2
species of organisms live together
and both obtain benefits from each
other
 Non-mutualism: two organisms are
not live together directly, but in close
relation with each other.
[1]
Food Web
[2]
Non-mutualism
Competition:
relationship in which
2 organisms (competitors)
attempt to obtain the same
requirement
Predation:
a relationship in which one species,
the predator, kills and feeds
on another species, the prey.
Food Web
i)
[3]
Interdependence
commensalisms
an association between 2 organisms of different
species, in which commensal is benefited while the
host is not affected.
ii) Parasitism
an association in which two species of organisms live
together. parasites gain benefit from and impose
harm to the hosts, which suffer from the loss of
nutrients and other discomforts.
Effect of urban development
 Hydrological alternation
1) Human activities: drainage, dredging, stream
channelization, ditching, levees, deposition of
fill material, stream diversion, ground water
withdrawal,and impoundment.
2) Affect the soil chemistry and plant and animal
community in the wetland
3) Reduce or increase the natural amount of
water/the period of saturation and inundation
 change ecosystem to an up land system /
riverine or lacustrine system
4) Loss of habitat and fragmentation
5) Alters water diversion structures and
impoundments
6) Change of water diversion structure can change the
patterns of sedimentation
7) High sediment loads entering wetland can smother
aquatic system shellfish beds and tidal flats, fill in
riffles and pools, and contribute to turbidity.
8) Saltwater may be upstream and cause species
change and mortality of salt-intolerant vegetation
in both upstream and downstream
9) Impoundment alters the natural wetland's
hydrology and decreases water circulation
10)Decreased circulation can cause an increase in
water temperature, lower dissolved oxygen levels,
and changes in salinity and pH
11)Prevent nutrient flow, increase in sedimentation.
12)Toxic substances may accumulate and
contaminate wetland biota.
 Urbanization
 Reclamation and dumping reduce the area
of wetland e.g Tin Shui Wai New Town
 Loss of wildlife habitats and water-storage
capability  loss of wildlife and flooding
 Reduces the productivity of the land and
their ecological value.
 Degradation of wetland: caused by the
change in water quality, quantity and flow
rates, increases in pollutant inputs; and
changes in species composition as a result
of introduction of non-native species
 Marinas / Boats
 Intense boating activity increase the
turbidity and degradation of wetlands
 Dumping of wastes increase the amount of
nutrients and organic matter  lead to
eutrophication
 Eutrophication: nutrient level in water is
much higher than the demand 
phytoplankton population explosion,
massive death, and damage the ecosystem
 Reclamation
 New HK International Airport is built, dumping of soil
and sludge raised the suspended solid level in water
 High suspended solid blocks respiratory system of
marine animal and plants that may cause death.
 Industry
 alter the wetland hydrology, increase water
temperature, input of pollutants, change of pH value
 pollutants can alter reproduction, growth, and
behaviour of wetland organisms and result in
mortality
 Agriculture
 Degrade wetlands, including harvesting
food, fiber, or forest products, maintenance
of drainage ditches, construction and
maintenance of irrigation ditches, farms
and roads, dams, dikes, and levees, direct
and aerial application of damaging
pesticides and groundwater withdrawals
 Alter water hydrology, water quality and
species composition. Excessive application
of fertilizers and animal waste can cause
eutrophication
Atmospheric Deposition
 Air pollutants released from industrial and agricultural
activities and from vehicles enter wetlands through
atmospheric deposition and therefore affect the
organisms in the wetlands.
 Pollution Problems
 new infrastructure and construction bring large
amount of trash and solid waste to the new landfalls
 Factories, farms and restaurants in N.T. dump out
large amount of sewage or even untreated waste into
the streams and the sea
 severe damage is irreversible and the creatures in the
sea are the direct victims of the capitalized city’s
effort
Victims:
 nature reserve and birds in Mei Po Marsh
threatened by the pig sewage flooding and the
increased pollution from Shenzhen
 bird forced to leave due to the government’s plan
to build huge residential housing estates in the
N.T
 nature environment around Mei Po is changing –
no longer a perfect heaven for the birds
 flora and fauna ,human being are affected by
ceaseless construction and large numbers of
diesel vehicles have made for dangerous levels of
particulate matter and nitrogen dioxide
Conservation
 Designation as Ramsar Site – Mai Po
 Sites of Special Scientific Interest (SSSI)
 Sixth Schedule of the Wild Animals
Protection Ordinance (Cap. 170)
 Access permit required
 Wetland management plan for Mai Po
Marshes
Managing zone
purpose
Core zone
provide an undisturbed, largely natural,
contiguous reference area where the
biological interest of the site is
concentrated
Biodiversity management zone
to provide a refuge for waterfowl and a
focus for biodiversity conservation,
education and training in a relatively
intensive management environment.
Public access zone
Wise use zone
to enable people to have unrestricted
but managed access to a part of the
Ramsar site in order to appreciate its
special values and enjoy contact with
wildlife
to allow ecologically sustainable use of
wetland and other natural resources to
be carried out
Private land zone
to obtain and maintain the cooperation
of the owners concerned to conduct
their management in an ecologically
sustainable manner consistent with the
purposes of the surrounding or
adjacent management zone
Effective measures:






stop damaging the wetlands
Setting up some laws to avoid people doing
something like deforestation, large amount of fishing
and hunting in wetlands.
monitor the wetlands to see whether changes are
happened.
construct more wetlands manually to increase the
proportion of wetlands. (animals have more choices
for them to live in)
Promoting the conservation of nature and natural
resources to the publics does not be neglected
(*children )
Tours of Mai Po can let the people know more about
the importance of wetlands.
Conclusion
Wetlands:
 home for many beautiful and rare species
 protect many of our sources of drinking water
 source of many commercially and recreationally
valuable species of fish, shellfish and wildlife
 retain flood waters and protect shorelines from
erosion
 Losing or degrading wetlands can lead to serious
consequences
 avoid these consequences by maintaining the
valuable wetlands we have and restoring wetlands
Relevant websites
Agriculture, Fisheries and Conservation Department
(http://www.afcd.gov.hk/web/)
World Wide Fund For Nature Hong Kong (http://www.wwf.org.hk/)
The Ramsar Convention on Wetlands
(http://www.ramsar.org/)
National wildlife Federation (USA) (http://www.nwf.org/wetlands)
Water, Soil, and Hydro-Environmental Decision Support system Information on Wetlands
(http://h2osparc.wq.ncsu.edu/info/wetlands/index.html)
Convention on Conservation of Migratory Species of Wild Animals
(Bonn Convention) (http://www.wcmc.org.uk/cms/)