Research

The environment exhibits significant variation in space and time. In nature, organisms move in such landscapes as they grow and/or as the environment change. To understand interactions of organisms in the nature, it is essential to take into account the environmental complexities and the movements and life cycles of organisms. I have been studying the effects of environmental complexities in support of biodiversity and the species interactions with focus in stream-riparian environments, where the environment is particularly complex.

Ecosystem linkages of forests, streams, and the ocean by animal migrations

Many animals migrate through their life cycles in free-flowing streams, and they often play large roles in shaping stream ecosystems by transporting resources and/or interacting with other species. While it has been long recognized that the salmon migrations from the ocean provide rich resources to stream and riparian ecosystems, not much attention has been paid to migrations of other organisms such as insects (Uno & Power, 2015), shrimps (Uno et al. 2022) and diverse non-commercial fishes (Kurasawa et al., under review; Onishi et al., in prep) and their ecological consequences. With intense field observations, tagging and experiments, I study migratory behaviors and movements of the diverse animals in the riverscape and their driving forces (Poinar et al. 2015; Uno 2019; Uno & Stillman 2020; Kanno et. al., 2020). With large-scale field manipulative experiments, I have shown the ecological significance of their migrations, through resource subsidies and species interactions (Uno & Power 2015; Uno et al. 2022; Kurasawa et al., under review; Onishi et al., in prep). I further document how diversity in migratory organisms contributes to the overall impacts (Uno et al. 2020; Tanaka et al. 2020, Onishi et al. in prep). A series of my studies have shown that the presence and diversity of migratory organisms extensively influence local stream communities and nutrient cycling through resource allocations and trophic interactions.

Biodiversity and geomorphic heterogeneity and hydrological regime

Natural rivers harbor various geomorphic structures providing heterogeneous habitats for aquatic and riparian organisms and the environment change from time to time with flow regime. I have shown that the heterogeneous environment not only supports habitats for diverse organisms (Uno et al. 2022), but also alters species interactions by creating refugia from predators and temporally asynchronizing the life history timing of species in space (Uno 2016). The spatial heterogeneity in rivers is also temporally variable in association with the flow regime, and such change in the environmental conditions also matters for the stream ecosystems (Uno 2016; Uno et al. 2022; Uno et al. in prep). I envision to develop this research in larger river systems, and am currently visiting the western United States, where we can find wild rivers. I am currently learning the geomorphology and develop more holistic research including the riparian vegetation, geomorphology and the freshwater ecosystem.

Tropical Ecology

Throughout my research career, I have been fascinated by tropical ecology because the ecosystems as well as the local people and cultures fascinate me. I carried out my undergraduate honor's research and master's research in Malaysia and Hong Kong (Uno 2010; Uno 2012). As a Ph.D. student, I participated in a field biology course in Costa Rica offered by organizations for tropical studies, and continued some research following the class (Esch et al. 2017; Young et al. 2018; Peniston et al. 2020). Currently, in collaboration with researchers from the National Research and Innovation Agency -BRIN (formerly LIPI) (Indonesia), I have an ongoing project on the floodplain ecosystem in Kalimantan, Indonesia (Subehi et al. 2022).