Publications

@phdthesis{Uno2016,

title = {Spatial and temporal linkage of stream-riparian food webs by seasonal migration of mayfly Ephemerella maculata},

author = {Hiromi Uno},

isbn = {978-1-369-05549-8},

year  = {2016},

date = {2016-05-30},

school = {University of California, Berkeley},

abstract = {Stream environments are spatially and temporally heterogeneous. Mainstem rivers are often wide, 

sunlit, warm and productive, while tributaries are shaded by riparian trees, unproductive, and 

remain cool in summer. Within mainstem rivers themselves there is substantial spatial 

heterogeneity in habitat structure and physical conditions, such as water temperature. River 

environments also change dramatically with season. Organisms that live in the riverine 

environment respond to and take advantage of such heterogeneous environments by moving 

between microhabitats or shifting their phenology. I studied the life cycle of a riverine mayfly, 

Ephemerella maculata (Ephemerellidae), in a northern California river system, its responses to 

spatial and temporal heterogeneity, and how its movements connect stream and riparian food webs 

in space and time. 

I discovered that E. maculata migrates between the mainstem and tributaries of rivers during its 

life cycle, thereby linking food webs in these two habitats, and enhancing predator growth in 

unproductive tributaries. The resource subsidy from productive but warm rivers to cool, 

unproductive tributaries associated with the mayfly migration increase the growth of stenothermic 

predators like juvenile salmonids in otherwise food-limited, cool thermal refuges, and increase 

their resilience to future warming. Furthermore, I examined the resilience of E. maculata to 

changes in water temperature using field surveys and lab rearing experiments. I discovered that 

different life stages of E. maculata have different thermal responses, and they shift their phenology 

depending on the water temperature, allowing each life stage to occur in the most desirable thermal 

condition. Therefore, as long as the natural seasonal pattern of the water temperature is sustained, 

E. maculata can resist temperature changes by shifting their phenology. Finally, I have shown that 

thermal spatial heterogeneity of rivers desynchronizes mayfly emergence timing, prolonging the 

subsidy period to riparian predators, and changing the predators’ responses to this subsidy.},

keywords = {Aquatic insect, Aquatic-terrestrial linkage, Biological sciences, ERCZO, food web, Spatial heterogeneity, subsidy, Temporal heterogeneity},

pubstate = {published},

tppubtype = {phdthesis}

}