AA BriefBrief IntroductionIntroduction toto thethe PearlPearl RiverRiver EstuaryEstuary Wetland,Wetland, SouthernSouthern ChinaChina

Y S Peng a* G Z Chen a a School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, China PR; * Author for correspondence

Nov. 15th, 2007 Salaya, Thailand ContentContent

1 Introduction

Overview of characteristics of the Pearl River 2 Estuary Wetland

Overview of current issues and management strategy 3 at the Pearl River Estuary Wetland

4 Conclusion 11 IntroductionIntroduction

The neritic area of South China Sea one of the tropical centres of biodiversity globally

Abundant habitats Rich fishery resources mangrove, coral in the eight countries of reefs, sea grass and highest shrimp yield in the coastal wetlands are world, there are five located more abundant than in the coastal area of South any other sea area in China Sea the world. 11 IntroductionIntroduction

™ The habitats and resources around South China Sea had been severely disturbed and destroyed ƒ over-fishing, ƒ absurd oceanic development and utilization, ƒ land-based pollution from adjacent areas, ƒ the mangrove was over-exploited (UNEP, 2004a), ƒ over 50% of coral reefs were endangered (UNEP, 2004b). ™ The globally significant biodiversity will be destroyed thoroughly in the next century unless the speed of destroy could not be slowed down effectively. 11 IntroductionIntroduction

Pearl River 3S Beilun River Estuary Wetland biology Estuary Wetland ecology Shantou Intertidal environmentology Wenchang Wetland hydrology Lagoon Wetland topography Hepu Intertidal meteorology Danzhou-Lin’gao Wetland Intertidal Wetland

wetlands of international importance important wetlands of South China Sea important wetlands of China 22 OverviewOverview ofof characteristicscharacteristics ofof thethe PearlPearl RiverRiver EstuaryEstuary WetlandWetland ., 2002; Xing, et al et Source Source ., 2001; Xing Xing 2001; ., ., 2000 ., et alet ., 2007 ., et alet et alet ., 2005 ., ., 2005 ., 2005 ., 2005 ., ., 2005 ., ., 2005 ., et alet et alet alet et alet et alet et alet Chen Chen Chen Chen Chen Chen Hou , 1956; Wu Wu Hou 1956; , Peng 2004; Chen Chen M acKonnon Chen Chen -3 -3 -3

-2 tropical floras 1500 ind·km Table 1 The biodiversity of general taxa in the Pearl River Estuary the Pearl in taxa 1 The general of biodiversity Table Taxa Species Species Taxa Notes Aves 227 227 Aves The Pearl River Estuary Wetland has abundant biodiversity. The detailed status of biodiversity is given below (Table 1). Fishes 302 Maximum species density: species Maximum Fishes 302 Reptiles 43 43 Reptiles Mammals 32 32 Mammals Amphibians 12 Zooplankton 418 biomass: 134 Mg·m aximum Higher plants > 3500 Temperate, subtropical &

2.1 Natural wetland resources M acrobenthos 518 biomass: 589 Mg·m aximum

2.1 Natural wetland resources ™

wastes, excess significant environmental deterioration. this delta, municipal density: ten (data not including Hong Kong rial wastewater and of -2 certain industrial km · 2 nutrients, and oil pollution. municipalities per 1,000 km population density: 674 people 28 cities and 420 towns are settled in legislation of the treatment indust several large cities in the delta, primarily due to residential and and Macau until 1999) Extremely rapid urbanization and industrialization ƒ ƒ ƒ ƒ One of the most populated areas in China mainland One of the most industrialized in China Pearl River in the delta is still heavily polluted

2.2 Social and economic background 2.2 Social and economic background ™ ™ ™ ™ organic content due to aquatic breeding (1) sea-level rise (2) high levels of pollution from land-based sources (3) discharge of city and industrial wastewater (4) discharge of substances with high (5) discharge of agricultural wastewater (6) oil pollution (7) over-fishing and aquaculture (8) reclaiming land from the sea (9) reclamation and development of coastal wetlands (10) excavation of coastal beaches, which destroys the habitat benthos, fish, and shrimp (11) increasing atmospheric pollution (Lan & Chen, 2006) ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ Internal sources: the changes in rate of siltation and land formation. External sources

2.3 Extent of threats 2.3 Extent of threats ™ ™ ) 2 2 d on the western coast of Humen, arl River arl River Estuary 1966 tokm from 1996 (Unit: -1 yr · 2 total reclaimed area in the entire delta: 344 km average rate: 11 km greater than that of the historical period Most of the land reclaimed is locate Modaomen, and Yamen Outlets ƒ ƒ ƒ ƒ In the Pearl River Estuary, rate of land reclamation is very high, which is changing the wetlands rapidly (Table 2). From 1966~1996 Total 21.7 49.9 21.0 10.0 42.6 10.0 21.0 21.7 Total 49.9 Table 2 Increases in in reclamation the in 2 Increases Peland Table Duration Duration Ken Sha & Sha Bao Ji Sha Qing Wan Men Heng Men Xing Jin Area Eastern 2.4 Rate of change 1966-1986 0 36.4 1986-1996 21.7 0 10 23.6 21.0 26.3 0 6.2 2.4 Rate of change ™ ™

33 OverviewOverview ofof currentcurrent issuesissues andand managementmanagement strategystrategy atat thethe PearlPearl RiverRiver EstuaryEstuary WetlandWetland

™ In the China National Wetland Conservation Action Plan: listed as a ‘Nationally Important Wetland’, all levels of the government provided financial, scientific, and material support to the protection of the wetland (SFA, 2000). ™ Several nature reserves existing ƒ Guangdong Neilingding-Futian Nature Reserve in 1984, for mangrove and monkey ƒ Zhuhai Qi’ao-Dan’gan Islands Nature Reserve in 2003, for mangrove, island ecosystem & monkey ƒ Mai Po Marshes & Inner Deep Bay in 1995, for wetland and migratory birds ƒ Pearl River Estuary Nature Reserve in 2001, for the Pacific Hump-backed Dolphin ™ Plan on provincial level ƒ from 2006~2010, setting up 22 wetland nature reserves, totalling 427,078.8 hm2, which represents 22.81 % of the total area of wetlands in Guangdong ƒ Along the coast of Pearl River Estuary, several thousand hectares of wetland has been rehabilitated in the past few years. mud bottom fish surrounded by crop dikes (mulberry, Pearl River Estuary for several system degradation and system degradation and crops dike-pond system manure rms o livestock silkw centuries - in low-lying area agro-ecosystem sustainable developed and practiced in the developed and practiced consists of fish ponds generally sugar cane, orchard, flowers or vegetables) ƒ ƒ The traditional dike-pond system (DPS) The input and output of material energy in the dike- pond system are basically balanced. (Ruddle & Chung, 1988; Korn, 1996).

3.1 Case study 1: dike-pond restoration - agroecology and wetland management 3.1 Case study 1: dike-pond restoration - agroecology and wetland management ™ ™ Livestocks Crops Pond

system degradation and system degradation and Fish Bottom mud Bottom Mulberry Silkworm

3.1 Case study 1: dike-pond 3.1 Case study 1: dike-pond restoration -restoration - agroecology agroecology and wetland management and wetland management tilizer: leading to the concentration many farmers did not want to run bottom mud filled up, the DPS

system degradation and system degradation and lization: mismanagement and unction of many dike-pond systems unction of contaminants along the food chain of contaminants replacement of mulberry, decline of traditional Chinese carps replacement of mulberry, decline traditional production, more intensive monoculture rapid urbanization & industria degradation pollution: loss of the normal f too much pesticide and chemical fer dilapidation: relatively low profit, degraded, productivity became lower the dike-pond system anymore, ƒ ƒ ƒ ƒ ƒ Since the late 1980s, DPS facing problems

3.1 Case study 1: dike-pond restoration - agroecology and wetland management 3.1 Case study 1: dike-pond restoration - agroecology and wetland management ™ . (2003) to et al

system degradation and system degradation and The degradation of the DPS and pollution low-lying land always promote each other, which have affected the agriculture and the regional environment, become trouble of the sustainable development. The environmental pollution, market-oriented, over- intensive mono-cultural systems which are focusing primarily on expanding pond surface to raise production value per unit area are becoming threats to the sustainability of the dike-pond system. A series of technologies was raised by Nie restore and reconstruct the dike-pond system. The detailed contents and technologies are given in Table 3.

3.1 Case study 1: dike-pond restoration - agroecology and wetland management 3.1 Case study 1: dike-pond restoration - agroecology and wetland management ™ ™ ™ technologies technologies of

system degradation and system degradation and Ecological planning for urban use; rural and region; planning for land for planning Ecological structureindustrial spatialregional development; and distribution of agriculture; for small watershed planning technologies renovation; technologies for the for landform of coast, control Technologies mud-rock flow, soil erosion; ecological auxiliary technologies for road for lake,woodland, field, DPS, build the and up river, mountain, design habitat landscapes biogas; cropping, on the stereo-culture rotation dike; mix Intercropping, culture, technologies for the for the erosion; technology; control of soil technologies no-till pest; and of the technologies control reinforcement ecological dike; of disease biotic for organic farming; fertility for soil technologies technologies improvement; for protectivetechnologies forest Table 3 Technologies and and contents reconstruction of dike-pond and system of restoration 3 Technologies Table Technologies Contents Technologies

3.1 Case study 1: dike-pond restoration - agroecology and wetland management

3.1 Case study 1: dike-pond restoration - agroecology and wetland management planning Ecological for regional technologies landscape auxiliaryA technology for restoration and landform landscape ecology of the Technologies restoration and reconstruction for the dike of dike-pond system s for the disconnecting of food chains; of food chains; s for the disconnecting

system degradation and system degradation and Technologies for the rotation of different ecological types of fishestheir andcapture; technologies for the hydrophyte planting; manufacture techniquesecological of feed; cultivation technologies for polyphagia and filter aquatic organisconstruction ms; technologies for the aquatic food chain; technologies forspiritualization; water technologies for water oxygen increase; technologies fortemperature water and light control; integrative control technologies for fish diseases;technologies for water exchange and mud cleanup within a stable period; for the technologies use of pondcomprehensive mud Technologies for the optimization of the dike-pondsystem spatial structure;integrative technologies for the plant cultivation and animal raise; technologiesthe adding or disconnecting for food chains; technologies for the technologies for the biodiversity between water land; and interaction mono-techniques integration of different conservation; Headstream control techniques for agricultural-oriented contamination;technologies separating for irrigation and drainage; technologies for water oxygen increase;technologies of artificial wetland; technologies for oxygenation pond; technologiesfor physics adsorption and filter; technologies for rapid deposition; technologiesplant for or microbial remediation; technologie technologies for the compost decaypond of mud Technologies of the restoration and pond the for reconstruction Technologies of the restoration and the for reconstruction dike-pondintegrative system of restoration Technologies and control for the aquatic environmental pollution

3.1 Case study 1: dike-pond 3.1 Case study 1: dike-pond restoration -restoration - agroecology agroecology and wetland management and wetland management ., et al

to control and to control and y loss in the world (Peng & Xiang, and southern coast of China, tland degradation problems intland degradation the the tidal flats (Mendelsshn, 2004) wetland degradation (Keddy, 2000) Sonneratia apetala Sonneratia apetala ., 2006) et al Spartina alterniflora Spartina alterniflora one of the main causes biodiversit for also the primary factor one of the most invasive species globally the most notorious exotic plant on in 1979, introduced to the northern and southern China (Wang currently, infested along the eastern 1999) creating biological invasion and we local area (Deng 2006) ƒ ƒ ƒ ƒ ƒ ƒ Biological invasion The Smooth Cord-grass, Spartina alterniflora

3.2 Case study 2: using remove 3.2 Case study 2: using remove ™ ™ ., can . et al . S apetala . E. (Lian S ′ and also restore to control and to control and 38.20 ° Aegiceras corniculatum N, 113 alterniflora to control the growth of S . ′ S and ndicated that planting 15.69 ° the Pearl River Estuary (Fig. 2) of tidal flats has been occupied by the Sonneratia apetala Sonneratia apetala 2 Sonneratia apetala Kandelia obovata . This occupation affected the regeneration of natural . This occupation affected the regeneration ., 2002) ’ s (2006) investigation i . et al et al Spartina alterniflora Spartina alterniflora 2003) 66.7 hm until late 1999, central geographical location: 22 located in the western area of alterniflora mangrove, such as (Chen since 2001, planting alterniflora Tang the mangrove wetland ecosystem. effectively control the rapid growth of ƒ ƒ ƒ ƒ ƒ Kei Ngou Island

3.2 Case study 2: using remove 3.2 Case study 2: using remove ™ should be to control and to control and ., 2003). . apetala S et al strong adaptabilities, extensively Sonneratia apetala Sonneratia apetala Spartina alterniflora Spartina alterniflora comparatively high growth rates and planted at the coastal area of Guangdong successful naturalization of in the future, monitoring on biology continued introduced to Hainan Island in 1985 (Zan . apetala ƒ ƒ ƒ ƒ It seems that using an introduced species with relatively rapid growth rate to control other alien species is effective and successful in this case. S

3.2 Case study 2: using remove 3.2 Case study 2: using remove ™ ™ 44 ConclusionConclusion

TwoTwo hintshints forfor wetlandwetland managementmanagement

conservation restoration 44 ConclusionConclusion

™ Utilization of wetland: dike-pond system ƒ excellent example for wetland wise use and sustainable development ™ The Pearl River Estuary Wetland ƒ the countermeasures could be hopefully effective to the wetland conservation and development ƒ the legislation of wetland conservation is necessary and useful ƒ more and more wetland nature reserves set up ™ Biological invasion in wetland – is Kei Ngou Island a successful example? ƒ using one alien species to control the other one is more or less dangerous ƒ the ecological risk of introducing S. apetala still needs monitoring and assessment This research is funded by UNEP/GEF South China Sea Project (GF/2730-02-4340). We thank those people who help us to summarize the data about the Pearl River Estuary Wetland. Thanks also go to Ms. Cheung Men who helps us prepare the maps and figures in this paper.

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