モニタリングデータと生態的特性から探る福井県三方湖流域の純淡水魚類相の変化とその要因

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Identifying the ecological and life history correlates of local extinction can help us to predict and target extinctionprone species, and to understand the causes and consequences of species extinctions. We examined temporal changes in the native, strictly freshwater, fish fauna around Lake Mikata, a component of the Ramsar wetland, by collecting and integrating fragmentary fish monitoring data for 1978-2007, as well as by conducting broad fish samplings in rivers, ditches, and the lake in 2009 and 2010. We also performed a trait analysis for 22 freshwater fish in an attempt to identify the ecological traits of the species that have disappeared since 1988, when the fish diversity was higher. The integrated monitoring data showed that 5 of the 22 species had disappeared, including endangered species. The generalized linear mixed models incorporating the phylogenetic effects revealed that dependency on spawning substrate (e.g., cobbles and mussels) was the only significant predictor; the species with high dependency on spawning substrate were more likely to disappear. Our results suggest that the loss, degradation, and fragmentation of spawning habitats are the main direct cause of the local extinction of freshwater fish fauna in and around Lake Mikata. Monitoring, investigating, and restoring spawning habitats should be the focus of proactive conservation or management strategies.
2011-11-30