Restoration of the Coconut Crab Birgus latro (L.) in Green Island： Artificial Cultivation of Larvae, Investigation of Juvenile Habitat and Community Education
Date Issued
2005
Date
2005
Author(s)
Wang, Fang-Lin
DOI
zh-TW
Abstract
The coconut crabs Birgus latro (L.) are terrestrial hermit crab which only occupy discarded molluscan shells during the post-larvae and early juvenile phases of their life history, and then discard shells after about 1-2 year and move further inland. To protect this rare species, our study focused on artificial cultivation of larvae, investigation of suitable features of habitat, and community education at Green Island.
Zoeae from two female crabs were collected at higt tide on July and August in 2003 and 2004 respectively, and were reared in filtered seawater at temperature 24-25℃, salinity 34-35‰, fed on Artemia nauplii. The results in 2003 showed that duration of 3~5 zoeal satges lasted 25 to 28 days. There were 13 glaucothoe metamorphosed from 300 zoeae, 7 of them were early metamorphosis from the 3rd zoeal stage, and 6 metamorphosed from the 5th. The characteristics of larvae at each stage were similar to those described by Reese (1968). Glaucothoes started their amphibian life at 38th days after hatching without carrying shells. In 2004, zoeae which fed on enriched Artemia nauplii with PUFA, (n-3)HUFA, EPA, and DHA increased size of 3rd stage zoeae and survival rate of 4th and 5th zoeae. A total of 20 5th stage zoeae metamorphosed to glaucothoes, and 75% of them from feeding on enriched Artemia groups. The glaucothoes carried shells at 36th days after hatching and lived amphibiously. The results on larval cultivation will pave the way for mass cultivation.
We found 4 juvenile crabs of B. latro which cephalothoracic length were 19-22 mm without carrying shells in the coastal shrubs beyond beach and farmland after sampling 6 sites in 2 years. Low number of juvenile and adult population of B. latro have reflected low recruitment in Green Island. The distribution of B. latro and other land hermit crabs tend to overlap. So the common feathers of habitat for these land hermit crab were high humidity, more crevices to provide hiding, and the area with sufficient food source. These results will provide the basis of habitat conservation and releasing artificial-reared juvenile crabs in hope to improve the recruitment of natural coconut crab population in Taiwan.
In addition, we initiated a conservation team composed of local residents and officials to plan and execute restoration works. Moreover, environmental education was carried out on local teachers, students, and residents. Participation of local communities is the key to sustainablely conserve the population of coconut crabs in Green Island.
Subjects
椰子蟹
陸棲寄居蟹
復育
coconut crab
Restoration
terrestrial hermit crab
SDGs
Type
other
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