2020
Kelson, Suzanne J.; Power, Mary E.; Finlay, Jacques C.; Carlson, Stephanie M.
Partial migration alters population ecology and food chain length: evidence from a salmonid fish Journal Article
In: Ecosphere, vol. 11, no. 2, pp. e03044, 2020.
Abstract | Links | BibTeX | Tags: eco-evolutionary dynamics, ERCZO, extended phenotype, food chain length, intraspecific variation, life history, O. mykiss, Oncorhynchus mykiss, partial migration, population ecology, size structure, steelhead/rainbow trout
@article{Kelson2020b,
title = {Partial migration alters population ecology and food chain length: evidence from a salmonid fish},
author = {Suzanne J. Kelson and Mary E. Power and Jacques C. Finlay and Stephanie M. Carlson},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/ecs2.3044.pdf},
doi = {10.1002/ecs2.3044},
year = {2020},
date = {2020-02-21},
journal = {Ecosphere},
volume = {11},
number = {2},
pages = {e03044},
abstract = {Many migratory species, from monarch butterflies to wildebeest, express partial migration, where only a subset of a population migrates. This intraspecific variation is likely to have large ecological consequences. We studied the ecological consequences of partial migration in a salmonid fish, Oncorhynchus mykiss, in coastal streams in California, USA. One ecotype, steelhead trout, migrates to the ocean, whereas the other, rainbow trout, completes its lifecycle in freshwater. Migration has a strong genetic basis in O. mykiss. In one stream, we found differences in the frequency of migration‐linked genotypes below and above a waterfall barrier (migratory allele frequency of 60% below vs. 31% above). Below the waterfall, in the migratory‐dominated region, the density of young fish (<1 yr old) was approximately twice that in the resident‐dominated region above the waterfall (0.46 vs. 0.26 individuals/m2, respectively), presumably reflecting the higher fecundity of migratory females. Additionally, there were half as many older fish (>1 yr old) in pools downstream of the waterfall (0.05 vs. 0.13 individuals/m2). In a second stream, between‐year variation in the dominance of migratory vs. resident fish allowed us to explore differences in fish density and size structure through time, and we found a consistent pattern. In brief, when migratory genotypes dominated, we found higher densities of young fish and lower densities of older fish, resulting in a simpler size structure, compared to when resident genotypes dominated. Moreover, large resident trout had a slightly higher trophic position than young fish (3.92 vs. 3.42 in one creek and 3.77 vs. 3.17 in the other), quantified with stable isotope data. The difference in fish size structure did not generate trophic cascades. Partial migration is widespread among migratory populations, as is phenotypic divergence between resident and migratory forms, suggesting the potential for widespread ecological effects arising from this common form of intraspecific variation.},
keywords = {eco-evolutionary dynamics, ERCZO, extended phenotype, food chain length, intraspecific variation, life history, O. mykiss, Oncorhynchus mykiss, partial migration, population ecology, size structure, steelhead/rainbow trout},
pubstate = {published},
tppubtype = {article}
}
Many migratory species, from monarch butterflies to wildebeest, express partial migration, where only a subset of a population migrates. This intraspecific variation is likely to have large ecological consequences. We studied the ecological consequences of partial migration in a salmonid fish, Oncorhynchus mykiss, in coastal streams in California, USA. One ecotype, steelhead trout, migrates to the ocean, whereas the other, rainbow trout, completes its lifecycle in freshwater. Migration has a strong genetic basis in O. mykiss. In one stream, we found differences in the frequency of migration‐linked genotypes below and above a waterfall barrier (migratory allele frequency of 60% below vs. 31% above). Below the waterfall, in the migratory‐dominated region, the density of young fish (<1 yr old) was approximately twice that in the resident‐dominated region above the waterfall (0.46 vs. 0.26 individuals/m2, respectively), presumably reflecting the higher fecundity of migratory females. Additionally, there were half as many older fish (>1 yr old) in pools downstream of the waterfall (0.05 vs. 0.13 individuals/m2). In a second stream, between‐year variation in the dominance of migratory vs. resident fish allowed us to explore differences in fish density and size structure through time, and we found a consistent pattern. In brief, when migratory genotypes dominated, we found higher densities of young fish and lower densities of older fish, resulting in a simpler size structure, compared to when resident genotypes dominated. Moreover, large resident trout had a slightly higher trophic position than young fish (3.92 vs. 3.42 in one creek and 3.77 vs. 3.17 in the other), quantified with stable isotope data. The difference in fish size structure did not generate trophic cascades. Partial migration is widespread among migratory populations, as is phenotypic divergence between resident and migratory forms, suggesting the potential for widespread ecological effects arising from this common form of intraspecific variation.
2008
Power, Mary E.; Parker, Michael S.; Dietrich, William E.
Seasonal Reassembly of a River Food Web: Floods, Droughts, and Impacts of Fish Journal Article
In: Ecological Monographs, vol. 78, no. 2, pp. 263–282, 2008, ISSN: 0012-9615.
Abstract | Links | BibTeX | Tags: Cladophora glomerata, context dependency, effect sizes, flood scour, food chain length, interaction strength, Lavinia (Hesperoleucas) symmetricus, long-term studies, Mediterranean hydrologic regimes, Oncorhynchus mykiss, population, predator impacts
@article{Power2008,
title = {Seasonal Reassembly of a River Food Web: Floods, Droughts, and Impacts of Fish},
author = {Mary E. Power and Michael S. Parker and William E. Dietrich},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_2008_EcoMono.pdf
https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_FoodWebDrouFloodFish_EcoMono2008.pdf
https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_AppA_EcoMono2008.pdf
https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_AppB_EcoMono2008.pdf},
doi = {10.1890/06-0902.1},
issn = {0012-9615},
year = {2008},
date = {2008-05-01},
journal = {Ecological Monographs},
volume = {78},
number = {2},
pages = {263–282},
abstract = {Eighteen years of field observations and five summer field experiments in a coastal California river suggest that hydrologic regimes influence algal blooms and the impacts of fish on algae, cyanobacteria, invertebrates, and small vertebrates. In this Mediterranean climate, rainy winters precede the biologically active summer low-flow season. Cladophora glomerata, the filamentous green alga that dominates primary producer biomass during summer, reaches peak biomass during late spring or early summer. Cladophora blooms are larger if floods during the preceding winter attained or exceeded ‘‘bankfull discharge’’ (sufficient to mobilize much of the river bed, estimated at 120 m3/s). In 9 out of 12 summers preceded by large bed-scouring floods, the average peak height of attached Cladophora turfs equaled or exceeded 50 cm. In five out of six years when flows remained below bankfull, Cladophora biomass peaked at lower levels. Flood effects on algae were partially mediated through impacts on consumers in food webs. In three experiments that followed scouring winter floods, juvenile steelhead (Oncorhynchus mykiss) and roach (Lavinia (Hesperoleucas) symmetricus) suppressed certain insects and young-of-the-year fish fry, affecting persistence or accrual of algae positively or negatively, depending on the predator-specific vulnerabilities of primary consumers capable of suppressing algae during a given year. During two post-flood years, these grazers were more vulnerable to small predators (odonates and fish fry, which stocked steelhead always suppressed) than to experimentally manipulated, larger fish, which had adverse effects on algae in those years. During one post-flood year, all enclosed grazers capable of suppressing algae were consumed by steelhead, which therefore had positive effects on algae. During drought years, when no bed-scouring winter flows occurred, large armored caddisflies (Dicosmoecus gilvipes) were more abundant during the subsequent summer. In drought-year experiments, stocked fish had little or no influence on algal standing crops, which increased only when Dicosmoecus were removed from enclosures. Flood scour, by suppressing invulnerable grazers, set the stage for fish mediated effects on algae in this river food web. Whether these effects were positive or negative depended on the predator-specific vulnerabilities of primary consumers that dominated during a given summer.},
keywords = {Cladophora glomerata, context dependency, effect sizes, flood scour, food chain length, interaction strength, Lavinia (Hesperoleucas) symmetricus, long-term studies, Mediterranean hydrologic regimes, Oncorhynchus mykiss, population, predator impacts},
pubstate = {published},
tppubtype = {article}
}
Eighteen years of field observations and five summer field experiments in a coastal California river suggest that hydrologic regimes influence algal blooms and the impacts of fish on algae, cyanobacteria, invertebrates, and small vertebrates. In this Mediterranean climate, rainy winters precede the biologically active summer low-flow season. Cladophora glomerata, the filamentous green alga that dominates primary producer biomass during summer, reaches peak biomass during late spring or early summer. Cladophora blooms are larger if floods during the preceding winter attained or exceeded ‘‘bankfull discharge’’ (sufficient to mobilize much of the river bed, estimated at 120 m3/s). In 9 out of 12 summers preceded by large bed-scouring floods, the average peak height of attached Cladophora turfs equaled or exceeded 50 cm. In five out of six years when flows remained below bankfull, Cladophora biomass peaked at lower levels. Flood effects on algae were partially mediated through impacts on consumers in food webs. In three experiments that followed scouring winter floods, juvenile steelhead (Oncorhynchus mykiss) and roach (Lavinia (Hesperoleucas) symmetricus) suppressed certain insects and young-of-the-year fish fry, affecting persistence or accrual of algae positively or negatively, depending on the predator-specific vulnerabilities of primary consumers capable of suppressing algae during a given year. During two post-flood years, these grazers were more vulnerable to small predators (odonates and fish fry, which stocked steelhead always suppressed) than to experimentally manipulated, larger fish, which had adverse effects on algae in those years. During one post-flood year, all enclosed grazers capable of suppressing algae were consumed by steelhead, which therefore had positive effects on algae. During drought years, when no bed-scouring winter flows occurred, large armored caddisflies (Dicosmoecus gilvipes) were more abundant during the subsequent summer. In drought-year experiments, stocked fish had little or no influence on algal standing crops, which increased only when Dicosmoecus were removed from enclosures. Flood scour, by suppressing invulnerable grazers, set the stage for fish mediated effects on algae in this river food web. Whether these effects were positive or negative depended on the predator-specific vulnerabilities of primary consumers that dominated during a given summer.
- https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_2008_EcoMono.pdf
- https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_FoodWebDrouFloodFi[…]
- https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_AppA_EcoMono2008.p[…]
- https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_AppB_EcoMono2008.p[…]
- doi:10.1890/06-0902.1
2002
Power, Mary E.; Dietrich, William E.
Food webs in river networks Journal Article
In: Ecological Research, vol. 17, no. 4, pp. 451-471, 2002.
Abstract | Links | BibTeX | Tags: food chain length, food webs, landscape heterogeneity, river networks, stream ecosystems
@article{Power2002,
title = {Food webs in river networks},
author = {Mary E. Power and William E. Dietrich},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Power_et_al-2002-Ecological_Research1.pdf},
doi = {10.1046/j.1440-1703.2002.00503.x},
year = {2002},
date = {2002-06-28},
journal = {Ecological Research},
volume = {17},
number = {4},
pages = {451-471},
abstract = {Food webs and river drainages are both hierarchical networks and complex adaptive systems. How does living within the second affect the first? Longitudinal gradients in productivity, disturbance regimes and habitat structure down rivers have long interested ecologists, but their effects on food web structure and dynamics are just beginning to be explored. Even less is known about how network structure per se influences river and riparian food webs and their members. We offer some preliminary observations and hypotheses about these interactions, emphasizing observations on upstream–downstream changes in food web structure and controls, and introducing some ideas and predictions about the unexplored question of food web responses to some of the network properties of river drainages.},
keywords = {food chain length, food webs, landscape heterogeneity, river networks, stream ecosystems},
pubstate = {published},
tppubtype = {article}
}
Food webs and river drainages are both hierarchical networks and complex adaptive systems. How does living within the second affect the first? Longitudinal gradients in productivity, disturbance regimes and habitat structure down rivers have long interested ecologists, but their effects on food web structure and dynamics are just beginning to be explored. Even less is known about how network structure per se influences river and riparian food webs and their members. We offer some preliminary observations and hypotheses about these interactions, emphasizing observations on upstream–downstream changes in food web structure and controls, and introducing some ideas and predictions about the unexplored question of food web responses to some of the network properties of river drainages.
2000
Marks, Jane C.; Power, Mary E.; Parker, Michael S.
Flood disturbance, algal productivity, and interannual variation in food chain length Journal Article
In: Oikos, vol. 90, no. 1, pp. 20-27, 2000.
Abstract | Links | BibTeX | Tags: algal productivity, flood, food chain length
@article{Marks2000,
title = {Flood disturbance, algal productivity, and interannual variation in food chain length},
author = {Jane C. Marks and Mary E. Power and Michael S. Parker},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Marks-et-al-2000-Oikos.pdf},
doi = {10.1034/j.1600-0706.2000.900103.x},
year = {2000},
date = {2000-07-00},
journal = {Oikos},
volume = {90},
number = {1},
pages = {20-27},
abstract = {The length of a river food chain changed from year to year, shifting with the hydrologic regime. During drought years, grazers suppressed algae across a nutrient gradient, while predators were functionally unimportant. Following flood disturbance, predators suppressed grazers, releasing algae. These results suggest that hydrologic regime, rather than productivity, determines the functional length of this river food chain. Within years, algae and grazer biomass responded to an experimental productivity gradient in patterns predicted by simple trophic models that assume efficient energy transfer. Understanding differences among species within trophic levels, however, was crucial in delineating the controlling interactions.},
keywords = {algal productivity, flood, food chain length},
pubstate = {published},
tppubtype = {article}
}
The length of a river food chain changed from year to year, shifting with the hydrologic regime. During drought years, grazers suppressed algae across a nutrient gradient, while predators were functionally unimportant. Following flood disturbance, predators suppressed grazers, releasing algae. These results suggest that hydrologic regime, rather than productivity, determines the functional length of this river food chain. Within years, algae and grazer biomass responded to an experimental productivity gradient in patterns predicted by simple trophic models that assume efficient energy transfer. Understanding differences among species within trophic levels, however, was crucial in delineating the controlling interactions.