Over 50% of the world's original mangroves have been lost, mainly due to aquaculture, agriculture, and deforestation. Shrimp farming in particular has led to significant mangrove loss in Asia and Latin America. In Thailand, shrimp farming expanded rapidly from 1970-1990 and resulted in the loss of over half of the country's mangroves. The expansion was driven by increasing global demand for shrimp and government support. While shrimp farming provided economic benefits, it also caused environmental problems like soil salinization, biodiversity loss, and pollution from farm effluent. Climate change further threatens mangroves by increasing risks of sea level rise, storms, and carbon release from destroyed mangrove forests. S

1. Threats to MangrovesA2 Geography

2. Learning ObjectivesUnderstand the nature and extent of mangrove lossWhat are the drivers of changeUnderstand the problems associated with Human activity within Mangroves, including exploitationAppreciate the consequences of climate change on Mangrove forests

3. Mangrove LossOver 50% of the world’s original mangroves have now been lostA size similar to 13 UK’sBy 2007 less 15 million left hectares leftCurrently the rate of loss is 1% p.a. (Roughly the size of London)

4. Rates of LossThailand has lost over half of its mangroves since 1961The Philippines 40% were lost to aquaculture between 1918 and 1988By 1993 123,000 hectares were left (70% loss in 70yrs)Ecuador – Mangrove loss is estimated to range between 20% to 50% of the 362,000 hectares of mangrove forested coast.

5. Why?Think in groups why this might happen and write them down on the post it notes providedThink why do we deem this a palatable thing to do.

6. Asia has lost 50% due to aquaculture (38% Shrimp. 14% fish) 25% due to deforestation. 11% to upstream freshwater diversion.Latin America – Mainly due to the expansion of agriculture and cattle rearing, as well as the cutting of fuelwood and building materials as well as the establishment of a shrimping industry.

7. Drivers of ChangeWhat are the main threats to biodiversity:Habitat changeClimate changeInvasive speciesOver-exploitationPollutionHabitat changeClimate changeInvasive SpeciesOver-ExploitationPollution (N, P)Coastal Wetlands

8. Shrimp Farming in Thailand Case Study (LEDC)

9. ShrimpingBeen done in Thailand for over 60 yearsTraditional method now known as ‘Extensive production’ Shrimp (Known as ‘fry’) are trapped in salt beds and padi-fields around estuaries and harvested when mature.Between 1970 -1990 the coastal shrimp industry expanded massivelyWith help from the govt the shrimping industry became more intensive

10. WhyTo help meet global demandExported to USA (500,000 tonnes a year – 2003)Japan = 250,000 tonnesFrance, Spain, UK and Italy = 500,000 tonnesSince 1990’s amount consumed in Thailand has also increased – rising incomes due to improved economic conditionsIncrease in tourist industry.

11. Production

12. Land Conversion

13. Shrimp farming area and Mangrove area

14. Impacts of the IndustryWhat are the positive impacts of the industry?Shrimp farming has had positive impacts such as increased wealth leading to improved infrastructure and reduction in migration to Bangkok many are negative

15. NegativesEffluent from shrimp farms has to be removed before next crop cycle beginsIt is full of decaying food, shells and chemicals (Antibiotics)

16. If chemicals get discharged into mangroves this can have a harmful effect on biodiversityConflicts arise due to this dischargeConstant threat of disease and infectionRice fields and channels suffer from salinisationDepletion of biodiversity in shrimp farms and surround areasLoss of mangrove forest or fertile land Degradation of the soil due to salinisation Deterioration of water quality

17. Future?Marine shrimp culture along the coast is one of the main economic activities in the countryIt provides employment and earns national incomeWithout management the environment maybe damaged beyond repairGovernments should promote the development of marine shrimp culture along the coast but before implementation, a development plan should be formulated and good management practices should be specified

18. Department of Fisheries, Bangkok advice on Shrimp farmingA land use plan should be formulated which does not allow the utilisation of mangrove for shrimp culture. The most suitable area for shrimp farming is rice fields or unused low land beyond the mangrove. The level of such land will be not over 1–2 m above the high tide level.To provide infrastructure which supports the shrimp culture industry such as drainage canals, roads, electricity and other necessary services. Control and enforcement of farm practices will be done by the official agency.To provide education on farm and water management to farm owners and farm operators before they start farming.Monitoring of sea water quality along the coast will be routinely conducted and information on water quality transferred to the farmers. Shrimp pond wastes will not be discharged directly into natural water ways. The waste treatment pond will be attached to the farm system and waste must be treated before discharge.Research on farm management, disease and parasite problems must be conducted and findings regularly transferred to the farmers

19. Climate ChangeThreats to Mangroves

20. Links to ASI in 10 people live less than 10m above sea level near the coastAsia contains 75% of these peopleGlobal warming leads to:Increased Arctic ice cap meltGreenpeace predict sea levels to rise between 15 – 95cm this centuryThis could cause some shorelines to retreat by upto 200m

21. Carbon Sequestration

22. Mangroves take up about 1.5million tonnes/hectare/year Current removal means we are losing 220,000 tonnes of sequestration potentialHigh levels of carbon in the soils is dug up and also releasedRemoval of mangroves means carbon release is often 50 times higher than rate of sequestrationBy converting 2% of mangroves it effectively means all advantages of sequestration are lost

23. Mangrove time bomb

24. Mangrove BenefitsHealthy mangroves can act as a buffer zone between the coastal fringes and inland areasIncreases are expected in hurricanes and cyclones and the mangrove can help protect landProtect against coastal erosion

25. HoweverRising seas levels will swamp the forests nullifying their benefitMangroves need a buffer zone themselves to develop and re-establish above the rising low tide – this too maybe lost

26. Over- HarvestingMangrove trees serve many purposesFuelwoodConstruction materialWood Chip and pulp productionCharcoalAnimal fodderHarvesting has been going on for centuries but it is no longer sustainable

27. Over Exploitation of Marine LifeUnregulated fishing is depleting fish stocksAs stocks of one become uneconomic to exploit people are simply turning to anotherDecline in biodiversity, loss of income and jobsOver fishing alters the food chain and webs and mangroves communities can be altered as a result

28. Other ThreatsTourismRemoval for golf coursesBuilding of new cruise ship portsMarinasHotels, apartments and restaurants

29. Oil ExplorationDeforestationChanges in Soil pHDischarge of solids and liquid waste

30. Other ThreatsDomestic and Industrial wasteWaste from aquacultureExploration of minerals

31. Learning ObjectivesUnderstand the nature and extent of mangrove loss

32. What are the drivers of change

33. Understand the problems associated with Human activity within Mangroves, including exploitation

34. Appreciate the consequences of climate change on Mangrove forestsHomeworkWrite a 500 word reportWithin which you must report on the threats to biodiversity in mangrovesHow far these are likely to changeWhether these threats reflect people’s attitudes to mangroves and biodiversity

35. LinksShrimp Culture in ThailandThe Rise and Fall of the Blue RevolutionThe Impact of International fish trade on Food security in ThailandManu Potaros, Department of Fisheries, Bangkok