濟州島 濕地의 水棲昆虫 群集 特性: 分布 樣相과 高度에 따른 種 多樣性

Abstract

Twenty-four wetlands including crater lakes of Jeju Island were surveyed from 2004-2008 to understand the distribution patterns of indigenous aquatic insects, examine the dynamics of species diversity along the altitudinal gradient and test the Rapoport' rule on the aquatic insects community. The conclusions of this study are as below.

1. Overall, 3327 individuals comprising seven orders, 31 families, 68 genera, and 92 species were identified in the 24 surveyed sites. The site with the most varied number of species(n=50) was Dongbaekdongsanmot. Saraak displayed the most abundant number of individuals(n=534). Generally, the lowlands and midlands contained many species, with few in the highlands. 2. One species of the genus Ephemeloptera, 23 of the Odonata, one of the Plecoptera, 21 of the Hemiptera, 41 of the Coleoptera, three of the Trichoptera, and two of the Diptera were identified in this study. 3. Lyriothemis pachygastra was found in 19 sites, and the most widely distributed species in 24 sites, followed by Ischnura asiatica, and Sigara substriata(n=18 sites for both), and Anax parthenope, Orthetrum albistylum and Anisops ogasawarensis(n=17 sites for both) and Plea (Paraplea) indistinguenda(n=16 sites). In the 7 orders identified, the aquatic insects in the orders Hemiptera and Odonata were most widely distributed, perhaps reflecting their capability of flight and superior adaptation behaviors. 4. Eighteen species including Gynacantha japonica were found only in one site, 14 species including Platycnemis phillopoda were resent in two sites, and five species including Epophthalmia elegans were detected in three sites. 5. Lethocerus deyrollei, the largest aquatic insect inland and an endangered species, was found in 16 lowlands, indicating that Jeju Island wetlands remain a suitable habitat for aquatic insects, highlighting the importance of preserving such habitats from destruction and pollution-related degradation. 6. Order Coleoptera family Hydrochidae, Hydrochus japonicus Sharp, and the sole species of the order Hemiptera, family Omaniidae, genus Corallocoris, which have not been hitherto reported in Korea were detected in one site. 7. Within 92 species, 71(77.2%) were carnivore, 14(15.2%) were herbivore, 5 (5.4%) were omnivore, and 2(2.2%) were detritivore. 8. The mean value of the dominance index(DI) was 0.245; the highest value was acquired from Muljangol with 0.772. In general, the DI was high in wetlands located in highlands. The mean value of the diversity index(H') was 3.647, with Dongbaekdongsanmot showing the highest value(4.971). Generally, H' of wetlands located in lowlands and midland were high, but those of highlands was relatively low. The mean value of the R' was 5.094, and Dongbaekdongsanmot showed the highest value(9.156). Like the H', the richness index(R') of the lowlands and midland were relatively high, compared with those of the highlands. 9. The mean value of the relative density(RD) was 0.673, with the highest value in Mulyeongari(0.906). Generally, the RD values from the midland wetlands were relatively high. The mean value of the evenness index(EI) was 1.165, with the highest value displayed by Suworimot(1.364). 10. Relative abundance(RA) analysis revealed abundant species twice in six sites including Dongbaekdongsanmot, and once in nine sites including Eouksaemimot. Rare species were found 15 times in Muljangol, seven times in Eoseungsaengak, four times in Baengnokdam, three times in Dongsuak, and one in Saraak. Rare species were found only in the sites at higher altitude than the Dongsuak. 11. Abundant species were found four times in Guignotus japonicus, three times in 3 three including Gerris (Gerris) latiabdominis, once in six species including Cloeon dipterum. Rare species were detected twice in six species including Ischnura asiatica and one in 20 species including Ceragrion melanurum. 12. Analysis of Similarity Index(SI) within 24 sites revealed that Saraak and Baengnokdam were similar with a values of 0.19. Within the value 1, 12 major communities were distinguished, and communities of a similar altitude closely grouped together. In contrast, five sites including Geolworimot revealed values that were distant from other sites, showing unique and independent characteristics of aquatic insect community. 13. Species richness of aquatic insects monotonically decreased with increasing altitude showing a significant inverse correlation(r=-0.64). However, the pattern of species richness with altitude showed a hump-shaped relationship, with a peak in species richness at intermediate elevations when the effects of area were removed. 14. Altitudinal range of species tended to increase with increasing altitude. There was a positive correlation between the altitudinal range size and the midpoint of the range size(Median) except of Hemiptera. 15. The extent of average altitudinal range of high-altitude species was 904.3m, and it was significantly wider than a 469.5m of low-altitude species. Consequently, the species richness of aquatic insects in wetlands along the altitudinal gradient strongly supports the Rapoport' rule.