Opsariichthys uncirostris uncirostris

Transcription

1 (Japanese Journal of Conservation Ecology) 19 : (2014) 調査報告 Opsariichthys uncirostris uncirostris * A detailed assessment of the distribution of Opsariichthys uncirostris uncirostris along the shoreline of Lake Biwa Akio Imamura* Osaka Museum of Natural History II 1 45 km / / / GLMM / 4 PERMANOVA GLMM PERMANOVA PERMANOVA Abstract: I investigated the distribution of the piscivorous fish Opsariichthys uncirostris uncirostris (classified as vulnerable [VU]) along 45 km of the southwest shoreline of Lake Biwa, central Japan. The species was observed at 58 of 175 sites studied. Although it mainly occurred north of Otsu City, i.e., the Shiga District, I also found the species in the city s densely populated southern districts. I used generalized linear mixed model (GLMM) analysis to examine the probability of adult and immature O. u. uncirostris occurrence (binary data) in terms of several explanatory variables: lake substrate type (sand, gravel, and other), watercourse shape (surface stream, subterranean stream, dried-up stream, and shore), the presence of reeds, embankments, and/or trees along the watercourse, and the season (spring, summer, autumn, and winter), with site as a random effect. The GLMM indicated a positive effect of sandy substrate on O. u. uncirostris presence. I used permutational analyses of variance (PERMANOVAs) to examine the presence/absence of adult and immature fish in terms of the same explanatory variables as the GLMM, with the exception of season. This analysis also showed that the substrate significantly affected O. u. uncirostris occurrence. Thus, sandy substrates should be protected to promote O. u. uncirostris inhabitance. Keywords: generalized linear mixed model, lake bottom, permutational multivariate analysis of variance, piscivorous fish, watercourse junction * Present Address: Hokkaido University of Education, Asahikawa Campus, Hokumon-cho 9, Asahikawa, Hokkaido , Japan ginryou715@yahoo.co.jp

2 Opsariichtys uncirostris uncirostris FishBase.org ex-danioninae O. u. bidens O. u. amurensis I HP fis000.html php?id=32&pid= t t HP gyoshu-gyokaku23.pdf II VU HP biodic.go.jp/rdb/rl2012/redlist2012_tansuigyorui.csv /1000 Micropterus salmoides km Kiffney et al N P Ohsawa et al 調査の概要 km 調査方法 m 152

3 解析 R3.1.0 for Mac OSX R core team R-project.org/ maptools GoogleMap / GLMM glmmml / 5 vegan / permutational multivariate analysis of variance PERMANOVA / / / 5 permutation < box/huwwpl> 100 m 2A-D 2D 2I-K 2K 5 GLMM 1 5 / PERMANOVA

4 1 2A-2K 2A-2K 2 5 km Fig. 1. Map of the research area in southwest Lake Biwa. Detailed maps are given in Figure 2, and letters 2A-2K correspond to each panel in Figure 2. Bar: 5 km; : Otsu City center. 5 7 / / PERMANOVA GLMM PERMANOVA R 2 = GLMM > >

5 2 / 1 km A B C D E F Fig. 2. Detailed maps of the research sites, which are aligned north to south along the overall research area. The presence/absence of Opsariichthys uncirostris uncirostris and the shape of the watercourse are plotted for each research site. Bar: 1 km. Letters indicate districts of Otsu City: (A) Northern Hourai; (B) Southern Hourai; (C) Wani; (D) Mano; (E) Katata; (F) Ogoto. : surface stream with O. u. uncirostris; : surface stream without O. u. uncirostris; : subterranean stream with O. u. uncirostris; : subterranean stream without O. u. uncirostris; : dried-up stream with O. u. uncirostris; : dried-up stream without O. u. uncirostris; : shore with O. u. uncirostris, : shore without O. u. uncirostris. 155

6 2 G H I J K Fig. 2 (continued). (G) Northern Sakamoto; (H) Southern Sakamoto; (I) Karasaki; (J) Central Otsu; and (K) Seta. : surface stream with O. u. uncirostris; : surface stream without O. u. uncirostris; : subterranean stream with O. u. uncirostris; : subterranean stream without O. u. uncirostris; : dried-up stream with O. u. uncirostris; : dried-up stream without O. u. uncirostris; : shore with O. u. uncirostris, : shore without O. u. uncirostris. 156

7 1 / GLMM Table 1. Summary of GLMM for the effects of environmental variables on occurrence of Opsariichthys uncirostris uncirostris. Estimate Std. Error z value Pr(> z ) AIC = 239 Intercept a * Lake bottom: gravel Lake bottom: sand * Watercourse: open Watercourse: underground Watercourse: dried-up Presence of reeds Embankment Presence of trees on the watercourse side Season: spring Season: summer Season: winter a: base of lake bottom is paved and other ; base of watercourse is shore ; bottom of season is autumn *: p< / PERMANOVA Table 2. Results of PERMANOVA for the effects of environmental variables on occurrence of the adult and immature fish of Opsariichthys uncirostris uncirostris. Df Sums of squares Mean squares F Model R 2 Pr(>F) Bottom of lake * Watercourse shape Presence of reeds Embankment Presence of trees on the watercourse side Residuals Total *: p< 0.05 PERMANOVA R 2 = GLMM P = 0.15 GLMM > > > kawamoyou/kawamoyou.html m

8 GoogleMap (2011) R,,. 61:3-20. (2013) Cyprinidae. ( ) 3. pp ,. (2011).,. Kiffney PM, Greene CM, Hall JE, Davies JR (2006) Tributary streams create spatial discontinuities in habitat, biological productivity, and diversity in mainstem rivers. Canadian Journal of Fisheries and Aquatic Sciences 63: (2003). ( ). pp ,. (2009).. pp 7-60.,.. (2009).,. Ohsawa T, Mitsuhashi H, Ushimaru A (2010) River confluences enhance riparian plant species diversity. Plant Ecology 209: (2012). 17: (2010).,. (2011) MAP.,. 158