Mangrove ecosystems consist of plants and animals that have adapted to living in the intertidal zone between land and sea in tropical and subtropical regions. Mangroves provide shelter and food for many species through their complex root systems and nutrient cycling between plants, consumers, and decomposers. However, mangroves are increasingly threatened by land conversion for development and pollution, which degrades these important coastal ecosystems.

1. Mangrove ecosystem

2. What are mangroves?
 Mangroves consists of different kinds
of plants living on protected soft
shores

3. Northeast New Territories

4. Environment

5. Tidal zone

7. Soil in anaerobic
condition

8. Distribution
 In tropical region between 20ºN and
20ºS where the annual temperature is
above 20 degrees

9. Environment
 Highly unstable environment as
sedimentation is active but the soil is
not consolidated
 Waterlogged soil, so aeration is poor
 In high salinity environment

10. Plants
 Plants adapt to the soft sea shore
where mud and sand are deposited
Root buttresses and stilt roots develop

11. Mai Po Marsh

12. Common mangrove
plants
 Kandelia candel
 Avicennia marina
 Lumnitzera Racemosa
 Bruguiera gymnorrhiza
 Heritiera littoralis
 Aegiceras corniculatum

13. Salt released on leaves

14. Avicennia marina

15. Lumnitzera Racemosa

16. Pneumatophores
Avicennia marina

17. Pneumatophores
Avicennia marina

18. Knee roots

19. Buttress roots

20. Derris trifoliata in Lai Chi Wo

22. Heritiera littoralis

23. Droppers

24. Cerbera
Manghas

25. Animals
 Crabs - fiddler crabs and sesarmine
crabs
 Oysters and barnacles
 Gastropods

26. Animals
 Mudskippers live between the high-
tide and low-tide level. They can live
without water for days
 Fish and shrimps
 larval

28. Mudskipper

29. Mudskipper

30. Mudskipper

32. Fiddler Crab (Uca borealis)

33. Crab

34. Crab

35. Fish

36. Egret

38. Energy flow
 Warm tropical climate provide a lot of
solar energy for photosynthesis
 Mangrove litter dropped on the ground
is consumed by crabs, shrimps and
fish

39. Energy flow
 The small animals are then eaten by
larger fish and then by resident and
migrant birds (egrets and spoonbills)
 The litter that is not consumed is
decomposed in the soil

40. Example
 The fish ponds and gei wais in South
China
 The marsh provides shelter for
juvenile and larval animals such as
shrimps and fish
 Litters, small plants and animals
provide food for these animals in the
ponds
 The animal wastes and litter enrich the
soil with nutrient

41. Nutrient cycling
 The sea and rivers carry nutrients to
the shore
 The nutrients are absorbed by
mangrove plants and seagrasses and
algae.
 The nutrient is then transferred to the
consumers such as crabs, fish and
shrimps
 then transferred to human beings,
birds and large fish

42. Nutrient
cycling

43. Nutrient cycling
 The dead bodies and litter are
decomposed by micro-organisms in
the soil
 Nutrient is released to the soil and sea
water

44. Utilization and threats
 Marsh lands have been dredged and
vegetation removed to form fish ponds
 They have been developed into
recreational grounds for fishing and
barbecue
 This provides income and can make
better use of mangrove resource.

48. Threats
 Increase in demand for land in coastal
areas.
– For industrial and residential development
– Recreational use
 Environmental pollution around the
wetland
 Other threats?

52. Tin Shui Wai

53. Yuen Long Industrial
Estate