Towards wetland restoration for the "Wetland Three Musketeers”, a horseshoe crab, a fiddler crab, and a coconut crab

Hwey-Lian Hsieh, Po-Fen Lin, Fang-Lin Wang, Chang-Po Chen
Research Center for Biodiversity, Academia Sinica, Nankang, Taipei, Taiwan 115, Republic of China


 Three arthropod species, the horseshoe crab Tachypleus tridentatus, the fiddler crab Uca formosensis, and the coconut crab Birgus latro, nicknamed here as the "Wetland Three Musketeers”, and which once thrived in the coastal wetlands of Taiwan, now survive in only a few small restricted areas. Their population declines were largely due to loss of suitable habitats caused by anthropogenic impacts and/or harvesting pressures from humans. We have chosen these three species as flagship species and have set up a three-step strategy advanced from understanding of life histories of these individual species to their habitat maintenance, and the issue of wise use of wetlands.

Fig. 1 The wetland Three Musketeer species: the horseshoe crab Tachypleus tridentatus, the fiddler crab Uca formosensis, and the coconut crab Birgus latro.

Fig. 2 Localities in Taiwan where viable populations of each flagship species are found.

 

Table 1 Criteria used to select the Three Musketeer species as flagship species for coastal wetland conservation in Taiwan.


Horseshoe crab: Establishment of a protected area and public education programs

Fig. 4 Some records of educational programs for conserving the horseshoe crab Tachypleus tridentatus. a~c, Activities for learning about horseshoe crabs; d, brochures and a book published to raise public awareness; e, visiting horseshoe crab habitats as a part of ecotourism tours.


Uca formosensis: Habitat requirements and public education programs

Investigating sedimentary microhabitats in U. formosensis
OSilt/Clay content: 10~43%
OTotal organic carbon and nitrogen content: 0.16~0.4% and 0.01~0.05%
OWater content:15~31%
OpH: 7.9~8.6(neutral to very weal alkaline)
ODepth of the oxidation layer: often > 16~40cm
OBenthic macroinvertebrates: 58.8~1189.0 individuals/m2 (polychetes, insects, and crabs)

Fig. 5 Some records of educational programs to conserve the fiddler crab Uca formosensis. a, b, Elementary school teachers and students designing and making traps to collect crabs; c, deployment of traps in the field; d, field observations of fiddler crab habitats; e, transplantation practice of fiddler crabs because their original shelters will be reclaimed soon for constructing a municipal swage treatment plant; f, a book written for public education.


Coconut crab: Larval development and metamorphosis and public education programs

Fig. 6 Morphology and development duration from hatching to the glaucothoe stage in the coconut crab Birgus latrounder laboratory condition and a scheme depicting natural habitats the coconut crab use through its life history.

Fig. 7 Newly metamorphosed and shell-carrying coconut crab juvenile in the laboratory. a: Close-up view; b: crab crawling on a piece of coral fragment.

Fig. 8 Some records of educational programs to promote conservation of the coconut crab Birgus latro. a, b, Public education for elementary school students and coastal guards; c, organization of a task force to conduct conservation affairs; d, book and postcard published to raise public awareness.


General strategies planning for wetlands conservation include the following:

(a) To conserve coastal wetlands as protected areas which still maintain sound function, to improve those that have been disturbed, and to restore those that have been destroyed. By connecting these three types of habitats to form a “Coastal Wetlands Conservation Greenway” (Hsieh et al. 2004), coastal wetlands conservation can be implemented;

(b) To accelerate studies of the life history and of habitat requirements of each stage of the Three Musketeer species;

(c) To develop and establish sea-farming techniques for ensuring population;

(d) To educate the public to be aware of wise uses of coastal wetlands by developing a multiple use scheme for natural resources. Wetlands serving as ecotourism and environmental education sites are such wise uses of wetlands services;

(e) To empower local communities and non-profit organizations to actively participate in local wetlands conservation;

(f) To establish a cooperative coalition involving participation from all relevant sectors including local communities, non-profit organizations, scientists, governmental agencies, and enterprises; and

(g) To promote innovations in ecological engineering for restoring habitats. Ecological engineering is a practice that incorporates both design and construction with nature;

(h) To establish international cooperation for designating marine protected areas and promoting wetland conservation.


Further work

(1)Horseshoe crab: A new nursing ground and juveniles were found in 2005 in Haoumeiliao wetland, Chiayi County. Local community, tour businessmen, teachers of elementary schools, and local government formed a team to protect and restore the horseshoe crab and its habitats.

(2)Fiddler crab: To rehabilitate the Uca formosensis habitats and to monitor and evaluate the effects of mangrove removal on intertidal ecosystems. To enhance local people’s participation in mangrove removal and protection of intertidal flat. To continue in public education.

(3)Coconut crab: To promote environmental education and local communication through the coconut crab conservation team work. Ecological corridors for crabs will be built through community-based works including the study of the distribution of coconut crab population and spawning migration. The research on larval mass cultivation will be continued in 2006. The study of genetic connectivity of Birgus latro in the Indo-Pacific region will help in strategic planning for coconut crab conservation.


Reference

Hsieh HL, Chen CP, Lin YY. 2004. Strategic planning for a wetlands conservation greenway along the west coast of Taiwan. Ocean and Coastal Management 47: 257-272.

Address: Room 636, Research Center of Biodiversity, 128 Sec. 2, Academia Rd, Nankang, Taipei 115 Taiwan, R.O.C.
E-Mail: zocp@gate.sinica.edu.tw
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