2016
Uno, Hiromi
Spatial and temporal linkage of stream-riparian food webs by seasonal migration of mayfly Ephemerella maculata PhD Thesis
University of California, Berkeley, 2016, ISBN: 978-1-369-05549-8.
Abstract | BibTeX | Tags: Aquatic insect, Aquatic-terrestrial linkage, Biological sciences, ERCZO, food web, Spatial heterogeneity, subsidy, Temporal heterogeneity
@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}
}
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.
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.
2004
Power, Mary; Vanni, Michael; Stapp, Paul; Polis, Gary
Subsidy Effects on Managed Ecosystems: Implications for Sustainable Harvest, Conservation, and Control Book Chapter
In: Polis, Gary; Power, Mary; Huxel, Gary (Ed.): Chapter 24, pp. 387-409, 2004, ISBN: 9780226673257.
Abstract | Links | BibTeX | Tags: food webs, landscape level, subsidy
@inbook{Power2004,
title = {Subsidy Effects on Managed Ecosystems: Implications for Sustainable Harvest, Conservation, and Control},
author = {Mary Power and Michael Vanni and Paul Stapp and Gary Polis},
editor = {Gary Polis and Mary Power and Gary Huxel},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_2004_FoodWebLandLev_SubsEffects.pdf},
isbn = {9780226673257},
year = {2004},
date = {2004-02-00},
pages = {387-409},
chapter = {24},
abstract = {Scientists rely on food webs—complex networks that trace the flow of nutrients and energy between species and through ecosystems—to understand the infrastructure of ecological communities.
But given the complexities of food webs—think of following the flow of nutrients through the microbes, fungi, roots, worms, ants, and birds that pass over or through a single cubic meter of prairie soil—it's not difficult to see why most experiments on food-web dynamics focus on small, local habitats. Yet as this book convincingly shows, important insights come when scientists expand the temporal and spatial scope of their research to look at the ways energy, organisms, nutrients, and pollutants flow not just at the local level, but across whole landscapes—between and among food webs in a wide variety of habitats.
Paying special attention to the fertile boundaries between terrestrial, freshwater, and marine ecosystems, Food Webs at the Landscape Level not only shows what this new methodology means for ecology, conservation, and agriculture but also serves as a fitting tribute to Gary Polis and his major contributions to the field.},
keywords = {food webs, landscape level, subsidy},
pubstate = {published},
tppubtype = {inbook}
}
Scientists rely on food webs—complex networks that trace the flow of nutrients and energy between species and through ecosystems—to understand the infrastructure of ecological communities.
But given the complexities of food webs—think of following the flow of nutrients through the microbes, fungi, roots, worms, ants, and birds that pass over or through a single cubic meter of prairie soil—it’s not difficult to see why most experiments on food-web dynamics focus on small, local habitats. Yet as this book convincingly shows, important insights come when scientists expand the temporal and spatial scope of their research to look at the ways energy, organisms, nutrients, and pollutants flow not just at the local level, but across whole landscapes—between and among food webs in a wide variety of habitats.
Paying special attention to the fertile boundaries between terrestrial, freshwater, and marine ecosystems, Food Webs at the Landscape Level not only shows what this new methodology means for ecology, conservation, and agriculture but also serves as a fitting tribute to Gary Polis and his major contributions to the field.
But given the complexities of food webs—think of following the flow of nutrients through the microbes, fungi, roots, worms, ants, and birds that pass over or through a single cubic meter of prairie soil—it’s not difficult to see why most experiments on food-web dynamics focus on small, local habitats. Yet as this book convincingly shows, important insights come when scientists expand the temporal and spatial scope of their research to look at the ways energy, organisms, nutrients, and pollutants flow not just at the local level, but across whole landscapes—between and among food webs in a wide variety of habitats.
Paying special attention to the fertile boundaries between terrestrial, freshwater, and marine ecosystems, Food Webs at the Landscape Level not only shows what this new methodology means for ecology, conservation, and agriculture but also serves as a fitting tribute to Gary Polis and his major contributions to the field.
2002
Bastow, Justin L.; Sabo, John L.; Finlay, Jacques C.; Power, Mary E.
A basal aquatic-terrestrial trophic link in rivers: algal subsidies via shore-dwelling grasshoppers Journal Article
In: Oecologia, vol. 131, no. 2, pp. 261-268, 2002.
Abstract | Links | BibTeX | Tags: pygmy grasshopper, Riparian, river-watershed exchange, subsidy, tetrigidae
@article{Bastow2002,
title = {A basal aquatic-terrestrial trophic link in rivers: algal subsidies via shore-dwelling grasshoppers},
author = {Justin L. Bastow and John L. Sabo and Jacques C. Finlay and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/A-Basal-Aquatic-Terrestrial-Trophic-Link-in-Rivers-Algal-Subsidies-via-Shore-Dwelling-Grasshoppers_Bastow_2002.pdf},
doi = {10.1007/S00442-002-0879-7},
year = {2002},
date = {2002-03-14},
journal = {Oecologia},
volume = {131},
number = {2},
pages = {261-268},
abstract = {Rivers provide important resources for riparian consumers, especially in arid or seasonally arid biomes. Pygmy grasshoppers (Paratettix aztecus and P. mexicanus; Tetrigidae) graze river algae stranded along shorelines of the South Fork Eel River in northern California (39°44′N, 123°39′W) as the river recedes during the summer drought. Densities of tetrigids during the mid to late summer were highest (1 $textindividual/textm^2$ in July) within 1 m of the river margin, and declined to near zero at 4 m from the margin, especially during peak temperatures in the afternoon. These observations suggested that the distribution of tetrigids was determined by the availability of algae, water, or both. We manipulated the presence/absence of water and beached algae (Cladophora glomerata) in a 2×2 factorial design. All treatments were positioned 2 m upslope from the river's edge (about 30 cm above the water table), where the cobble bar was naturally dry and devoid of algae and densities of tetrigids were lower than at the river margin (0.4 individuals/m2 in July). Tetrigids responded only to the wet Cladophora treatment, which had 30× higher densities than other treatments. Stable isotopic signatures (δ 13C) of tetrigids (-19.7‰) collected from the same cobble bars were more similar to those of epilithic algae (-20.4‰) than terrestrial plants (-28.2‰), and higher than those of acridid grasshoppers (-27.9‰) from the same habitats. Mixing models suggest that 88-100% of the C in tetrigid grasshoppers at our study site is derived from riverine algae. A preliminary analysis suggests that tetrigids ingested sufficient quantities of algae to easily meet their energetic demands during the summer. This study supports the idea that algae, produced in stream systems, can determine the distribution and relative abundance of a common terrestrial scavenger and provide an additional pathway for energy exchange between rivers and riparian food webs.},
keywords = {pygmy grasshopper, Riparian, river-watershed exchange, subsidy, tetrigidae},
pubstate = {published},
tppubtype = {article}
}
Rivers provide important resources for riparian consumers, especially in arid or seasonally arid biomes. Pygmy grasshoppers (Paratettix aztecus and P. mexicanus; Tetrigidae) graze river algae stranded along shorelines of the South Fork Eel River in northern California (39°44′N, 123°39′W) as the river recedes during the summer drought. Densities of tetrigids during the mid to late summer were highest (1 $textindividual/textm^2$ in July) within 1 m of the river margin, and declined to near zero at 4 m from the margin, especially during peak temperatures in the afternoon. These observations suggested that the distribution of tetrigids was determined by the availability of algae, water, or both. We manipulated the presence/absence of water and beached algae (Cladophora glomerata) in a 2×2 factorial design. All treatments were positioned 2 m upslope from the river’s edge (about 30 cm above the water table), where the cobble bar was naturally dry and devoid of algae and densities of tetrigids were lower than at the river margin (0.4 individuals/m2 in July). Tetrigids responded only to the wet Cladophora treatment, which had 30× higher densities than other treatments. Stable isotopic signatures (δ 13C) of tetrigids (-19.7‰) collected from the same cobble bars were more similar to those of epilithic algae (-20.4‰) than terrestrial plants (-28.2‰), and higher than those of acridid grasshoppers (-27.9‰) from the same habitats. Mixing models suggest that 88-100% of the C in tetrigid grasshoppers at our study site is derived from riverine algae. A preliminary analysis suggests that tetrigids ingested sufficient quantities of algae to easily meet their energetic demands during the summer. This study supports the idea that algae, produced in stream systems, can determine the distribution and relative abundance of a common terrestrial scavenger and provide an additional pathway for energy exchange between rivers and riparian food webs.
Sabo, John L.; Power, Mary E.
Numerical response of riparian lizards to aquatic insects and the short-term consequences for alternate terrestrial prey Journal Article
In: Ecology, vol. 83, no. 11, pp. 3023-3036, 2002.
Abstract | Links | BibTeX | Tags: Carabidae, food web, indirect effects, insect, lizard, Lycosidae, numerical response, Riparian, river–watershed exchange, Sceloporus occidentalis, subsidy, Western fence lizard
@article{Sabo2002e,
title = {Numerical response of riparian lizards to aquatic insects and the short-term consequences for alternate terrestrial prey},
author = {John L. Sabo and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Numerical-response-of-riparian-lizards-to-aquatic-insects-and-the-short-term-consequences-for-alternate-terrestrial-prey_Sabo_2002.pdf},
doi = {10.2307/3071839},
year = {2002},
date = {2002-00-00},
journal = {Ecology},
volume = {83},
number = {11},
pages = {3023-3036},
abstract = {Spatial subsidies, or inputs of resources from more productive donor habitats, can cause numerical responses in consumer populations via behavioral and demographic mechanisms. In addition, subsidies may have indirect effects on the in situ prey of these consumers. These indirect effects can be either negative (e.g., apparent competition) or positive (e.g., via diet shifts) depending on the relative strength of the predator’s functional and numerical responses to prey subsidies. Here we report a numerical response by a lizard (Western fence lizard, Sceloporus occidentalis) to experimental reductions in the flux of river-derived insects. Initially, equal densities of lizards declined significantly faster in plots in which aquatic insect abundance was reduced by nearly 50% (season average) relative to controls. Abundance and biomass of terrestrial arthropods declined significantly between the start and end of the experiment across treatments. Despite consistently lower lizard abundance in plots with reduced subsidy levels, however, relative declines in the abundance and biomass of in situ terrestrial arthropods (all taxa combined) were not significantly different between reduced- and ambient-subsidy plots. Relative declines in spider biomass differed significantly between treatments and were higher in reduced-subsidy than ambient-subsidy plots, but only over one of three 3-wk sampling intervals. Thus, over the biologically active summer season, aquatic subsidies exerted brief positive or no significant indirect effects on the in situ prey of riparian lizards. These results suggest that, although aquatic insect prey may determine the spatial distribution and local abundance of riparian predators, the effects of increased predator density on in situ prey may be offset by higher per capita predation by these consumers on in situ prey in subsidy-poor relative to subsidy-rich habitats.
Numerical response of lizards to aquatic insects and short-term consequences for terrestrial prey.},
keywords = {Carabidae, food web, indirect effects, insect, lizard, Lycosidae, numerical response, Riparian, river–watershed exchange, Sceloporus occidentalis, subsidy, Western fence lizard},
pubstate = {published},
tppubtype = {article}
}
Spatial subsidies, or inputs of resources from more productive donor habitats, can cause numerical responses in consumer populations via behavioral and demographic mechanisms. In addition, subsidies may have indirect effects on the in situ prey of these consumers. These indirect effects can be either negative (e.g., apparent competition) or positive (e.g., via diet shifts) depending on the relative strength of the predator’s functional and numerical responses to prey subsidies. Here we report a numerical response by a lizard (Western fence lizard, Sceloporus occidentalis) to experimental reductions in the flux of river-derived insects. Initially, equal densities of lizards declined significantly faster in plots in which aquatic insect abundance was reduced by nearly 50% (season average) relative to controls. Abundance and biomass of terrestrial arthropods declined significantly between the start and end of the experiment across treatments. Despite consistently lower lizard abundance in plots with reduced subsidy levels, however, relative declines in the abundance and biomass of in situ terrestrial arthropods (all taxa combined) were not significantly different between reduced- and ambient-subsidy plots. Relative declines in spider biomass differed significantly between treatments and were higher in reduced-subsidy than ambient-subsidy plots, but only over one of three 3-wk sampling intervals. Thus, over the biologically active summer season, aquatic subsidies exerted brief positive or no significant indirect effects on the in situ prey of riparian lizards. These results suggest that, although aquatic insect prey may determine the spatial distribution and local abundance of riparian predators, the effects of increased predator density on in situ prey may be offset by higher per capita predation by these consumers on in situ prey in subsidy-poor relative to subsidy-rich habitats.
Numerical response of lizards to aquatic insects and short-term consequences for terrestrial prey.
Numerical response of lizards to aquatic insects and short-term consequences for terrestrial prey.