Threats of loss of fish breeding grounds due to loss of mangroves in

Asia

Dhiman GainSvetlana Vasic

Outline

• Introduction• Who is affected and what the effects are• What values are at stake, and how the ethical

theories discussed would apply in considering the issue

• Who bears responsibility for addressing the situation

• What policies should be applied

Introduction• Locality: River mouths, river banks, coasts, small islands • Wave action: Preference to grow at areas with low wave action -

Why mangroves do not grow on most shores, e.g. sandy beaches? • Dynamic environment: periodically submerged by tidal flows (recall

definition!)• Elevation: relatively low elevation (compared to other forest)• Sediment: prefers to grow on muddy-silty terrain• Temperature and weather: sunny and tropical all-year long

Introduction…

• Mangroves are various large and extensive types of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics—mainly between latitudes 25° N and 25° S.

• Mangroves are salt tolerant trees (halophytes) adapted to live in harsh coastal conditions.

• Some of the largest mangrove forests in the world are found in Asia, the most well known being the Sundarbans, a transboundary forest covering approximately 1 million hectares in Bangladesh and India.

• Other Asian countries with a significant extent of mangroves are (in order of mangrove area) Malaysia, Myanmar, Bangladesh and India, which, together with Indonesia, account for more than 80 percent of total Asian mangrove area.

Introduction…• Human pressure on coastal areas and

increasing demand for land for agriculture represent increasing threats to mangroves in these countries

• In this region some 1 900 million hectares of mangroves – or about 25 % of the 1980 area – have been lost during the last 25 years. More than 90 % of this loss has been caused by the major mangrove area changes in Indonesia, Pakistan, Viet Nam, Malaysia and India, which experienced a cumulative loss of more than 1700 million hectares.

-Buffer Zone between the land and sea.-Protect the land from erosion. -Play an invaluable role as nature's shield against cyclones, ecological disasters and as protector of shorelines.-Breeding and nursery grounds for a variety of marine animals.-Harbor a variety of life forms like invertebrates, fish, amphibians, reptiles, birds and even mammals like tigers.-Good source of timber, fuel and fodder.-Main source of income generation for shoreline communities like fisherfolk.-Save the marine diversity, which is fast diminishing.-Purify the water by absorbing impurities and harmful heavy metals and help us to breathe a clean air by absorbing pollutants in the air.-Potential source for recreation and tourism.

Importance of Mangrove

Figure from Yee et. al (2000) The present extent of mangroves in Singapore, NIS,

Provides coastal protection: attenuates wave energyPrevents erosion

Ongoing threats to mangroves1. Clearing(Major factor of mangrove loss!) -seen as unproductive and smelly- cleared to make room for agricultural land, human settlements and infrastructure (such as harbours), tourist developments, shrimpaquaculture, and salt farms

2. Overharvesting-non-sustainable harvest of timber

3. River changes- Dams and irrigation: reduce water and sediment reaching mangrove forests, increases salinity level in mangroves -freshwater diversions can also lead to mangroves drying out.

4. Overfishing:- ecological balance of food chains and mangrove fish communities can also be altered.

5. Destruction of coral reefs -when they are destroyed, the stronger-than-normal waves and currents reach coasts

6. Pollution-Fertilizers, pesticides and chemicals kill animals living in mangrove forests- Oil pollution can smother mangrove roots and suffocate the trees.

Ongoing threats to mangrovesOngoing threats to mangroves

7. Overexploitation of abiotic resourcese.g. Timber, honey etc8. Shrimp aquaculture9. Natural calamities e.g coastal cyclones, Tsunamies

etc

• The main causes of mangrove loss in Indonesia are conversion of land for shrimp farms (East Java, Sulawesi and Sumatra), excessive logging and, to a lesser extent, conversion of land to agriculture or salt pans (Java and Sulawesi).

• Malaysia lost about 110 000 ha of mangroves from 1980 to 2005.

Why Mangrove loss is a threat to fisheries

• Mangroves trap debris and silt, stabilizing the near shore environment and clarifying adjacent open water, which facilitates photosynthesis in marine plants. The fringing network on Mangroves buffers natural forces such as hurricanes, wave action, tidal change and run-off, preventing soil loss with its firm, flexible barrier.

• MANGROVES ARE NUTRIENT PRODUCERS that shed and drop about seven and a half tons of leaf litter per acre per year. The constantly-shed leaves are quickly broken down by bacteria and fungi and released into the water, providing food for sea-life.

Mangrove species Food use Medical use Tool use

Avicennia marina, white mangrove

fruit eaten after treatment, (Mornington Is; Tiwi; Boorroloola, Roper R; Belyuen; Bardi; Dampierland); flavour in cooking mussels (Groote Eylandt); nectar

sting-ray and stonefish ‘stings’ (Milingimbi);ringworms, sores and boils (Yirrkala); scabies (general); 'cheeky' mangrove worm medicine for coughs (Tiwi)

shields

Bruguiera gymnorrhiza mangrove worm (Tiwi);hypocotyls eaten after treatment (Cape York)

spear tips (Belyuen); throwing sticks for hunting magpie geese (Tiwi);boomerangs

Ceriops australis spear shafts (Tiwi)

Excoecaria ovalis nectar (Groote Eylandt)

toxic plant, latex causes skin to swell (Milingimbi);leprosy sores, marine stings, body pain

floats for turtle hunting, firewood (Groote Eylandt);cordage

Lumnitzera littorea nectar-rich flowers as sweets (Yirrkala)

digging sticks, throwing sticks (Belyuen)

Rhizophora stylosa mangrove worm (Tiwi); mud crabs found at roots (Belyuen; Tiwi)

skin sores (Tiwi); ulcers and yaws (NT)

ceremonial armbands (Tiwi);boomerangs, spears, firewood (Bardi); clubs (Arhnem Land)

Sonneratia alba nectar skin disorders (Tiwi) tops (Tiwi); carving wood

The major effects of mangrove loss

• Economic loss• Environmental alterations • Social impacts

Responsibility for addressing the this adverse situation

• Community who use this resource and directly dependent on it for their livelihood:

- Fisher- Honey collector - Wood collector • People who are indirectly dependent on it- General people• Local authority e.g. Forest department • Government

Policies that should be applied to mitigate the problem

• Bottom-up approach can be applied rather top-down• Giving ownership to the community• Community based management by giving ownership

to the community• Mangrove restoration by plantation through paid

work e.g. Nypa frutican

• Ecosystem based management

• Declared as a protected area e.g. MPA

Who is responsible to develop and apply the policies

• The Government and the local authorities are responsible to make the right policies and management approach

• Community as well as general people need to respect, follow, apply and act according to that policies

Thanks To All