2021
Georgakakos, Philip B.
2021.
Abstract | Links | BibTeX | Tags: aquatic ecosystems, ERCZO, O. mykiss, pacific lamprey, Rana boylii, river communities, Sacramento pikeminnow, steelhead trout
@phdthesis{Georgakakos2021,
title = {Impacts of Native and Introduced Species on Native Vertebrates in a Salmon-Bearing River Under Contrasting Thermal and Hydrologic Regimes},
author = {Philip B. Georgakakos},
url = {https://media.proquest.com/media/hms/PFT/2/1qTlI?_s=%2Bx7JvOkubzD%2B%2Bv%2B6Qi79aySM%2FUc%3D},
year = {2021},
date = {2021-03-01},
abstract = {As organisms undergo life history transitions, track resources, avoid stress, and evade death, they distribute themselves across landscapes. Organismal co-occurrence sets the stage for biotic interactions, which can feedback to control the distribution and abundance of interacting species in ecological communities. Classically, competition and bottom-up forces have been thought to be the most important drivers of community structure, however, examples of predation, parasitism, mutualism, and facilitation highlight the ubiquity and importance of these other interactions. In freshwaters, anthropogenic impacts, especially species introductions and climate warming, have resulted in novel species assemblages, with altered webs of interactions compared to historic conditions. Human management often seeks to provide conditions that favor native species and inhibit non-natives. Success requires an understanding species interactions and their roles in community dynamics. In my first chapter, I describe the distributional dynamics of the assemblage of aquatic fishes, reptiles and amphibians in the South Fork Eel River. In Chapter 2, I describe the seasonal migration of an introduced predatory fish, Sacramento Pikeminnow (Ptychocheilus grandis), and how climate warming and water withdrawals could increase their negative impact on rearing native salmonids and other fauna.In Chapter 3, my colleagues and I explore the positive interactions between Pacific Lamprey(Entosphenus tridentatus), juvenile Steelhead trout (Oncorhynchus mykiss), and Foothill Yellow-legged Frogs(Rana boylii). These case studies emphasize the need to consider ecological interactions, and in general, community ecology thinking, as we try to restore and manage ecosystems},
keywords = {aquatic ecosystems, ERCZO, O. mykiss, pacific lamprey, Rana boylii, river communities, Sacramento pikeminnow, steelhead trout},
pubstate = {published},
tppubtype = {phdthesis}
}
As organisms undergo life history transitions, track resources, avoid stress, and evade death, they distribute themselves across landscapes. Organismal co-occurrence sets the stage for biotic interactions, which can feedback to control the distribution and abundance of interacting species in ecological communities. Classically, competition and bottom-up forces have been thought to be the most important drivers of community structure, however, examples of predation, parasitism, mutualism, and facilitation highlight the ubiquity and importance of these other interactions. In freshwaters, anthropogenic impacts, especially species introductions and climate warming, have resulted in novel species assemblages, with altered webs of interactions compared to historic conditions. Human management often seeks to provide conditions that favor native species and inhibit non-natives. Success requires an understanding species interactions and their roles in community dynamics. In my first chapter, I describe the distributional dynamics of the assemblage of aquatic fishes, reptiles and amphibians in the South Fork Eel River. In Chapter 2, I describe the seasonal migration of an introduced predatory fish, Sacramento Pikeminnow (Ptychocheilus grandis), and how climate warming and water withdrawals could increase their negative impact on rearing native salmonids and other fauna.In Chapter 3, my colleagues and I explore the positive interactions between Pacific Lamprey(Entosphenus tridentatus), juvenile Steelhead trout (Oncorhynchus mykiss), and Foothill Yellow-legged Frogs(Rana boylii). These case studies emphasize the need to consider ecological interactions, and in general, community ecology thinking, as we try to restore and manage ecosystems
2017
Schaaf, Cody J.; Kelson, Suzanne J.; Nusslé, Sébastien C.; Carlson, Stephanie M.
Black spot infection in juvenile steelhead trout increases with stream temperature in northern California Journal Article
In: Environmental Biology of Fishes, vol. 100, no. 6, pp. 733-744, 2017.
Abstract | Links | BibTeX | Tags: black spot disease, ecology, ERCZO, parasitism, steelhead trout, water temperature
@article{Schaaf2017,
title = {Black spot infection in juvenile steelhead trout increases with stream temperature in northern California},
author = {Cody J. Schaaf and Suzanne J. Kelson and Sébastien C. Nusslé and Stephanie M. Carlson},
doi = {10.1007/s10641-017-0599-9},
year = {2017},
date = {2017-04-13},
journal = {Environmental Biology of Fishes},
volume = {100},
number = {6},
pages = {733-744},
abstract = {Climate change will increase water temperature in rivers and streams that provide critical habitat for imperiled species. Warmer water temperatures will influence the intensity and nature of biotic interactions, including parasitism. To better understand the factors influencing a neascus-type parasitic infection known as black spot disease, we examined the relationship between infection rate in juvenile steelhead trout (Oncorhynchus mykiss), abundance of another intermediate host (ramshorn snail, Planorbella trivolvis), and water temperature. We quantified infection patterns of trout at seven sites within the South Fork Eel River in northern California, visiting each site on three different occasions across the summer, and recording water temperature at each site. We also quantified infection patterns in trout captured from two tributaries to the South Fork Eel River. Overall, trout infection rates were highest in sites with the warmest temperatures. The abundance of ramshorn snails was positively related to both water temperature and black spot infection rates in juvenile trout. Both snail abundance and infection rates increased rapidly above a 23 °C daily maximum, suggesting a threshold effect at this temperature. We suggest that warmer temperatures are associated with environmental and biotic conditions that increase black spot disease prevalence in threatened steelhead trout. A comparison of our results with similar data collected from a more northern latitude suggests that salmonids in California may be warm-adapted in terms of their parasite susceptibility.},
keywords = {black spot disease, ecology, ERCZO, parasitism, steelhead trout, water temperature},
pubstate = {published},
tppubtype = {article}
}
Climate change will increase water temperature in rivers and streams that provide critical habitat for imperiled species. Warmer water temperatures will influence the intensity and nature of biotic interactions, including parasitism. To better understand the factors influencing a neascus-type parasitic infection known as black spot disease, we examined the relationship between infection rate in juvenile steelhead trout (Oncorhynchus mykiss), abundance of another intermediate host (ramshorn snail, Planorbella trivolvis), and water temperature. We quantified infection patterns of trout at seven sites within the South Fork Eel River in northern California, visiting each site on three different occasions across the summer, and recording water temperature at each site. We also quantified infection patterns in trout captured from two tributaries to the South Fork Eel River. Overall, trout infection rates were highest in sites with the warmest temperatures. The abundance of ramshorn snails was positively related to both water temperature and black spot infection rates in juvenile trout. Both snail abundance and infection rates increased rapidly above a 23 °C daily maximum, suggesting a threshold effect at this temperature. We suggest that warmer temperatures are associated with environmental and biotic conditions that increase black spot disease prevalence in threatened steelhead trout. A comparison of our results with similar data collected from a more northern latitude suggests that salmonids in California may be warm-adapted in terms of their parasite susceptibility.
2004
Suttle, Kenwyn B.; Power, Mary E.; Levine, Jonathan M.; McNeely, Camille
How Fine Sediment in Riverbeds Impairs Growth and Survival of Juvenile Salmonids Journal Article
In: Ecological Applications, vol. 14, no. 4, pp. 969-974, 2004.
Abstract | Links | BibTeX | Tags: fine sediment, Oncorhynchus mykiss, Pacific salmonids, parr, river food web, sedimentation, steelhead trout
@article{Suttle2004,
title = {How Fine Sediment in Riverbeds Impairs Growth and Survival of Juvenile Salmonids},
author = {Kenwyn B. Suttle and Mary E. Power and Jonathan M. Levine and Camille McNeely},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/How-Fine-Sediment-in-Riverbeds-Impairs-Growth-and-Survival-of-Juvenile-Salmonids_Suttle_Power_Levine_McNeely.pdf},
doi = {http://dx.doi.org/10.1890/03-5190},
year = {2004},
date = {2004-08-01},
journal = {Ecological Applications},
volume = {14},
number = {4},
pages = {969-974},
abstract = {Although excessive loading of fine sediments into rivers is well known to degrade salmonid spawning habitat, its effects on rearing juveniles have been unclear. We experimentally manipulated fine bed sediment in a northern California river and examined responses of juvenile salmonids and the food webs supporting them. Increasing concentrations of deposited fine sediment decreased growth and survival of juvenile steelhead trout. These declines were associated with a shift in invertebrates toward burrowing taxa unavailable as prey and with increased steelhead activity and injury at higher levels of fine sediment. The linear relationship between deposited fine sediment and juvenile steelhead growth suggests that there is no threshold below which exacerbation of fine-sediment delivery and storage in gravel bedded rivers will be harmless, but also that any reduction could produce immediate benefits for salmonid restoration.},
keywords = {fine sediment, Oncorhynchus mykiss, Pacific salmonids, parr, river food web, sedimentation, steelhead trout},
pubstate = {published},
tppubtype = {article}
}
Although excessive loading of fine sediments into rivers is well known to degrade salmonid spawning habitat, its effects on rearing juveniles have been unclear. We experimentally manipulated fine bed sediment in a northern California river and examined responses of juvenile salmonids and the food webs supporting them. Increasing concentrations of deposited fine sediment decreased growth and survival of juvenile steelhead trout. These declines were associated with a shift in invertebrates toward burrowing taxa unavailable as prey and with increased steelhead activity and injury at higher levels of fine sediment. The linear relationship between deposited fine sediment and juvenile steelhead growth suggests that there is no threshold below which exacerbation of fine-sediment delivery and storage in gravel bedded rivers will be harmless, but also that any reduction could produce immediate benefits for salmonid restoration.
2002
Finlay, Jacques C.; Khandwala, Sapna; Power, Mary E.
Spatial scales of carbon flow in a river food web Journal Article
In: Ecology, vol. 83, no. 7, pp. 1845-1859, 2002.
Abstract | Links | BibTeX | Tags: cannibalism, carbon and nitrogen stable-isotope ratios, carbon flow, Oncorhynchus mykiss, river food webs, scraper and collector-gatherer (SCG) taxa, spatial scale, steelhead trout, terrestrial detritus, trophic structure
@article{Finlay2002,
title = {Spatial scales of carbon flow in a river food web},
author = {Jacques C. Finlay and Sapna Khandwala and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Spatial-scales-of-energy-flow-in-food-webs-of-the-South-Fork-Eel-River_Finlay_2002.pdf},
doi = {10.2307/3071769},
year = {2002},
date = {2002-00-00},
journal = {Ecology},
volume = {83},
number = {7},
pages = {1845-1859},
abstract = {Spatial extents of food webs that support stream and river consumers are largely unknown, but such information is essential for basic understanding and management of lotic ecosystems. We used predictable variation in algal δ13C with water velocity, and measurements of consumer δ13C and δ15N to examine carbon flow and trophic structure in food webs of the South Fork Eel River in Northern California. Analyses of δ13C showed that the most abundant macroinvertebrate groups (collector-gatherers and scrapers) relied on algae from local sources within their riffle or shallow pool habitats. In contrast, filter-feeding invertebrates in riffles relied in part on algal production derived from upstream shallow pools. Riffle invertebrate predators also relied in part on consumers of pool-derived algal carbon. One abundant taxon drifting from shallow pools and riffles (baetid mayflies) relied on algal production derived from the habitats from which they dispersed. The trophic linkage from pool algae to riffle invertebrate predators was thus mediated through either predation on pool herbivores dispersing into riffles, or on filter feeders. Algal production in shallow pool habitats dominated the resource base of vertebrate predators in all habitats at the end of the summer. We could not distinguish between the trophic roles of riffle algae and terrestrial detritus, but both carbon sources appeared to play minor roles for vertebrate consumers. In shallow pools, small vertebrates, including three-spined stickleback (Gasterosteus aculeatus), roach (Hesperoleucas symmetricus), and rough-skinned newts (Taricha granulosa), relied on invertebrate prey derived from local pool habitats. During the most productive summer period, growth of all size classes of steelhead and resident rainbow trout (Oncorhynchus mykiss) in all habitats (shallow pools, riffles, and deep unproductive pools) was largely derived from algal production in shallow pools. Preliminary data suggest that the strong role of shallow pool algae in riffle steelhead growth during summer periods was due to drift of pool invertebrates to riffles, rather than movement of riffle trout. Data for δ15N showed that resident rainbow trout (25-33 cm standard length) in deep pools preyed upon small size classes of juvenile steelhead that were most often found in riffles or shallow pools. While many invertebrate consumers relied primarily on algal production derived from local habitats, our study shows that growth of top predators in the river is strongly linked to food webs in adjacent habitats. These results suggest a key role for emigration of aquatic prey in determining carbon flow to top predators.},
keywords = {cannibalism, carbon and nitrogen stable-isotope ratios, carbon flow, Oncorhynchus mykiss, river food webs, scraper and collector-gatherer (SCG) taxa, spatial scale, steelhead trout, terrestrial detritus, trophic structure},
pubstate = {published},
tppubtype = {article}
}
Spatial extents of food webs that support stream and river consumers are largely unknown, but such information is essential for basic understanding and management of lotic ecosystems. We used predictable variation in algal δ13C with water velocity, and measurements of consumer δ13C and δ15N to examine carbon flow and trophic structure in food webs of the South Fork Eel River in Northern California. Analyses of δ13C showed that the most abundant macroinvertebrate groups (collector-gatherers and scrapers) relied on algae from local sources within their riffle or shallow pool habitats. In contrast, filter-feeding invertebrates in riffles relied in part on algal production derived from upstream shallow pools. Riffle invertebrate predators also relied in part on consumers of pool-derived algal carbon. One abundant taxon drifting from shallow pools and riffles (baetid mayflies) relied on algal production derived from the habitats from which they dispersed. The trophic linkage from pool algae to riffle invertebrate predators was thus mediated through either predation on pool herbivores dispersing into riffles, or on filter feeders. Algal production in shallow pool habitats dominated the resource base of vertebrate predators in all habitats at the end of the summer. We could not distinguish between the trophic roles of riffle algae and terrestrial detritus, but both carbon sources appeared to play minor roles for vertebrate consumers. In shallow pools, small vertebrates, including three-spined stickleback (Gasterosteus aculeatus), roach (Hesperoleucas symmetricus), and rough-skinned newts (Taricha granulosa), relied on invertebrate prey derived from local pool habitats. During the most productive summer period, growth of all size classes of steelhead and resident rainbow trout (Oncorhynchus mykiss) in all habitats (shallow pools, riffles, and deep unproductive pools) was largely derived from algal production in shallow pools. Preliminary data suggest that the strong role of shallow pool algae in riffle steelhead growth during summer periods was due to drift of pool invertebrates to riffles, rather than movement of riffle trout. Data for δ15N showed that resident rainbow trout (25-33 cm standard length) in deep pools preyed upon small size classes of juvenile steelhead that were most often found in riffles or shallow pools. While many invertebrate consumers relied primarily on algal production derived from local habitats, our study shows that growth of top predators in the river is strongly linked to food webs in adjacent habitats. These results suggest a key role for emigration of aquatic prey in determining carbon flow to top predators.
2001
Finlay, Jacques C.; Power, Mary E.
In: Technical Completion Report, vol. UCAL-WRC-W-906, 2001.
Abstract | Links | BibTeX | Tags: cannibalism, Carbon and nitrogen stable isotope ratios, energy flow, Oncorhynchus mykiss, river food webs, river-watershed exchange, spatial scale, steelhead trout, terrestrial detritus, trophic structure
@article{Power2001,
title = {Carbon isotope signatures and spatial scales of energy flow in food webs supporting salmonids in food webs supporting salmonids in Northern California rivers},
author = {Jacques C. Finlay and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/eScholarship-UC-item-79t2s4f8.pdf},
year = {2001},
date = {2001-05-01},
journal = {Technical Completion Report},
volume = {UCAL-WRC-W-906},
abstract = {Spatial scales of the food webs that support the growth of juvenile salmonids in California rivers are largely unknown, but such information is essential for management of flows, species, and other ecosystem factors influencing salmonid production. Our project objectives were:
1. to determine whether predictable variation in algal d13C with water velocity, and measurements of consumer d13C and d15N could be used to examine energy flow and trophic structure in food webs of the South Fork Eel River, and other salmon-bearing streams in Northern California, and
2. to provide this information as a basis for examining how changes in access to energy sources following river regulation or invasions of exotic species might influence the access of various web members, including salmonids, to these sources.},
keywords = {cannibalism, Carbon and nitrogen stable isotope ratios, energy flow, Oncorhynchus mykiss, river food webs, river-watershed exchange, spatial scale, steelhead trout, terrestrial detritus, trophic structure},
pubstate = {published},
tppubtype = {article}
}
Spatial scales of the food webs that support the growth of juvenile salmonids in California rivers are largely unknown, but such information is essential for management of flows, species, and other ecosystem factors influencing salmonid production. Our project objectives were:
1. to determine whether predictable variation in algal d13C with water velocity, and measurements of consumer d13C and d15N could be used to examine energy flow and trophic structure in food webs of the South Fork Eel River, and other salmon-bearing streams in Northern California, and
2. to provide this information as a basis for examining how changes in access to energy sources following river regulation or invasions of exotic species might influence the access of various web members, including salmonids, to these sources.
1. to determine whether predictable variation in algal d13C with water velocity, and measurements of consumer d13C and d15N could be used to examine energy flow and trophic structure in food webs of the South Fork Eel River, and other salmon-bearing streams in Northern California, and
2. to provide this information as a basis for examining how changes in access to energy sources following river regulation or invasions of exotic species might influence the access of various web members, including salmonids, to these sources.